Lead screw size?

[websterz]

I need to make a new set of half-nuts for my HF 7x12. Cheap folks that they are the Chinese had only installed the lower half of my half-nut but I got on with it because I wasn't too worried at the time. Well, the half that I got is wearing out...cheap Chinese iron you know, and my power feed is beginning to slip. I recently had 200+ pounds of century-old cast iron delivered by a friend of mine in the form of a junked out upright piano harp. The material is fantastic...cuts like butter! Anyway, I am going to take advantage of the bounty and make a proper SET of half-nuts for my lathe but I have no idea what the leadscrew size and pitch is. Anyone know off the top of their head? All I know is that it is an Imperial, not a metric screw. 

 

[Darren]

16tpi I believe http://www.littlemachineshop.com/Reference/change_gears.php

Metric is 1.5mm pitch

[websterz]

16tpi I believe http://www.littlemachineshop.com/Reference/change_gears.php

Metric is 1.5mm pitch

hmmm...I may be removing that and putting a 5/8-16 ACME on in it's place.

[Bernd]

websterz,

My 8 X 20 Grizzly has a 16tpi. I wondered why I couldn't cut a good Imperial thread.

The lathe is going to go through a total rebuild. I've already started  on the frame al Bogstandards fix of (i think it was ) Darren's lathe. Not going to put threading capabilities on it though. I have the Logan lathe for that.

I was also thinking of going for an ACME thread but maybe 1/2-20. Might even try to cut my own using the Logan.

Unfortunatly right now I'm to busy with "need to do stuff" that doesn't include playing in the shop. 

Bernd

[No1_sonuk]

hmmm...I may be removing that and putting a 5/8-16 ACME on in it's place.

If you're going to replace it, I would suggest making the right-hand end longer through the bearing if you can.
Doing that means you could more easily add a separate fine feed and/or CNC motor, handwheel, etc.  

[andyf]

Unless you have a bad case of  , it might be easier to buy some from LMS, considering what they cost:
http://littlemachineshop.com/products/product_view.php?ProductID=1373&category=5

The Yahoo 7x12 minilathe group seem to think that the thread is Acme-style, tho' perhaps not true Acme. If you need it, in their "Files" there's one called "Half nuts +threading". It includes details of switching from an inch to a metric leadscrew, with instructions on how to fit/adjust the half-nuts. The procedure will apply to either version.
Andy