“Self-aligning spherical washers” for a 6in grinder with side-wobble?

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“Self-aligning spherical washers” for a 6in grinder with side-wobble?

This topic has 19 replies, 10 voices, and was last updated 11 January 2022 at 23:30 by John Smith 47.

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11 January 2022 at 19:07 #579893
John Smith 47
Participant
@johnsmith47
Hello

Should I buy these Self-Aligning Spherical Washers?

Background:
I am trying to fit a new wheel onto my Charnwood 6inch Bench Grinder (BG6). My new wheel is:

A) Thinner
My new wheel is thinner at only 25mm thick compared to the 40mm thick (fine white grinding wheel) that it is replacing.

B) Wobble
There is also a small amount of side-wobble in the new wheel.

My BG6 off-the-shelf grinder looks like this:

==> It is the white wheel on the right that I need to replace.

The spindle is 1/2inch. Due to the new wheel being thinner, the thread it not long enough so I need some sort of spacer to make up the 15mm difference (from 40 – 25mm).

I am also keen to eliminate some side-wobble at the same time.

This guy on YouTube is recommending "Self-Aligning Spherical Wheels"

**LINK**
https://youtu.be/xOKOsBpcQjE?t=18

For example do you think this "Indexa – FC25 13mm BORE 2PC SPHERICAL WASHER SET" would do the job?

**LINK**

https://www.cromwell.co.uk/shop/cutting-tools/fixing-components/fc25-13mm-bore-2pc-spherical-washer-set/p/IND4252860D

Any advice?

J

Edited By John Smith 47 on 11/01/2022 19:10:21
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11 January 2022 at 19:07 #20572
John Smith 47
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@johnsmith47
11 January 2022 at 19:20 #579900
Clive Foster
Participant
@clivefoster55965
Have you tried a plain spacer?

The plastic centring bushes used with modern wheels aren't a tight fit on the grinder spindle so a little rock or wobble is pretty normal when testing with the wheel just sat on the shaft. When the nut tightens up on the clamp washers, via a spacer if need be, things should pull nice and straight.

If the bush were a tight fit on the shaft any any errors would lead to the wheel being stressed as the nuts are tightened. Slight slack lets it find the natural position held between the dished washers.

I used an alloy spacer once in a similar situation. Delrin or nylon might have been a better material due to having a little more compliance.

As ever tighten gently and make sure the wheel is sitting nicely.

Clive
11 January 2022 at 20:07 #579911
John Smith 47
Participant
@johnsmith47
What a curious situation! I would have thought that if everything was made accurately one could just use a gentle push-fit and tighten it up using one plate flange on either side of the wheel… but that's obviously not how the world works!

> Have you tried a plain spacer?
No. To tell the truth, I don't have any plain spacers. Nor spare washers that are large enough.
So either way I'm going to have to buy something… !

Or maybe I should just buy some washers with 13mm holes.
Either way, do you have any firm views on what material it should be made out of?
e.g. Buy default would you suggest nylon/steel/aluminium & where would you buy them from for rapid delivery?

J

Edited By John Smith 47 on 11/01/2022 20:19:15
11 January 2022 at 20:32 #579916
Neil Lickfold
Participant
@neillickfold44316
I am seeing grinding wheels now where the wheel is not true to the centre bore. So the wheel will either require dressing on the sides to true it up, or you will need something like the pair of aligning washers that will allow some adjustment. In my case, I just dressed the sides of the wheel. Not always easy and great care is needed to avoid a bad incident. Do check that the wheel does RING, before mounting it to your grinder.
11 January 2022 at 20:40 #579920
Clive Foster
Participant
@clivefoster55965
I imagine that, as always, there are variations and tolerances involved. I don't recall ever handling anything tight enough to be legitimately called push fit. Mostly variations of slide on with a touch of slackness varying from "does it wobble or not" to "yep its got a bit". But not, I think, ever loose enough to have proper up and down shake on the spindle.

As ever the objective is to hold the wheel firmly without any bending stresses so there is a presumtion in favour of materials having a certain inherent flexibility just in case things are well out or a distracting Gremlin visitation occurs at exactly the wrong time.

I don't doubt that the spherical washer pair will work well, albeit rather expensively.

Objectively I can't see that material matters greatly given appropriate care when tightening up. Alloy worked fine for me the one time I needed such a spacer but choice was mostly down to having a ready made spacer just the right size in the handy bits collection. Salvaged from something no doubt or possibly an overmake.

Clive
11 January 2022 at 20:43 #579923
John Smith 47
Participant
@johnsmith47
Dressing both sides isn't really an option.

I suppose another option would be to use a stack of M12 washers like this:

e.g. "M12 Flat Penny Washer (Pack of 10) Plain Wide Round Metal Alloy Steel Washers for Screws – Zinc Coated Plated Galvanized Heavy Duty Certified Standart ISO7089 DIN125 M12 (13mm x 24mm)"

https://www.amazon.co.uk/dp/B08C3554WM
https://www.amazon.co.uk/dp/B08C3554WM

Maybe I could just jam the odd sheet of paper between one or two of them to help line things up?But from watching the video (see original post, above) it looked like self-aligning washers would magically sort out the problem (if that is the problem was caused by the thread on the spindle being slightly mis-aligned…) ??

J

PS When people say "alloy" do they normally mean stainless steel or aluminium?
I mean technically speaking aren't almost ALL industrially available metals in fact alloys?

EDIT
> I don't doubt that the spherical washer pair will work well, albeit rather expensively.
What did you make of the what was said in the youtube video?

Edited By John Smith 47 on 11/01/2022 20:54:41
11 January 2022 at 20:56 #579927
Dave Halford
Participant
@davehalford22513
There should be thick card washers supplied with the wheel you need to use them on both sides.
11 January 2022 at 21:29 #579934
John Smith 47
Participant
@johnsmith47
Posted by Dave Halford on 11/01/2022 20:56:17:

There should be thick card washers supplied with the wheel you need to use them on both sides.

I have 2 new wheels. One just fits onto a 0.5inch spindle with a fairly snug fit. The other comes with what I can only describe as recessed spacers that are made of plastic. The latter looks like this:

It helps align the wheel centrally but does nothing to help the flange reach the wheel when I run out of thread on the spindle…

EDIT:
Btw, what does it say about the modern world that if I type in "Self-Aligning Spherical Washers" into my search engine (duckduckgo.com), the first search result is THIS THREAD… which I only started at 7PM this evening!

Edited By John Smith 47 on 11/01/2022 21:32:51
11 January 2022 at 21:30 #579936
Grindstone Cowboy
Participant
@grindstonecowboy
From the pictures, it looks like a Scotchbrite de-burring wheel, so possibly has inherent wobble in any case.

Rob
11 January 2022 at 21:34 #579939
Ian P
Participant
@ianp
I think one would have to read the manufacturers specification but the wheel you show on the spindle is not a grinding wheel in the usual sense. Its specifically made for surface finishing or surface preparation rather than for, say toolgrinding.

Whilst I dont have the same wheel I have seen that particular one on a floor standing double ended polishing machine with those wheels mounted on the tapered screwed shafts. I'm sure its acceptable (and maybe preferred) to have them clamped between the usual two flanges but as the wheel itself is not solid (as a normal carborundum) wheel then it probably does not need the normal paper washers as it crushes to some extent when its clamped.

I certainly dont think it needs spherical washers, a spacer of plastic, ali or whatever you have lying around will do.

Ian P
11 January 2022 at 21:36 #579940
Dave S
Participant
@daves59043
I would probably root about and stack a number of M12 washers on it until I could get the nut to tighten.

Cheap offhand grinders always have some wheel runout and wobble. The culprits are cheap pressed flanges and cheap slightly eccentric spindles mated with cheap wheels. Looks like you fixed the cheap wheels part…

Screwfix sell washers, there is most likely one near you

Alloy is in generic conversation usually taken to mean aluminium unless further qualified.

Dave
11 January 2022 at 21:39 #579942
John Smith 47
Participant
@johnsmith47
Posted by Grindstone Cowboy on 11/01/2022 21:30:44:

From the pictures, it looks like a Scotchbrite de-burring wheel, so possibly has inherent wobble in any case.

Rob

Actually it's the other wheel that has the wobble. For this wheel, I just want the plate flanges to actually reach it… (!) In truth, the specific details don't really matter. But given that I am going to have to buy something… I may as well buy something appropriate, that could be used on all my wheels.

EDIT:
Yes, my Charnwood GB6 was pretty cheap (c. £105 inc VAT & delivery) and build quality for the table etc is very weak, but I quite like how it runs nice and quiet.

Since you raise the issue of quality, what WAS rather shocking was that the spindle was already rusty when it arrived… In fact it was almost impossible to get the wheels off!

I have raised the issue with the suppliers, sending them this photo…

The supplier strongly implied that other customers have had the same problem, but he has promised that Charnwood themselves will get back to me. The label says that it was made in China. Maybe it had a dip in the South China Sea on the way over…

Edited By John Smith 47 on 11/01/2022 21:56:42
11 January 2022 at 21:56 #579951
David George 1
Participant
@davidgeorge1
The inside washer should be wider than the original supplied and I would recommend one at least 12mm thick but with a bore with a shoulder halfway down to locate on both diameters on the spindle and a tap on fit on both diameters. This will make the wheel run flat, also the outside diamiter should match the outside clamp washer diamiter. It is better if a band is recessed in the center so the wheel holds at the same part of the wheel as the outside washer. A standard wheel spacer to match the wheel width and bore should be used. Don't forget to use a cardboard washer both sides of the wheel. Cornflake cardboard is perfect as a replacement.

David
11 January 2022 at 22:19 #579957
John Smith 47
Participant
@johnsmith47
Posted by David George 1 on 11/01/2022 21:56:40:

The inside washer should be wider than the original supplied and I would recommend one at least 12mm thick but with a bore with a shoulder halfway down to locate on both diameters on the spindle and a tap on fit on both diameters. This will make the wheel run flat, also the outside diamiter should match the outside clamp washer diamiter. It is better if a band is recessed in the center so the wheel holds at the same part of the wheel as the outside washer. A standard wheel spacer to match the wheel width and bore should be used. Don't forget to use a cardboard washer both sides of the wheel. Cornflake cardboard is perfect as a replacement.

David

To be completely honest, I only 3/4s understand all of that.
> A standard wheel spacer to match the wheel width and bore should be used.
Fine. But where would I find such a thing?

Also, to get clear, do none of you buy into this chat about "self aligning spherical washers"
https://youtu.be/xOKOsBpcQjE?t=18
https://youtu.be/xOKOsBpcQjE?t=18

Edited By John Smith 47 on 11/01/2022 22:19:48
11 January 2022 at 22:26 #579958
David George 1
Participant
@davidgeorge1
I will do a drawing tomorrow after I get back from moving a milling machine, it's a bit late tonight. No way would I recommend using a self aligning washer on a grinding wheel.

David

Edited By David George 1 on 11/01/2022 22:27:32
11 January 2022 at 22:29 #579960
Robert Butler
Participant
@robertbutler92161
The issue seems to revolve around (pun intended) the right hand wheel which is 40mm thick compared to a standard wheel which is approximately 20mm thick. According to the Charnwood website the tool is specifically designed for woodworkers and labelled as such. The spindle length on the right is adapted for 40mm thick wheels. Not an ideal choice of grinder for metal working. Simple arithmetic gives a clue as to the spacer thickness required. Job done.

Robert Butler

Edited By Robert Butler on 11/01/2022 22:31:04
11 January 2022 at 22:45 #579965
Ian P
Participant
@ianp
Posted by John Smith 47 on 11/01/2022 22:19:27:

To be completely honest, I only 3/4s understand all of that.
> A standard wheel spacer to match the wheel width and bore should be used.
Fine. But where would I find such a thing?

Also, to get clear, do none of you buy into this chat about "self aligning spherical washers"
**LINK**
https://youtu.be/xOKOsBpcQjE?t=18

Edited By John Smith 47 on 11/01/2022 22:19:48

I cannot speak for the other "you's" on here, but I dont buy in the the spherical washers at all. The soft Scotchbrite material will conform to whatever is clamping it.

If you want a non wobbling driving flange to mount a rigid grinding wheel on a cheap bench grinder then some engineering is involved. I made a custom ali flanges for mine and did the final machining by clamping the whole thing on the lathe bed so that it could be powered up and machined using its own motor.

Ian P
11 January 2022 at 23:22 #579972
MikeK
Participant
@mikek40713
Posted by Ian P on 11/01/2022 22:45:43:

If you want a non wobbling driving flange to mount a rigid grinding wheel on a cheap bench grinder then some engineering is involved. I made a custom ali flanges for mine and did the final machining by clamping the whole thing on the lathe bed so that it could be powered up and machined using its own motor.

Ian P

And also suggested by Harold Hall in his good book "Tool and Cutter Sharpening".
11 January 2022 at 23:30 #579975
John Smith 47
Participant
@johnsmith47
My rationale was that it spins at 2850RPM and is cheap and quiet which is what I needed. Yes, some adaptations may be required.

> Simple arithmetic gives a clue as to the spacer thickness required. Job done.

OK I'm out of time on this. I couldn't find where to buy a 15mm spacer with 0.5" bore, for rapid delivery… so I have bought some M12 washers which should arrive tomorrow. Maybe I'll just have to live with some side wobble.

J
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