Reversing lathes

[Seanie]

Hi guys, I have a Raglan Little John lathe with a reversing switch, which I'm teaching myself to use- no books, broken gears etc etc.

Got it working quite well, welded up gears & so forth- my question is re the reverse switch. If you have a chuck holding your work & put the lathe in reverse- wouldn't the chuck come undone & fall off??

I've heard of that happening, & can't really work out just why they have a reversing switch- is it just when work is held between centres without using a chuck?

 

[tel]

The chuck can come off if you're not careful. Having said that, there are a multitude of uses for the reverse function. Cutting left hand threads springs to mind.

 

[DickDastardly40]

If you have a rear tool post and like the tool to be the right way up reverse is useful and if you are cutting an imperial thread on a metric leadscrew lathe or vice versa you need leave the half nuts engaged and reverse the spindle to take the carriage back to the start of the thread.

Tel, IMS left hand threads are cut with the spindle going forwards, the tool starts on the left and the leadscrew is reversed.

If you have to reverse at high speed where the possibility of unscrewing is increased when you stop the spindle and the chuck has inertia it's best to support the work with the tailstock and live centre which should stop any flying ironmongery.

Al

 

[tel]

Yer right, of course, DD - just me having a senior moment, won't be long before I slip into full blown senility by the looks of it.

 

[kf2qd]

Doesn't take reverse to loosen a chuck - I once ran a Monarch with a clutch problem that would some times hit hard enough that it would knock the chuck loose when starting it in forward. No matter how hard you slammed it when mounting the chuck. I have never had any other machine loosen a chuck under forward or reverse operation.

 

[rake60]

The China Import 9 X 20 lathes have that all worked out.
They have a little set screw to hold the chuck from coming loose
when running in reverse.

What that set screw does in reality, is gouge the hell out of the back
thread when the chuck DOES come loose.
Then you get to learn how to hand dress a spindle thread.

Yeah, I've done that a time or two... :

Rick

 

[Loose nut]

If you don't want to disengage the half nut while threading you can run the lathe in reverse to move the tool back to the starting point for the next cut.