Sherline - Lead Screw Pitch ?

[Curmudgeon]

Bought a pair of Sherline CNC benchtop machines at a school auction. They turned out to be Paxto-Patterson (PP) machines and according to PP at least 13 years old. Originaly produced with Micro-kenetics motion controler hardware and propriatary software of some sort.

One I have already retrofitted with modern steppers a Rockcliff Driver board. This one is up and trunning under Mach3 as I wright this. The other needs a tailstock and a few small parts. I think I will leave the original steppers on it (I have a spare now as well) and get it all cleaned, adjusted and ready for someone else to power up.

I'm impressed with the quality of the parts machined for the retrofit by PP, the CNC add on parts are really nicely made and they look good as well.

Anyway, the reason for the post.... I need to know the pitch of the lead screws so I can accuratly configure Mach.

Anyone know this, I'm pretty sure they are old, original, standard, stock screws and not special CNC versions, but then I could be wrong...

[vlmarshall]

Sherline uses 20 TPI leadscrews. Post some photos of your machines!

[Curmudgeon]

Thanks for the info VL !
I'll post up as soon as I'm turing something accuratly, hopefully that will be soon. Spent the 3 day weekend tweaking the DIY router and fine tunning one of the jig and offset set ups. Now it's time to find CAD/CAM software for the lathe. What I have now won't draw a cylinder.

[vlmarshall]

Thanks for the info VL !
Now it's time to find CAD/CAM software for the lathe. What I have now won't draw a cylinder.

Ah, but you don't NEED to draw a cylinder. Just work out the tool path in X and Z, the rest of the part will follow when it's spinning.

I use FeatureCAM at work, and even that doesn't actually render a cylindrical part onscreen until you run a cutting simulation.

-Vernon

[Curmudgeon]

Thanks Vernon. I'm starting to see some real value in learning to write/adjust g-code. I hate the thought of having a third tool just for the lathe code. I found a neat utility called cad2lathe that builds a X-Y based tool path from a flat profile drawn in DXF. It's got it's quirks, but if you draw the part according to a few rules, it will render usable g-code. For what I need to do, I think it will sufice just fine, especialy once I master fine tuning the g-code directly. The author, Bob Adams, has been very helpfull, and patient.

[vlmarshall]

Definitely learn how to work with G-code yourself, it'll save a ton of time running back to your CAM program when you need to change some little thing.

That program you mention sounds interesting, I think I'll check it out.