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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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SFPM dilema and some questions on homemade bandsaw
In the process of making my 3 wheel bandsaw. I am wanting to use a DC
motor of 1 1/2 hp with a speed controller, but would like to add a jack shaft. as well, just to make sure I can keep up the torque on the saw at the necessary speeds needed for general metal cutting. The motor I have is 1 1/2hp Leeson Electric, (removed from a typical treadmill) and runs up to 5120 rpm and pulls 15 amps. The controller I have for it is made by Dart and is supposedly capable of handling up to a 2 HP motor. I understand this controller is supposed to be able to keep the motors torque up at low speeds, but I would not bet my life on it. Guess I am just paranoid, as I do not have to much dealings with DC motors and controllers. So what ratios would I need to go with to get the saw down to useable speeds for metal cutting? (Looking for 65 to 550 SFPM from what I have found out in regards to speed), although it would be nice to jack it up in speed for wood cutting. Would I be better off initially reducing the speed with a gear reducer that drives a jackshaft and then the saw or what? Or should I still be able to get by with just a 4:1 ration jackshaft and rely on the speed controller to do its job? So far except for this problem, the project is going fine. I have one more wheel (drive wheel) yet to cast and machine, shuld have my tires next week, have the caster / camber tension assembly made, starting to work on the blade guides. This brings anopther question to light. Lots of saws today use simple ball bearing for guides. They seem to last ok on my H/V bandsaw, but have a habit of allowing lots of crub get by or get beat into the bearings or blade, so I was thinking on using some guides similar to what DoAll uses. Is there any materials out there that I can machine in a home shop thatw ould serve usefull in making these guides. They need to work with 3/8" at a minimum to no more than a 3/4" blade. Buying those Cool Cut guides is out of the question, so I need to come up with a home brew deal. I was also thinking of using a small engine valve tappet (like found in B & S engines) that runs in a bushing and is adjustable in and out with a setscrew. Any other ideas greatly appreciated. Presently I have just the basic shape of the frame laid out and am concentrating on making all the actual working parts, so I can juggle things here and there, and the frame will be built around these last. Looks like it will have a 17" + - 1" throat size, 8 1/2" to 9" cutting height, stand 71" tall, have a width of 29" and be 8 1/2" in depth, take a 107" blade is usiing the three wheels or a 86" blade if utilizing just two wheels. Table size 20 x 22. The table is still one item that I need to dio a bit of thinking on. I wiuld like to be able to mill it out so I can use a push type rip fence so it looks like a piece of steel plate or perhaps 1/2" thickness is in order, so if anyone has any other suggestions on a table they would also be appreciated. I already have a mitre / rip gauge from a large Delta belt / disk sander that I would like to use. Visit my website: http://www.frugalmachinist.com Opinions expressed are those of my wifes, I had no input whatsoever. Remove "nospam" from email addy. |
#2
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SFPM dilema and some questions on homemade bandsaw
Wood speed is something like 2000 to 3000 fpm or 5 times what you
need for metal. If you want to do wood, I'd suggest some sort of belt deal to switch back and forth. You would need to change blades also so why not just make a big deal out of it and do it right. You want the 5120 to match up with 565 fpm. You didn't say what size wheels you plan but assuming 14" or so you will need about 150rpm on the shaft or a 34 to 1 reduction. Only thing that will do that in one step is a worm drive. I'd suggest a belt reduction of about 6 or 8 with a gear reduction of 4:1 or 5:1. You might be able to use the gear reduction bearings for the drive pulley mount. For 1-1/2 hp, the smallest v-belt drive pulley you should use is 2", 2-1/2" is better. Go smaller and you will have slippage and excessive belt wear. Assuiming you can even get a 12" pulley, that means a maximum of 6:1 reduction in a single V-belt recuction. 2x on this would be 36 to 1, about where you want to be. You can source the large pulleys at a farm store, they have an array of hubs, plus an array of wheels, weld them up. Sounds awful, works fine, about $16 for a 12" pulley in your choice of hub sizes. If you still want to do wood, use 1 reduction for wood, 2 reductions and a jackshaft for metal. You should be able to get the DC motor to run at 1/10th rated speed if you have good parts. Keep in mind that the TORQUE available is the same at all the various speeds. Since HP is speed x torque you have 1/10th the HP at the lowest speed. Exceeding this means overheating the motor. Cheers. Roy wrote: In the process of making my 3 wheel bandsaw. I am wanting to use a DC motor of 1 1/2 hp with a speed controller, but would like to add a jack shaft. as well, just to make sure I can keep up the torque on the saw at the necessary speeds needed for general metal cutting. The motor I have is 1 1/2hp Leeson Electric, (removed from a typical treadmill) and runs up to 5120 rpm and pulls 15 amps. The controller I have for it is made by Dart and is supposedly capable of handling up to a 2 HP motor. I understand this controller is supposed to be able to keep the motors torque up at low speeds, but I would not bet my life on it. Guess I am just paranoid, as I do not have to much dealings with DC motors and controllers. So what ratios would I need to go with to get the saw down to useable speeds for metal cutting? (Looking for 65 to 550 SFPM from what I have found out in regards to speed), although it would be nice to jack it up in speed for wood cutting. Would I be better off initially reducing the speed with a gear reducer that drives a jackshaft and then the saw or what? Or should I still be able to get by with just a 4:1 ration jackshaft and rely on the speed controller to do its job? So far except for this problem, the project is going fine. I have one more wheel (drive wheel) yet to cast and machine, shuld have my tires next week, have the caster / camber tension assembly made, starting to work on the blade guides. This brings anopther question to light. Lots of saws today use simple ball bearing for guides. They seem to last ok on my H/V bandsaw, but have a habit of allowing lots of crub get by or get beat into the bearings or blade, so I was thinking on using some guides similar to what DoAll uses. Is there any materials out there that I can machine in a home shop thatw ould serve usefull in making these guides. They need to work with 3/8" at a minimum to no more than a 3/4" blade. Buying those Cool Cut guides is out of the question, so I need to come up with a home brew deal. I was also thinking of using a small engine valve tappet (like found in B & S engines) that runs in a bushing and is adjustable in and out with a setscrew. Any other ideas greatly appreciated. Presently I have just the basic shape of the frame laid out and am concentrating on making all the actual working parts, so I can juggle things here and there, and the frame will be built around these last. Looks like it will have a 17" + - 1" throat size, 8 1/2" to 9" cutting height, stand 71" tall, have a width of 29" and be 8 1/2" in depth, take a 107" blade is usiing the three wheels or a 86" blade if utilizing just two wheels. Table size 20 x 22. The table is still one item that I need to dio a bit of thinking on. I wiuld like to be able to mill it out so I can use a push type rip fence so it looks like a piece of steel plate or perhaps 1/2" thickness is in order, so if anyone has any other suggestions on a table they would also be appreciated. I already have a mitre / rip gauge from a large Delta belt / disk sander that I would like to use. Visit my website: http://www.frugalmachinist.com Opinions expressed are those of my wifes, I had no input whatsoever. Remove "nospam" from email addy. |
#3
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SFPM dilema and some questions on homemade bandsaw
Roy, I run a speed of 125 linear FPM on my saw at work and 200 LFPM fixed on
my upright home saw. The work saw has a mechanical variable speed, which I seldom change except in using it to cut wood. My home saw uses a reduction gearbox off of a conveyor system with a chain drive to the lower wheel. In cutting metal, it works perfectly fine. My bandsaw for wood however, runs at 4,300 LFPM fixed. That thing cuts most any wood faster than you can feed it. Hopefully these figures will be of some sort of help in your planning. RJ "Roy" wrote in message ... In the process of making my 3 wheel bandsaw. I am wanting to use a DC motor of 1 1/2 hp with a speed controller, but would like to add a jack shaft. as well, just to make sure I can keep up the torque on the saw at the necessary speeds needed for general metal cutting. The motor I have is 1 1/2hp Leeson Electric, (removed from a typical treadmill) and runs up to 5120 rpm and pulls 15 amps. The controller I have for it is made by Dart and is supposedly capable of handling up to a 2 HP motor. I understand this controller is supposed to be able to keep the motors torque up at low speeds, but I would not bet my life on it. Guess I am just paranoid, as I do not have to much dealings with DC motors and controllers. So what ratios would I need to go with to get the saw down to useable speeds for metal cutting? (Looking for 65 to 550 SFPM from what I have found out in regards to speed), although it would be nice to jack it up in speed for wood cutting. Would I be better off initially reducing the speed with a gear reducer that drives a jackshaft and then the saw or what? Or should I still be able to get by with just a 4:1 ration jackshaft and rely on the speed controller to do its job? So far except for this problem, the project is going fine. I have one more wheel (drive wheel) yet to cast and machine, shuld have my tires next week, have the caster / camber tension assembly made, starting to work on the blade guides. This brings anopther question to light. Lots of saws today use simple ball bearing for guides. They seem to last ok on my H/V bandsaw, but have a habit of allowing lots of crub get by or get beat into the bearings or blade, so I was thinking on using some guides similar to what DoAll uses. Is there any materials out there that I can machine in a home shop thatw ould serve usefull in making these guides. They need to work with 3/8" at a minimum to no more than a 3/4" blade. Buying those Cool Cut guides is out of the question, so I need to come up with a home brew deal. I was also thinking of using a small engine valve tappet (like found in B & S engines) that runs in a bushing and is adjustable in and out with a setscrew. Any other ideas greatly appreciated. Presently I have just the basic shape of the frame laid out and am concentrating on making all the actual working parts, so I can juggle things here and there, and the frame will be built around these last. Looks like it will have a 17" + - 1" throat size, 8 1/2" to 9" cutting height, stand 71" tall, have a width of 29" and be 8 1/2" in depth, take a 107" blade is usiing the three wheels or a 86" blade if utilizing just two wheels. Table size 20 x 22. The table is still one item that I need to dio a bit of thinking on. I wiuld like to be able to mill it out so I can use a push type rip fence so it looks like a piece of steel plate or perhaps 1/2" thickness is in order, so if anyone has any other suggestions on a table they would also be appreciated. I already have a mitre / rip gauge from a large Delta belt / disk sander that I would like to use. Visit my website: http://www.frugalmachinist.com Opinions expressed are those of my wifes, I had no input whatsoever. Remove "nospam" from email addy. |
#4
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SFPM dilema and some questions on homemade bandsaw
On Wed, 24 Dec 2003 16:13:14 GMT, (Roy) wrote:
===In the process of making my 3 wheel bandsaw. I am wanting to use a DC ===motor of 1 1/2 hp with a speed controller, but would like to add a snip I forgot, the wheels are 12 inches in diameter that I cast for this saw as I could not swing larger and machine them in my lathe. Regards Visit my website: http://www.frugalmachinist.com Opinions expressed are those of my wifes, I had no input whatsoever. Remove "nospam" from email addy. |
#6
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SFPM dilema and some questions on homemade bandsaw
I've pondered making a couple of tables with guide slots, but haven't gotten
around to making them yet. I think the way I'll approach the fabrication is to use 2 thinner plates (maybe 1/8") on each side of a bar. If the slot wouldn't be deep enough, the bar could have a slot milled in it. The plates could be welded to the bar, or attached with flat head countersunk screws (which could be filled with epoxy to avoid collecting chips in them). Some reinforcement ribs could be added where needed. I'll most likely frame the underside of the tables with bar stock. WB .............. The table is still one item that I need to dio a bit of thinking on. I wiuld like to be able to mill it out so I can use a push type rip fence so it looks like a piece of steel plate or perhaps 1/2" thickness is in order, so if anyone has any other suggestions on a table they would also be appreciated. I already have a mitre / rip gauge from a large Delta belt / disk sander that I would like to use. |
#7
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SFPM dilema and some questions on homemade bandsaw
Wild Bill wrote:
I've pondered making a couple of tables with guide slots, but haven't gotten around to making them yet. When I went to work on an old wood cutting bandsaw, I started by reading up on bandsaws. It seems that the bandsaw that cuts dead straight in the plane of the blade has yet to be invented so instead of a table with guide slots, I made a flat table and supplied myself with a piece of angle and two C clamps. A careful test cut allows me to draw a line on the table in the direction the saw cuts. This changes slowly with use on a given blade and also changes from blade to blade. The line is easily erased and re-drawn. My experience with my metal cutting bandsaw has been similar. Ted |
#8
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SFPM dilema and some questions on homemade bandsaw
Yep, I know whatcha mean. The test cut generally reveals which way, how much
to adjust for each time. It's almost funny that blades wander so much. Cuts made with narrow blades (on sabre saws, for example) seem to be even less predictable. My other applications are for slots in tables for grinding operations, where they'll provide a reference angle. WB ..................... "Ted Edwards" wrote in message ... Wild Bill wrote: I've pondered making a couple of tables with guide slots, but haven't gotten around to making them yet. When I went to work on an old wood cutting bandsaw, I started by reading up on bandsaws. It seems that the bandsaw that cuts dead straight in the plane of the blade has yet to be invented so instead of a table with guide slots, I made a flat table and supplied myself with a piece of angle and two C clamps. A careful test cut allows me to draw a line on the table in the direction the saw cuts. This changes slowly with use on a given blade and also changes from blade to blade. The line is easily erased and re-drawn. My experience with my metal cutting bandsaw has been similar. Ted |
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