machining through breaking end mills

[wildwestpat]

Hi Folks

I recall one guy solving this sort of problem from way back with double sided sticky tape to mount the thin sheets he was cutting to a scrap sheet of what I think was MDF or hardboard that he had soaked in something - probably celulose paint as a lot of the work was dipped prior to storage / inspection at a later stage.

Also sounds as if you might do better holding the part and the scrap down with clamps moving them as necessary but not removing them. The scrap has to be held as well as the wanted part or else the cutter gets pinched and breaks.

If my memory serves me right the stuff being machined was a lattice work of aerial support stucture for a small satelite dish that was to be an investment casting after machining from the solid had proved the dimensions etc. The sections were very light and in consequence the cut depth and rate of feed were comensurately light.

I think the jewellery fraternity make use of what they call dopping wax for similar purposes to mount difficult to hold parts for machining or hand work. The way is warmed and used to stick the part onto a backing piece which becomes scrap as it is also cut on the final run.

Hope this helps before you run out of tools or patience. Take care as these sorts of part can get picked up by a fast moving tool and can inflict real damage.

Good luck.

[wildwestpat]

Hi Folks

Forgot to add that the parts we about the size of a half pound of butter and there were the ocasional screwup with the tape giving up. The jobs were aditionally held using conventional pivot clamps but in the latter stages ther would not be sufficient metal remaining to permit mechanical clamping. I don't recall the final cuts as being the problem as the breakaways were during the initial roughing out.

Hope this helps and you can find some suitable double sided stick tape.

Good luck and stay safe.

[woffler]

Thanks for all the help still working on it here is a dxf file for those that can open it .Ill try and get a pic as soon as i can find the dang camera!!

[woffler]

Ok here is a jpeg image could not figure out how to get a thumb nail in the reply though hopes this helps . And again thanks for your very kind and genoures help.

[MrWild]

Fixturing is everything. I'd make it with a thicker material, make it to size, then lip it, set it in a female fixture and machine the back side off.

[mc-motorsports]

Are you trying to just "drop" that out of plate or bar? As in hanging it out of a milling vice and profiling? You'll have problems trying to "drop" anything thicker than 3x your EM diameter.

[jalessi]

I would make a fixture as Mr. Wild suggested.

Machine part to finished thickness + .025

Make Delrin fixture with a pocket that flipped part fits in.

Flip part, insert part in fixture and face part.

The fixture could be designed to expand and hold the part if needed.

Jeff...

[LeeWay]

I did something similar when I made a few guitar pickups for a Buddy.
I just held the parts in a vise. Then flipped and faced. I didn't need an extra fixture as you would, but you can see how well that should work.

The speeds and feeds on this video were less than about half of what I could use.
"http://www.youtube.com/watch?v=9eyA2kq7lDM&feature=channel_page"]YouTube - Milling Brass guitar part

[woffler]

Thats what i am going to do ill make a flip fixture as discribed and then face off .I want to thank all that contributed and maybe someday ill be able to help you if i can again thanks.