Ryobi BGH827 bench grinder vibration saga continues

Another chapter in the saga of the Ryobi BGH827 8" bench grinder, which vibrates badly.

The basic problem appears to be that the grinding wheels are not reliably held perpendicular to the arbor shaft, and also can slide about radially perpendicular to the shaft.

It occurred to me that I could solve or at least greatly reduce this wiggling problem by machining a combined dished washer and sleeve (0.625" ID, 1.000" OD) in one piece, sharply reducing the ability of the wheel to move in undesired ways. Today, I machined the first such flanged sleeve from 6061 aluminum. The sleeve protrudes 1" from the flange (~2.75" diameter), and the sleeve is a tight slip fit on the shaft. The flange face is undercut, and so rests on the stone only in a ring, just like a dished washer. The vibration is much reduced. So far so good.

Next I'll make another flanged sleeve for the other wheel. Hmm. If it has a 1" hole, leaving sufficient space for the sleeve.

And re-dress both wheels, as they were dressed wrong before: I would dress them to what seemed like true, but it was really wobbling. This would have been OK, except the wheel would then shift on the arbor, doubling the wobble. Maddening.

I suppose it could be useful to make flanged sleeves to accept wheels with 1.25" center holes, or larger.

I've never had the opportunity to take a Baldor grinder apart. How are the wheels attached to the arbors? Are the dished washers machined? Are they keyed to each other and/or the arbor shaft? What manuals I've seen are not clear. Does anybody have pictures? I've always imagined that all that Baldor really does is accurate machining of arbors designed so that they don't let the wheels wiggle around.

Joe Gwinn

Reply to
Joseph Gwinn
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I believe that Baldor arbors are also thicker. I looked at my Baldor, Cat. no 7351, 1/2 HP grinder. The arbor is at least an inch thick up to the first washer (closest to motor). The part on which the wheels go, I think is 5/8", but the 1" shoulder provides some truing to the wheels.

Reply to
Ignoramus13011

Joseph Gwinn wrote in news:joegwinn- snipped-for-privacy@news.giganews.com:

I missed the first chapter. Are the stones the ones that came with the grinder?

Reply to
Charles U Farley

One yes, one no. I bought a Norton white aluminum oxide wheel for HSS, and it has the 1" center hole.

Joe Gwinn

Reply to
Joseph Gwinn

Baldor arbors are something like 1/8 inch larger in diameter for a given wheel diameter than anybody else. The Ryobi does have a shoulder, but it's like a mm or two, which really isn't enough.. I bought a set of hardened 5/8" ID steel washers to rest on this shoulder. The aluminum flanged sleeve rests on this hard washer.

Given that stiffness varies as the cube of diameter (or is it the forth power), having a 1" diameter shaft should abolish and bending modes in the arbor.

From your description, I'm reinventing the Baldor, one step at a time.

Joe Gwinn

Reply to
Joseph Gwinn

Also consider that Baldor washers are extremely big and heavy.

Eggzactly.

But at a comparatively enormous cost.

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Buy a Baldor and live happily thereafter. Or something else that is heavy duty, comes with cast guards, etc.

I have a Baldor 1/2 HP grinder, Baldor 3/4 HP buffer (really a grinder, but with buffing wheels) and a 3/4 HP heavy duty Dayton grinder with dust collector, which is what I mainly use due to dust collection.

I also have a small Delta cheap grinder, which I do not like but I thought to use it with green wheels for lathe cutters. It vibrates a lot, as they are wont to do.

Reply to
Ignoramus13011

Joseph Gwinn wrote in news: snipped-for-privacy@news.giganews.com:

I've read that the cheap stones provided are not necessairly of uniform density and may never balance, even when dressed. Not sure if that's universally true or not, but you may want to test with two name brand stones once you get your flanges sorted.

Reply to
Charles U Farley

I've read this too. The simple test is to run with only one stone.

Actually, I have two Norton wheels, now that I thionk of it.

Joe Gwinn

Reply to
Joseph Gwinn

[snip]

Now as I think of it, the arbor is bigger both in the motor (1") and where the wheel is attached (3/4" versus 5/8" for instance).

What was the shipping?

On the local craigslist a fellow has been advertising an old industrial Delta 220-volt pedestal grinder, but apparently no takers, probably because of the voltage.

What do the arbor washers look like? How are the wheels attached to the arbor?

I always wondered if the Delta grinders were any better than the Ryobi. Apparently not. Probably all such grinders come from the same noodle factory.

Joe Gwinn

Reply to
Joseph Gwinn

I agree.

I do not know, but, I figure, you can always buy local.

Would make a good application for a electronic motor drive, what is the HP? Is that 3 phase?

They are approximately 2 inches in diameter, 1/8 to 3/16 inch thick and have a "cup" form.

There are different kinds of Delta grinders. Cheap and heavy duty.

I have seen Delta grinders that are very heavy and well built.

i
Reply to
Ignoramus32631

Single phase, 1/2 HP, wheel diameter not stated. but they look small:

Machined from steel? Are they keyed to anything, or are they free-spinning?

So have I. They were a respected industrial brand, 30 years ago.

I also wonder if the present day Wilton grinders are any better, or do they come from that same noodle factory?

Joe Gwinn

Reply to
Joseph Gwinn

Would be interesting to find out the phase. I would pay $100 tops if it was 3 phase, $120 tops if it was single phase. Every factory has at least one bench or pedestal grinder, usually at least one good one, so if you like going to liquidations, you could get one for less.

I can sell you a VFD that would run a 1/2 HP 3 phase motor from single phase input for $30 plus shipping.

Made from steel (maybe stamped, but maybe turned), no key.

No idea about those. You can usually tell when you look at the grinder. There is no magic to making them, there is a cheap way to make them and an expensive way. The people's noodle factory could make good grinders too, if their customers asked for it. All they need is to use good motors, good bearings, thick shafts, big washers and all.

Reply to
Ignoramus32631

They didn't say how many phases, but I assumed single phase. Perhaps not.

My reaction to the price ($200) is the they are awfully close (~1/2) to the price for a new Baldor of similar wheel diameter and equipment.

This grinder has been reappearing on Craigslist for months. If I offered $100, who knows? Maybe. They seem awfully proud of that old grinder.

Thanks.

So, made reasonably accurately, and very stiff.

Maybe my flanged sleeves will do the trick. If the key is not the arbor shaft diameter, which I cannot change.

Yes, capability was never the issue, it was always intent, as controlled by the customer (that's Wilton et al, not us).

Joe Gwinn

Reply to
Joseph Gwinn

I would give 60% odds that it is 3 phase.

I agree totally.

I have seen fools like this. Very annoying. Still, I would send an email asking the phase.

Very stiff.

They well might help.

Yes, it is the US retailers that order some rather abominable but cheap machines.

Reply to
Ignoramus32631

It's certainly possible, and if they said 208 volts I would also guess 3 phase.

I have not developed enough interest so far. This has to be the story of their lives, as that grinder has languished on the market for months.

I suppose if it were 3 phase, that would also slow things down.

Does Baldor have any manuals that are clear on the issue of how the wheels are held?

We will soon enough have a datapoint. With luck, this weekend.

Joe Gwinn

Reply to
Joseph Gwinn

Not really. 208-230 is a standard sopecification for many single phase motors. But if you see 230-460, it is guaranteed to be 3 phase.

Does not hurt to ask. All sorts of odd things have happened. It is a buyer's market now.

I do not have any.

Let us know. Maybe you can bolt it to a 4x6 wood base, might help some also.

Reply to
Ignoramus14358

You are right, but I'm not sure I want to own this grinder, so I hesitate.

Or a big hunk of metal. But I want to eliminate the vibration at the source.

Joe Gwinn

Reply to
Joseph Gwinn

Joseph Gwinn wrote: (...)

Joe, did I miss the part where you installed sleeve spacers press fit between the grinder axle and the wheel?

--Winston

Reply to
Winston

[snip]

Aha! I did not know the history, but I did know that Delta/Rockwell's days of glory were long past. One knows this instantly when looking at any current Delta product.

That said, I do have a small Delta variable-speed drill press that does work, and is made of iron and steel. But I did have to replace the chuck with a real Jacobs chuck.

When did these changes happen?

And probably many parts from the peoples' noodle factory. At least approximately.

What I do not understand is why the noodle factory does not do a better job of copying the real grinders. Making the arbor shoulders wide enough to ensure that the dished washers are definitely located cannot be that expensive. One can use stamped washers and perhaps spherical washers, so nothing need be that precise.

One assumes that the problem is simple ignorance.

Joe Gwinn

Reply to
Joseph Gwinn

I did try machined steel spacer sleeves, but they are a slip fit on the

5/8" arbor shaft. Didn't help because the dished washers were not constrained to remain perpendicular to the arbor shaft, and wiggled around.

What's new is to make a one-piece flanged sleeve, with the flange taking the place of the inner dished washer, and a tighter slip fit as well.

Joe Gwinn

Reply to
Joseph Gwinn

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