eclipse hss tool broken in 2

Just ground myself a really nice facing tool for plastic very sharp etc and when i took it out of my tool post it was broken in 2

what would cause this is the tool post uneven am i tightning the screws too much

or is it just a very old hss tool piece probably older than me maybe been dropped on the floor

any ideas thanks

What sort of tool post is it?

Was there swarf under one end of the tool?

A photograph would help.

Edited By David Standing 1 on 24/10/2017 17:37:54

The position at which it fractured should give you some indication of the likely cause.

If not a straightness of holder problem, it could be caused by tightening down beyond any packing pieces.

While the tightening screws do not need to be extreeemly tight, over-tightening should more likely damage the screws/threads of the holder.

I've done that to a 1/4" square bit when I tightened all 3 toolpost screws down onto it, but had forgotten that the packing only extended under the front 2. Didn't know I'd done it till I took the tool out.

Its a 4 tool post myford super 7 i think it might have been swarf under the tool maybe as i broke 2 tools one after another

Always brush your tool holder out before putting a tool in!

But you know that now.........

By the way, with my reply to your RDG thread, it isn't 'pick on lug lord' day, honest

Are you sure the metal is HSS? I wonder if you have tool-steel - it's more brittle.

Dave

I was taught to put a piece of packing between the screws and the tool bit to minimise any tendency to a point contact.

Mike

Now there's a good tip. I learn something new on this site every day.

Cheers for advice in future I will use a thick shim on the top to stop the point of the screws on the tools and make sure no swarf on my tool post thanks ian

Not just on the tool-post. Swarf goes everywhere it's not wanted. D*** stuff is a pain in the rear-end, sometimes literally!

Well worth keeping chucks and leadscrews etc clean with a toothbrush. In theory I wipe off bearing surfaces like tapers and chuck backs every time I change tool. (In practice I often forget but that's a different problem.) Quite small bits of swarf in the wrong place can throw accuracy off as well as cause damage.

Dave