Thread: Hercus 260 - Single point threading questions

Guys,
I've done a lot of reading and a bit of playing, generally getting used to the 260

It's a metric machine with what I believe to be the standard change gears (thanks to Mal for the pictures in another thread on here).

I can select the correct pitch on the gearbox and think I understand how to use the thread chase indicator.

Things Im not sure about...

1. When engaging the power drive should I use the leaver to engage the half nuts or turn the clutch screw? The clutch screw appears to drive the saddle much slower than the half nut lever.

2. The metric thread chaser appears as though it can be installed in three positions against the lead screw, each position having a different sized cog to drive it. How do I know where it should be.

Maybe I'm an idiot, but the Hercus book of turning seems a bit vague to my limited experience so any pointers and assistance would be greatly appreciated.



Thx
Jon

When refering to POWER drive are you talking about turning the OD or facing or talking about Screw Cutting.

If turning/facing use the star wheel/clutch.

If Screw cutting use the Half nuts.

The reason why there is a difference between the traverse speed when using the clutch compared to the Half nuts is to do with the gearing in the clutch,the Half nut is direct off the leadscrew.

Ever if your clutch was to play up you can use the Half nuts for turning an OD you just cant face with them.If you were to ever do this you would need to change your Screw gear to the smallest size gear you can get (16 tooth) to compensate for not having the reduction in your clutch.

In regards to the Chasing dial the information you require is in the Hercus book on pages 74/75,It details which gear to place where on the Chasing dial to cut the desired pitch that you want and what number to engage on.

Thanks Pipeclay. Everything was related to screw cutting, so half nuts it is. Thanks. I had a feeling this was the answer because the pitch appeared wrong using the clutch. Now I know for sure.

I'll check out pg 74/75 and have another read.

I'm guessing its a case of more reading and much more practice

Thanks.


Thx
Jon

The thing to realise about your lathe is that it uses the same shaft to do 2 jobs - that of a leadscrew (the thread) and of a feed shaft (the long keyway). Note that similar lathes usually have two separate shafts.
They both move the carriage, but you select the appropriate method.
It's impossible to select them both at the same time, so no worries there.

Some simpler lathes, including Hercus model C, use the leadscrew for both screw cutting and the more ordinary duty of automatically providing for carriage movement (no slot in the shaft). The down side is that you're subjecting the leadscrew thread to much more wear.

Your Hercus is a descendant of the South Bend workshop lathe which was very well thought out.

Jordan

Thanks. I didn't know what the long keyway was for... now I do

Thx
J