Do you wear a mask grinding HSS tool bits?

I have to admit that I don't wear a dust mask if I'm only touching up a tool, as Neil said. For grinding a HSS toolbit to shape I wear a dust mask. Inhaling a lot of fine dust particles isn't healthy.

Thor

Are you sure that isn't just for thoriated tungsten TIG electrodes?

Rod

What bit don't you understand and I'll try and explain?

Andrew

Continued exposure to grinding dust will give you miners lung. The same thing from wood working and car paint refinishing. It is all basically the same thing. Stuff getting into your lungs that will cause an otherwise early departure. I can recall a test being done with exposure to Beryllium from grinding and milling it, making injection tools in the early 80's. The grinding wheel dust from wheel dressing and the tungsten dust from making D'bits was the highest risks. When 1 cutter was resharpened, it could not show a particle count. Making a cutter from the blank was measurable on that day. Initially it was a 1 morning test, that lead to a 1 month test. In that whole time, they had no Be gas collected that they could measure. Loads of carbide, and diamond wheel and regular grinding wheel dust. Also lots of BeCu dust from the surface grinding, but no Be only.

Neil

Andrew,

I am interested in your thoughts on this.

Are you suggesting that if I want to grind a 60 degree HSS thread cutting bit from a square blank that I could use a carbide milling bit to rought it out then a final sharpen on a stone or a diamond plate ?

If that is a poor example then how about something bigger ie a  boring bar from a hss blank ? 

LINK

https://www.model-engineer.co.uk/sites/7/images/member_albums/45510/377913.jpg

Bill

Edited By BW on 29/05/2019 06:28:19

Have to admit I have never thought of that. Does ordinary carbide tooling cut HSS without problems?

I read that carbide would machine HSS so had to try, it turned very easily but I have not tried milling. It would make sense to me that it mills and it sounds as though it is well tried by Andrew. I suppose it has to be given a go, could save holding hot bits of HSS in your fingers.

Mike

As a model engineer, I do very little time grinding and would be extremely unlucky to develope any type of illness. A bit different from doing it in a full time job. I do wear protective glasses and the grinder is in a well ventilated area. Most of us are retired citizens and will die of old age before we do so by grinding dust.

For rough machining of a HSS cutter I use an angle grinder with a thin blade then a grinder/belt grinder and finish with a diamond stone.

Paul.

I just looked at my two 8" bench grinders and linisher where they are mounted to an outdoor workbench under a lean too (Its hot in Australia) and the amount of grinding dust around the area is quite substantial.

How do you guys get on with your bench grinders inside your workshops? Do you get grit everywhere and on everything?

I have a Dormer 108 drill grinder with built in diamond dresser, it has a cover built into the guard to contain the dust when dressing, guess who forgot to put it down and dressed the wheel ? It created an unbelievable amount of fine dust which was 100% aluminium oxide, fortunately my lathe and mill were not in the same room.

Mike

Yes, although the cutter isn't going to last for ever. Basic cutting parameters are similar to turning hardened steel, ie, high speed, shallow depth of cut and high feedrate. I don't rough by mill that often as I have a large selection of pre-used HSS blanks, so I can usually find something close to what I need. Here's a HSS blank machined on a CNC mill with a 6mm uncoated carbide endmill:

The cutter was for shaping an internal gear so I wanted an exact profile, as drawn in CAD. Milling is especially useful for grooving tools where you need to take a substantial amount off the width of the blank - it would take for ever with a grinder.

Andrew

Fine if you have carbide milling cutters - i don't. All my milling cutters are HSS.

A linisher with an Al/Ox belt as i said earlier will do the job faster and cheaper than a mill & having to buy carbide.

Getting to the exact stuff, once finished, use the T&CG.