Tool and Cutter Grinder

I have a Machine Mart style 6" bench grinder which isn't particularly brilliant for grinding HSS tool bits. I am thinking of using it as a basis for a simple but effective tool and cutter grinder. Has anybody done such a conversion. I did try a search on here but didn't find anything along these lines

Phil H

Hi Phil,
A few years ago I made a very basic tool grinder based on a Machine mart cross vice and a cheap 5" grinder (I think from Aldi or Lidl.) There are some pictures in one of my albums called cross vice tool grinder. It might give you some ideas. Note the hub on which the grinding wheel is mounted is keyed onto the shaft so it is safe to run the motor in either direction.

Les.

It's no Quorn and it sure ain't pretty but Stub Mandrel tossed a few bits in the air and got this...

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What makes you think it will make anything brilliant if, as you say, “ bench grinder which isn't particularly brilliant”

If it is no good it will likely make a “less than brilliant” anything else.

Neil, That is exactly the type of thing I was thinking about - thank you very much. Simple but effective - I like it.

Not done it yet; Perhaps I should have given a little bit more detail instead of being so vague. I think it is the 6", relatively small radii grinding wheel arrangement that is the issue. The motor still runs very nicely so I think that changing over to a proper cupped wheel as Neil has shown will work well. Can you see any issue with his suggestion?

Phil H

Les, Thanks. More food for thought.

I use one of those diamond grinding wheels on my cutter grinder (pic below) but don't use it for sharpening hss cutters .. they are only intended for carbide.

it clogs up and the wheel can't be dressed again...unless someone knows differently..!

...Bob...

Bob,

Yes you are correct. Diamond for tungsten and white for HSS.

Phil H

The Caseley-Colier is a design that can be further simplified and is a sort of easy Quorn. More pics in my album to understand the concept, reduce to single rod and bar/tube pivoting upstand. Then you have the Tinker even simpler (no picture, google it)

here is another simple design, seen at a Bristol exhibition.

Or CBN for hard and High Speed steels - much better finish and control. Although if just putting the fine edge back, you can safely do tungstons on CBN, and HSS on Diamond. At very low DOC and if the wheel particles and tool are not allowed to get too hot, the Diamond will suffer no ill effects with HSS. I regularly mix and match with no problems.

Don't do low carbon steels on either wheel type - they just clog up.

If you are clogging a diamond wheel when grinding HSS, it is most likely due to high removal rate and heat - the diamond dissolves in the steel with high heat and the surface looses the cutting ability. Very difficult to recover. It's the heat at the particle cutting edge that is the issue, not the heat of the wheel - although that should not run at hundreds of degrees C anyway!

The particle bond method also plays a role - some have a resin bond that can soften under too much heat and smear over the particles - giving the impression of a clogged wheel - this applies to both diamond and CBN wheels.

Joe

Well I'm glad I read this.....I have a diamond cup wheel on my grinder ready for sharpening....my white wheel is in transit...Looks like I need to wait for the postie before sharpening my end mills...,,

But that said, my drill sharpener has a diamond wheel.....confused now!

Bob, yes diamond for tungsten carbide and CBN for HSS, the wheels can be dressed, perhaps you need a coarser diamond wheel?

It might have been an economics thing but in the toolroom - we always changed to a white wheel for HSS. It might have been a coincidence that the wheel was white and who knows what grit colour is around these days but that was the rule of thumb.

Oh, please don't take this as gospel because it was a very long time ago but I think we used a green grit for roughing the tungsten. It was great to remove material but left tiny chips on the cutting edge. the wheel was changed for diamond to get a keen, clean edge.

Phil H

This may be of some help you decide, a while ago I reground an old oil stone and I used a diamond wheel as I thought it a good idea at the time, it cleaned the diamond wheel up a treat, carnt quite remember but by the time the stone was flat I had may be took 1.5mm of it.

Hi Phil,

Model engineers have been coddling together these sorts of thing for donkeys years , Harold Hall has some useful designes which you can get either from the workshop practice series of books or iirc his website or if you want to go the whole hog the acto tct design does just about everything but is a far more complex project .

One thing to be mindful of with bench grinders is armature end float , all electric motors have to have some end float to allow for expansion and this is usually taken up by a wavy washer in one end bearing housing so check to see how much end float you have and minimise it as much as possible .

Excellent point XD and another good point regarding Harold.

I think I will get sorted for the next exhibition that I go to - probably in Manchester. Ill either decide to make use of this small mountain of HSS steel, buy some cupped wheels and make some form of cutter grinder or sell the majority of the tool steel and buy a load of tungsten tips.

Phil H