experiences threading on the new Patriot VFD?

[grizzlymog]

Hi All, Brand new as a registered forum user but I've lurked here on and off over the years.

I currently have a ~2000 Smithy midas 1720 3-1 machine. I guess I purchased it at about the time they discontinued this model. It's been *okay* as a lathe, really not usable as a mill on any sort of metal which I guess was the reason it was discontinued so quickly.

I'm looking to replace the smithy, and since I am familiar with cnc (I have a cnc plasma cutting gantry and router for ~10 years now), I thought why not have that capability on a 3-1 machine. I see that the new Patriot VFD's have no gearbox, hence no way to manually thread, and you have to rely completely on the stepper motors to drive x,y. My question for the group is has anybody cut threads with the new Patriot and, if so, what are your impressions? Are the ballscrews a must for fine threading, say like 18 tpi?

I've used the smithy for various tasks over the years, mostly for machining parts for various vehicles I have and implements I've built. The vid below is of a hydraulic snowblower I made using the cnc plasma cutter for the big stuff, and the lathe for various small parts and fixtures.

Cheers - Paul
http://www.youtube.com/user/mtmogs#p/a/u/1/GYku0xoAmh4

[grizzlymog]

Really? Nobody out there cuts threads?

Anyhow, I can probably answer my own question. As mentioned on another post, I decided to CNC retrofit my Smithy 1720 including an upgrade to C7 anti-backlash ball screws instead of purchasing a new Patriot. The project is basically complete. I am using basically the same camtronics cnc electronics as on the Patriot. My guess it that the lathe now functions pretty similar to the Patriot w/ball screws. So to answer my own question...I bet you can cut threads pretty well.

I've attached a photo of my first threading attempt using a hunk of some old 3/4" concrete stake and a hastily ground HSS 60º toolbit. I tried to duplicate a wheel lug thread, in this case it's soemthing like 1/2"-23 as I recall. I programmed about 6 cutting passes and a few spring cuts. I have to say I was surprised and impressed by how good the fit was. I'm sold on CNC machining.

[instructor37]

Originally Posted by grizzlymog Really? Nobody out there cuts threads? I am using basically the same camtronics cnc electronics as on the Patriot. My guess it that the lathe now functions pretty similar to the Patriot w/ball screws. So to answer my own question...I bet you can cut threads pretty well. I've attached a photo of my first threading attempt using a hunk of some old 3/4" concrete stake and a hastily ground HSS 60º toolbit. I tried to duplicate a wheel lug thread, in this case it's soemthing like 1/2"-23 as I recall. I programmed about 6 cutting passes and a few spring cuts. I have to say I was surprised and impressed by how good the fit was. I'm sold on CNC machining.

Good to hear you got your retrofit done- probably should have posted over on the Smithy site. That may be why you aren't getting much response here.