Friday, December 14, 2018

CNC Threading Scratching Metal

Since my last post on the CNC Lathe project, I made the mount for the optical sensor permanent (that is, not blue painter's tape) and permanently mounted the optical sensor board inside my control box. The optical sensor mount is adjustable to rock forward and backward as well as swivel little bit clockwise/counter CW around the two 1/4-20 bolts visible. 

The CNC4PC board is visible at the top left of the box in this picture.  Besides saying "CNC4PC" on it, it has two blue terminal strips on the right, toward the centerline of the box it's in. 

This was all done by the 6th (file date on those pictures).  The optical pulses were being read by the Mach3 software and it displayed RPM on the monitor.   

The holiday intervened, as it tends to do, and I only today got back to trying to get all the hardware and software to actually play nice with each other. 

I was going to "go for it" and try to cut a 1/4-20 thread, but I figured I'd better start with a "try to walk before you run" day.  The idea was cut a few passes of 1/4-20 in brass to see how the threads looked.  Good thing I did.  Something isn't right. 

To begin with, anything you see that's brass colored has been cut into the blue-dyed brass blank.  If you look at the threads on the right, you'll see a thin blue line in the middle of the wider brass color.  That means the cutter didn't retrace the same cuts exactly.  If you could look into the profile of the thread, instead of being a sharp "V", it's more like a "W".  The high spot in the middle of the W is the dark blue line in the middle of the scratched thread. 

The next task will be troubleshooting this and getting the scratch to come out as a V.  After that, it should thread properly.

1 comment:

  1. As a guess, I'd say you missed engaging the threading lever on the same number / line / letter as you did the first time.