Fun with CNC

by James

One of the things I do at work is run a HAAS CNC mill. For the last few weeks, I've had to design and cut several short run press tools. I was milling them out of plywood, (it makes a biblical amount of mess in the mill). I've gotten pretty good at it, so the owner of the company started to think I could make anything, if just given over-night for the mill to run. This afternoon, He asked me if I could make a prototype for a test fit on Monday. Have you seen the movie The Princess Bride, where Wesley is told he needs to come up with a plan to storm the castle??? I looked at the design, and explained that it would take at least 4 tools, not one, and that they were too deep to cut anyway, so each would probably have to be split in two, making 8 tools... minimum a week or more, with the mill running around the clock.

As an aside, Let me explain why depth is a problem in a mill. To reach deep into a part being machined takes a long bit. I'm limited in how deep I can machine, by the length of the bits I have. My workhorse 1/4" bits I can't find any longer than 6" long. They cost more than $100, and they snap easily if I try to take too much cut extended that long. Thus, if a part is deeper than 6", it needs to have enough slope that the bit holder doesn't hit the part. What he wanted was about 14" tall, and needed complex machining on at least 4 of it's 6 faces.

Back to the story. So he asked what I could have done by Monday. Since it was just for a fit up, I asked if it could be made of foam. By cutting off one side, and sitting flat on that cut, I could put most of the contouring on the top. By using foam, I could machine faster, or at least with less stress. Now I just needed to magically find a 10" long, 1/4" bit, (If such a bit exists, I've never seen one), and do late on a Friday. Fortunately, I happened to have a 1/4" 12" drill bit. I also had some scraps of insulation foam. The only real asset I had was 2 and 1/2 days of uninterrupted machine time. I cobbled stuff together, did some test cuts on a scrap of foam, then created a huge program that takes no more than a 0.2" cut, deep or sideways. If all goes well, it will finish sometime around 5AM Monday morning.

I expect the bit will break before then but I had to give it a try.

Wish it luck.

Here it is making it's first few passes.

[linked image]

Posted on Jun 9, 2017, 11:52 PM

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  1. dont know what your making but here some help.. smorizio, Jun 10, 2017
  2. An update. James, Jun 13, 2017
    1. reset.... ydna-zds, Jun 13, 2017
      1. Thanks. James, Jun 13, 2017

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