[Potatohead908]

"Cutting threads" ( I could not edit after I noticed the error)

Has anyone tried to cut threads using a CNCed G0704 mill as a CNC lathe? I am attempting to make a worm gear set with something like a 15:1 ratio. What I am wondering most about is if the spindle speed given on the stock G0704 is accurate enough to us as a data point in MACH3?

[Fastest1]

There is no spindle speed info shared on a G0704. It would work just fine if you connected a trigger/encoder to the spindle and fed your BOB the info. Or to possibly share the signal the RPM display uses.

I know MHackney was working on this but I dont know the outcome.

http://www.cnczone.com/forums/bencht...uestion-5.html

Check out post number 45.

[Potatohead908]

Just to try a couple of one of projects can't I just input the data into mach3? I know that is not very accurate. I was more wondering if I will get a usable thread by this before I go through the setup and find I don't, wasting time and material. My plan was to give it a shot tonight after work. Project is trying to make a worm out of drill rod about 2" long x .375" diameter with a long pitch.

[SCzEngrgGroup]

Without spindle feedback, it is exceedingly unlikely you will get a usable thread.

Regards,
Ray L.

[Potatohead908]

Well I will look into making this on my G0602 then. Thinking along the lines of 4 or 5 TPI pitch. Have not done any thread making other than tap/die so I don't know what my options are for threading via lathe. Thank you both for the reply!

[Potatohead908]

Looks like using the stock threading chart the closest I can get is 7.257 TPI using metric threading gears. I'm wondering if I can make my own combination of gearing to get to the 4 to 5 TPI. I'm thinking it is possible. So my project is still on for tonight....just using a different machine.

[hoss2006]

The guy in this thread made a couple pdf's that show all the possible gearing combinations.
Forum | Projects In Metal, LLC |
There was an app but the link doesn't work anymore.
Found this g0602 threading app which might be the same.
http://www.cnczone.com/forums/bencht...ndows-app.html
Hoss

[Potatohead908]

Hoss yet again thank you! With dials set to III B, "a" gear = 60 and "b" gear = 27 I can get less than 4 TPI. If I am understanding that right which I think I am. I was more wondering what my max would be and 4 TPI should be well beyond what I need. I think in actuality I need like a 6.75 TPI thread which I can get close enough using your link!!

[millhead]

The best way to cut threads on a cnc mill is Threadmilling.
Make a single point Threadmill and use helical interpolation G02/03

[Potatohead908]

Millhead I think the setup on this would be a pain and deflection would make it near impossible to do what I am wanting which is .375" drill rod with somewhere around an 8tpi thread 2in's long.

Right now after experimenting yesterday I am trying to figure out the proper profile to cut with. Oh and FYI trying to cut 8tpi for about an inch SUCKS with 150RPM minimum. I ended up spinning the lathe by hand for hours yesterday experimenting.

[SCzEngrgGroup]

Millhead I think the setup on this would be a pain and deflection would make it near impossible to do what I am wanting which is .375" drill rod with somewhere around an 8tpi thread 2in's long.

Right now after experimenting yesterday I am trying to figure out the proper profile to cut with. Oh and FYI trying to cut 8tpi for about an inch SUCKS with 150RPM minimum. I ended up spinning the lathe by hand for hours yesterday experimenting.

Deflection, of the workpiece or tool, is almost a non-issue with threadmilling, especially with an external thread, where you can use a large diameter threadmill.

Regards,
Ray L.

[Potatohead908]

Ray that is good to know. Problem now is making something with the right tooth profile. I'm just trying to prototype something right now and have reached out to a small gear maker to ask for help and maybe three sets of gears for three prototypes. The gears are a worm set, around a 15:1 reduction, the worm should be around .375" diameter and the worm gear about 1" diameter. One worm has to be about 1.25" long and left handed.

[SCzEngrgGroup]

Worst case, you turn/grind your own form cutter using tool steel, then harden it. There are plenty of sites on the web that will show you how. The same cutter will do both left and right hand. if ground properly.

Regards,
Ray L.

[millhead]

I have a question and a comment. Why does the thread need to be 2" long? What diameter is the gear?
As for the Threadmill profile, if you can find a Lefthand threading insert of thr right profile, you can make a Threadmill using that.

[Potatohead908]

Millhead, I don't know if this will work but I am hoping to be able to move the position of the worm gear in relation to the worm. 1.25" maybe more realistic for what I need but I haven't completed the design.

I did reach out to a small gear manufacturer and repair guy who hopefully will help steer me in the right direction. Maybe able to make me a few gears to try too.

Any Gear Made Quickly Inexpensively & Perfectly Al Meekins GearsMade.com. --Delrin gears Plastic gears Bevel gears Worm gears Spur gears Helical gears Phenolic gears Stainless steel gears Cast iron gears Machine gears Steel gears Metric gears Bronze g