[Silentelk]

I am fairly new to machining of metals and short on knowledge on feeds and speeds. My experience is primarily using solidworks 3D cad, mastercam programming and doing 5 axis machining wood mock ups of full sized front ends of vehicles.

A project has come along where I need to make a copper heatsink, well 50 at first but eventually 100's. Now copper is real PITA to machine I hear and so I have found a suitable replacement, tellurium copper, which seems to have a machinability rating of about 75-80 verses 10-20 for copper.

I have at my disposal an older bridgeport knee mill we have converted over to CNC. I have to manually change the rpm but isnt a problem. I believe it has a max rpm of spindle is about 3500-4000 with about 2 Hp but I dont think I will need it all, or even close, as the bits will be small enough they will not take much abuse anyways.

Will be doing some slots about 0.25" depth and 0.125" width. Looking at using a .125" or smaller flatendmill for most. Also have some smaller holes I would like to drill and tap using 0-80 thread. Now I know this is small, very small at 3/64" dia and need to countersink the heads using a 1/16" flat endmill. Holes are shallow so cutting time doesnt bother me at all at snail rates. And lastly, will be using 2 sizes of ball endmills for 3D surface contouring. Most 3/8" diameter but a small engraving with a 1/64" dia ball end.

Flute size, cutter material, depth,cut, feedrate or any other advice greatly appreciated!


Also, any idea of the price of this stuff? I am hoping to get it for less than $25 a pound. I have not yet inquired on pricing yet but will do so tomorrow.

thanks for help in advance! Long time reader, first time poster.

[Silentelk]

If no one is familiar with cutting this specific material with these tool sizes, thats ok. Even just some rules of thumb for how to cut it. I have done some general work with AL, but this is just hand milling one off items. I dont claim to know the feeds and speeds I was hand cranking but it would be slow overall. 5 ipm or less hand spraying lots of cooling.

Does it cut like Aluminum? Little worse, slower, etc. 2 flutes or 4? The other day, i did order a book. I am sure many on this website are familiar with it. Machinery's Handbook 28th. Not looking for someone to do all the work for, just some general guidelines would be greatly appreciated.

Hope everyone is having a good weekend!

[Andre' B]

I machined some one time. It seems to cut like some of the harder aluminum alloys. I even had it on the surface grinder for a bit with no problems.

[Silentelk]

I machined some one time. It seems to cut like some of the harder aluminum alloys. I even had it on the surface grinder for a bit with no problems.

Thats encouraging and I am glad to hear it. Any one else have any thought sthey would care to share? they are all appreciated.

[Delw]

the tellurium copper I cut on the cnc lathe cuts really good alot easier than alum with NO chips, its like cutting brass only softer and not as gritty. I guess it would be more like cutting delrin without the stringy chips

I use only tool steel bits for it as carbide doesn't cut as well.

25 bucks a lb , I havent priced it in a while but I would think it would be over that now.