cutting metric threads

[savarin]

I think I have this correct but really need to double check as I havnt yet cut a single thread. (or anything else really)
This is for a generic 9x20 asian lathe.
So, if I wanted a 6mm dia thread I would turn the metal down to 6mm dia,
set the change gears to 30 - 127/120 (stacked) - 45 and the gear lever in position 1.
This I believe will give me the 1mm pitch or 1mm between crests.
And if I wanted the 6mm fine thread I would change the gears to 30 - 127 - 120 - 60, gear lever position 1 to get a 6mm dia 0.75mm pitch.
Have I got it right?
Thanks

 

[pdentrem]

Is your lathe's native threads Imperial or Metric? It makes a difference to how you operate the lathe.
Pierre

 

[jumps4]

i'm not in front of my lathe but i remember that in the diagram it is hard to see the right setup on the gearing on the 120/127 gear and easy to miss something there. look at it real close if your pitch is wrong. I had the problem once.
also If you get time check the yahoo 9x20 lathe site
http://groups.yahoo.com/group/9x20Lathe
steve

 

[Mr. V.]

just thought i'd throw it out there that if you're cutting your first thread, remember it is usually a good idea to go about .10-.15mm smaller than nominal. the bigger the nominal size the smaller than nominal you may go. This just gives you clearance for burrs and dirt so your nut will spin on freely.

 

[savarin]

Thanks all, just have to do a bit more work on my compound clamp and then I'm good to go again.