2x72 Grinder. How wide are idler wheels?

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PaMtnBkr

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Dec 31, 2009
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I am building a 2x72 Belt grinder and a friend of mine gave me some aluminum round stock (3.5" Dia) that I am going to make into idler wheels on a lathe at work. How wide do the wheels need to be? Thank you!
 
go for 2 1/8 to 2 1/4 just incase your alignment is not perfect the tracking pulley, with crown is 2.250
 
I was thinking I may want to go a bit wider than the belt? The tracking wheel I was going to go at least 2.5" wide? Is there any reason to NOT go 3.5" for the Dia (not width) of the wheels? I figured that it probably would not matter on the Dia? Thanks again!
 
PaMtnBkr said:
I was thinking I may want to go a bit wider than the belt? The tracking wheel I was going to go at least 2.5" wide?

Is there any reason to NOT go 3.5" for the Dia (not width) of the wheels? I figured that it probably would not matter on the Dia? Thanks again!
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The larger the diameter of the wheel, the fewer revolutions the bearings get, the cooler they stay and the longer they last.

I think mine is about 4 or 5"

Look at the size of the TW-90 wheel, it's bigger than most others & I don't think it's an accident.
 
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My drive wheel and tracking wheel that I made are both 4" diameter, and 2.5" wide. You will need to turn a crown on the tracking wheel.
 
Since my machining skills are weak at best, I was going to just cut a croove in the tracking wheel and use a large O ring in it for the crown.
 
The crown is not that hard, just put a couple of degrees on the compound and peel off cuts until the high spot is in the middle, repeat for the other side.

Since the OD doesn't have to meet any real measurement, no problems.
 
Some guys just put electrical tape on their wheel for a crown and says it works fine.
 
I'm not trying to contradict the Count, just adding that I made my platen wheels 2"x2" and my tracking wheel 2.5" wide by 3.5" tall, and they all work well. He's right too, the crown is easy. You could even do it adequately without the compound, mark the center and leave about 1/2" wide as the high part, then drag light passes in steps off both sides. Doesn't have to be precise.
 
I didn't mean to imply that the size you listed wouldn't work, just that the bigger the better.
The sizes make a difference in a hurry,
4" is 25% slower than a 3",
5 is 40% slower than 3"
6 is 50% slower than a 3".

A 6" piece of AL costs a few $ though.



You will be limited by the material, but also the lathe size too.


Have a watch on the Beaumont wheel video for work-holding and order of operations
It makes good sense to do it their way
with inside bore and outside all with the same setup


If they are wheels with bearings, make a spacer of the right length so when you mount the bearings, they don't squeeze tight.

[video=youtube;klzHjz1_G78]http://www.youtube.com/watch?v=klzHjz1_G78[/video]
 
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Forget the electrical tape that will soon want to come off and use some ordinary tan coloured masking tape. It will stay on for months or longer. Frank
 
Frank Niro said:
Forget the electrical tape that will soon want to come off and use some ordinary tan coloured masking tape. It will stay on for months or longer. Frank
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Oh....sorry that is what I meant. Good catch Frank
 
If you have the lathe available you can do a simple crown like the count said. I machined mine with an 8" radius on my wheels, but I used a CNC lathe. On a manual machine set your compound for 5° and cut and angles from the center of the wheel to each edge of the wheel. Then set the compound to 10° and split each 5° angle in half (¼ of the width of the wheel) and cut the 10° angle to the edge of the wheel. You will have 3 points where your angles meet on the wheel from there file a slight radius on the transition points to blend them in and sand with some emery paper and your good to go. Be sure to machine the o.d. and the i.d for the bearings in the same set-up so your wheel will run concentric on your grinder. Forget the tape of any kind. A properly machined wheel is forever and simple to do if you have the right machinery.
 
Thank you folks for the insight. I have access to a manual lathe, a fairly large one. My materials are 3.5 and 3.75 Dia 6061 Alum round stock Pcs anywhere from 3-4" long. I was going to keep the wheels simple and not hog out any excess material. Is that proper thinking? To keep as much mass as possible w/the wheels? Also, when I make my bearing seats, do I want the Dia to be EXACTLY the same size as the OD of the bearings? Thank you for all the help on this exciting process! Don
 
You want the I.D. that the bearings will go in to be about +.0003 / .0005 over the bearing size. If you machine them to the same size as the bearing o.d. you can sand the last .0003 of material out. You do not want a tight press fit or you will ruin the bearings. If you take more material than you wanted you can always loctite the bearings in place.

I just noticed that you live close by. If you need any help I may be able to help you out.
 
Ah, a textbook example of why filling your profile out is a very good idea.

That's a good point, Count about idler wheel OD and RPM.
 
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