Thread: Shop Talk!
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Old 11-23-2012, 10:54 PM   #109 (permalink)
y0da900's Avatar
Join Date: Oct 2007
Location: Plattsburgh, NY

I decided to jog before walking. This is a milled version of the blank prototype body from the MCB open source project (breech end insert instead of machined in).

Other than testing operations making a trigger, making a stepper mounting plate for a 4th axis project, and putting some tool free removal features on the back of a prototype valve back cap, this is the fourth project I've done with the CNC mill thus far (not counting using it like a manual mill with digital control). All 2.5D as I don't have the 4th axis up yet. Single setup. Modeling was done mostly in AutoCAD, exported to IGES, tweaked slightly in SolidWorks, and CAM done using HSMWorks inside of SolidWorks. Roughed with a flat 1/4" endmill using the 3D adaptive clearing feature, and cleaned up using a 1/4" ball mill with contouring and scalloping.

Total time was about an hour. I had 2 minor fixture crashes that made doing an actual time duration tough. Poorly placed locating pins....

There is a slight bit of eccentricity to the milling that I believe is mostly due to having used the center of the feedneck hole as the origin (I love touch probing with a center finding routine in Mach3), and that was probably not located perfectly centered as I had done that well before the mill was converted to CNC, and the tubing the body is made from has an actual OD of 1.512 instead of the 1.500 in the model.

Little bit of fine tuning to learn as far as stepover control and what CAM features are best suited for which aspect of the milling, but I think it came out pretty well considering.

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