Myford screwcutting

[johnthefish]

Hope someone can help? A mate of mine bought a Myford http://www.lathes.co.uk/myfordsuper7/ new about 12 years ago and has only just got round to do some screwcutting on it. He said he couldn't get it right and the threads were coming out to a different T.P.I. to what he set his gearbox to. Impossible I thought. I went round to see what was going on,but sure enough when you set to 8 T.P.I it comes out 10,and when you set to 10,they come out 12. Other than strip the gearbox and count all the gears,we are at a loss. Has anyone else come across this?
My thanks in anticipation..John

[John Stevenson]

Yup,
Get him to count the number of teeth on the first gear past the fibre tumblers.
It should be 24 teeth

[wheeltapper]

Hi
On my mates Myford there are two gears on a hollow shaft that  fits behind the end cover and held with a latch.
the assembly goes one way for fine feeds and round the other way for screwcutting.

it could be round the wrong way.

just a thought.

Roy

[johnthefish]

John, I think you've hit the nail on the head.I just rang him and he's been out to check and his is a 20 tooth gear .. suppose that would make it a bit slower and cut more T.P.I Thanks for that. Suppose RGT will do a 24 tooth gear.
Wheeltapper.. I know the gear you mentioned, that's for slowing down the feed for normal traversing. Thanks for your input.
Will update when he gets the new gear on. 

[johnthefish]

24 tooth gear ordered from RDG Tools yesterday.Arrived this morning and fitted.Now cuts threads as per gearbox label. Thanks from us both.