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treadmill motor disc sander

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4K views 23 replies 11 participants last post by  cebfish 
#1 · (Edited by Moderator)
I have a treadmill motor and I am making a disc sander. Is there an advantage of making it an 8" or a 12" disc? The 8" disc are cheaper. What is the advantage of making it 12"?
 
#3 ·
Larger usable surface area. Only one half of the sander is safe to use for many operations. 12" disk gives you 2 more inches of disk that are moving towards the table.

- RobHannon
+1 in sanding bigger is better
 
#5 ·
Thanks for posting this question…
I have an old treadmill motor gathering dust. I don't have a disc sander. Be sure to share your finished project. Perhaps I will be inspired to blow the dust off that motor.
 
#6 ·
8 inch are cheaper, meaning easier and cheaper to change. But in all honesty i very rarely change my discs. I change belts more(combo belt/disc). The discs i tend to just leave an 80ish grit on for years and keep clean with one of those gummy stick things.
 
#7 ·
I am curious, why would you use a treadmill motor for a disc sander? Treadmill motors are DC and variable speed via PWM (pulse width modulation) disc sanders don't need variable speed. I would consider using the DC motor to make my drill press, band saw, or Reeves drive type lathe variable speed. Think about it, no more pulleys to change speed on the drill press, could make that old band saw slow enough to cut steel. Just a thought folks.
 
#8 ·
I think changing speeds on a disk sander would absolutely be beneficial. I have a fixed speed belt/disk combo and a 2×72 with variable speed. The 2×72 gets used much more often and the variable speed is a big reason why.
 
#9 ·
I think changing speeds on a disk sander would absolutely be beneficial. I have a fixed speed belt/disk combo and a 2×72 with variable speed. The 2×72 gets used much more often and the variable speed is a big reason why.

- HokieKen
ok kenny tell us,why variable speed on a disc sander? i dont get it.
 
#11 ·
You may not use the variable speed option often, but when you need it, it would be great.

I acquired a four wheel grinder off craigslist. It came with a 1,700 RPM, 220 AC motor and I ran it that way, until I scored a 3/4 hp DC motor and controller at a yard sale for twenty. I swapped the 220 for the variable speed, 115 VDC unit, and now I can reverse the grinder and vary it between zero and two thousand RPM.

When sharpening things, slow is king.

Variable speed can be great even when grinding away at wood. Fir, pine and other softwoods tolerate high speeds much better than, say, cherry or other hardwoods that are prone to burning.
 
#12 ·
What they said pottz^ There are times I may have a really hard wood like oak or Hickory that I need to hog down to a line and I really want to lean on it, at those times, I want that thing spinning fast. On the other hand, if I'm shaving a piece of Cherry down to final size, I want that thing spinning slow since Cherry usually burns if I look at it funny.

I'm not suggesting that VS is necessary or that it would be used all the time but, I would even like to have the option of 2 speeds for my belt/disk combo sander. It would be a lot more versatile IMO.
 
#14 ·
What they said pottz^ There are times I may have a really hard wood like oak or Hickory that I need to hog down to a line and I really want to lean on it, at those times, I want that thing spinning fast. On the other hand, if I m shaving a piece of Cherry down to final size, I want that thing spinning slow since Cherry usually burns if I look at it funny.

I m not suggesting that VS is necessary or that it would be used all the time but, I would even like to have the option of 2 speeds for my belt/disk combo sander. It would be a lot more versatile IMO.

- HokieKen
ok ill buy that,never thought about before because ive never had a vs disc sander,but it makes sense.although burning wood means too much heat caused by too much pressure.
 
#15 ·
...

ok ill buy that,never thought about before because ive never had a vs disc sander,but it makes sense.although burning wood means too much heat caused by too much pressure.

- pottz
To be clear, I don't have a VS disk sander either. I just think it would be handy ;-) I do have a fixed speed 4×36 belt and a variable speed 2×72 and can say for sure that the variable speed is useful as heck with a belt. I suspect the same would be true with a disk but, I could be totally wrong…

And heat is caused by a combination of pressure and speed. So, to prevent burning, you can indeed apply less pressure. Or you can reduce speed.
 
#16 ·
...

ok ill buy that,never thought about before because ive never had a vs disc sander,but it makes sense.although burning wood means too much heat caused by too much pressure.

- pottz

To be clear, I don t have a VS disk sander either. I just think it would be handy ;-) I do have a fixed speed 4×36 belt and a variable speed 2×72 and can say for sure that the variable speed is useful as heck with a belt. I suspect the same would be true with a disk but, I could be totally wrong…

And heat is caused by a combination of pressure and speed. So, to prevent burning, you can indeed apply less pressure. Or you can reduce speed.

- HokieKen
what do you think about adding a speed control to the sander as you would a router? should work right?
 
#18 ·
Depends on the motor type Larry. My belt/disk has an AC brushless motor so a speed controller won't work with it. If you have one that has a brushed motor though, a router speed controller would do the trick.
 
#19 ·
A few years back, I used a treadmill motor to resurrect a lathe. See lumberjock blog link below.

I use the lathe from time to time but find it a bit difficult to get use to. You see the motor controller does a great job keeping the lathe running at constant speed but there is a bit of a lag when I apply pressure to the wood.

This is the results when the motor controller's circuit detects a drop in the rpm's and then it will sends more voltage to the motor to increase the speed. There is a noticeable lag in this process because the controller also has a soft increase/decrease circuit so you won't be thrown off the treadmill.

You may find the same results in your build.

http://www.lumberjocks.com/Sawdustonmyshoulder/blog/44473
 
#20 · (Edited by Moderator)
I am curious, why would you use a treadmill motor for a disc sander?
- Brawler
Hmmm….

  • Because you already have it.
  • Because it won't cost very much. if anything to do.
  • Because variable speed can come in handy under some circumstances
    (such as when using it to sharpen stuff)
  • Because otherwise the motor is just sitting there gathering dust.
  • Because re-purposing stuff into usable tools is just plain cool.

I have three or four 2+hp treadmill motors and controllers out in the garage that I got for free (along with lots of extra stuff stripped out of the treadmills). If I didn't already have a belt/disc sander, I'd consider using one for the task. YMMV.

Cheers,
Brad
 
#21 ·
I am curious, why would you use a treadmill motor for a disc sander?
- Brawler

Hmmm….

  • Because you already have it.
  • Because it won t cost very much. if anything to do.
  • Because variable speed can come in handy under some circumstances
    (such as when using it to sharpen stuff)
  • Because otherwise the motor is just sitting there gathering dust.
  • Because re-purposing stuff into usable tools is just plain cool.

I have three or four 2+hp treadmill motors and controllers out in the garage that I got for free (along with lots of extra stuff stripped out of the treadmills). If I didn t already have a belt/disc sander, I d consider using one for the task. YMMV.

Cheers,
Brad

- MrUnix
I agree with all of you post except I don't sharpen things on a disc sander. Re-purposing the treadmill motor to be useful is cool, I plan on updating my drill press when I come across DC motor. I'm also going to build a disc sander out of an old AC induction motor I have laying around. I can see the use in a VS belt sander but the original thread was about a disc sander, how they are used I don't see the value in VS. My original post was to meant to promote other cool alternatives ideas for tool upgrades.
 
#22 ·
Totally understood Daniel and a valid point of view for sure! To be honest, if I had an extra DC motor laying around, I'd be more inclined to put it on the drill press too!
 
#23 · (Edited by Moderator)
A lighter touch [which doesn't always work] aside, it was mentioned, above, that slowing the sander down reduced burning on woods like cherry. Friction being what it is, higher speeds mean more heat.

I guess you could say it's a bit like table saw kick back - you can't beat the machine, so you're going to get some burning.

I mentioned my four wheel grinder ran from a 3/4 horse, DC motor and controller (industrial sewing machine motors). It makes most grinders [that run at 1,700 or 3,400 RPM] look like ancient, outdated technology.

It's obvious to those who've ran grinders that different metals and woods react differently to those speeds. Sometimes your best efforts to go lightly are not enough. Being able to turn a wheel down to 300-500 RPM makes stock removal, while avoiding heat, a cake walk.
 
#24 ·
Thank you all for your input. I may explore putting it on my drill press. The only problem I see is if I put it on drill press and it quits working at a time when I need it most I would have reconfigure my drill press. The motor I found was dumped out on the side of the road so it may last a day or for years
 
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