Adaptation of grinding wheel to a spindle

This topic has 13 replies, 9 voices, and was last updated 24 March 2018 at 21:36 by Martin Dowing.

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23 March 2018 at 19:31 #25898
Martin Dowing
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@martindowing58466
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23 March 2018 at 19:31 #347272
Martin Dowing
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@martindowing58466
I am intending to replace grinding wheel on offhand grinder.

Want to install a green silicon carbide one and I need to fabricate adaptor ring because spindle is 5/8" and wheel has 32mm hole.

Wheel is 20 mm wide, very much like one already on machine.

I want to make a ring out of textolite (tufnol) bar (which is at hand). It is going to be 19.5 mm wide, eg 0.5 mm narrower than a wheel.

I want to make it rather close fit but avoid situation were forcing it in is necessary, particularly into a wheel hole.

Is that OK or I need to look on something else as well.

Martin
23 March 2018 at 19:38 #347274
David George 1
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@davidgeorge1
Grinding wheel manufacturers supply wheel spacers to fit your wheel if you ask your suplier he should let you have two to fit your wheel.

David
23 March 2018 at 19:44 #347276
Tractor man
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@tractorman
Spacers and adaptors are usually pretty flimsy plastic jobs so there is no need to be overly complex in what you make. I have turned spacers and the like with no problems.
Just make sure you use decent blotters if the new wheel doesn’t have them fitted. Remember a blotter can be a label but a label cannot be a blotter. That comes from the HSE handbook on grinding wheel mounting which is essential reading if you’re doing any modification on any grinding machine or wheel.
Best regards Mick
23 March 2018 at 19:44 #347277
Tractor man
Participant
@tractorman
Spacers and adaptors are usually pretty flimsy plastic jobs so there is no need to be overly complex in what you make. I have turned spacers and the like with no problems.
Just make sure you use decent blotters if the new wheel doesn’t have them fitted. Remember a blotter can be a label but a label cannot be a blotter. That comes from the HSE handbook on grinding wheel mounting which is essential reading if you’re doing any modification on any grinding machine or wheel.
Best regards Mick
23 March 2018 at 20:03 #347282
Martin Dowing
Participant
@martindowing58466
@David,

Supplier of the wheel have already advised me that "Noone is asking for these and we don't have them. Make your own or go to someone who has a lathe so he will make it for you".

Wheel is from Andre Abrasives, so it is a reasonably good one.

@Tractor Man,

Just want to make sure that wheel will run true and not develope a "throw" which leads to vibrations etc.

Btw, I have a "bloaters are also labels" case – thick paper

Martin

Edited By Martin Dowing on 23/03/2018 20:06:09
23 March 2018 at 20:43 #347285
David George 1
Participant
@davidgeorge1
I have just looked on local suppliers web site and they are 60 pence a pair (free to wheel purchaser) but check the bore of the wheel it may be 31.75 mm bore.

David
23 March 2018 at 21:42 #347291
ChrisH
Participant
@chrish
Harold Hall has designed a very good 'holder' to fit grinding wheels, it should be on his web site I guess. I have made one, excellent!

Chris
23 March 2018 at 21:56 #347294
DMB
Participant
@dmb
When I purchased a wheel from Cromwell Tools, they supplied umpteen different sized plastic spacers included in the price. The wheel was a reasonable price, safely wrapped and I got exactly what I wanted, not a second hand compromise on the spec.

John
24 March 2018 at 06:30 #347307
Joseph Noci 1
Participant
@josephnoci1
But no one answered your question…

Tufnol is just fine for your bushing.

On running true – your bush may be true, but I doubt the wheel will be, especially if the grinder has those pressed/dished metal ends that clamp the wheel sides. Those rarely run true..Also, the hole in the wheel is not true to lathe type standards and so the periphery of the wheel will need truing anyway. Do however try to get the wheel running co-planar, even if it means machining up decent side dished clamps – all to ensure minimal side truing.

Joe
24 March 2018 at 11:38 #347340
Ian S C
Participant
@iansc
Pretty much any plastic will do, years ago wood was the norm, I'v also seen lead used. I think it would even be ok to wrap a strip of paper around a suitable bar, and use the resulting tube.

Ian S C
24 March 2018 at 13:16 #347361
Nicholas Farr
Participant
@nicholasfarr14254
Hi, just about any reasonable material can be used, even the likes of cardboard tubes. The main thing is it must have a concentric wall thickness and fit correctly in the wheel and the shaft, without binding or slope, as the only function should be to locate the wheel centrally on the shaft during mounting. No forces as such, should be transmitted through the bush if the clamping discs are correctly fitted, as these are there to transmit all the forces that are applied to the wheel.

Regards Nick.

P.S. see for more info, http://www.model-engineer.co.uk/albums/member_photo.asp?a=12754&p=724876

Edited By Nicholas Farr on 24/03/2018 13:21:17
24 March 2018 at 18:32 #347415
duncan webster 1
Participant
@duncanwebster1
Back in the bad old days I once bored out a grinding wheel as the hole wasn't big enough. Run it very slowly and the grains are dragged out rather than it grinding away the tool. Then cast some lead into the resultant raggy hole making sure there was a meniscus. When it cooled down the lead sharank away from the wall, which is where the meniscus comes in, hitting it with a ball peen hammer swelled it back up, and it could then be bored to fit the shaft, leaving about 1/8" lead if I remember.

Having since seen what happens if a wheel breaks, I wouldn't do this again for all the tea in China, wheels aren't that expensive
24 March 2018 at 21:36 #347448
Martin Dowing
Participant
@martindowing58466
I have made these 2 bushes out of tufnol.

Paid attention to get good accuracy which hopefully will help to get wheel centered better to reduce dressing efforts and possible vibrations in use.

They are a bit tight on spindle, though easy enough to locate while pushing and twisting but the wheel feels like h6/H7 fit – I know it is not but just feels like – easy slide and no play.

Another thing I have found that I can fit 25mm wide SiC wheels on nominally 20mm wheel grinder.

Wheel catching plates have 3.5 mm recess and I believe that 1 mm deep recess on each plate made of sound material of the same thickness is more than enough. So I can win 5mm!

It is also worth to notice that 25 mm wide SiC (silicon carbide) wheel has a weight approximately the same like 20 mm wide corundum wheel because of lower density of silicon carbide (3.2g*cm-3 v. 4g*cm-3 for corundum).

Hence machine will work with a weight (and angular momentum) which it was designed for.

@Duncan Webster

If you poured lead – bismuth alloy of appropriate composition, you would not face contraction upon solidyfication issue.

Martin

NB. I like Tufnol – it is synthetic polymeric material which I can trust. Resistant to oil and temperatures in range of 100-250*C, depending on grade. Good insulator. Mechanically sound and easy to work with.

Edited By Martin Dowing on 24/03/2018 21:51:34

Edited By Martin Dowing on 24/03/2018 22:08:04
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