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Metal failure
I was vacuuming leaves the other day when the "6.5 hp" Harbor
Freight-powered vac let out a terrible bam-bam-bam... and started slowing quickly. Quickly shut off and locked tight. Oh, crap! Up to my ass in leaves and a broken vac! It had to be the engine, of course, but when I got it in the shop, I found this: http://home.comcast.net/~bobengelhardt/DSCF1165.JPG When the blade failed, its backing plate bent and the blade tip started hitting bolt heads in the case. All the blades had real cracks - one is circled - and were not far from failure. I can think of no other reason than centrifugal force. The blades are about 3/16" thick - pretty surprising that they would crack like that. Now, here's the best part: I had a spare impeller in the shed! Who keeps spare impellers? Impellers don't fail, why would anyone have a spare? You're looking at him, as they say. Fixed in a flash and back to the leaves. Very satisfying. Bob |
Metal failure
On 2014-11-15, Bob Engelhardt wrote:
I was vacuuming leaves the other day when the "6.5 hp" Harbor Freight-powered vac let out a terrible bam-bam-bam... and started slowing quickly. Quickly shut off and locked tight. Oh, crap! Up to my ass in leaves and a broken vac! It had to be the engine, of course, but when I got it in the shop, I found this: http://home.comcast.net/~bobengelhardt/DSCF1165.JPG When the blade failed, its backing plate bent and the blade tip started hitting bolt heads in the case. All the blades had real cracks - one is circled - and were not far from failure. I can think of no other reason than centrifugal force. The blades are about 3/16" thick - pretty surprising that they would crack like that. Now, here's the best part: I had a spare impeller in the shed! Who keeps spare impellers? Impellers don't fail, why would anyone have a spare? You're looking at him, as they say. Fixed in a flash and back to the leaves. Very satisfying. Bob Bob, my best guess is that the steel used was substandard (ie perhaps too much sulphur), and welded in a way that left some residual stress. |
Metal failure
On 11/15/2014 10:14 AM, Bob Engelhardt wrote:
I was vacuuming leaves the other day when the "6.5 hp" Harbor Freight-powered vac let out a terrible bam-bam-bam... and started slowing quickly. Quickly shut off and locked tight. Oh, crap! Up to my ass in leaves and a broken vac! It had to be the engine, of course, but when I got it in the shop, I found this: http://home.comcast.net/~bobengelhardt/DSCF1165.JPG When the blade failed, its backing plate bent and the blade tip started hitting bolt heads in the case. All the blades had real cracks - one is circled - and were not far from failure. I can think of no other reason than centrifugal force. The blades are about 3/16" thick - pretty surprising that they would crack like that. Now, here's the best part: I had a spare impeller in the shed! Who keeps spare impellers? Impellers don't fail, why would anyone have a spare? You're looking at him, as they say. Fixed in a flash and back to the leaves. Very satisfying. Bob You'll pay for that...later. |
Metal failure
On Sat, 15 Nov 2014 10:14:21 -0500, Bob Engelhardt
wrote: I was vacuuming leaves the other day when the "6.5 hp" Harbor Freight-powered vac let out a terrible bam-bam-bam... and started slowing quickly. Quickly shut off and locked tight. Oh, crap! Up to my ass in leaves and a broken vac! It had to be the engine, of course, but when I got it in the shop, I found this: http://home.comcast.net/~bobengelhardt/DSCF1165.JPG When the blade failed, its backing plate bent and the blade tip started hitting bolt heads in the case. All the blades had real cracks - one is circled - and were not far from failure. I can think of no other reason than centrifugal force. The blades are about 3/16" thick - pretty surprising that they would crack like that. Now, here's the best part: I had a spare impeller in the shed! Who keeps spare impellers? Impellers don't fail, why would anyone have a spare? You're looking at him, as they say. Fixed in a flash and back to the leaves. Very satisfying. Bob Ugh. FWIW, the centrifugal force is unlikely to have done it. Without a macro-level photo of the break, it's hard to tell, but it probably is fatigue, possibly on weakened areas that, as Iggy says, could have been bad welds. When a fan or turbine spins, unless it's precision-balanced, it will vibrate. Ekven a balanced one can vibrate if the air currents are "noisy" from preceding blades. That can put a lot of stress on fan blades. -- Ed Huntress |
Metal failure
On 11/15/2014 10:34 AM, Ed Huntress wrote:
... but it probably is fatigue, ... When a fan or turbine spins, ... it will vibrate. ... That makes a lot of sense. More so when you consider that it's being driven by a 1-cylinder gas engine, hardly a smooth power source. Maybe I should grind stress relief at the top of the blades where they meet the hub. Like so (engage imagination): / ____ / U | | Bob |
Metal failure
On Sat, 15 Nov 2014 11:37:33 -0500, Bob Engelhardt
wrote: On 11/15/2014 10:34 AM, Ed Huntress wrote: ... but it probably is fatigue, ... When a fan or turbine spins, ... it will vibrate. ... That makes a lot of sense. More so when you consider that it's being driven by a 1-cylinder gas engine, hardly a smooth power source. Maybe I should grind stress relief at the top of the blades where they meet the hub. Like so (engage imagination): / ____ / U | | Bob I can't help you there. If it's fatigue, it's very dependent upon two things: the number of cycles it goes through, and the percentage of yield strength that the load applies. Steel has a very long fatigue life unless it's stressed close to the yield limit. (Aluminum, for the record, has much less resistance to fatigue.) If you reduce the thickness or length to which the load is applied, by grinding in relief, the result could be worse than just leaving it alone. That depends on whether you're starting off with microcracks at or near the surface of the welds. If there are microcracks, they're starting points for fatigue. Unless you're making parts for an aircraft turbine, trying to calculate these things is not worth it. Just go with your sense of how metal behaves and be thankful your fan isn't made out of some expensive superalloy. d8-) BTW, look closely at the breaks. If some part of the break area is shiny, you're dealing with fatigue. It could be a ring around the break, or some area across the break. When metal fatigues it "frets," or rubs against itself, before it fails. That usually leaves a small shiny area. As the break progresses, the area to which the load is applied gets smaller, until the metal breaks from being overstressed. That part of the break is likely to be dull or crystalline in appearance. But it's not so cut-and-dried. Sometimes it's hard to tell. -- Ed Huntress |
Metal failure
On 11/15/2014 7:14 AM, Bob Engelhardt wrote:
I was vacuuming leaves the other day when the "6.5 hp" Harbor Freight-powered vac let out a terrible bam-bam-bam... and started slowing quickly. Quickly shut off and locked tight. Oh, crap! Up to my ass in leaves and a broken vac! It had to be the engine, of course, but when I got it in the shop, I found this: http://home.comcast.net/~bobengelhardt/DSCF1165.JPG When the blade failed, its backing plate bent and the blade tip started hitting bolt heads in the case. All the blades had real cracks - one is circled - and were not far from failure. I can think of no other reason than centrifugal force. The blades are about 3/16" thick - pretty surprising that they would crack like that. Now, here's the best part: I had a spare impeller in the shed! Who keeps spare impellers? Impellers don't fail, why would anyone have a spare? You're looking at him, as they say. Fixed in a flash and back to the leaves. Very satisfying. Bob Bob, are you sure you didn't vacuum something other than leaves? Like a rock or piece of metal lying in the leaves? Paul |
Metal failure
On Sat, 15 Nov 2014 09:26:19 -0600, Ignoramus30301
wrote: On 2014-11-15, Bob Engelhardt wrote: I was vacuuming leaves the other day when the "6.5 hp" Harbor Freight-powered vac let out a terrible bam-bam-bam... and started slowing quickly. Quickly shut off and locked tight. Oh, crap! Up to my ass in leaves and a broken vac! It had to be the engine, of course, but when I got it in the shop, I found this: http://home.comcast.net/~bobengelhardt/DSCF1165.JPG When the blade failed, its backing plate bent and the blade tip started hitting bolt heads in the case. All the blades had real cracks - one is circled - and were not far from failure. I can think of no other reason than centrifugal force. The blades are about 3/16" thick - pretty surprising that they would crack like that. Now, here's the best part: I had a spare impeller in the shed! Who keeps spare impellers? Impellers don't fail, why would anyone have a spare? You're looking at him, as they say. Fixed in a flash and back to the leaves. Very satisfying. Bob Bob, my best guess is that the steel used was substandard (ie perhaps too much sulphur), and welded in a way that left some residual stress. AKA Made in China |
Metal failure
On Sat, 15 Nov 2014 09:02:50 -0800
Paul Drahn wrote: snip Bob, are you sure you didn't vacuum something other than leaves? Like a rock or piece of metal lying in the leaves? Paul That would be my guess too. It doesn't take long, just a few seconds to make a mess that looks like it took many hours to create. The offending piece/part could have easily been thrown out and is many feet away. The "hammers" used in tub grinders have been known to break and get thrown. They have gone through roofs and walls many blocks away from where the grinder was operating... -- Leon Fisk Grand Rapids MI/Zone 5b Remove no.spam for email |
Metal failure
On 11/15/2014 12:02 PM, Paul Drahn wrote:
Bob, are you sure you didn't vacuum something other than leaves? Like a rock or piece of metal lying in the leaves? I'm pretty sure that I have, over the years of using it. But I don't think that was a rock: there isn't a dent in the blade. And all the blades are cracked - a single rock would only be hit by a single blade before being ejected. It might be that the accumulated impacts of pebbles over the years was what caused the fatigue. Bob |
Metal failure
On 11/15/2014 1:43 PM, Leon Fisk wrote:
That would be my guess too. It doesn't take long, just a few seconds to make a mess that looks like it took many hours to create. The offending piece/part could have easily been thrown out and is many feet away. .... When I do suck up something larger than sand, I know it. There is a single whang when a blade hits it and it's ejected. Bob BTW - the leaf vac is a set up of my power wagon. See page 9 he http://www.mwdropbox.com/dropbox/PowerWagon.pdf |
Metal failure
On Sat, 15 Nov 2014 19:53:03 -0500
Bob Engelhardt wrote: On 11/15/2014 1:43 PM, Leon Fisk wrote: That would be my guess too. It doesn't take long, just a few seconds to make a mess that looks like it took many hours to create. The offending piece/part could have easily been thrown out and is many feet away. ... When I do suck up something larger than sand, I know it. There is a single whang when a blade hits it and it's ejected. That's usually the problem. What got sucked up didn't get thrown out right away. I remember something similar happening years ago but I can't remember it clearly enough. Been bugging me ever since you posted this. Anyway... it happened so fast and looked so bad it was hard to believe all the damage done in just a few seconds. It was probably when I worked on a farm ~40 years ago... I do remember pulling odds & ends out of the grinder-mixer. It could bring a 50hp tractor to a stall if you pushed the input too hard. Typical hammer-mill with different sized screens for determining how coarse the output feed would be. You would have to shut down and remove the screen to find the foreign noise maker. A lot of times you really couldn't tell what the offending beat up piece of metal taken out once was... BTW - the leaf vac is a set up of my power wagon. See page 9 he http://www.mwdropbox.com/dropbox/PowerWagon.pdf I like it, nice write up. I have a similar version in my mind but I still need the exercise. Also agree that the DR version costs way too much. If I live long enough though, there will come a day... -- Leon Fisk Grand Rapids MI/Zone 5b Remove no.spam for email |
Metal failure
On 11/15/2014 11:51 AM, Ed Huntress wrote:
... BTW, look closely at the breaks. If some part of the break area is shiny, you're dealing with fatigue. ... I had taken the impeller to the dump yesterday. I went back today, intending to retrieve it, cut out a sample of a crack, and examine it for signs of fatigue. It was gone! Who would want an old, really beat up, impeller? |
Metal failure
"Bob Engelhardt" wrote in message
... On 11/15/2014 11:51 AM, Ed Huntress wrote: ... BTW, look closely at the breaks. If some part of the break area is shiny, you're dealing with fatigue. ... I had taken the impeller to the dump yesterday. I went back today, intending to retrieve it, cut out a sample of a crack, and examine it for signs of fatigue. It was gone! Who would want an old, really beat up, impeller? I bartered some cast iron for a rusty wagon front axle with an old man who picks up -any- scrap metal to sell to the junkyard. I was hoping it might be wrought iron, but a little cleaning showed that the rust pattern isn't directional. |
Metal failure
On Sun, 16 Nov 2014 16:47:17 -0500, Bob Engelhardt
wrote: On 11/15/2014 11:51 AM, Ed Huntress wrote: ... BTW, look closely at the breaks. If some part of the break area is shiny, you're dealing with fatigue. ... I had taken the impeller to the dump yesterday. I went back today, intending to retrieve it, cut out a sample of a crack, and examine it for signs of fatigue. It was gone! Who would want an old, really beat up, impeller? Hmm...somebody who wants an excuse to give to his wife for not gathering up the leaves? d8-) -- Ed Huntress |
Metal failure
On 11/16/2014 5:55 PM, Ed Huntress wrote:
On Sun, 16 Nov 2014 16:47:17 -0500, Bob Engelhardt wrote: ... Who would want an old, really beat up, impeller? Hmm...somebody who wants an excuse to give to his wife for not gathering up the leaves? d8-) That's good! I'm going to have to stockpile a few broken parts to use that with. "Oh, honey, my squeegee is broken - I can't do the windows today." |
Metal failure
On Sun, 16 Nov 2014 18:57:24 -0500, Bob Engelhardt
wrote: On 11/16/2014 5:55 PM, Ed Huntress wrote: On Sun, 16 Nov 2014 16:47:17 -0500, Bob Engelhardt wrote: ... Who would want an old, really beat up, impeller? Hmm...somebody who wants an excuse to give to his wife for not gathering up the leaves? d8-) That's good! I'm going to have to stockpile a few broken parts to use that with. "Oh, honey, my squeegee is broken - I can't do the windows today." In my house, I could get multi-season use out of it. "Sorry, hon, but the lawnmower blade is broken." "Oh, sorry, babe, but the fan for the weed-wacker just took a dive." "Omigosh, the snow blower compressor just broke into pieces." My wife is not a machinery type. d8-) -- Ed Huntress |
Metal failure
Ed Huntress wrote:
On Sun, 16 Nov 2014 18:57:24 -0500, Bob Engelhardt wrote: On 11/16/2014 5:55 PM, Ed Huntress wrote: On Sun, 16 Nov 2014 16:47:17 -0500, Bob Engelhardt wrote: ... Who would want an old, really beat up, impeller? Hmm...somebody who wants an excuse to give to his wife for not gathering up the leaves? d8-) That's good! I'm going to have to stockpile a few broken parts to use that with. "Oh, honey, my squeegee is broken - I can't do the windows today." In my house, I could get multi-season use out of it. "Sorry, hon, but the lawnmower blade is broken." "Oh, sorry, babe, but the fan for the weed-wacker just took a dive." "Omigosh, the snow blower compressor just broke into pieces." My wife is not a machinery type. d8-) My wife would just give me "the look" and tell me "You've got a machine shop . Either fix it or make a new one . " . Sometimes a blessing is also a curse . -- Snag |
Metal failure
On Sun, 16 Nov 2014 18:32:11 -0600, "Terry Coombs"
wrote: Ed Huntress wrote: On Sun, 16 Nov 2014 18:57:24 -0500, Bob Engelhardt wrote: On 11/16/2014 5:55 PM, Ed Huntress wrote: On Sun, 16 Nov 2014 16:47:17 -0500, Bob Engelhardt wrote: ... Who would want an old, really beat up, impeller? Hmm...somebody who wants an excuse to give to his wife for not gathering up the leaves? d8-) That's good! I'm going to have to stockpile a few broken parts to use that with. "Oh, honey, my squeegee is broken - I can't do the windows today." In my house, I could get multi-season use out of it. "Sorry, hon, but the lawnmower blade is broken." "Oh, sorry, babe, but the fan for the weed-wacker just took a dive." "Omigosh, the snow blower compressor just broke into pieces." My wife is not a machinery type. d8-) My wife would just give me "the look" and tell me "You've got a machine shop . Either fix it or make a new one . " . Sometimes a blessing is also a curse . At least THAT would give you an excuse and permission to go out to the shop and work on something (else) |
Metal failure
"Bob Engelhardt" wrote in message
... On 11/16/2014 5:55 PM, Ed Huntress wrote: On Sun, 16 Nov 2014 16:47:17 -0500, Bob Engelhardt wrote: ... Who would want an old, really beat up, impeller? Hmm...somebody who wants an excuse to give to his wife for not gathering up the leaves? d8-) That's good! I'm going to have to stockpile a few broken parts to use that with. "Oh, honey, my squeegee is broken - I can't do the windows today." In Mensa we made a game of trying to fit a previously chosen odd word or phrase smoothly into a dinner conversation. I'm going to see how long it takes to use "My squeegee is broken". |
Metal failure
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Metal failure
On Sun, 16 Nov 2014 18:32:11 -0600, "Terry Coombs"
wrote: Ed Huntress wrote: On Sun, 16 Nov 2014 18:57:24 -0500, Bob Engelhardt wrote: On 11/16/2014 5:55 PM, Ed Huntress wrote: On Sun, 16 Nov 2014 16:47:17 -0500, Bob Engelhardt wrote: ... Who would want an old, really beat up, impeller? Hmm...somebody who wants an excuse to give to his wife for not gathering up the leaves? d8-) That's good! I'm going to have to stockpile a few broken parts to use that with. "Oh, honey, my squeegee is broken - I can't do the windows today." In my house, I could get multi-season use out of it. "Sorry, hon, but the lawnmower blade is broken." "Oh, sorry, babe, but the fan for the weed-wacker just took a dive." "Omigosh, the snow blower compressor just broke into pieces." My wife is not a machinery type. d8-) My wife would just give me "the look" and tell me "You've got a machine shop . Either fix it or make a new one . " . Sometimes a blessing is also a curse . Use logic, Terry. "Honey, for only $1,732, I can buy 'billet' g and make the parts and fix it myself in about 2 months. Or, for $283, I can buy a bolt-on replacement and have it fixed the day after it arrives. What would you suggest I do?" Then give _her_ The Look. -- I started out with nothing and I still have most of it left! --anon |
Metal failure; Act 2, Scene 1
I was back at the leaves yesterday, with the freshly repaired vac. At
the end of the day, and the end of the leaves (almost), this happened: http://home.comcast.net/~bobengelhardt/DSCF1170.JPG In case it isn't obvious, that is the end of the HF engine crankshaft! It was quite an alarming event: a heavy steel impeller, running 3000 rpm, coming off and bouncing around inside its housing! The engine was only $100, but it also only ran 10 - 15 hours before falling apart. Unfortunately, those hours were over a 3 year period and I'm SOL on any warranty. I've emailed HF Customer Service for the part and even if it has to ship from China, I'll be glad for it. But I'm not optimistic about it being available. Sigh Bob |
Metal failure; Act 2, Scene 1
On Mon, 17 Nov 2014 12:36:24 -0500
Bob Engelhardt wrote: snip I've emailed HF Customer Service for the part and even if it has to ship from China, I'll be glad for it. But I'm not optimistic about it being available. Seems like you said it was the horizontal 6.5hp. If so they are still selling them for $99 with coupon (ask if you need one). I bought one a couple years ago for that, thinking I would never see that price again. There has been coupons and parking lot sales with that price ever since... -- Leon Fisk Grand Rapids MI/Zone 5b Remove no.spam for email |
Metal failure; Act 2, Scene 1
On Mon, 17 Nov 2014 12:36:24 -0500, Bob Engelhardt
wrote: I was back at the leaves yesterday, with the freshly repaired vac. At the end of the day, and the end of the leaves (almost), this happened: http://home.comcast.net/~bobengelhardt/DSCF1170.JPG In case it isn't obvious, that is the end of the HF engine crankshaft! It was quite an alarming event: a heavy steel impeller, running 3000 rpm, coming off and bouncing around inside its housing! The engine was only $100, but it also only ran 10 - 15 hours before falling apart. Unfortunately, those hours were over a 3 year period and I'm SOL on any warranty. I've emailed HF Customer Service for the part and even if it has to ship from China, I'll be glad for it. But I'm not optimistic about it being available. Sigh Bob One good reason to have the impeller on a "spindle" shaft and belt drive it off the motor. But on a 3 gang pulley with a back tensioner and all the stress is taken off the "expensive bits" I know, it doubles the cost of the project, beyond the price of the engine - but it does save the engine - and you can make all the other failure prone parts!!! |
Metal failure; Act 2, Scene 1
On 11/17/2014 12:45 PM, Leon Fisk wrote:
Seems like you said it was the horizontal 6.5hp. If so they are still selling them for $99 with coupon (ask if you need one). ... That's the one. $120 now, less 20% would be $96. But given my experience with this one, I would probably get a used B&S or Honda. Failed-pump pressure washers seem to be a good source for horizontal shaft engines. Here's one: http://boston.craigslist.org/nos/grd/4730588264.htm Bob |
Metal failure; Act 2, Scene 1
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Metal failure; Act 2, Scene 1
Bob Engelhardt wrote:
I was back at the leaves yesterday, with the freshly repaired vac. At the end of the day, and the end of the leaves (almost), this happened: http://home.comcast.net/~bobengelhardt/DSCF1170.JPG In case it isn't obvious, that is the end of the HF engine crankshaft! It was quite an alarming event: a heavy steel impeller, running 3000 rpm, coming off and bouncing around inside its housing! The engine was only $100, but it also only ran 10 - 15 hours before falling apart. Unfortunately, those hours were over a 3 year period and I'm SOL on any warranty. I've emailed HF Customer Service for the part and even if it has to ship from China, I'll be glad for it. But I'm not optimistic about it being available. Sigh Bob Check around for a Honda motor of the same size. A lot of folks in the cart world have been interchanging the parts as bolt ons. Crank, rod, piston are supposedly direct interchange. -- Steve W. |
Metal failure; Act 2, Scene 1
"Bob Engelhardt" wrote in message ... On 11/17/2014 12:46 PM, wrote: One good reason to have the impeller on a "spindle" shaft and belt drive it off the motor. But on a 3 gang pulley with a back tensioner and all the stress is taken off the "expensive bits" I know, it doubles the cost of the project, beyond the price of the engine - but it does save the engine - and you can make all the other failure prone parts!!! That would be a much better approach. What is a "back tensioned", anyway? It goes on opposite a front tensioner. Speaking of which, this seems to work decently, or at least repeatably: http://www.amazon.com/Gates-91132-Be.../dp/B000CRDLZM I haven't rigged up a calibration load yet. |
Metal failure; Act 2, Scene 1
On Mon, 17 Nov 2014 13:15:20 -0500
Bob Engelhardt wrote: On 11/17/2014 12:45 PM, Leon Fisk wrote: Seems like you said it was the horizontal 6.5hp. If so they are still selling them for $99 with coupon (ask if you need one). ... That's the one. $120 now, less 20% would be $96. But given my experience with this one, I would probably get a used B&S or Honda. Failed-pump pressure washers seem to be a good source for horizontal shaft engines. Here's one: http://boston.craigslist.org/nos/grd/4730588264.htm Read the fine print on your 20% off coupon. I don't think it will work on "Predator" stuff... Here is one of the $99 coupons: http://widgets.harborfreight.com/wsw...tm_source=1031 Both Honda and B&S have different quality lines. The cheap stuff may be no better than HF nowadays. Make sure you research the model numbers/prices first... -- Leon Fisk Grand Rapids MI/Zone 5b Remove no.spam for email |
Metal failure; Act 2, Scene 1
On 11/17/2014 1:59 PM, Steve W. wrote:
Check around for a Honda motor of the same size. A lot of folks in the cart world have been interchanging the parts as bolt ons. Crank, rod, piston are supposedly direct interchange. Good to know. Thanks. |
Metal failure; Act 2, Scene 1
On 11/17/2014 2:14 PM, Jim Wilkins wrote:
"Bob Engelhardt" wrote in message .... What is a "back tensioned", anyway? It goes on opposite a front tensioner. Jim! Wait a minute ... a belt travels onto a pulley at its front and exits the pulley at the back, yes? If so, I got it. If not, not. Speaking of which, this seems to work decently, or at least repeatably: http://www.amazon.com/Gates-91132-Be.../dp/B000CRDLZM Years ago I wanted to check the belt tension on my compressor and didn't see anything like what you referenced. So I made my own: http://www.mwdropbox.com/dropbox/BeltTensionGauge.pdf Bob |
Metal failure; Act 2, Scene 1
"Bob Engelhardt" wrote in message
... On 11/17/2014 2:14 PM, Jim Wilkins wrote: "Bob Engelhardt" wrote in message ... What is a "back tensioned", anyway? It goes on opposite a front tensioner. Jim! Wait a minute ... a belt travels onto a pulley at its front and exits the pulley at the back, yes? If so, I got it. If not, not. Speaking of which, this seems to work decently, or at least repeatably: http://www.amazon.com/Gates-91132-Be.../dp/B000CRDLZM Years ago I wanted to check the belt tension on my compressor and didn't see anything like what you referenced. So I made my own: http://www.mwdropbox.com/dropbox/BeltTensionGauge.pdf Bob You did a very nice job on it. This past weekend while I was digging through tool boxes for something to extract a spark plug boot from its secret hideaway behind the intake manifold I found a pencil-type tension gauge that appears to work on the same principle, if I would just cut out the radiator support to view it from the proper angle. The Krikit has the advantages of signalling the correct application force by feel and sound, and holding its reading until reset. It agreed reasonably closely to the quarter-turn test which is how the dealership mechanics set belts. I asked a service manager about the proper tool and suffered through a runaround that everyone was too busy to help me. On the way out I found them clustered around the Snap-On truck and got the real answer. -jsw |
Metal failure; Act 2, Scene 1
"Bob Engelhardt" wrote in message
... On 11/17/2014 2:14 PM, Jim Wilkins wrote: "Bob Engelhardt" wrote in message ... What is a "back tensioned", anyway? It goes on opposite a front tensioner. Jim! Wait a minute ... a belt travels onto a pulley at its front and exits the pulley at the back, yes? If so, I got it. If not, not. Seriously, the force a belt transmits appears as the difference between the tensions on the pulled and the return sides, so a tensioner on the back or return side suffers less abuse. -jsw |
Metal failure; Act 2, Scene 1
On Mon, 17 Nov 2014 13:21:26 -0500, Bob Engelhardt
wrote: On 11/17/2014 12:46 PM, wrote: One good reason to have the impeller on a "spindle" shaft and belt drive it off the motor. But on a 3 gang pulley with a back tensioner and all the stress is taken off the "expensive bits" I know, it doubles the cost of the project, beyond the price of the engine - but it does save the engine - and you can make all the other failure prone parts!!! That would be a much better approach. What is a "back tensioned", anyway? Tensioner running on the flat of the belt- back tensioning increases the wrap around the pully where a regular tensioner would reduce the wrap. Back tensioner goes on the slack side of the belt. (also the most common way of tensioning a belt other than some equipment that pivots the motor mount or slides the motor on the mount for a fixed tension) |
Metal failure; Act 2, Scene 1
On Mon, 17 Nov 2014 14:02:54 -0500, "Steve W."
wrote: wrote: On Mon, 17 Nov 2014 12:36:24 -0500, Bob Engelhardt wrote: I was back at the leaves yesterday, with the freshly repaired vac. At the end of the day, and the end of the leaves (almost), this happened: http://home.comcast.net/~bobengelhardt/DSCF1170.JPG In case it isn't obvious, that is the end of the HF engine crankshaft! It was quite an alarming event: a heavy steel impeller, running 3000 rpm, coming off and bouncing around inside its housing! The engine was only $100, but it also only ran 10 - 15 hours before falling apart. Unfortunately, those hours were over a 3 year period and I'm SOL on any warranty. I've emailed HF Customer Service for the part and even if it has to ship from China, I'll be glad for it. But I'm not optimistic about it being available. Sigh Bob One good reason to have the impeller on a "spindle" shaft and belt drive it off the motor. But on a 3 gang pulley with a back tensioner and all the stress is taken off the "expensive bits" I know, it doubles the cost of the project, beyond the price of the engine - but it does save the engine - and you can make all the other failure prone parts!!! Wonder if you could cut the crankshaft a bit short, then install a stub shaft out to a carrier bearing mounted on the other side to help carry the load? and beat the heck out of a Lovejoy coupler every 10 hours or so - - - |
Metal failure; Act 2, Scene 1
wrote:
On Mon, 17 Nov 2014 14:02:54 -0500, "Steve W." wrote: wrote: On Mon, 17 Nov 2014 12:36:24 -0500, Bob Engelhardt wrote: I was back at the leaves yesterday, with the freshly repaired vac. At the end of the day, and the end of the leaves (almost), this happened: http://home.comcast.net/~bobengelhardt/DSCF1170.JPG In case it isn't obvious, that is the end of the HF engine crankshaft! It was quite an alarming event: a heavy steel impeller, running 3000 rpm, coming off and bouncing around inside its housing! The engine was only $100, but it also only ran 10 - 15 hours before falling apart. Unfortunately, those hours were over a 3 year period and I'm SOL on any warranty. I've emailed HF Customer Service for the part and even if it has to ship from China, I'll be glad for it. But I'm not optimistic about it being available. Sigh Bob One good reason to have the impeller on a "spindle" shaft and belt drive it off the motor. But on a 3 gang pulley with a back tensioner and all the stress is taken off the "expensive bits" I know, it doubles the cost of the project, beyond the price of the engine - but it does save the engine - and you can make all the other failure prone parts!!! Wonder if you could cut the crankshaft a bit short, then install a stub shaft out to a carrier bearing mounted on the other side to help carry the load? and beat the heck out of a Lovejoy coupler every 10 hours or so - - - The stub would go into the hub of the impeller and simply extend the crankshaft out to the bearing. If the shaft is threaded inside, the extension could be machined to thread into place to make it more secure. -- Steve W. |
Metal failure; Act 2, Scene 1
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Metal failure; Act 2, Scene 1
On 11/17/2014 12:36 PM, Bob Engelhardt wrote:
... I've emailed HF Customer Service for the part and even if it has to ship from China, I'll be glad for it. But I'm not optimistic about it being available. HF: "Part not available" But a guy on eBay parts out "freight damaged" HF engines. Crankshaft is $42 shipped. I have 3 alternatives: 1. A new crank: $42 delivered. Several hours to R&R. It's still HF. 2. A used Honda engine: $70, 2 hrs to pick up. May require some fitting to the vac. It's _used_. 3. A new HF engine: $114 delivered. Bolt on. I'd have the old for spare parts. It's _HF_. What to do, what to do? Bob |
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