# 2" X 42" Belt Grinder



## Mork (Apr 1, 2016)

I made this belt grinder with two 1/2"x 6"x 6" printing press shims (to level the press). I chucked one of the pieces in my 4-jaw and cut the hole then turned the pulleys on my Logan 200. The crowns were cut by setting the compound at 1.5 degrees cutting to the center, flipped the piece and did the same (V shaped crown). The belt tracks perfect and 1.5 HP is plenty. 80-grit is great for hogging off tons of steel, 120 is good for general deburing and shaping and 800 grit is amazing for sharpening knives and chisels! 

Link has more pictures and videos

https://onedrive.live.com/redir?res...30&authkey=!AFxCzARorkHfL90&ithint=folder,mp4


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## mikey (Apr 2, 2016)

Nice and clean - great job, Mork!!


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## rwm (Apr 2, 2016)

I love the simplicity and compactness of that design. No tracking adjustment? What are the pulley diameters?
R


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## TommyD (Apr 2, 2016)

Nice work


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## kvt (Apr 2, 2016)

That looks good,  simple but effective.  Thanks


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## Mork (Apr 2, 2016)

The pulley diameters are 3" for the drive and 2" for the idler. I used a similar grinder (at work) as a model in some respects but the one at work is 1725 PPM. My motor is 3450. The one at work had a 4" pulley so the belt surface speed is 50% faster on mine. I'm sure their are advantages to slower speeds, like less heat but, I'm glad I made mine faster. Most often I just want to shape metal or deburr and if I want to sharpen I can limit contact time to reduce heat. Honestly, if I was to make another one I'd go a little faster...  this little sander runs circles around the Baldor at work! 

As far as tracking goes...  I think I got lucky and everything is well aligned. As a test I took an adjustable wrench and put twisting pressure on the tension arm and it made the belt miss track.

One great aspect is cost. The 1-inch grinder at work sells for nearly $500 and mine cost me about $35.


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## rwm (Apr 2, 2016)

Thanks for the details. Especially the speed information. I'll see what motors I have. Any issues with slippage on the metal pulleys?
I am thining I could align the top pulley by laying a weld bead on one side of the vertical support as necessary. Once it's aligned it should stay that way yes?
R


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## mikey (Apr 2, 2016)

I think you can still buy the parts that Sears uses on their 2 X 42 belt sanders from Sears Parts Direct. You might look at the tracking mechanism on their sander as its quite good and very precise. Tracking will vary from belt to belt so some way to adjust tracking is necessary. Oftentimes, you need to track the belt off to one side or the other to grind a step into a part so adjustable tracking is really nice to have. A really solid platen, ideally with a Pyroceram liner on it, and a precisely adjustable tool rest are other must-haves, I think. 

Again, nice job.


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## Mork (Apr 2, 2016)

RWM, I have had no problem at all with slippage. I was somewhat concerned about this when I build the grinder but at least so far it's not an issue. I think more crown on the pulley would create more slippage (less contact area). I think I mentioned this about but the crown I used was 1.5 degrees. I can't say if less would be better but this worked very well. 

I put a set screw just under the top lever pivot point but ended up removing it. This seems a bit crude but it there is a problem its very effective. The belt pulling pulling down on the upper pulley will try to deflect it downward and the set screw would remove any slop in the pivot point and compensate. 

Here's a theory I have based on working in the printing industry for many years. We have all kinds of belts ranging from about 18 inches wide doe 1/2" inch wide. The wider the belt the more difficult it is to keep it tracking right. 2 to 3 inch Also a larger crown works better to a point but tends to cup the belt. 

So to answer your question, Yes I suspect that once the tracking is adjusted it should stay put unless something wears. I have a 4 inch belt sander for woodworking and it seems I have to tweak the tracking fairly often...  again, this is over that 3 inch width and with a shallow crown. 

Mikey, thats a great idea to buy the pulleys but it was actually fun to make the pulleys. Also, the motor I was working with had a strange end in the shaft. It had a threaded shaft...  this may or may not be an issue if you buy the pulleys.


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## rwm (Apr 2, 2016)

Thank you. Makes sense.
In my motor stock I have a Baldor 3/4 HP 1725 motor. What say ye?
R


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## Mork (Apr 2, 2016)

A 6-inch pulley at 1725 should produce the same surface speed as 3-inch at 3450. 3/4HP should be more than enough...

But check my math!


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## rwm (Apr 2, 2016)

I think you are correct on both counts. I may run a 5" pulley on the motor and use a 2" tracking pulley. I guess I will make a tracking adjustment mechanism somehow.
Thinking about this:


I will start my own thread when I get going.
Robert


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## Mork (Apr 2, 2016)

I thought about the math...  you need a 6-inch to get the same surface speed as mine. Your tracking adjustment would work well but keep in mind only very small amount of adjustments will be needed. If I was making mine again I would make the tension arm a bit wider so that there was more room for a set screw below the pivot point. My arm is 1.25" but 1.5 or 1.75 would leave room for a single set screw. Look at this picture and you will see what I mean. I installed 2 screw but one would have worked just as well. Ultimately I found I needed nothing for tracking but I was probably lucky. Despite the fact that the pivot point it a bit tight (no slop) tightening the tracking screw even a small amount drastically effects tracking.

Something I just thought of...  a 6-inch drive wheel or pulley would drastically increase belt contact area. I don't have any problems with slippage but with a 6-inch drive would probably eliminate this possibility completely.


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## Mork (Apr 2, 2016)

3-inch drive pulley. The short motor shaft was 5/8" with a reduced threaded end. I had to bore fairly deep to leave enough thread exposure for the nut. On the other side the shaft is about 1-inch deep. I was very careful to get a perfect fit because of the limited depth. I'm fairly new to the hobby and was proud of the fit...  same with the bearing fits on the upper pulley. My Logan 200 adjustments are 1:1. In other words, if you move the tool .001 it reduces the diameter by .002. It would be a lot better if it was made like new lathes...  a movement of .001 is actually .0005 or .001 in diameter. I don't mind the math but small moves are hard to make.


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## rwm (Apr 3, 2016)

Maybe the tracking adjustment is overkill. Hmmm...what about using a a long bolt mounted along the side of the vertical support between two blocks. Tightening the bolt would cause minor flex in the vertical support and very slightly tilt the tracking wheel? Thoughts?
I'm going to use aluminum for the base and place a piece vertically outboard of the drive pulley. That piece will have a fitting for dust collection. The drive pulley will essentially be enclosed in a box that way.
I'm looking at 5" stock and its pretty pricey. Maybe I'll have to cast a pulley.
R

Edit: After doing some napkin math and playing with my 12" disc sander I believe a 1725 rpm motor with a 5" pulley will be too slow. I think I need a 3450 motor or I would have to use at least an 8" pulley to get good speeds for steel. I may try to find a 3450 motor and use the 5" pulley.

Robert


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## Mork (Apr 3, 2016)

RWM, I thought about doing exactly as you suggested but I used angle iron for the upright which won't flex as needed. If I had used 1.25" x 3/8" this method would work excellent. 

A 6 inch pulley would be the same speed as my 3 inch pulley on a 1725 motor...  which is fast enough. 3450 with a 5 inch pulley would be smoking! My biggest concern would be vibration but if you are careful it would be one mean machine )  Be careful with things like setscrews and key ways. My motor has no key way and the pulley mounts with a nut on the end. When I got the motor I saw this as a bad thing but in hindsight it's probably a big plus....  the grinder is smooth as silk. I would suggest looking at commercial belt grinders and see what they use. 

Here's a fairly fast one. Belt SFPM: 4400 

Hmmm...  My sander figures out to be 2700 FPM  - Interesting. Your idea about using a 5 inch is about the same as the link. Go for it! 

https://www.zoro.com/dayton-beltdis...ktHi3NMeV8u8FqZ72mzm0BoCgfjw_wcB&gclsrc=aw.ds

Dust collection would be nice but don't sand any wood. I heard they had a fire at work because somebody sanded a bunch of wood. Somebody else was grinding away on metal and saw smoke. Apparently there wasn't enough sawdust to create a big fire but they did have to replace the bag. Just a comical side note. Be careful vacuuming up ashes around a wood stove too. I had a vacuum turn into a jet engine!


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## rwm (Apr 3, 2016)

Oops...I just bought a Marathon 3/4 HP TEFC washdown motor on Ebay for $70. Are Marathons' any good?
R


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## Mork (Apr 3, 2016)

Ha...  I have no idea. I'm sure if you are not in an industrial environment just about any motor is a good one. The only one I know to be good is Baldor. I can't even remember what my motor is...  i think it's a Wagner. It has a noising bearing but unless it gets worse I'm not going to fool with it.


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## VaBob (Apr 4, 2016)

I also work in the print industry.  And unless a belt in the press is sloppy loose or has a cut half way across it, theres no worry about it shooting off into the machine.  Its very much like watching antique tractors run a belt to other equipment.  You see it flip around, and jerk on that pulley, but because of the crown on it the belt hardly ever falls off.

I like your set up, mind if I copy it someday?


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## Mork (Apr 4, 2016)

Copy?  Go for it. 

Harrisonburg???  Do you also work at RRD?


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## rwm (Apr 4, 2016)

This is great! $400 worth of raw materials and I will have a $300 grinder. I need to start doing some better scrounging.
R


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## rwm (Apr 6, 2016)

OK. I gotta ask....Why  2 x 42? On Mcmasters website 2 x 48 are about half the cost for belts. What gives?
R


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## Mork (Apr 6, 2016)

Very good question. I looked for availability on Amazon and 42 and 48 were about the same price...  averaged about $18 to $20 for 6 belts and free shipping if you have Prime. Wow...  you are right about McMaster. I wonder why? 48" must be more common. I also looked at available belt grinders on Amazon and 42 was about as common as 48. 

There isn't much difference when it comes to exposed belt and 42 is more than enough for what I do but based on McMaster I might go with 48 if I was just starting to build one. Either way I don't think it will ever be hard to find the 42 for close to the same price. I don't shop much at McMaster unless I can't find it somewhere else. They have just about everything you can possibly imagine and an excellent web site but you almost always pay more. 

If you have a 1725 motor with a larger pulley your exposed belt length will be reduced so based this and McMaster's price I'd go with 48".


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## rwm (Apr 7, 2016)

Got it. I got the 3450 RPM motor. I started another thread rather that hijack this. I think I will go with 48". I am going with a 4" drive pulley which I will machine out of billet. I was afraid if I cast one there could be balance issues.

R


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## Mork (Apr 7, 2016)

That sounds like a good speed. Have fun and post some pictures.


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