Bearing drag on Poly Wheel for my 2"x72"

Brian Ayres

Brian Ayres

Joined
Feb 4, 2011
Messages
1,429
So.... I'm almost ready to fire up my GIB.... question... Am I over thinking my set up? When I ran my bolt through the platen, and tightened up the wheels to eliminate slop, they don't roll freely. If I loosen them up, then there's slop side to side... I'm talking a hundredth or less, but...

It's my first grinder, so I don't know what's "normal".

I got these bronze bushings from our local bearing supply that have the same ID and OD as the inner raceway on the bearings hoping they'd concentrate the force onto the inner raceway only...., but still have drag when I tighten too much. I assume it's because the bearings aren't engineered for much lateral force?

I got the poly wheels, and the recommended machine bushing/washers from Tracy when I ordered my parts. The reason I'm wondering about this, is because I can tighten the Idler/Tracking wheel pretty tight, and it doesn't appear to have any drag the way the poly wheels do... Will they loosen up after running for a bit if I tighten them up?


PolyWHeel2.jpg
 
Sealed bearings do break in. They will get better with some time on them. On a grinder I suspect that it wont take very long, maybe 30 minutes tops. Run it and shut it down to recheck the run-out and vertically and horizontally.


-Xander
 
fluidsteel, I'm going to assume that's the same 2" "economy" wheel I got from usaknifemaker. If so, I had, and still have the same issue.

The 10" wheel for some reason has none of these issues and runs free and easy with fair tightening, but the 2" wheel no matter what, always was either really sloppy (any looseness with the nut), or had some drag and wouldn't spin very freely. In the end, I've just left mine as tight as needs be to keep it running slop free, it generates some heat, and I see some small bleeding of bearing grease, but it's working fine for me so far, and I've been using it a lot.

The heat generated wont make the bolt so hot that you can't touch it, but it's definitely hot. YMMV, I thought about asking Tracy if that was normal, but decided to just run with it.
 
Yeah now that I'm looking around, I'm guessing mine is ultimately being destroyed by this resistance. I tried tons of varieties of bushings however, and never had any luck making them not drag.
 
javand said:
fluidsteel, I'm going to assume that's the same 2" "economy" wheel I got from usaknifemaker. If so, I had, and still have the same issue.

The 10" wheel for some reason has none of these issues and runs free and easy with fair tightening, but the 2" wheel no matter what, always was either really sloppy (any looseness with the nut), or had some drag and wouldn't spin very freely. In the end, I've just left mine as tight as needs be to keep it running slop free, it generates some heat, and I see some small bleeding of bearing grease, but it's working fine for me so far, and I've been using it a lot.

The heat generated wont make the bolt so hot that you can't touch it, but it's definitely hot. YMMV, I thought about asking Tracy if that was normal, but decided to just run with it.
Click to expand...

Yup, from Tracy at usaknifemaker.... I checked before posting and the 4" idler/tracking wheel has the same bearings, but no drag. :confused:
I "feel" like it's a quality of the bearing issue. Maybe I should get new bearings pressed in?
Or, just use them as is, and buy better wheels from Rob at Beaumont down the road?
I know Unki Gumby(George) was having problems at first too, but thought it was because he didn't order the machine bushings to start?
 
Is the inside of the wheel stepped with a shoulder?

Or

Is the ID continuous all the way through?


I would want one bushing in the middle. It looks like your bushings are short & you need more than one.

The length would be determined by the space between the bearings when pressed in up against the shoulder (assuming a shoulder)

If you can tighten the screw and make the bearings bind, I would check to see the bushing is too short
- or press in the bearings a bit to seat against the bushing (assuming no shoulder)



The problems I see with using hex head cap screws screws is that they are tapered & the wheel won't mount straight.
 
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Hmm sounds as if the bearings are suspect. Try your local bicycle shop for new bearings or if you have a machine supply near by. Maybe try ceramic bearings, I have had nothing but good luck with these guys: http://www.bocabearings.com/ for all kinds of stuff. I think ceramic hybrid would be good for a grinder. Steel inner and outer races but with ceramic balls.


-Xander
 
12345678910 said:
Is the inside of the wheel stepped with a shoulder?

Or

Is the ID continuous all the way through?


I would want one bushing in the middle. It looks like your bushings are short & you need more than one.

The length would be determined by the space between the bearings when pressed in up against the shoulder (assuming a shoulder)

If you can tighten the screw and make the bearings bind, I would check to see the bushing is too short
- or press in the bearings a bit to seat against the bushing (assuming no shoulder)



The problems I see with using hex head cap screws screws is that they are tapered & the wheel won't mount straight.
Click to expand...

The inside does have a shoulder.... I could put a bushing inside. The bushings I got were an attempt to keep all the force from the nut on the inner raceway.

The wheels should be able to be used as is. I'll call Tracy tomorrow. If needed I can put a bushing through the center.

The hex cap screws have 2" shoulders so they run through the wheels and have the same OD the entire length so no wobble... The hex bolt, connects to the platen and I run a nut out the shaft of the bolt to hold the wheel straight.
 
Is there a spacer inside the wheel?
A cylinder inside that presses against the inner race when you tighten it up?
 
Fellhoelter said:
Is there a spacer inside the wheel?
A cylinder inside that presses against the inner race when you tighten it up?
Click to expand...

No, I imagine that's the problem. Tighten the nut and it forces the inner race latterly causing friction. I just removed the tracking wheel.... Same bearings, BUT, it has a spacer inside. :confused:

Looks like I need to pull the bearings and add a spacer... Any idea on a source for a 1/2" ID x 1-1/2ish spacer? I have enough of the bronze bushings to stack if needed, maybe McGuire bearing has longer ones.....Hmmmm.

Will I have to buy new bearings if I add a spacer, I assume it's likely I'll damage them getting them out?

Thanks for all the help! :D
 
You may need to add shims additionally to the spacers, they need to be pretty spot on to work properly.

It doesn't take much pressure to cause binding.
 
The problem with the budget wheels isn't the bearings, it is because they don't have an inner sleeve. This causes the inner race to bind when tightened. I have the same wheels and the same problem, with a lot of tinkering and using the lock nut system you can get it spinning freely. The better solution is to knock out the original bearings and replace them with new ones and adding an inner sleeve to the wheels. My 8" wheel spins nicely and was easy to get the right preload on, but the small wheel is taking a lot of trial and error:o and I was a bike mechanic and did this sort of bearing adjustment 8+ times a day. Once the bearings are shot I am going to replace them and sleeve the inside on mine, good bearings are cheep enough to buy, but I am just being lazy right now:p

The tracking wheel has an inner sleeve BTW and I have my wheels running reasonably drag free so that they don't generate a lot of heat.
 
Maybe contact Tracy and let him know. I am sure he would be cool with helping get it straightened out, after all, he is the one selling them and would probably want to know.
 
Mike Davis said:
Maybe contact Tracy and let him know. I am sure he would be cool with helping get it straightened out, after all, he is the one selling them and would probably want to know.
Click to expand...

I'll e-mail Tracy tonight.. Now that I know the issue. Thanks!
 
When I talked with Tracy about them(I had the same issue) he said them warming up was normal, but if they get too hot to touch comfortably, the nut is probably too tight.

It is the lack of sleeve on the inside that is the culprit. The lateral force on the inner raceway causes binding. The bearings are cheap enough that you should probably just use them as is until you wear them out and when you replace them add a sleeve.
 
Actually, I had the grinder running for about 3 hours tonight(not constantly, but pretty heavily), and actually, the bearings are no longer heating up significantly. So I guess they've broken in. YMMV of course.
 
If the wheel was made properly (bearing pockets coaxial/parallel/snug fit on outer bearing race) then as 65355 stated it is all about using shims. McMaster offers them in .001" thickness progressions. If the bearing is side loaded until it is running hot then you are causing premuture wear. Additional,when this happens, the outer race can potentially spin in its pocket damaging the wheel.

Best,
Steve
 
I got an e-mail back from Tracy, he says that the sideloading is occurring because the less expensive poly wheels don't have an inner sleeve like the Beaumont wheels. He's aware of the problem but there's not an easy fix that allows the poly wheels to be economical... "I'm paraphrasing what he said...." I can upgrade to Beaumont wheels, or fine tune how tight I adjust the bolts.
I'll run with the wheels as is, and when I order my 10" and 3" I'll get them from Rob....
Maybe add a spacer down the road.
I looked on McMaster-Carr and if I end up getting the 11 second quench instead of Parks 50 I'll order bearings and sleeves too...
 
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