Hello all, I do hope this is the correct place for this question.

I'm in the process of building a 2"X72" belt grinder - doing as much as possible myself - my time is cheap since I'm retired.

Question about the wheels used on the grinder - The motor drive wheel I built from a 4" aluminum rod - 2" wide and flat across the top. Is flat across the top normal? OR do they have a slight crown? If so, how much of a crown - 1/8"?

The tracking wheel (this is the spring loaded wheel) - I'd plan to make it from 3" diameter aluminum rod with 1/2" ID roller bearings. Question, does this tracking wheel normally have a crown? If so, how much?

The two platen wheels - I'd planned 2" aluminum rod for these, and from photos I've seen they look flat across the top - of course as the other wheels the edges are "broke over" with perhaps an 1/8" (or slightly less?) radius.

Thank you all for any help or suggestions.

Ken H>

I got mine from beaumont metals since i did not have access to a lathe. the ones i have do have a 1 degree crown on the idle wheel and drive. the crown is good for your tracking but not sure if it makes a difference on the drive. they are broke over on the edges. about an 1/8 in or so. hope this helps.


Best regards

Thank you for the response, and that's the type of info I am looking for. I'm not sure I understand the "1 degree crown" statement - to me that would mean measuring from outside edge of a 2" wheel, the top would form a 1º angle, and that's only about 1/32" or less higher in the middle than at edges - unless I'm missing something.

I can surely try to put a crown on - it's harder than it sounds to make an even rounded top to the wheel using hand feed on the lathe. Maybe I can rig some type of template and follow that?

Thank you again for the info,

Ken H>

it's a very Small Crown in the wheels but it is there, give it a shot with out it, I started out on mine using castor wheels I put bearings in. it did the job just fine.
it also tracked the belt ok as well... Just saying ( my kids say that all the time) :P

Thanks for the clarification - I think I'll try the drive wheel flat to start, but maybe try to put a tad of crown in the tracking wheel. You've given me a good idea of what's in the commercial wheels. I've never seen one and trying to build.

Thanks again - isn't this internet a wonderful thing?

Ken H>

I put about an 1/8" on mine. Had a crown on both idlers, but must not have had them true with one another and the belt wobbled a bit. Turned one roller flat again and no more belt wobble.

Dodge, how did you get the 1/8" crown? Was it a even rounded crown from side to side?

Another question - how important is reverse on this type of grinder? I've only experience with a 6"X48" HF grinder and those tend to have a direction on the sanding belt. I suspect it would be ok to reverse for short times?

Thanks again to all for info and guidance,
Ken H>

the belts I buy have an arrow for the direction of travel, don't believe it's too safe to put them in reverse, I have done it with no issues though...

the grinders I have used never needed a revers direction, the direction for the belts is mainly for the glue/tape joint

Thank you gentlemen for the response - I'd never considered running a belt grinder in reverse, then reading some posts, and builds of grinders they talked about having the reverse option - and sometimes at extra cost. I like my grinder throwing the sparks downward, and just couldn't understand the reverse option. Hence, my questions. Not much bother or cost, but I don't think I'll bother wiring in a reverse switch.

Thanks again - I do hope to have a grinder completed in a couple of weeks..... UNLESS this turns into more problems than I'm expecting.

Ken H>

Ive been building my grinder in my spare time too. all with scrap pieces and I found that in order to adjust the belt better. I had to crown the tensioner pulley slightly. The pulley on the motor was left flat. i should have it running by this weekend.

Most modern belts will work okay in either direction. I sometimes flip my belts to get a little more wear from them. That reverses the direction of the belt though the grinder still goes in only one direction.

KenH, crown on a grinder wheel is just like crown on a flat belt pully. If you have a Machineries Manual shows a table for.
But in short the high point is dead center in the wheel and there is straight taper in both directions from the center. You can set up you compound if you have one to easily make a 1 degree. The swing 1 degree from center the other way.
I use the table in the machineries as they reccomend different crowning for different od pullies, but it is probably not a critical issue.

@ptree, thank you for the comment - from your comment and others it seems like the crown isn't as critical in shape or size as I was concerned it was.

 

I've got the basic grinder running now with a 1hp, 1750 rpm motor setup in direct drive with a 4" direct drive pulley. (I'm waiting for the flanges and step pulleys) I built based on the KMG grinder, and have made good use of the grinder plans by Mike Clerc:http://www.metalwebnews.com/manuals/knife-grinder.pdf  I have the platen setup with a 2" aluminum wheel at top and bottom of platen support and a 3" tensioner/tracking wheel.

 

With this setup, the grinder runs pretty quiet and belt tracks - as I adjust the tensioner wheel, the belt will move from side to side just as it should.  My question:  When adjusting the tracking wheel to get belt to run in center of drive pulley and other wheels, the tracking wheel is angled down rather than looking level. Is that an issue? If so, what could be some of the causes? By adjusting the tracking wheel, I can move the belt from side to side on the wheel to run where I wish.  When grinding (slack belt mode) the belt stays where it is set ok.

 

2. When adjusting the Platen support with the Platen mounted - Just how much clearance should there be between the platen and back of belt? I'm thinking the belt should just "kiss" the face of platen putting only a slight pressure (1/32" interference?). OR should it have a bit more pressure just sitting there? Or just clearing platen when not running?

Thanks for any help or suggestions.... (I need all the guidance I can get<

Ken H>