Helical milling with a diagonal repeat ?

Hi all,

I've just tried out the sub routine for a spiral (posted by Andy) and it seems to generate a perfect spiral for the most part, but the first 1/4 of a circle pass and the last passes at the bottom of the hole are slightly elliptical. Do you have any idea why and how to correct this? My G-code arc fu is weak!

Thanks,
Ed

edsimmons wrote: the first 1/4 of a circle pass and the last passes at the bottom of the hole are slightly elliptical.

G-code can't actually do ellipses. Is it possibly a backlash/flex thing?

Interesting - it's certainly doing something odd, there's a definite difference between the radius of the spiral and the radius of the start/stop points. It shows it in axis too when run, I set up the sub routine file then called it using the command entry in axis, this gave me a little test spiral but definitely not quite what I expected!

Thanks,
Ed

I don't suppose you've got a lathe, Andy? I could stop all these circular shenanegans if I could find someone who'd be willing to run a few passes on a little alu part!

edsimmons wrote: I don't suppose you've got a lathe, Andy?

Yes, actually.
It isn't a very good one, but it is at least CNC.

No eBay APP ID and/or Cert ID defined in Kunena configurationWell, I was just considering purchasing this: to do what amounts to about 10 seconds work for a CNC lathe.

I have a little threaded part with an internal bore, this needs to be enlarged to be a snug fit onto a tube. If you'd like a small job of this ilk, name a price and I'm sure we can work something out! Thanks

Ed