Grinding cup wheel help

Evening all

Bit of help/advice on grinding wheels and cup wheels please.

I like grinding my own HSS tooling for my lathe and shaper, mainly free hand but i need to machine a acme thread in a couple of projects time. So im correctly making a grinding rest to help me achieve accurate angles on the tool. The grinder rest design iv settled on is a mash up of several iv seen on YouTube and sites like this. So my question is what grit and what type/style of wheel would best suit my needs. The HSS i mainly have is mo max and super mo max up to 3/4. I should ad ill mainly finishing my hand ground tooling not hogging off large amounts as iv got a bigger grinder for roughing. 

Thanks

Steve

Edited By Steve King 5 on 30/08/2019 20:12:13

Hi Steve for grinding a HSS tool I would use a WA100 grinding wheel for finishing it depends on the machine you are using and wheel diameter. I have an adjustable diamond which rests on the edge of the footrest to dress the wheel. On a cup wheel you can also use it to dress the side face. Make sure that the gap from wheel to rest is as close as possible. For a screw cutting tool I have the skill to grind by hand most forms using a thread form gauge and a radius gauge set but I have been grinding for 50 plus years. Practice and having good lighting and a solid toolrest helps.

David

I was thinking about this the other day when there was a post re using the lathe with a cup wheel. A while back I bought a cheap flat diamond coated disc to try attached to the face of my Tormek grinding system but the rpm there is way to slow for efficiency and I abandoned it. Using such a disc backed by the lathe faceplate might be a simple way of getting angles accurately pending my getting 'a round tuit'.

Sadly can't recall where I bought the cheapo chinese diamond but this link has similar: **LINK**

pgk

Since you are only generating a straight line for the edge of the tool, why do you need a cup wheel? Grinding on the periphery of a 5 or 6" disk wheel will give a perfectly adequate tool for cutting acme (or most other thread forms), albeit with a slightly hollow clearance face.

I have both types of wheel on my homespun cutter grinder, but the periphery is the "go to" option when possible.

Martin

I don’t like the idea of grinding anywhere near my lathe. I like to keep grinding away from the lathe as much as possible, although there are exceptions - but these mean a good clean afterwards (and usually some paper/card to cover anywhere the dust might get on rubbing surfaces, before starting).

Maybe not so important if you change your lathe, for a new one, every couple or three years - like people do with cars...

Steve,

Did you see this previous post about grinding your own lathe cutters. The simple grinding jig published in Popular Mechanics and a wheel mounted on a lathe spindle would be slow but OK for a one-off project.

**LINK**

Paul.

For what my advice is worth, DON'T grind on the lathe. Keep abrasives away from it.

An ACME thread needs the sides of the tool to be ground at 14.5 degrees to each side, with a clearance. The radius produced will provide that clearance. So why not make up a simple jig, and as already suggested grind on the face of a normal Bench Grinder?

The simpler things are, the less there is to go / get wrong.

If you are determined to make life complicated, make a cutter grinder,.

Then you can grind almost anything to almost any angle.

But that is another project!

Howard

Edited By Howard Lewis on 31/08/2019 11:42:31

I'm essentially in agreement with the above . However the OP was looking to make a specific tool rather than keep using the new system and this would be a one-off (or few off) expedient solution.

I was in Lidl last week and bought one of their cheap chainsaw sharpening tools. I'm pretty good at hand sharpening my chainsaws but thought this was worth a punt. It looks ideally suited for conversion to a tool grinding system if again one considers using a diamond disc on it's face.

pgk

Agree that grinding dust is not good around a lathe but for a one-off application, Cover the ways to protect them and do a good clean afterwards. Similarly on the odd occasion where I use a tool post grinder.

Although I don't have the free hand grinding skills of an expert, I have successfully ground my own Acme cutters from HSS with a standard bench grinder by hand using a profile gauge to check the angle. Thread grinding gauges are inexpensive. Also use one to set the tool perpendicular to the lathe axis.

Paul

Edited By Paul Lousick on 31/08/2019 14:28:28