CAD CAM EDM DRO - Yahoo Group Archive

First example case

Posted by dannym@a...
on 2008-01-28 23:54:11 UTC
OK, this is one of the first things on my list of actual things I need to do:
I need to cut a 2D part out. It's part of a crossbow trigger, basically a "T" shape, got some curves and things but no complicated features that I see. About 2.25" long 1.5" wide.
The inside corners would be fine with a 3/8" radius.
It has a single hole 0.075" dia. I have a drill press if necessary.
I have a 36" long piece of 2" wide steel from the hardware store, 3/16" thick, described only as "plain".

My assumptions:
I need to get an end mill 3/8" and 2-flute would be ok
The milling process cannot help with my circular hole. I should drill that first and use it as a reference point for the CNC process.
Since this is a 2" wide stock with a 1.5" wide part being cut with a 3/8" kerf on either side, I must clamp along the long axis to avoid striking the clamps.
I would get some MDF as a spoil board to protect the Taig rails and possibly raise the stock so the chuck won't hit the clamp (hitting the chunk on the clamp probably won't be a prob).
I would modify the design to leave tabs say 1/4" wide on the long, clamped sides so it isn't cut free. The tabs can be basically in-line with the clamping axis so it's not at risk of forming a "Z" that squishes down and loses clamping pressure. I could also thin the metal at these points to make it easier to cut free with the band saw. Thinning is also necessary so I can see the line to cut.
I do not have a coolant mister setup. I should spray it with WD40 and set the XY speed low to keep the heat down.

I could also clamp the whole strip in a clamp along its 2" width, leaving 2.75" extending past the clamp, still resting on MDF, so the machining can be done on the part extending past the clamp without running into the clamps. That means the clamping force is not trying to flex the part and squish it so this sounds better, maybe the tab could be thinner and the machine could cut it free as the last step. Also I would not have to worry that the cut ends of the stock being put in the clamp are cut square as in my first case. Downside is the part's only being supported from one side during this process though, but the force isn't going to be high enough to bend the part around or anything, is it? This seems like the better plan actually.

Comments?

Thanks,
Danny

Discussion Thread

dannym@a... 2008-01-28 23:54:11 UTC First example case Michael Fagan 2008-01-29 00:29:41 UTC Re: [CAD_CAM_EDM_DRO] First example case a3sigma 2008-01-29 03:31:36 UTC Re: First example case Michael Fagan 2008-01-31 00:31:15 UTC Re: [CAD_CAM_EDM_DRO] Re: First example case mycroft@c... 2008-01-31 01:34:06 UTC Re: [CAD_CAM_EDM_DRO] Re: First example case