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Commercial Grinding Rest

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Colin LLoyd30/03/2015 13:16:29
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I know I could make a Grinding Rest from the excellent articles in this magazine by Harold Hall - and I may well do that later. But right now I need an off-the-shelf grinding rest. I've seen several in books - and am looking at one right now in David Clarke's "Metal Turning on the Lathe" which he states was designed to sharpen plane irons and chisels - but is fine for lathe tools.

Anybody got any suggestions?

Martin Kyte30/03/2015 13:36:17
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2061 forum posts
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Try Axminster.

**LINK**

regards Martin

Clive Foster30/03/2015 16:29:27
2377 forum posts
76 photos

Re Martins link:-

Axminster used to do a device very similar to thier own brand £38 adjustable grinding rest with a larger table, about 6" wide by 3", and simple fixed position base using the same style of twin arm setting thingies in plain bores rather than the slot provided for height adjustment on the current version. Came with the Chinee standard cheap plastic protractor on a stick with matching slot in the table for the stick.

I got one several years back for around £15 and find it quite effective. Not perfect but failings are not irritating enough for me to bother to fix them. Proper angle setting templates would be much better than the protractor but I just do things by eye. Hopefully someone here has a link to a current supplier of the old style one as, judging by my experience, the table on the current version will be far too small for lathe tools and the whole thing is too clever by half. The screw setting and height adjustment provisions being un-necessary in this case.

Clive

Colin LLoyd30/03/2015 17:37:21
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210 forum posts
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Martin, thanks for the link (Clive - thanks for corroborating it) - it shows exactly the same grinding rest as in the book the "Axminster Adjustable Sharpening rest- cost £38-95. So an order is on its way. That will do me until I discover its deficiencies. I only have a small Chester hobby lathe - so it will probably be adequate for my needs.

Oompa Lumpa31/03/2015 10:43:45
888 forum posts
36 photos

I actually have that £75 Veritas rest shown in Martins link above. Fortunately somebody gave it to me because if I had paid that sort of money for such a small and flimsy collection of aluminium parts not only would I have wanted my money back, I would want compensation for having wasted my time!

graham.

Jon Gibbs31/03/2015 11:00:55
739 forum posts

Colin,

I had the same problem as you and feared that the cheap ones would end up as Graham suggests the Veritas ones are like.

So I decided to make a pair of rests of that style myself but mine also work for woodturning gouges. I'm glad to say they're rock solid.

Much less complex than even Harold's simple rest, although not as easy to adjust for angle and presentation as HH says in his sharpening book.

HTH

Jon

 

Edited By Jon Gibbs on 31/03/2015 11:02:43

Clive Foster31/03/2015 12:12:14
2377 forum posts
76 photos

This is mine :-

grinding rest, axminster.jpg

Fundamentally the same as Jons but somewhat less sturdy. I fully expected that the side arms would need replacement with something rather more sturdy but under £20 for a finished casting kit complete with bristol handles was still pretty good value. In the event its fine for tool sharpening duties. Especially as I use the side of a white cup wheel which is rather less stressful than going in radially on the usual grey wheel. I'd want something a bit more engineered for roughing out but I do my roughing with a 1 mm cutting disk and angle grinder. Alloy top is a weakness as it abrades rather easily, mine is about due for re-skinning with something a little more robust.

Clive

Colin LLoyd01/04/2015 17:36:49
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210 forum posts
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Thanks for all the input. Now here's a thing - when I did metalwork at school way back in the 1960's I was always told to finish sharpening a tool by pulling away from the sharpened edge - just to give it that final edge. All the grinding wheel machines I have had (2 to be precise) have the wheels rotating in such a way that the upper part rotates towards me. With all the grinding rests I have seen - they present to tool to the grinding wheel in such a way that the edge is tending to dig into the wheel whereas a safer and (to my mind) a better edge would be given if the tool was presented in such a way that the wheel slides beneath the tool.

So my question is: is it possible to reverse the rotation of bench grinding units so that they rotate away from the tool? I'm guessing that if I took the grinder apart and physically reversed the motor - this would work. Alternatively, turn the whole unit round and move the wheel guards instead.

Tony Pratt 101/04/2015 17:46:56
1234 forum posts
5 photos

Hi Colin,

If you run the motor in reverse both the wheel clamping nuts will come undone. Is that what you mean?

Tony

Clive Foster01/04/2015 19:07:32
2377 forum posts
76 photos

Colin

Engineering grinders generally have the rests positioned so that contact is made close to, and preferably a little above, the line where the wheel is moving pretty much vertically downwards as it acts on the tool. So dig in isn't really an issue provided the rests are sturdy and you make a point of holding the back of the tool down. Our small 6" bench grinders are geometrically poor in this respect when compared to the 8" and 10" sizes normally found in industrial shops. The larger diameter means that the working part of the wheel is much, much closer to true vertical as it traverses a tool. Main advantage of this arrangement is that it allows a tool to be held firmly against the wheel for relatively rapid rough grinding. With the geometry you suggest it would be very difficult to hold a large tool in sufficiently hard contact for rapid rough grinding.

Ideally final sharpening of lathe tools should be done on the straight face of a cup wheel. The curved side produced by rough grinding on the periphery of a grinding wheel gives natural clearance below the cutting edge. Hence only a small amount of material needs to be removed by the finishing grinder to produce a small land of the correct angle for the material the tool is to be used with. When you think about it there is no great merit in extending the correct clearance angles significantly past the depth of cut. Probably twice is more than plenty. Due to the small amount of metal being removed and the predominantly vertical path of the wheel relative to the tool axis any dig in tendency is very small. There are a goodly number of breed of finishing grinders using cup wheels around e.g. Tiplap but it has to be said that a goodly proportion of professional users grinding on the periphery for both roughing and finishing using an ordinary double ended grinder with every success. Usually the roughing wheel tool-rest angle is set to produce a slightly larger clearance angle than the finishing wheel to reduce the amount of work needed when touching up a tool.

Clive

Colin LLoyd01/04/2015 21:31:12
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210 forum posts
18 photos

Thanks Clive - even something apparently as simple as sharpening tools has such technical depth - thank you for the in-depth explanation.

Colin LLoyd24/10/2017 16:44:38
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210 forum posts
18 photos

As an update to this thread, I've made a grinding stand using one of 3 Leica Microscope stands I bought from a local scrap yard for £6. I've cut the upper microscope arm off. Even so it's still very heavy and provides me with vernier movement in all three orthogonal directions. The whole arm then tilts in the forward direction towards the grinding wheels (with protractor angle setting and sideways tilt is provided on the base with simple threaded jacks either side of a central knife-edge. The blank HSS tool is then held, on what was the specimen table, using my lathe quick-release toolpost. Seems to work OK and, although a little over the top for experienced machinists provides this grinding novice with fine control over the grinding process until I get more experienced. As this is a "proof-of-concept" build - there are various parts in this build that I will replace especially the wooden base to the grinding rest.grinder_rest-small.jpg

Neil Wyatt24/10/2017 18:06:42
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18237 forum posts
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I bet Clive and Michael G. are having kittens at teh thought of someone butchering a Leica scope base, whatever it cost!

Neil

Colin LLoyd24/10/2017 18:24:10
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210 forum posts
18 photos
Posted by Neil Wyatt on 24/10/2017 18:06:42:

I bet Clive and Michael G. are having kittens at teh thought of someone butchering a Leica scope base, whatever it cost!

Neil

The other two2 are fine - one is set up as the stand for a digital microscope and the other I've adapted to copy 35mm slides using my DSLR positioned on the Leica table.

Ian Skeldon 224/10/2017 18:32:44
489 forum posts
41 photos

Nicely done Colin, should be as much as you will need for a long time.

Michael Gilligan24/10/2017 22:49:41
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16389 forum posts
715 photos
Posted by Neil Wyatt on 24/10/2017 18:06:42:

I bet Clive and Michael G. are having kittens at teh thought of someone butchering a Leica scope base, whatever it cost!

Neil

.

The astonishing truth, Neil, is that microscope stands are in plentiful supply.

Many complete microscopes are being junked by colleges, and then the optical bits are stripped for sale on ebay, etc.

[much bigger profit margins]

The quality of Leitz focusing blocks is legendary [ask NASA about Orthoplan components], so Colin has made a wise, albeit emotionally distressing, choice.

MichaelG.

 

 

Edited By Michael Gilligan on 24/10/2017 23:19:09

SillyOldDuffer25/10/2017 09:41:10
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6330 forum posts
1389 photos

Is butchering a microscope a good idea? Me no Leica.

Groan...

ega25/10/2017 10:03:50
1812 forum posts
153 photos

The Eccentric Engineering Acute sharpening system table is an expensive but effective grinding rest (the table kit, which is apparently available separately, is very quick and easy to put together). It does not have the range of angular movement that some do, however; on its own, grinding on the side of the wheel is only at 90 degrees.

I have had several amateur-use bench grinders over the years and have always been struck by how poor the supplied rests are.

Edited By ega on 25/10/2017 10:04:22

Colin LLoyd25/10/2017 10:37:17
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210 forum posts
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Posted by SillyOldDuffer on 25/10/2017 09:41:10:

Is butchering a microscope a good idea? Me no Leica.

Groan...

There was no microscope on the stand - but I accept butchering. These are incredibly solid stands and what started out as a fun hacksaw project rapidly descended into angle-grinder territory. Like a good animal rescue centre I could have also bought the other 5 Leica stands sitting out in the rain next to the old disemboweled Ford Focus, but I only had use for three and where was I going to put the other five. As Michael G says - these appear to be in plentiful supply as schools and colleges switch to digital microscopes.

Neil Wyatt25/10/2017 13:25:45
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18237 forum posts
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Posted by Michael Gilligan on 24/10/2017 22:49:41:
Posted by Neil Wyatt on 24/10/2017 18:06:42:

I bet Clive and Michael G. are having kittens at teh thought of someone butchering a Leica scope base, whatever it cost!

Neil

.

The astonishing truth, Neil, is that microscope stands are in plentiful supply.

Many complete microscopes are being junked by colleges, and then the optical bits are stripped for sale on ebay, etc.

I must see if I can get one for my cheap digital scope

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