Maybe not Andy, As I said I've never used G76 as I was using a mill to do the thread.
I literally just lowered the knee by the required amount without altering the code, quick and dirty but it got the job done.
I had to do this because I was making a small steam engine and I tapped the cast Iron valve block for the gland nut M6 fine then threaded the nut with the M6 fine die only to find the tap was M6X1.5 twin start so I had a machined casting with the wrong thread.
My solution was to make a new nut with the twin start thread to fit and it worked brilliantly, my first milled thread and a twin start to boot.

Moral of the story, don't assume the cheap tap and die set you bought 15 years ago has the right threads in it M6X1.5 twin start looks very much like M6X0.75 so they must have got them mixed up in the factory!

Lol , I asked an engineering company to quote me for a tap and die custom 4 start set....£600 eeek!

 A while ago I cam acros an article about threading on the mill with a single toothed cutter, is somthing you have tried?  I am keen to give it ago, my mill should arrive next week!

Andy

Yes that's what I was doing, it was actually a tool with 4 flutes and a single point in profile, if you get what I mean.

Great thing about single point is you can use the same cutter for any pitch as long as it cuts deep enough, I have a small one for around 3 -10mm and a larger one that can cut to about 4mm deep so quite large threads.

Steve

Bowber did you buy this tool or make it your self, ... got a pic your willing to share )

I was going to try making one.

Andy

Yes I got it from the USA via Ebay.
I'll dig out the sellers username and let you know, their not perfect but good enough to do the job.

Steve

That would be great.

Thanks,

Andy

Hm

Ebay username cmtchtools

Unfortunatly they are no longer a registered use on Ebay and the web address doesn't work either, so back to searching again, hope mine doesn't break soon.

People have used the inserts out of threading heads to make them so maybe you could search some out at Auto jumbles.

Steve

Hi All,

I tried to multi start thread after upgrading to the latest version, no joy yet...when displacing the start by x do you have to do the z end by the same?

i.e if I want a 1.5 pitch thread and 3 starts I displace the start point by .5 so it goes

z0 0

thread code

z0.5

thread code

z1.0

thread code

end

However in thre thread code do I need to put the thread en point .5 mm earlier?

A

tef9
May be wrong, but if the thread code for length was the same, then each cut  would finish longer after the first thread, by the pitch / lead, because the Z start point is changing the start point. The nut would be the same thus you need not change anything on the end.

May i ask why you are doing a mut-i-start thread?
RICH

Have you tried the angle offset way that I pasted details about in another thread you were enquiring about multi start threads?
Hood