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Metalworking (rec.crafts.metalworking) Discuss various aspects of working with metal, such as machining, welding, metal joining, screwing, casting, hardening/tempering, blacksmithing/forging, spinning and hammer work, sheet metal work. |
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#1
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Electric chainsaw motor
I have a new 3.5hp (I think) "Works" largest 14" chainsaw that I want to
use the motor for a project. I need to know the RPM. I've had no luck researching this and I no longer have an RPM meter. I imagine all chainsaws have similar rpm. I need to get the ratios on timing belt sprockets close to optimal. If this works, you will all be dazzled by my brilliance! |
#2
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Electric chainsaw motor
On Thu, 2 Nov 2017 13:24:25 -0400
Tom Gardner wrote: I have a new 3.5hp (I think) "Works" largest 14" chainsaw that I want to use the motor for a project. I need to know the RPM. I've had no luck researching this and I no longer have an RPM meter. I imagine all chainsaws have similar rpm. I need to get the ratios on timing belt sprockets close to optimal. If this works, you will all be dazzled by my brilliance! Affix something to the chain that sticks out a little. Now make another attachment or hold something close by that will hit it. Like the old clothespin, playing card and bicycle spokes. Turn it on and record the sound. Use something like Audacity to measure the frequency. Viola! -- Leon Fisk Grand Rapids MI/Zone 5b Remove no.spam for email |
#3
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Electric chainsaw motor
"Tom Gardner" wrote in message news
I have a new 3.5hp (I think) "Works" largest 14" chainsaw that I want to use the motor for a project. I need to know the RPM. I've had no luck researching this and I no longer have an RPM meter. I imagine all chainsaws have similar rpm. I need to get the ratios on timing belt sprockets close to optimal. " If this works, you will all be dazzled by my brilliance! " Or baffled by your bull****. Either way I am looking forward to being entertained. |
#4
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Electric chainsaw motor
On Thu, 2 Nov 2017 13:38:23 -0400, Leon Fisk
wrote: On Thu, 2 Nov 2017 13:24:25 -0400 Tom Gardner wrote: I have a new 3.5hp (I think) "Works" largest 14" chainsaw that I want to use the motor for a project. I need to know the RPM. I've had no luck researching this and I no longer have an RPM meter. I imagine all chainsaws have similar rpm. I need to get the ratios on timing belt sprockets close to optimal. If this works, you will all be dazzled by my brilliance! Affix something to the chain that sticks out a little. Now make another attachment or hold something close by that will hit it. Like the old clothespin, playing card and bicycle spokes. Turn it on and record the sound. Use something like Audacity to measure the frequency. Viola! A big, 16" bar, 15A corded electric Makita chainsaw has a no-load chain speed of 2900 ft/min -- 48 fps. I'd use my digital camera in timed multi-shot mode (10 frames/sec., I think) and take a series of photos, and then measure the distance between a marker in two sequential shots. You'd have to do it multiple times to be sure you get two visible, sequential photos with the marker. Then work backward from the sprocket and chain pitches to get the motor rpm. (Yes, there must be a simpler way.) For reference, I saw specs on a Greenworks corded 14.5A saw that said 6000 rpm. Another saw said 5500 rpm. A Remington Versa 12A 16" says 3200 rpm. If this is a cordless saw, all bets are off. As for 3.5 hp...that sounds like Sears or Ridgid horsepower to me -- like 22A, if they're talking gross horsepower. -- Ed Huntress |
#5
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Electric chainsaw motor
On Thu, 02 Nov 2017 14:29:51 -0400, Ed Huntress
wrote: On Thu, 2 Nov 2017 13:38:23 -0400, Leon Fisk wrote: On Thu, 2 Nov 2017 13:24:25 -0400 Tom Gardner wrote: I have a new 3.5hp (I think) "Works" largest 14" chainsaw that I want to use the motor for a project. I need to know the RPM. I've had no luck researching this and I no longer have an RPM meter. I imagine all chainsaws have similar rpm. I need to get the ratios on timing belt sprockets close to optimal. If this works, you will all be dazzled by my brilliance! Affix something to the chain that sticks out a little. Now make another attachment or hold something close by that will hit it. Like the old clothespin, playing card and bicycle spokes. Turn it on and record the sound. Use something like Audacity to measure the frequency. Viola! A big, 16" bar, 15A corded electric Makita chainsaw has a no-load chain speed of 2900 ft/min -- 48 fps. I'd use my digital camera in timed multi-shot mode (10 frames/sec., I think) and take a series of photos, and then measure the distance between a marker in two sequential shots. You'd have to do it multiple times to be sure you get two visible, sequential photos with the marker. Then work backward from the sprocket and chain pitches to get the motor rpm. (Yes, there must be a simpler way.) For reference, I saw specs on a Greenworks corded 14.5A saw that said 6000 rpm. Another saw said 5500 rpm. A Remington Versa 12A 16" says 3200 rpm. If this is a cordless saw, all bets are off. As for 3.5 hp...that sounds like Sears or Ridgid horsepower to me -- like 22A, if they're talking gross horsepower. Remove the chain and take the thing to an RC hobby shop. They will for sure have optical tachs for sale. They will probably check the RPM for free if you ask nicely. Make a constrasting mark on the sprocket before you bring it in. Maybe color half the sproket with a black Sharpie. Eric |
#6
Posted to rec.crafts.metalworking
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Electric chainsaw motor
On 11/2/2017 10:24 AM, Tom Gardner wrote:
I have a new 3.5hp (I think) "Works" largest 14" chainsaw that I want to use the motor for a project. I need to know the RPM. I've had no luck researching this and I no longer have an RPM meter. I imagine all chainsaws have similar rpm. I need to get the ratios on timing belt sprockets close to optimal. If this works, you will all be dazzled by my brilliance! Hard to know from your (lack of) description, but I'll offer warning... My limited experience with Works tools is that they're near the bottom for ruggedness. In general, a cheap hand tool rated at 3.5 HP may deliver that for short bursts, maybe. It's not designed for ANY continuous duty, at any power level. Again, my limited experience with electric chainsaws and related devices is that the universal motors with brushes fail because the brush overheats and melts the plastic, yes, the brush holders are typically plastic. It seems to be working fine, but the next time you turn it on, the plastic has hardened around the brush and it's stuck. You can often take it apart and free it up. It will work for a while until it freezes up again. I'd not put a lot of time or $$ into a project based on a Worx motor. |
#7
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Electric chainsaw motor
"Tom Gardner" wrote in message
news I have a new 3.5hp (I think) "Works" largest 14" chainsaw that I want to use the motor for a project. I need to know the RPM. I've had no luck researching this and I no longer have an RPM meter. I imagine all chainsaws have similar rpm. I need to get the ratios on timing belt sprockets close to optimal. If this works, you will all be dazzled by my brilliance! and if it doesn't work...? My Husqvarna 350 tops out around 12,000 RPM. |
#8
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Electric chainsaw motor
"Ed Huntress" wrote in message
... On Thu, 2 Nov 2017 13:38:23 -0400, Leon Fisk wrote: On Thu, 2 Nov 2017 13:24:25 -0400 Tom Gardner wrote: I have a new 3.5hp (I think) "Works" largest 14" chainsaw that I want to use the motor for a project. I need to know the RPM. I've had no luck researching this and I no longer have an RPM meter. I imagine all chainsaws have similar rpm. I need to get the ratios on timing belt sprockets close to optimal. If this works, you will all be dazzled by my brilliance! Affix something to the chain that sticks out a little. Now make another attachment or hold something close by that will hit it. Like the old clothespin, playing card and bicycle spokes. Turn it on and record the sound. Use something like Audacity to measure the frequency. Viola! A big, 16" bar, 15A corded electric Makita chainsaw has a no-load chain speed of 2900 ft/min -- 48 fps. I'd use my digital camera in timed multi-shot mode (10 frames/sec., I think) and take a series of photos, and then measure the distance between a marker in two sequential shots. You'd have to do it multiple times to be sure you get two visible, sequential photos with the marker. Then work backward from the sprocket and chain pitches to get the motor rpm. (Yes, there must be a simpler way.) For reference, I saw specs on a Greenworks corded 14.5A saw that said 6000 rpm. Another saw said 5500 rpm. A Remington Versa 12A 16" says 3200 rpm. If this is a cordless saw, all bets are off. As for 3.5 hp...that sounds like Sears or Ridgid horsepower to me -- like 22A, if they're talking gross horsepower. -- Ed Huntress I've seen a rating in "electrical horsepower" calculated from how much juice it pulls, probably without considering efficiency or power factor. |
#9
Posted to rec.crafts.metalworking
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Electric chainsaw motor
"Tom Gardner" wrote in message
news I have a new 3.5hp (I think) "Works" largest 14" chainsaw that I want to use the motor for a project. I need to know the RPM. I've had no luck researching this and I no longer have an RPM meter. I imagine all chainsaws have similar rpm. I need to get the ratios on timing belt sprockets close to optimal. If this works, you will all be dazzled by my brilliance! The question is what is its RPM when producing the power the load needs. Could you fake the drive with hardware store vee belts and pulleys to find out? My collection of pulleys that weren't the right size has helped a lot on subsequent projects. |
#10
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Electric chainsaw motor
On Thu, 2 Nov 2017 16:18:31 -0400, "Jim Wilkins"
wrote: "Ed Huntress" wrote in message .. . On Thu, 2 Nov 2017 13:38:23 -0400, Leon Fisk wrote: On Thu, 2 Nov 2017 13:24:25 -0400 Tom Gardner wrote: I have a new 3.5hp (I think) "Works" largest 14" chainsaw that I want to use the motor for a project. I need to know the RPM. I've had no luck researching this and I no longer have an RPM meter. I imagine all chainsaws have similar rpm. I need to get the ratios on timing belt sprockets close to optimal. If this works, you will all be dazzled by my brilliance! Affix something to the chain that sticks out a little. Now make another attachment or hold something close by that will hit it. Like the old clothespin, playing card and bicycle spokes. Turn it on and record the sound. Use something like Audacity to measure the frequency. Viola! A big, 16" bar, 15A corded electric Makita chainsaw has a no-load chain speed of 2900 ft/min -- 48 fps. I'd use my digital camera in timed multi-shot mode (10 frames/sec., I think) and take a series of photos, and then measure the distance between a marker in two sequential shots. You'd have to do it multiple times to be sure you get two visible, sequential photos with the marker. Then work backward from the sprocket and chain pitches to get the motor rpm. (Yes, there must be a simpler way.) For reference, I saw specs on a Greenworks corded 14.5A saw that said 6000 rpm. Another saw said 5500 rpm. A Remington Versa 12A 16" says 3200 rpm. If this is a cordless saw, all bets are off. As for 3.5 hp...that sounds like Sears or Ridgid horsepower to me -- like 22A, if they're talking gross horsepower. -- Ed Huntress I've seen a rating in "electrical horsepower" calculated from how much juice it pulls, probably without considering efficiency or power factor. I think that some of them, including Ridgid, don't even go that far. They stall it and measure the current; multiply by the voltage; divide by 750; and claim that as "horsepower." My Ridgid shop vac draws, I think, 10A when it's running. But they claim it has "4.25 [peak] horsepower." HA-Ha-ha-ho! -- Ed Huntress |
#11
Posted to rec.crafts.metalworking
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Electric chainsaw motor
Tom Gardner wrote:
I have a new 3.5hp (I think) "Works" largest 14" chainsaw that I want to use the motor for a project. I need to know the RPM. I've had no luck researching this and I no longer have an RPM meter. I imagine all chainsaws have similar rpm. I need to get the ratios on timing belt sprockets close to optimal. If this works, you will all be dazzled by my brilliance! The RPM at what point? Under load? Tht's going to be tough unless you can rig up a brake or drive a pump with a restricting valve. Just driving the chain? A couple of people have proposed some methods. Under no load? Be careful. If it's a shunt wound or permanent magnet motor, it will be OK. If it's a series wound motor, there is no theoretical maximum RPM and it could be damaged by overspeed. -- Paul Hovnanian ------------------------------------------------------------------ Plaese porrf raed befre postng. |
#12
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Electric chainsaw motor
"Ed Huntress" wrote in message ... On Thu, 2 Nov 2017 16:18:31 -0400, "Jim Wilkins" wrote: "Ed Huntress" wrote in message . .. On Thu, 2 Nov 2017 13:38:23 -0400, Leon Fisk wrote: On Thu, 2 Nov 2017 13:24:25 -0400 Tom Gardner wrote: I have a new 3.5hp (I think) "Works" largest 14" chainsaw that I want to use the motor for a project. I need to know the RPM. I've had no luck researching this and I no longer have an RPM meter. I imagine all chainsaws have similar rpm. I need to get the ratios on timing belt sprockets close to optimal. If this works, you will all be dazzled by my brilliance! Affix something to the chain that sticks out a little. Now make another attachment or hold something close by that will hit it. Like the old clothespin, playing card and bicycle spokes. Turn it on and record the sound. Use something like Audacity to measure the frequency. Viola! A big, 16" bar, 15A corded electric Makita chainsaw has a no-load chain speed of 2900 ft/min -- 48 fps. I'd use my digital camera in timed multi-shot mode (10 frames/sec., I think) and take a series of photos, and then measure the distance between a marker in two sequential shots. You'd have to do it multiple times to be sure you get two visible, sequential photos with the marker. Then work backward from the sprocket and chain pitches to get the motor rpm. (Yes, there must be a simpler way.) For reference, I saw specs on a Greenworks corded 14.5A saw that said 6000 rpm. Another saw said 5500 rpm. A Remington Versa 12A 16" says 3200 rpm. If this is a cordless saw, all bets are off. As for 3.5 hp...that sounds like Sears or Ridgid horsepower to me -- like 22A, if they're talking gross horsepower. -- Ed Huntress I've seen a rating in "electrical horsepower" calculated from how much juice it pulls, probably without considering efficiency or power factor. I think that some of them, including Ridgid, don't even go that far. They stall it and measure the current; multiply by the voltage; divide by 750; and claim that as "horsepower." My Ridgid shop vac draws, I think, 10A when it's running. But they claim it has "4.25 [peak] horsepower." HA-Ha-ha-ho! -- Ed Huntress We should call that "puke" horsepower since the motor is about to toss its magic smoke.. |
#13
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Electric chainsaw motor
On Thu, 2 Nov 2017 18:30:47 -0400, "Jim Wilkins"
wrote: "Ed Huntress" wrote in message .. . On Thu, 2 Nov 2017 16:18:31 -0400, "Jim Wilkins" wrote: "Ed Huntress" wrote in message ... On Thu, 2 Nov 2017 13:38:23 -0400, Leon Fisk wrote: On Thu, 2 Nov 2017 13:24:25 -0400 Tom Gardner wrote: I have a new 3.5hp (I think) "Works" largest 14" chainsaw that I want to use the motor for a project. I need to know the RPM. I've had no luck researching this and I no longer have an RPM meter. I imagine all chainsaws have similar rpm. I need to get the ratios on timing belt sprockets close to optimal. If this works, you will all be dazzled by my brilliance! Affix something to the chain that sticks out a little. Now make another attachment or hold something close by that will hit it. Like the old clothespin, playing card and bicycle spokes. Turn it on and record the sound. Use something like Audacity to measure the frequency. Viola! A big, 16" bar, 15A corded electric Makita chainsaw has a no-load chain speed of 2900 ft/min -- 48 fps. I'd use my digital camera in timed multi-shot mode (10 frames/sec., I think) and take a series of photos, and then measure the distance between a marker in two sequential shots. You'd have to do it multiple times to be sure you get two visible, sequential photos with the marker. Then work backward from the sprocket and chain pitches to get the motor rpm. (Yes, there must be a simpler way.) For reference, I saw specs on a Greenworks corded 14.5A saw that said 6000 rpm. Another saw said 5500 rpm. A Remington Versa 12A 16" says 3200 rpm. If this is a cordless saw, all bets are off. As for 3.5 hp...that sounds like Sears or Ridgid horsepower to me -- like 22A, if they're talking gross horsepower. -- Ed Huntress I've seen a rating in "electrical horsepower" calculated from how much juice it pulls, probably without considering efficiency or power factor. I think that some of them, including Ridgid, don't even go that far. They stall it and measure the current; multiply by the voltage; divide by 750; and claim that as "horsepower." My Ridgid shop vac draws, I think, 10A when it's running. But they claim it has "4.25 [peak] horsepower." HA-Ha-ha-ho! -- Ed Huntress We should call that "puke" horsepower since the motor is about to toss its magic smoke.. Yeah, that would be a better term for it. This is what Popular Mechanics said about it in a shop-vac comparison. To me, this is unbelievable: "In addition to being designated by capacity, most wet/dry vacs carry a horsepower rating—our test units range up to 6.5 hp. But if you think that means a vac motor is as powerful as a garden-tiller engine, think again. Like many other consumer-grade tools, the horsepower rating is modified by the word "peak." This indicates the electrical draw at the point where the motor is overloaded and stalls. The upshot? Horsepower ratings aren't the most accurate way to compare wet/dry vacs. Looking at amperage makes more sense." -- Ed Huntress |
#14
Posted to rec.crafts.metalworking
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Electric chainsaw motor
"Ed Huntress" wrote in message
... On Thu, 2 Nov 2017 18:30:47 -0400, "Jim Wilkins" wrote: "Ed Huntress" wrote in message . .. On Thu, 2 Nov 2017 16:18:31 -0400, "Jim Wilkins" wrote: "Ed Huntress" wrote in message m... On Thu, 2 Nov 2017 13:38:23 -0400, Leon Fisk wrote: On Thu, 2 Nov 2017 13:24:25 -0400 Tom Gardner wrote: I have a new 3.5hp (I think) "Works" largest 14" chainsaw that I want to use the motor for a project. I need to know the RPM. I've had no luck researching this and I no longer have an RPM meter. I imagine all chainsaws have similar rpm. I need to get the ratios on timing belt sprockets close to optimal. If this works, you will all be dazzled by my brilliance! Affix something to the chain that sticks out a little. Now make another attachment or hold something close by that will hit it. Like the old clothespin, playing card and bicycle spokes. Turn it on and record the sound. Use something like Audacity to measure the frequency. Viola! A big, 16" bar, 15A corded electric Makita chainsaw has a no-load chain speed of 2900 ft/min -- 48 fps. I'd use my digital camera in timed multi-shot mode (10 frames/sec., I think) and take a series of photos, and then measure the distance between a marker in two sequential shots. You'd have to do it multiple times to be sure you get two visible, sequential photos with the marker. Then work backward from the sprocket and chain pitches to get the motor rpm. (Yes, there must be a simpler way.) For reference, I saw specs on a Greenworks corded 14.5A saw that said 6000 rpm. Another saw said 5500 rpm. A Remington Versa 12A 16" says 3200 rpm. If this is a cordless saw, all bets are off. As for 3.5 hp...that sounds like Sears or Ridgid horsepower to me -- like 22A, if they're talking gross horsepower. -- Ed Huntress I've seen a rating in "electrical horsepower" calculated from how much juice it pulls, probably without considering efficiency or power factor. I think that some of them, including Ridgid, don't even go that far. They stall it and measure the current; multiply by the voltage; divide by 750; and claim that as "horsepower." My Ridgid shop vac draws, I think, 10A when it's running. But they claim it has "4.25 [peak] horsepower." HA-Ha-ha-ho! -- Ed Huntress We should call that "puke" horsepower since the motor is about to toss its magic smoke.. Yeah, that would be a better term for it. This is what Popular Mechanics said about it in a shop-vac comparison. To me, this is unbelievable: "In addition to being designated by capacity, most wet/dry vacs carry a horsepower rating-our test units range up to 6.5 hp. But if you think that means a vac motor is as powerful as a garden-tiller engine, think again. Like many other consumer-grade tools, the horsepower rating is modified by the word "peak." This indicates the electrical draw at the point where the motor is overloaded and stalls. The upshot? Horsepower ratings aren't the most accurate way to compare wet/dry vacs. Looking at amperage makes more sense." -- Ed Huntress Well, the motor is physically able to do it, just not for long. Kettering made the automotive electric starter practical by designing for brief peak power, 5 HP from a motor smaller than a 1/2 HP continuous-duty motor. -jsw |
#15
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Electric chainsaw motor
On Thu, 2 Nov 2017 20:26:14 -0400, "Jim Wilkins"
wrote: "Ed Huntress" wrote in message .. . On Thu, 2 Nov 2017 18:30:47 -0400, "Jim Wilkins" wrote: "Ed Huntress" wrote in message ... On Thu, 2 Nov 2017 16:18:31 -0400, "Jim Wilkins" wrote: "Ed Huntress" wrote in message om... On Thu, 2 Nov 2017 13:38:23 -0400, Leon Fisk wrote: On Thu, 2 Nov 2017 13:24:25 -0400 Tom Gardner wrote: I have a new 3.5hp (I think) "Works" largest 14" chainsaw that I want to use the motor for a project. I need to know the RPM. I've had no luck researching this and I no longer have an RPM meter. I imagine all chainsaws have similar rpm. I need to get the ratios on timing belt sprockets close to optimal. If this works, you will all be dazzled by my brilliance! Affix something to the chain that sticks out a little. Now make another attachment or hold something close by that will hit it. Like the old clothespin, playing card and bicycle spokes. Turn it on and record the sound. Use something like Audacity to measure the frequency. Viola! A big, 16" bar, 15A corded electric Makita chainsaw has a no-load chain speed of 2900 ft/min -- 48 fps. I'd use my digital camera in timed multi-shot mode (10 frames/sec., I think) and take a series of photos, and then measure the distance between a marker in two sequential shots. You'd have to do it multiple times to be sure you get two visible, sequential photos with the marker. Then work backward from the sprocket and chain pitches to get the motor rpm. (Yes, there must be a simpler way.) For reference, I saw specs on a Greenworks corded 14.5A saw that said 6000 rpm. Another saw said 5500 rpm. A Remington Versa 12A 16" says 3200 rpm. If this is a cordless saw, all bets are off. As for 3.5 hp...that sounds like Sears or Ridgid horsepower to me -- like 22A, if they're talking gross horsepower. -- Ed Huntress I've seen a rating in "electrical horsepower" calculated from how much juice it pulls, probably without considering efficiency or power factor. I think that some of them, including Ridgid, don't even go that far. They stall it and measure the current; multiply by the voltage; divide by 750; and claim that as "horsepower." My Ridgid shop vac draws, I think, 10A when it's running. But they claim it has "4.25 [peak] horsepower." HA-Ha-ha-ho! -- Ed Huntress We should call that "puke" horsepower since the motor is about to toss its magic smoke.. Yeah, that would be a better term for it. This is what Popular Mechanics said about it in a shop-vac comparison. To me, this is unbelievable: "In addition to being designated by capacity, most wet/dry vacs carry a horsepower rating-our test units range up to 6.5 hp. But if you think that means a vac motor is as powerful as a garden-tiller engine, think again. Like many other consumer-grade tools, the horsepower rating is modified by the word "peak." This indicates the electrical draw at the point where the motor is overloaded and stalls. The upshot? Horsepower ratings aren't the most accurate way to compare wet/dry vacs. Looking at amperage makes more sense." -- Ed Huntress Well, the motor is physically able to do it, just not for long. Kettering made the automotive electric starter practical by designing for brief peak power, 5 HP from a motor smaller than a 1/2 HP continuous-duty motor. -jsw OK, but this isn't real horsepower they're talking about -- even for a minute. They're defining "horsepower" as current times voltage (/747). But if that's "horsepower, then you could have a really big power resistor that developed 10 horsepower. g That electrical value is "power," but it's just *potential* horsepower. If you measured actual, kinetic horsepower, in terms of torque times rpm, it would be a minute fraction of that. If the motor is stalled, there's no real horsepower at all. I wonder if Sears started that practice? That was the first place I remember seeing it. -- Ed Huntress |
#16
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Electric chainsaw motor
On Thu, 02 Nov 2017 15:13:59 -0700, "Paul Hovnanian P.E."
wrote: Tom Gardner wrote: I have a new 3.5hp (I think) "Works" largest 14" chainsaw that I want to use the motor for a project. I need to know the RPM. I've had no luck researching this and I no longer have an RPM meter. I imagine all chainsaws have similar rpm. I need to get the ratios on timing belt sprockets close to optimal. If this works, you will all be dazzled by my brilliance! The RPM at what point? Under load? Tht's going to be tough unless you can rig up a brake or drive a pump with a restricting valve. Just driving the chain? A couple of people have proposed some methods. Under no load? Be careful. If it's a shunt wound or permanent magnet motor, it will be OK. If it's a series wound motor, there is no theoretical maximum RPM and it could be damaged by overspeed. Only one thing I can say for certain - it will NOT be a series motor. |
#17
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Electric chainsaw motor
On Thu, 02 Nov 2017 19:09:44 -0400, Ed Huntress
wrote: On Thu, 2 Nov 2017 18:30:47 -0400, "Jim Wilkins" wrote: "Ed Huntress" wrote in message . .. On Thu, 2 Nov 2017 16:18:31 -0400, "Jim Wilkins" wrote: "Ed Huntress" wrote in message m... On Thu, 2 Nov 2017 13:38:23 -0400, Leon Fisk wrote: On Thu, 2 Nov 2017 13:24:25 -0400 Tom Gardner wrote: I have a new 3.5hp (I think) "Works" largest 14" chainsaw that I want to use the motor for a project. I need to know the RPM. I've had no luck researching this and I no longer have an RPM meter. I imagine all chainsaws have similar rpm. I need to get the ratios on timing belt sprockets close to optimal. If this works, you will all be dazzled by my brilliance! Affix something to the chain that sticks out a little. Now make another attachment or hold something close by that will hit it. Like the old clothespin, playing card and bicycle spokes. Turn it on and record the sound. Use something like Audacity to measure the frequency. Viola! A big, 16" bar, 15A corded electric Makita chainsaw has a no-load chain speed of 2900 ft/min -- 48 fps. I'd use my digital camera in timed multi-shot mode (10 frames/sec., I think) and take a series of photos, and then measure the distance between a marker in two sequential shots. You'd have to do it multiple times to be sure you get two visible, sequential photos with the marker. Then work backward from the sprocket and chain pitches to get the motor rpm. (Yes, there must be a simpler way.) For reference, I saw specs on a Greenworks corded 14.5A saw that said 6000 rpm. Another saw said 5500 rpm. A Remington Versa 12A 16" says 3200 rpm. If this is a cordless saw, all bets are off. As for 3.5 hp...that sounds like Sears or Ridgid horsepower to me -- like 22A, if they're talking gross horsepower. -- Ed Huntress I've seen a rating in "electrical horsepower" calculated from how much juice it pulls, probably without considering efficiency or power factor. I think that some of them, including Ridgid, don't even go that far. They stall it and measure the current; multiply by the voltage; divide by 750; and claim that as "horsepower." My Ridgid shop vac draws, I think, 10A when it's running. But they claim it has "4.25 [peak] horsepower." HA-Ha-ha-ho! -- Ed Huntress We should call that "puke" horsepower since the motor is about to toss its magic smoke.. Yeah, that would be a better term for it. This is what Popular Mechanics said about it in a shop-vac comparison. To me, this is unbelievable: "In addition to being designated by capacity, most wet/dry vacs carry a horsepower rating—our test units range up to 6.5 hp. But if you think that means a vac motor is as powerful as a garden-tiller engine, think again. Like many other consumer-grade tools, the horsepower rating is modified by the word "peak." This indicates the electrical draw at the point where the motor is overloaded and stalls. The upshot? Horsepower ratings aren't the most accurate way to compare wet/dry vacs. Looking at amperage makes more sense." It's called "smoke horsepower" |
#18
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Electric chainsaw motor
"Ed Huntress" wrote in message
news On Thu, 2 Nov 2017 20:26:14 -0400, "Jim Wilkins" wrote: "Ed Huntress" wrote in message . .. On Thu, 2 Nov 2017 18:30:47 -0400, "Jim Wilkins" wrote: "Ed Huntress" wrote in message m... On Thu, 2 Nov 2017 16:18:31 -0400, "Jim Wilkins" wrote: "Ed Huntress" wrote in message news:1unmvc95lkhs0ufmfla2ta6nanaamsk20r@4ax. com... On Thu, 2 Nov 2017 13:38:23 -0400, Leon Fisk wrote: On Thu, 2 Nov 2017 13:24:25 -0400 Tom Gardner wrote: I have a new 3.5hp (I think) "Works" largest 14" chainsaw that I want to use the motor for a project. I need to know the RPM. I've had no luck researching this and I no longer have an RPM meter. I imagine all chainsaws have similar rpm. I need to get the ratios on timing belt sprockets close to optimal. If this works, you will all be dazzled by my brilliance! Affix something to the chain that sticks out a little. Now make another attachment or hold something close by that will hit it. Like the old clothespin, playing card and bicycle spokes. Turn it on and record the sound. Use something like Audacity to measure the frequency. Viola! A big, 16" bar, 15A corded electric Makita chainsaw has a no-load chain speed of 2900 ft/min -- 48 fps. I'd use my digital camera in timed multi-shot mode (10 frames/sec., I think) and take a series of photos, and then measure the distance between a marker in two sequential shots. You'd have to do it multiple times to be sure you get two visible, sequential photos with the marker. Then work backward from the sprocket and chain pitches to get the motor rpm. (Yes, there must be a simpler way.) For reference, I saw specs on a Greenworks corded 14.5A saw that said 6000 rpm. Another saw said 5500 rpm. A Remington Versa 12A 16" says 3200 rpm. If this is a cordless saw, all bets are off. As for 3.5 hp...that sounds like Sears or Ridgid horsepower to me -- like 22A, if they're talking gross horsepower. -- Ed Huntress I've seen a rating in "electrical horsepower" calculated from how much juice it pulls, probably without considering efficiency or power factor. I think that some of them, including Ridgid, don't even go that far. They stall it and measure the current; multiply by the voltage; divide by 750; and claim that as "horsepower." My Ridgid shop vac draws, I think, 10A when it's running. But they claim it has "4.25 [peak] horsepower." HA-Ha-ha-ho! -- Ed Huntress We should call that "puke" horsepower since the motor is about to toss its magic smoke.. Yeah, that would be a better term for it. This is what Popular Mechanics said about it in a shop-vac comparison. To me, this is unbelievable: "In addition to being designated by capacity, most wet/dry vacs carry a horsepower rating-our test units range up to 6.5 hp. But if you think that means a vac motor is as powerful as a garden-tiller engine, think again. Like many other consumer-grade tools, the horsepower rating is modified by the word "peak." This indicates the electrical draw at the point where the motor is overloaded and stalls. The upshot? Horsepower ratings aren't the most accurate way to compare wet/dry vacs. Looking at amperage makes more sense." -- Ed Huntress Well, the motor is physically able to do it, just not for long. Kettering made the automotive electric starter practical by designing for brief peak power, 5 HP from a motor smaller than a 1/2 HP continuous-duty motor. -jsw OK, but this isn't real horsepower they're talking about -- even for a minute. They're defining "horsepower" as current times voltage (/747). But if that's "horsepower, then you could have a really big power resistor that developed 10 horsepower. g That electrical value is "power," but it's just *potential* horsepower. If you measured actual, kinetic horsepower, in terms of torque times rpm, it would be a minute fraction of that. If the motor is stalled, there's no real horsepower at all. I wonder if Sears started that practice? That was the first place I remember seeing it. -- Ed Huntress I thought they measured the peak power at the motor's breakdown torque, just before speed drops. http://industrialelectricalco.com/wp...que-curves.pdf I have a 5.5HP, 3750W generator that struggles to start a 1/2 HP motor on an air compressor, as long as the tank pressure is low. I can't measure the compressor motor's torque vs RPM curve but it clearly is drawing that much electrical power at startup. -jsw |
#19
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Electric chainsaw motor
On Thu, 02 Nov 2017 21:09:44 -0400, Ed Huntress
wrote: On Thu, 2 Nov 2017 20:26:14 -0400, "Jim Wilkins" wrote: "Ed Huntress" wrote in message . .. On Thu, 2 Nov 2017 18:30:47 -0400, "Jim Wilkins" wrote: "Ed Huntress" wrote in message m... On Thu, 2 Nov 2017 16:18:31 -0400, "Jim Wilkins" wrote: "Ed Huntress" wrote in message news:1unmvc95lkhs0ufmfla2ta6nanaamsk20r@4ax. com... On Thu, 2 Nov 2017 13:38:23 -0400, Leon Fisk wrote: On Thu, 2 Nov 2017 13:24:25 -0400 Tom Gardner wrote: I have a new 3.5hp (I think) "Works" largest 14" chainsaw that I want to use the motor for a project. I need to know the RPM. I've had no luck researching this and I no longer have an RPM meter. I imagine all chainsaws have similar rpm. I need to get the ratios on timing belt sprockets close to optimal. If this works, you will all be dazzled by my brilliance! Affix something to the chain that sticks out a little. Now make another attachment or hold something close by that will hit it. Like the old clothespin, playing card and bicycle spokes. Turn it on and record the sound. Use something like Audacity to measure the frequency. Viola! A big, 16" bar, 15A corded electric Makita chainsaw has a no-load chain speed of 2900 ft/min -- 48 fps. I'd use my digital camera in timed multi-shot mode (10 frames/sec., I think) and take a series of photos, and then measure the distance between a marker in two sequential shots. You'd have to do it multiple times to be sure you get two visible, sequential photos with the marker. Then work backward from the sprocket and chain pitches to get the motor rpm. (Yes, there must be a simpler way.) For reference, I saw specs on a Greenworks corded 14.5A saw that said 6000 rpm. Another saw said 5500 rpm. A Remington Versa 12A 16" says 3200 rpm. If this is a cordless saw, all bets are off. As for 3.5 hp...that sounds like Sears or Ridgid horsepower to me -- like 22A, if they're talking gross horsepower. -- Ed Huntress I've seen a rating in "electrical horsepower" calculated from how much juice it pulls, probably without considering efficiency or power factor. I think that some of them, including Ridgid, don't even go that far. They stall it and measure the current; multiply by the voltage; divide by 750; and claim that as "horsepower." My Ridgid shop vac draws, I think, 10A when it's running. But they claim it has "4.25 [peak] horsepower." HA-Ha-ha-ho! -- Ed Huntress We should call that "puke" horsepower since the motor is about to toss its magic smoke.. Yeah, that would be a better term for it. This is what Popular Mechanics said about it in a shop-vac comparison. To me, this is unbelievable: "In addition to being designated by capacity, most wet/dry vacs carry a horsepower rating-our test units range up to 6.5 hp. But if you think that means a vac motor is as powerful as a garden-tiller engine, think again. Like many other consumer-grade tools, the horsepower rating is modified by the word "peak." This indicates the electrical draw at the point where the motor is overloaded and stalls. The upshot? Horsepower ratings aren't the most accurate way to compare wet/dry vacs. Looking at amperage makes more sense." -- Ed Huntress Well, the motor is physically able to do it, just not for long. Kettering made the automotive electric starter practical by designing for brief peak power, 5 HP from a motor smaller than a 1/2 HP continuous-duty motor. -jsw OK, but this isn't real horsepower they're talking about -- even for a minute. They're defining "horsepower" as current times voltage (/747). But if that's "horsepower, then you could have a really big power resistor that developed 10 horsepower. g That electrical value is "power," but it's just *potential* horsepower. If you measured actual, kinetic horsepower, in terms of torque times rpm, it would be a minute fraction of that. If the motor is stalled, there's no real horsepower at all. I wonder if Sears started that practice? That was the first place I remember seeing it. On vacuums and compressors it's actually "air horsepower" - and there is a defined specification Air horsepower = flow rate ( cubic feet / minute) × pressure (inches water column) / 6,356 |
#20
Posted to rec.crafts.metalworking
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Electric chainsaw motor
On Thu, 02 Nov 2017 19:09:44 -0400, Ed Huntress
wrote: On Thu, 2 Nov 2017 18:30:47 -0400, "Jim Wilkins" wrote: "Ed Huntress" wrote in message . .. On Thu, 2 Nov 2017 16:18:31 -0400, "Jim Wilkins" wrote: "Ed Huntress" wrote in message m... On Thu, 2 Nov 2017 13:38:23 -0400, Leon Fisk wrote: On Thu, 2 Nov 2017 13:24:25 -0400 Tom Gardner wrote: I have a new 3.5hp (I think) "Works" largest 14" chainsaw that I want to use the motor for a project. I need to know the RPM. I've had no luck researching this and I no longer have an RPM meter. I imagine all chainsaws have similar rpm. I need to get the ratios on timing belt sprockets close to optimal. If this works, you will all be dazzled by my brilliance! Affix something to the chain that sticks out a little. Now make another attachment or hold something close by that will hit it. Like the old clothespin, playing card and bicycle spokes. Turn it on and record the sound. Use something like Audacity to measure the frequency. Viola! A big, 16" bar, 15A corded electric Makita chainsaw has a no-load chain speed of 2900 ft/min -- 48 fps. I'd use my digital camera in timed multi-shot mode (10 frames/sec., I think) and take a series of photos, and then measure the distance between a marker in two sequential shots. You'd have to do it multiple times to be sure you get two visible, sequential photos with the marker. Then work backward from the sprocket and chain pitches to get the motor rpm. (Yes, there must be a simpler way.) For reference, I saw specs on a Greenworks corded 14.5A saw that said 6000 rpm. Another saw said 5500 rpm. A Remington Versa 12A 16" says 3200 rpm. If this is a cordless saw, all bets are off. As for 3.5 hp...that sounds like Sears or Ridgid horsepower to me -- like 22A, if they're talking gross horsepower. -- Ed Huntress I've seen a rating in "electrical horsepower" calculated from how much juice it pulls, probably without considering efficiency or power factor. I think that some of them, including Ridgid, don't even go that far. They stall it and measure the current; multiply by the voltage; divide by 750; and claim that as "horsepower." My Ridgid shop vac draws, I think, 10A when it's running. But they claim it has "4.25 [peak] horsepower." HA-Ha-ha-ho! -- Ed Huntress We should call that "puke" horsepower since the motor is about to toss its magic smoke.. Yeah, that would be a better term for it. This is what Popular Mechanics said about it in a shop-vac comparison. To me, this is unbelievable: "In addition to being designated by capacity, most wet/dry vacs carry a horsepower rating—our test units range up to 6.5 hp. But if you think that means a vac motor is as powerful as a garden-tiller engine, think again. Like many other consumer-grade tools, the horsepower rating is modified by the word "peak." This indicates the electrical draw at the point where the motor is overloaded and stalls. The upshot? Horsepower ratings aren't the most accurate way to compare wet/dry vacs. Looking at amperage makes more sense." Don't know about HP of the "TECO Master" (TECO = T Eato Co) shop vac I picked up for five bux six years ago - the seller let it go because no one was interested since it wasn't wet/dry - he had kept it in the original box with the printed printed sheet "owners manual". When I opened it up for inspection I found the date stamp "Aug.31 1971". My son's evaluation as a shop vac is "IT REALLY SUCKS" I keep it in the laundry room outside the shop door for lint trap cleaning, puppy haircut cleanup and any other use I come up with like disk/belt sander dust removal. |
#21
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Electric chainsaw motor
On Thu, 2 Nov 2017 16:37:00 -0400, "Jim Wilkins"
wrote: "Tom Gardner" wrote in message news I have a new 3.5hp (I think) "Works" largest 14" chainsaw that I want to use the motor for a project. I need to know the RPM. I've had no luck researching this and I no longer have an RPM meter. I imagine all chainsaws have similar rpm. I need to get the ratios on timing belt sprockets close to optimal. If this works, you will all be dazzled by my brilliance! The question is what is its RPM when producing the power the load needs. Could you fake the drive with hardware store vee belts and pulleys to find out? My collection of pulleys that weren't the right size has helped a lot on subsequent projects. I never pass up 25cent pulleys at yard sales, at worst, most come with a set screw. |
#22
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Electric chainsaw motor
On Thu, 02 Nov 2017 21:09:44 -0400, Ed Huntress
wrote: On Thu, 2 Nov 2017 20:26:14 -0400, "Jim Wilkins" wrote: "Ed Huntress" wrote in message . .. On Thu, 2 Nov 2017 18:30:47 -0400, "Jim Wilkins" wrote: "Ed Huntress" wrote in message m... On Thu, 2 Nov 2017 16:18:31 -0400, "Jim Wilkins" wrote: "Ed Huntress" wrote in message news:1unmvc95lkhs0ufmfla2ta6nanaamsk20r@4ax. com... On Thu, 2 Nov 2017 13:38:23 -0400, Leon Fisk wrote: On Thu, 2 Nov 2017 13:24:25 -0400 Tom Gardner wrote: I have a new 3.5hp (I think) "Works" largest 14" chainsaw that I want to use the motor for a project. I need to know the RPM. I've had no luck researching this and I no longer have an RPM meter. I imagine all chainsaws have similar rpm. I need to get the ratios on timing belt sprockets close to optimal. If this works, you will all be dazzled by my brilliance! Affix something to the chain that sticks out a little. Now make another attachment or hold something close by that will hit it. Like the old clothespin, playing card and bicycle spokes. Turn it on and record the sound. Use something like Audacity to measure the frequency. Viola! A big, 16" bar, 15A corded electric Makita chainsaw has a no-load chain speed of 2900 ft/min -- 48 fps. I'd use my digital camera in timed multi-shot mode (10 frames/sec., I think) and take a series of photos, and then measure the distance between a marker in two sequential shots. You'd have to do it multiple times to be sure you get two visible, sequential photos with the marker. Then work backward from the sprocket and chain pitches to get the motor rpm. (Yes, there must be a simpler way.) For reference, I saw specs on a Greenworks corded 14.5A saw that said 6000 rpm. Another saw said 5500 rpm. A Remington Versa 12A 16" says 3200 rpm. If this is a cordless saw, all bets are off. As for 3.5 hp...that sounds like Sears or Ridgid horsepower to me -- like 22A, if they're talking gross horsepower. -- Ed Huntress I've seen a rating in "electrical horsepower" calculated from how much juice it pulls, probably without considering efficiency or power factor. I think that some of them, including Ridgid, don't even go that far. They stall it and measure the current; multiply by the voltage; divide by 750; and claim that as "horsepower." My Ridgid shop vac draws, I think, 10A when it's running. But they claim it has "4.25 [peak] horsepower." HA-Ha-ha-ho! -- Ed Huntress We should call that "puke" horsepower since the motor is about to toss its magic smoke.. Yeah, that would be a better term for it. This is what Popular Mechanics said about it in a shop-vac comparison. To me, this is unbelievable: "In addition to being designated by capacity, most wet/dry vacs carry a horsepower rating-our test units range up to 6.5 hp. But if you think that means a vac motor is as powerful as a garden-tiller engine, think again. Like many other consumer-grade tools, the horsepower rating is modified by the word "peak." This indicates the electrical draw at the point where the motor is overloaded and stalls. The upshot? Horsepower ratings aren't the most accurate way to compare wet/dry vacs. Looking at amperage makes more sense." -- Ed Huntress Well, the motor is physically able to do it, just not for long. Kettering made the automotive electric starter practical by designing for brief peak power, 5 HP from a motor smaller than a 1/2 HP continuous-duty motor. -jsw OK, but this isn't real horsepower they're talking about -- even for a minute. They're defining "horsepower" as current times voltage (/747). But if that's "horsepower, then you could have a really big power resistor that developed 10 horsepower. g That electrical value is "power," but it's just *potential* horsepower. If you measured actual, kinetic horsepower, in terms of torque times rpm, it would be a minute fraction of that. If the motor is stalled, there's no real horsepower at all. I wonder if Sears started that practice? That was the first place I remember seeing it. I think chainsaw horsepower is measured by how fast it cuts human flesh. |
#23
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Electric chainsaw motor
On Thu, 2 Nov 2017 13:38:23 -0400, Leon Fisk
wrote: On Thu, 2 Nov 2017 13:24:25 -0400 Tom Gardner wrote: I have a new 3.5hp (I think) "Works" largest 14" chainsaw that I want to use the motor for a project. I need to know the RPM. I've had no luck researching this and I no longer have an RPM meter. I imagine all chainsaws have similar rpm. I need to get the ratios on timing belt sprockets close to optimal. If this works, you will all be dazzled by my brilliance! Affix something to the chain that sticks out a little. Now make another attachment or hold something close by that will hit it. Like the old clothespin, playing card and bicycle spokes. Turn it on and record the sound. Use something like Audacity to measure the frequency. Viola! Cello. The Portland HF is selling now lists no-load RPM as 5,500, Tawm. https://manuals.harborfreight.com/ma...7999/67255.pdf pg 8 -- The Road to Success...is always under construction. --anon |
#24
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Electric chainsaw motor
On Thu, 2 Nov 2017 22:15:02 -0400, "Jim Wilkins"
wrote: I have a 5.5HP, 3750W generator that struggles to start a 1/2 HP motor on an air compressor, as long as the tank pressure is low. I can't measure the compressor motor's torque vs RPM curve but it clearly is drawing that much electrical power at startup. That's a 10x start-load! I've read that motor startup uses 4-10x the current, but most I've seen were closer to 4x. That's a biggie. Have you tried an idler pulley setup to remove the flywheel load from the motor on startup? Is it time to plumb in an unloader/pressure switch, or does it already have one? http://tinyurl.com/yb6f8hgu Any way to wire in a start cap to help with the current onrush? Have you verified the genset specs under load? Are you trying to fix this, or is it posted here only as info, since the genset does start the compressor? -- The Road to Success...is always under construction. --anon |
#25
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Electric chainsaw motor
On Thu, 2 Nov 2017 22:15:02 -0400, "Jim Wilkins"
wrote: "Ed Huntress" wrote in message news On Thu, 2 Nov 2017 20:26:14 -0400, "Jim Wilkins" wrote: "Ed Huntress" wrote in message ... On Thu, 2 Nov 2017 18:30:47 -0400, "Jim Wilkins" wrote: "Ed Huntress" wrote in message om... On Thu, 2 Nov 2017 16:18:31 -0400, "Jim Wilkins" wrote: "Ed Huntress" wrote in message news:1unmvc95lkhs0ufmfla2ta6nanaamsk20r@4ax .com... On Thu, 2 Nov 2017 13:38:23 -0400, Leon Fisk wrote: On Thu, 2 Nov 2017 13:24:25 -0400 Tom Gardner wrote: I have a new 3.5hp (I think) "Works" largest 14" chainsaw that I want to use the motor for a project. I need to know the RPM. I've had no luck researching this and I no longer have an RPM meter. I imagine all chainsaws have similar rpm. I need to get the ratios on timing belt sprockets close to optimal. If this works, you will all be dazzled by my brilliance! Affix something to the chain that sticks out a little. Now make another attachment or hold something close by that will hit it. Like the old clothespin, playing card and bicycle spokes. Turn it on and record the sound. Use something like Audacity to measure the frequency. Viola! A big, 16" bar, 15A corded electric Makita chainsaw has a no-load chain speed of 2900 ft/min -- 48 fps. I'd use my digital camera in timed multi-shot mode (10 frames/sec., I think) and take a series of photos, and then measure the distance between a marker in two sequential shots. You'd have to do it multiple times to be sure you get two visible, sequential photos with the marker. Then work backward from the sprocket and chain pitches to get the motor rpm. (Yes, there must be a simpler way.) For reference, I saw specs on a Greenworks corded 14.5A saw that said 6000 rpm. Another saw said 5500 rpm. A Remington Versa 12A 16" says 3200 rpm. If this is a cordless saw, all bets are off. As for 3.5 hp...that sounds like Sears or Ridgid horsepower to me -- like 22A, if they're talking gross horsepower. -- Ed Huntress I've seen a rating in "electrical horsepower" calculated from how much juice it pulls, probably without considering efficiency or power factor. I think that some of them, including Ridgid, don't even go that far. They stall it and measure the current; multiply by the voltage; divide by 750; and claim that as "horsepower." My Ridgid shop vac draws, I think, 10A when it's running. But they claim it has "4.25 [peak] horsepower." HA-Ha-ha-ho! -- Ed Huntress We should call that "puke" horsepower since the motor is about to toss its magic smoke.. Yeah, that would be a better term for it. This is what Popular Mechanics said about it in a shop-vac comparison. To me, this is unbelievable: "In addition to being designated by capacity, most wet/dry vacs carry a horsepower rating-our test units range up to 6.5 hp. But if you think that means a vac motor is as powerful as a garden-tiller engine, think again. Like many other consumer-grade tools, the horsepower rating is modified by the word "peak." This indicates the electrical draw at the point where the motor is overloaded and stalls. The upshot? Horsepower ratings aren't the most accurate way to compare wet/dry vacs. Looking at amperage makes more sense." -- Ed Huntress Well, the motor is physically able to do it, just not for long. Kettering made the automotive electric starter practical by designing for brief peak power, 5 HP from a motor smaller than a 1/2 HP continuous-duty motor. -jsw OK, but this isn't real horsepower they're talking about -- even for a minute. They're defining "horsepower" as current times voltage (/747). But if that's "horsepower, then you could have a really big power resistor that developed 10 horsepower. g That electrical value is "power," but it's just *potential* horsepower. If you measured actual, kinetic horsepower, in terms of torque times rpm, it would be a minute fraction of that. If the motor is stalled, there's no real horsepower at all. I wonder if Sears started that practice? That was the first place I remember seeing it. -- Ed Huntress I thought they measured the peak power at the motor's breakdown torque, just before speed drops. http://industrialelectricalco.com/wp...que-curves.pdf I have a 5.5HP, 3750W generator that struggles to start a 1/2 HP motor on an air compressor, as long as the tank pressure is low. I can't measure the compressor motor's torque vs RPM curve but it clearly is drawing that much electrical power at startup. -jsw There are various legitimate ways to measure horsepower, but electrical power is being misused in those consumer-product ratings we were discussing. At stall, all of that power is converted directly to heat. That's power, but it isn't horsepower. -- Ed Huntress |
#26
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Electric chainsaw motor
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#27
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Electric chainsaw motor
On Fri, 03 Nov 2017 00:13:05 -0400, Gerry
wrote: On Thu, 02 Nov 2017 21:09:44 -0400, Ed Huntress wrote: On Thu, 2 Nov 2017 20:26:14 -0400, "Jim Wilkins" wrote: "Ed Huntress" wrote in message ... On Thu, 2 Nov 2017 18:30:47 -0400, "Jim Wilkins" wrote: "Ed Huntress" wrote in message om... On Thu, 2 Nov 2017 16:18:31 -0400, "Jim Wilkins" wrote: "Ed Huntress" wrote in message news:1unmvc95lkhs0ufmfla2ta6nanaamsk20r@4ax .com... On Thu, 2 Nov 2017 13:38:23 -0400, Leon Fisk wrote: On Thu, 2 Nov 2017 13:24:25 -0400 Tom Gardner wrote: I have a new 3.5hp (I think) "Works" largest 14" chainsaw that I want to use the motor for a project. I need to know the RPM. I've had no luck researching this and I no longer have an RPM meter. I imagine all chainsaws have similar rpm. I need to get the ratios on timing belt sprockets close to optimal. If this works, you will all be dazzled by my brilliance! Affix something to the chain that sticks out a little. Now make another attachment or hold something close by that will hit it. Like the old clothespin, playing card and bicycle spokes. Turn it on and record the sound. Use something like Audacity to measure the frequency. Viola! A big, 16" bar, 15A corded electric Makita chainsaw has a no-load chain speed of 2900 ft/min -- 48 fps. I'd use my digital camera in timed multi-shot mode (10 frames/sec., I think) and take a series of photos, and then measure the distance between a marker in two sequential shots. You'd have to do it multiple times to be sure you get two visible, sequential photos with the marker. Then work backward from the sprocket and chain pitches to get the motor rpm. (Yes, there must be a simpler way.) For reference, I saw specs on a Greenworks corded 14.5A saw that said 6000 rpm. Another saw said 5500 rpm. A Remington Versa 12A 16" says 3200 rpm. If this is a cordless saw, all bets are off. As for 3.5 hp...that sounds like Sears or Ridgid horsepower to me -- like 22A, if they're talking gross horsepower. -- Ed Huntress I've seen a rating in "electrical horsepower" calculated from how much juice it pulls, probably without considering efficiency or power factor. I think that some of them, including Ridgid, don't even go that far. They stall it and measure the current; multiply by the voltage; divide by 750; and claim that as "horsepower." My Ridgid shop vac draws, I think, 10A when it's running. But they claim it has "4.25 [peak] horsepower." HA-Ha-ha-ho! -- Ed Huntress We should call that "puke" horsepower since the motor is about to toss its magic smoke.. Yeah, that would be a better term for it. This is what Popular Mechanics said about it in a shop-vac comparison. To me, this is unbelievable: "In addition to being designated by capacity, most wet/dry vacs carry a horsepower rating-our test units range up to 6.5 hp. But if you think that means a vac motor is as powerful as a garden-tiller engine, think again. Like many other consumer-grade tools, the horsepower rating is modified by the word "peak." This indicates the electrical draw at the point where the motor is overloaded and stalls. The upshot? Horsepower ratings aren't the most accurate way to compare wet/dry vacs. Looking at amperage makes more sense." -- Ed Huntress Well, the motor is physically able to do it, just not for long. Kettering made the automotive electric starter practical by designing for brief peak power, 5 HP from a motor smaller than a 1/2 HP continuous-duty motor. -jsw OK, but this isn't real horsepower they're talking about -- even for a minute. They're defining "horsepower" as current times voltage (/747). But if that's "horsepower, then you could have a really big power resistor that developed 10 horsepower. g That electrical value is "power," but it's just *potential* horsepower. If you measured actual, kinetic horsepower, in terms of torque times rpm, it would be a minute fraction of that. If the motor is stalled, there's no real horsepower at all. I wonder if Sears started that practice? That was the first place I remember seeing it. I think chainsaw horsepower is measured by how fast it cuts human flesh. That's Texas Chainsaw Horsepower (TCH). -- Ed Huntress |
#28
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Electric chainsaw motor
On Fri, 03 Nov 2017 00:13:05 -0400, Gerry
wrote: I think chainsaw horsepower is measured by how fast it cuts human flesh. Gerry has been watching too many Texas Chainsaw Massacre movies. -- The Road to Success...is always under construction. --anon |
#29
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Electric chainsaw motor
On Thu, 2 Nov 2017 16:10:28 -0400, "Jim Wilkins"
wrote: "Tom Gardner" wrote in message news I have a new 3.5hp (I think) "Works" largest 14" chainsaw that I want to use the motor for a project. I need to know the RPM. I've had no luck researching this and I no longer have an RPM meter. I imagine all chainsaws have similar rpm. I need to get the ratios on timing belt sprockets close to optimal. If this works, you will all be dazzled by my brilliance! and if it doesn't work...? My Husqvarna 350 tops out around 12,000 RPM. But that's a gas model. Electrics are much, much tamer. -- The Road to Success...is always under construction. --anon |
#30
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Electric chainsaw motor
"Larry Jaques" wrote in message
... On Thu, 2 Nov 2017 22:15:02 -0400, "Jim Wilkins" wrote: I have a 5.5HP, 3750W generator that struggles to start a 1/2 HP motor on an air compressor, as long as the tank pressure is low. I can't measure the compressor motor's torque vs RPM curve but it clearly is drawing that much electrical power at startup. That's a 10x start-load! I've read that motor startup uses 4-10x the current, but most I've seen were closer to 4x. That's a biggie. Have you tried an idler pulley setup to remove the flywheel load from the motor on startup? Is it time to plumb in an unloader/pressure switch, or does it already have one? http://tinyurl.com/yb6f8hgu Any way to wire in a start cap to help with the current onrush? Have you verified the genset specs under load? Are you trying to fix this, or is it posted here only as info, since the genset does start the compressor? The compressor motor has a starting cap. I replaced the 1970's Load Genie unloader and swapped the copper tube that may have been stressing it for rubber power steering hose rated 175PSI, 302F but still don't hear the hiss of it unloading, however the compressor works fine on grid power. I only noticed the no-start during a long power outage. If I have to inflate another tire on someone's neglected generator during an outage I can loosen the head outlet fitting or use the 12V compressor from the car. -jsw |
#31
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Electric chainsaw motor
On Thursday, November 2, 2017 at 10:18:27 PM UTC-4, Clare wrote:
On Thu, 02 Nov 2017 21:09:44 -0400, Ed Huntress wrote: On Thu, 2 Nov 2017 20:26:14 -0400, "Jim Wilkins" wrote: "Ed Huntress" wrote in message . .. On Thu, 2 Nov 2017 18:30:47 -0400, "Jim Wilkins" wrote: "Ed Huntress" wrote in message m... On Thu, 2 Nov 2017 16:18:31 -0400, "Jim Wilkins" wrote: "Ed Huntress" wrote in message news:1unmvc95lkhs0ufmfla2ta6nanaamsk20r@4ax. com... On Thu, 2 Nov 2017 13:38:23 -0400, Leon Fisk wrote: On Thu, 2 Nov 2017 13:24:25 -0400 Tom Gardner wrote: I have a new 3.5hp (I think) "Works" largest 14" chainsaw that I want to use the motor for a project. I need to know the RPM. I've had no luck researching this and I no longer have an RPM meter. I imagine all chainsaws have similar rpm. I need to get the ratios on timing belt sprockets close to optimal. If this works, you will all be dazzled by my brilliance! Affix something to the chain that sticks out a little. Now make another attachment or hold something close by that will hit it. Like the old clothespin, playing card and bicycle spokes. Turn it on and record the sound. Use something like Audacity to measure the frequency. Viola! A big, 16" bar, 15A corded electric Makita chainsaw has a no-load chain speed of 2900 ft/min -- 48 fps. I'd use my digital camera in timed multi-shot mode (10 frames/sec., I think) and take a series of photos, and then measure the distance between a marker in two sequential shots. You'd have to do it multiple times to be sure you get two visible, sequential photos with the marker. Then work backward from the sprocket and chain pitches to get the motor rpm. (Yes, there must be a simpler way.) For reference, I saw specs on a Greenworks corded 14.5A saw that said 6000 rpm. Another saw said 5500 rpm. A Remington Versa 12A 16" says 3200 rpm. If this is a cordless saw, all bets are off. As for 3.5 hp...that sounds like Sears or Ridgid horsepower to me -- like 22A, if they're talking gross horsepower. -- Ed Huntress I've seen a rating in "electrical horsepower" calculated from how much juice it pulls, probably without considering efficiency or power factor. I think that some of them, including Ridgid, don't even go that far. They stall it and measure the current; multiply by the voltage; divide by 750; and claim that as "horsepower." My Ridgid shop vac draws, I think, 10A when it's running. But they claim it has "4.25 [peak] horsepower." HA-Ha-ha-ho! -- Ed Huntress We should call that "puke" horsepower since the motor is about to toss its magic smoke.. Yeah, that would be a better term for it. This is what Popular Mechanics said about it in a shop-vac comparison. To me, this is unbelievable: "In addition to being designated by capacity, most wet/dry vacs carry a horsepower rating-our test units range up to 6.5 hp. But if you think that means a vac motor is as powerful as a garden-tiller engine, think again. Like many other consumer-grade tools, the horsepower rating is modified by the word "peak." This indicates the electrical draw at the point where the motor is overloaded and stalls. The upshot? Horsepower ratings aren't the most accurate way to compare wet/dry vacs. Looking at amperage makes more sense." -- Ed Huntress Well, the motor is physically able to do it, just not for long. Kettering made the automotive electric starter practical by designing for brief peak power, 5 HP from a motor smaller than a 1/2 HP continuous-duty motor. -jsw OK, but this isn't real horsepower they're talking about -- even for a minute. They're defining "horsepower" as current times voltage (/747). But if that's "horsepower, then you could have a really big power resistor that developed 10 horsepower. g That electrical value is "power," but it's just *potential* horsepower. If you measured actual, kinetic horsepower, in terms of torque times rpm, it would be a minute fraction of that. If the motor is stalled, there's no real horsepower at all. I wonder if Sears started that practice? That was the first place I remember seeing it. On vacuums and compressors it's actually "air horsepower" - and there is a defined specification Air horsepower = flow rate ( cubic feet / minute) × pressure (inches water column) / 6,356 and on (non electric) motors, it's 550 foot-pounds per second. the picture that makes in my head is this: A motor with a 1 foot radius drum attached, winding a rope. If that rope can lift a one pound weight 550 feet in one second, that's a one horsepower motor. If nothing is moving, it's not doing useful work. |
#32
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Electric chainsaw motor
"rangerssuck" wrote in message
... ... and on (non electric) motors, it's 550 foot-pounds per second. the picture that makes in my head is this: A motor with a 1 foot radius drum attached, winding a rope. If that rope can lift a one pound weight 550 feet in one second, that's a one horsepower motor. If nothing is moving, it's not doing useful work. ====================== Th Harbor Freight 1300Lb electric hoist can give an easily measured demonstration of electrical and mechanical horsepower. -jsw |
#33
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Electric chainsaw motor
On 11/2/2017 9:09 PM, Ed Huntress wrote:
That electrical value is "power," but it's just *potential* horsepower. If you measured actual, kinetic horsepower, in terms of torque times rpm, it would be a minute fraction of that. If the motor is stalled, there's no real horsepower at all. I wonder if Sears started that practice? That was the first place I remember seeing it. It was the same guy that measured amplifier output in car stereos in the 70's. |
#34
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Electric chainsaw motor
On 11/2/2017 2:04 PM, Bob La Londe wrote:
"Tom Gardner"Â* wrote in message news I have a new 3.5hp (I think) "Works" largest 14" chainsaw that I want to use the motor for a project.Â* I need to know the RPM.Â* I've had no luck researching this and I no longer have an RPM meter. I imagine all chainsaws have similar rpm.Â* I need to get the ratios on timing belt sprockets close to optimal. " If this works, you will all be dazzled by my brilliance! " Or baffled by your bull****.Â* Either way I am looking forward to being entertained. It really is a good, useful idea, it will be a bit harder to build now that I no longer have a machine shop. But using hand tools is good practice. I will have to farm out a couple of turnings and a bit of mill work. |
#35
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Electric chainsaw motor
On 11/2/2017 3:44 PM, mike wrote:
On 11/2/2017 10:24 AM, Tom Gardner wrote: I have a new 3.5hp (I think) "Works" largest 14" chainsaw that I want to use the motor for a project.Â* I need to know the RPM.Â* I've had no luck researching this and I no longer have an RPM meter. I imagine all chainsaws have similar rpm.Â* I need to get the ratios on timing belt sprockets close to optimal.Â* If this works, you will all be dazzled by my brilliance! Hard to know from your (lack of) description, but I'll offerÂ* warning... My limited experience with Works tools is that they're near the bottom for ruggedness. In general, a cheap hand tool rated at 3.5 HP may deliver that for short bursts, maybe.Â* It's not designed for ANY continuous duty, at any power level. Again, my limited experience with electric chainsaws and related devices is that the universal motors with brushes fail because the brush overheats and melts the plastic, yes, the brush holders are typically plastic.Â* It seems to be working fine, but the next time you turn it on, the plastic has hardened around the brush and it's stuck. You can often take it apart and free it up.Â* It will work for a while until it freezes up again. I'd not put a lot of time or $$ into a project based on a Worx motor. I wont be taxing the motor very much and it doesn't need to last long, just long enough to demonstrate the concept for a while. I got the cheapest one with the most "power". It should do the job as I have defines it. |
#36
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Electric chainsaw motor
On Sat, 4 Nov 2017 03:28:42 -0400
Tom Gardner wrote: snip It really is a good, useful idea, it will be a bit harder to build now that I no longer have a machine shop. But using hand tools is good practice. I will have to farm out a couple of turnings and a bit of mill work. There is a maker-space kind of operation locally here that has mills, lathes, tools... for use. You pay a monthly fee or some such for access. It looks like there is something similar in Cleveland. Might be worth checking out if you haven't already... http://www.makersalliance.org/ The Cleveland Library has a 3D printer and a few other goodies too: https://cpl.org/subjectscollections/...al/makerspace/ -- Leon Fisk Grand Rapids MI/Zone 5b Remove no.spam for email |
#37
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Electric chainsaw motor
On 11/2/2017 1:38 PM, Leon Fisk wrote:
Affix something to the chain that sticks out a little. Now make another attachment or hold something close by that will hit it. Like the old clothespin, playing card and bicycle spokes. Turn it on and record the sound. Use something like Audacity to measure the frequency. Viola! I like it ... that's really clever! The only tricky part is affixing something to the chain - there's not much clearance. I'd tack weld, or solder, a bit of wire. |
#38
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Electric chainsaw motor
On Fri, 3 Nov 2017 12:40:20 -0400, "Jim Wilkins"
wrote: "Larry Jaques" wrote in message .. . On Thu, 2 Nov 2017 22:15:02 -0400, "Jim Wilkins" wrote: I have a 5.5HP, 3750W generator that struggles to start a 1/2 HP motor on an air compressor, as long as the tank pressure is low. I can't measure the compressor motor's torque vs RPM curve but it clearly is drawing that much electrical power at startup. That's a 10x start-load! I've read that motor startup uses 4-10x the current, but most I've seen were closer to 4x. That's a biggie. Have you tried an idler pulley setup to remove the flywheel load from the motor on startup? Is it time to plumb in an unloader/pressure switch, or does it already have one? http://tinyurl.com/yb6f8hgu Any way to wire in a start cap to help with the current onrush? Have you verified the genset specs under load? Are you trying to fix this, or is it posted here only as info, since the genset does start the compressor? The compressor motor has a starting cap. I replaced the 1970's Load Genie unloader and swapped the copper tube that may have been stressing it for rubber power steering hose rated 175PSI, 302F but still don't hear the hiss of it unloading, however the compressor works fine on grid power. I only noticed the no-start during a long power outage. So do you hear the hiss when on grid power? Could the resiliency of the rubber hose bypass the function of the unloader? I haven't seen a crossection of the valve, or had one apart, so I'm not certain how it works. It sounds like there may be a spool in there which opens the check valve to allow filling, and it then releases the valve and covers the orifice/uncovers the vent orifice when the pressure switch turns off the compressor motor. If it's only affected after a power outage, could the start cap on the motor be leaking down? If I have to inflate another tire on someone's neglected generator during an outage I can loosen the head outlet fitting or use the 12V compressor from the car. I finally bought one of those 12v jobs. Haven't had a flat for 30 years, but the time-before-last when I did, the spare was down. After that, I regularly thumped the spare to verify air. Now, my Tundra spare and the 4 on the ground have pressure sensors. Handy! -- The Road to Success...is always under construction. --anon |
#39
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Electric chainsaw motor
On Sat, 4 Nov 2017 03:16:24 -0400, Tom Gardner wrote:
On 11/2/2017 9:09 PM, Ed Huntress wrote: That electrical value is "power," but it's just *potential* horsepower. If you measured actual, kinetic horsepower, in terms of torque times rpm, it would be a minute fraction of that. If the motor is stalled, there's no real horsepower at all. I wonder if Sears started that practice? That was the first place I remember seeing it. It was the same guy that measured amplifier output in car stereos in the 70's. Ayup. Is that a real poncho or is that a Searz poncho? -- If you're trying to take a roomful of people by surprise, it's a lot easier to hit your targets if you don't yell going through the door. -- Lois McMaster Bujold |
#40
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Electric chainsaw motor
"Tom Gardner" wrote in message news
On 11/2/2017 2:04 PM, Bob La Londe wrote: "Tom Gardner" wrote in message news I have a new 3.5hp (I think) "Works" largest 14" chainsaw that I want to use the motor for a project. I need to know the RPM. I've had no luck researching this and I no longer have an RPM meter. I imagine all chainsaws have similar rpm. I need to get the ratios on timing belt sprockets close to optimal. " If this works, you will all be dazzled by my brilliance! " Or baffled by your bull****. Either way I am looking forward to being entertained. It really is a good, useful idea, it will be a bit harder to build now that I no longer have a machine shop. But using hand tools is good practice. I will have to farm out a couple of turnings and a bit of mill work. *** If you don't mind some shipping costs I can help you out with some basic stuff. I'm not a "real" machinist, but I am perfectly competent at turning stock into a pile of unrecoverable chips. |
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