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Slowing down a Craftsman 2 x 42" grinder
- Thread starter tedinatl
- Start date
I have the bigger one, the 3 wheeled, 1hp version. And it too runs fast. I can't conceive of a way to slow it down easily.
About the only way it could be done would be to remove the motor assembly, add in a step pulley, then add another motor (1750 rpm) and belt to drive it. If that was the approach you would take, it might be best to preserve the shaft, bearings, and housing and then fit the step pulley on the left side where the disk sander is attached. However, I'm not sure of the shaft diameter on those so finding the correct step pulley could be difficult.
All this is probably an attempt at making a silk purse out of a sows ear.
About the only way it could be done would be to remove the motor assembly, add in a step pulley, then add another motor (1750 rpm) and belt to drive it. If that was the approach you would take, it might be best to preserve the shaft, bearings, and housing and then fit the step pulley on the left side where the disk sander is attached. However, I'm not sure of the shaft diameter on those so finding the correct step pulley could be difficult.
All this is probably an attempt at making a silk purse out of a sows ear.
james terrio
Sharpest Knife in the Light Socket
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- Apr 15, 2010
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The short answer is no.
The good news is, if you can learn to use a light touch and grind accurately with a fast grinder, the skill will stay with you.
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- Sep 16, 2002
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I have no experience what so ever with the grinder you're speaking of, but it seems to me that if you could put a voltage regulator on it, and limit the amount of voltage going to the motor, it would slow down. Again, I have no experience with the grinder or it's design, but in general, the less volts an electric motor gets fed, the slower it runs. I think. 
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Yeah - I initially thought of doing this, but the power loss would be too great to still be useful.
It'll probably make more sense to just save up and buy a proper one in the near future. in the meantime, I'll keep practicing my light touch.
Thanks for you input, guys.
- Joined
- Jan 25, 2006
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- 211
Hi
1 Total budget for mods?
2 Skills and other tools you have, welder, lathe, mill/drill?
3 What Model, newer 2 wheel or older 3 wheel 2x42 (137.215280)?
It is quite easy to fit a new motor to the older model. I fitted a 1725RPM 1.5hp baldor. I used a screwed motor arbor adapter to get the drive wheel mated to the shaft and give sufficient extension to get through the casing. I used mdf board as the base and a wood block to raise the motor the appropriate. Motor $50 (used), arbor adapter 5/8 to 1/2 threaded $7 and wood offcuts free from a carpenter friend. See a picture here http://sites.google.com/site/alexnharvey/home/knifemaking/craftsman-2x42-grinder and a knife I made on it elsewhere on my site.
If you could find a motor with a 1/2" shaft and keyway you could skip the adaptor. You will need a motor with a shaft around 3-4" long I think if you go this way.
If you have the older type I would advise getting a thick section of angle iron cut to 2" wide, and use this as the platen instead of the stock part. You can also fit tile or pyroceramic to the face.
Future mods, I have considered increasing belt length in two ways.
1. Moving motor back, cutting slots in casing to allow belt to reach to the new drive wheel position.
2. Adding a tool shaft receiver tube, a square 1.5 id tube is mounted to a plate, plate screwed to the current platen mount hole or work table mount hole or both. Positioned to allow tool shaft to pass just above the motor shaft or stop short thereof. Then all kmg type attachments can be mounted. Casing must also be cut a little to allow belt to reach the new contact wheel or platen.
With the newer 2x42 you could fit a new 1725 motor behind the current motor and run 2x72 belts, using the current motor as a ball bearing arbor. Otherwise you need to find a motor that the belt unit can be attached to. I think maybe with a face mount motor and a custom made adaptor plate you could work something out. Other larger slower grinder and buffers units may have the same mounting holes as the craftsman, but I'm not sure if this is a standard drilling, I think it may be.
1 Total budget for mods?
2 Skills and other tools you have, welder, lathe, mill/drill?
3 What Model, newer 2 wheel or older 3 wheel 2x42 (137.215280)?
It is quite easy to fit a new motor to the older model. I fitted a 1725RPM 1.5hp baldor. I used a screwed motor arbor adapter to get the drive wheel mated to the shaft and give sufficient extension to get through the casing. I used mdf board as the base and a wood block to raise the motor the appropriate. Motor $50 (used), arbor adapter 5/8 to 1/2 threaded $7 and wood offcuts free from a carpenter friend. See a picture here http://sites.google.com/site/alexnharvey/home/knifemaking/craftsman-2x42-grinder and a knife I made on it elsewhere on my site.
If you could find a motor with a 1/2" shaft and keyway you could skip the adaptor. You will need a motor with a shaft around 3-4" long I think if you go this way.
If you have the older type I would advise getting a thick section of angle iron cut to 2" wide, and use this as the platen instead of the stock part. You can also fit tile or pyroceramic to the face.
Future mods, I have considered increasing belt length in two ways.
1. Moving motor back, cutting slots in casing to allow belt to reach to the new drive wheel position.
2. Adding a tool shaft receiver tube, a square 1.5 id tube is mounted to a plate, plate screwed to the current platen mount hole or work table mount hole or both. Positioned to allow tool shaft to pass just above the motor shaft or stop short thereof. Then all kmg type attachments can be mounted. Casing must also be cut a little to allow belt to reach the new contact wheel or platen.
With the newer 2x42 you could fit a new 1725 motor behind the current motor and run 2x72 belts, using the current motor as a ball bearing arbor. Otherwise you need to find a motor that the belt unit can be attached to. I think maybe with a face mount motor and a custom made adaptor plate you could work something out. Other larger slower grinder and buffers units may have the same mounting holes as the craftsman, but I'm not sure if this is a standard drilling, I think it may be.
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- Nov 1, 2010
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Thanks for the detailed response, Ernestrome. I like the mod that you did on your machine.
I have the newer one with two wheels, so I can probably look at ripping out the old motor, similar to what you did. I like the idea of a rear-mounted machine, which would add a third wheel but I'm not sure how I would cut/reconfigure the housing in that case. This would add the advantage of being able to run 72" belts on it, which is huge +.
I'll start by looking for a second hand motor similar to what you have, and go from there.
Thanks again for your input!
I have the newer one with two wheels, so I can probably look at ripping out the old motor, similar to what you did. I like the idea of a rear-mounted machine, which would add a third wheel but I'm not sure how I would cut/reconfigure the housing in that case. This would add the advantage of being able to run 72" belts on it, which is huge +.
I'll start by looking for a second hand motor similar to what you have, and go from there.
Thanks again for your input!
- Joined
- Jan 25, 2006
- Messages
- 211
I found my motor on craigslist, you can also try ebay and maybe a wanted post here. 1725 or 1140 rpm are good and may also have more torque than a 3450. 1HP plus is ok. I can stall my 1.5 as the belt slips- more belt tension probably solves this, or more masking tape on the drive wheel.
With the newer machine it is probably easier to leave the current motor in place as it is also the mounting point for the belt unit and provides a axle shaft for the lower wheel.
You can cut the case with a angle grinder and cutoff wheel or maybe hacksaw. I know others have done this with your type machine as they feel the guards get in the way, they then get more access to the wheel. I'm sure there are pictures here or at one of the other knife forums of such work. But you could also cut or file slots just for the belt and leave the rest in place. Post pics when done.
With the newer machine it is probably easier to leave the current motor in place as it is also the mounting point for the belt unit and provides a axle shaft for the lower wheel.
You can cut the case with a angle grinder and cutoff wheel or maybe hacksaw. I know others have done this with your type machine as they feel the guards get in the way, they then get more access to the wheel. I'm sure there are pictures here or at one of the other knife forums of such work. But you could also cut or file slots just for the belt and leave the rest in place. Post pics when done.
Stacy E. Apelt - Bladesmith
ilmarinen - MODERATOR
Moderator
Knifemaker / Craftsman / Service Provider
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- Aug 20, 2004
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If a sander has a disk on the other end of the motor shaft, take off the disk and mount a pulley.coil up the power cord and do not plug it in. Mount a second motor below the sander, and run a belt to it. Either use a VS motor, or mount a pulley of the size to make the sander run at the required speed. When you no longer need the sander, you can re-mount the disk and sell the unit as it used to be.
I have done this and it works well for making a slow speed sander.
I have done this and it works well for making a slow speed sander.
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Bingo!! I'm gonna try that....3400 rpm is way too fast for anything that I do...:thumbup:
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Just a couple months after I bought the Craftsman, I came across one a buddy was discarding......I rigged it up to a 1750 rpm motor and it's much better to do leather work, handles, etc. (I'm not a knife maker). I can also adjust it to run 48" belts by raising it on the mounting rack.
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Thanks for the replies everyone.
Stacy, I actually use the disc on mine a lot, so even though your suggestion is probably the easiest to implement, I'm not sure how I can implement it.
Rayban, that is a pretty cool setup you've got there. Thanks for sharing the picture!
Stacy, I actually use the disc on mine a lot, so even though your suggestion is probably the easiest to implement, I'm not sure how I can implement it.
Rayban, that is a pretty cool setup you've got there. Thanks for sharing the picture!
Last edited:
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Rayban I would like to see more pics of how you rigged yours up to run a different motor. Looks cool!
Stacy, that's a VERY good idea for alternately powering the 2x42!! How would one mount a pulley to where the disk portion is at?
Stacy, that's a VERY good idea for alternately powering the 2x42!! How would one mount a pulley to where the disk portion is at?
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I cut the frame in two, just below the platen brackets. I wanted to be able to move the tracking wheel assembly up to accept a 48" belt. I'm able to do that by unbolting it from "the rack of life" my Ironworker buddy built for me, and moving it up to the next set of holes.
So that left the drive wheel detached and on it's own ......so onto a 1/2 hp/1750 rpm with 1/2" arbor it went. That's really all there is to it.
I use it way more than I do the stock Craftsman sitting right next to it.
