If only I could acquire a widget to ...

[hughc]

17 hours ago, agg221 said:

Thanks - I am mostly making 1/4", 5/16" and 3/8" at the moment. The lathe can't pull a die down the stock in a single pass so I end up using a die by hand in the vice (having got them nicely started square using the lathe tailstock). I will have to get to grips with screwcutting, but my one attempt so far at 5/16" BSF which required 22tpi was not a complete success as I didn't have the tailstock centre in so I got too much deflection and the stock kept jumping the tool.

 

Alec

Use a tailstock die holder. Most of the machining I do is in these three sizes to fit Kelvins and for these the die holder works well.

[Victor Vectis]

1 hour ago, jake_crew said:

Do you know the first rule of using a lathe ? 

Clue - something to do with the chuck key.

A bit like leaving a windlass on a spindle?

[BEngo]

19 hours ago, agg221 said:

Thanks - I am mostly making 1/4", 5/16" and 3/8" at the moment. The lathe can't pull a die down the stock in a single pass so I end up using a die by hand in the vice (having got them nicely started square using the lathe tailstock). I will have to get to grips with screwcutting, but my one attempt so far at 5/16" BSF which required 22tpi was not a complete success as I didn't have the tailstock centre in so I got too much deflection and the stock kept jumping the tool.

 

Alec

As hughc says, tailstock die holder is good, but if the lathe wont pull the die someone has perhaps fitted a smaller motor.  There should be no problem in back gear, even with 3/8 stainless.

 

For single point thread cutting I find the angled approach (add cut with topslide at 27.5 deg) or stepped angled  approach (most of cut with topslide at 26 deg and the final cut with cross slide)  the best as the cutting is taking place on just one flank and the thrust is toward the chuck  rather than encouraging the job to climb over the tool.  HSS is better than carbide cos it is cheaper,  easier to sharpen, takes and holds a better edge and doesn't chip.  If you don't mind resetting after sharpening you can even have a bit of top rake.

 

 

N

[system 4-50]

6 hours ago, jake_crew said:

I think you're trying to run before you can walk if thinking of selling what you make.  Get used to using the machines.  Make anything just for the practice.   Maybe get some training ?  Join a local model engineering club or get some evening classes.

 

Do you know the first rule of using a lathe ? 

Clue - something to do with the chuck key.

If your comments are meant for me, can I suggest you read what I have already posted, again?

[agg221]

Thanks Hugh & Nigel,

 

I have done quite a bit of plain turning and have cut plenty of threads with dies by hand, but screwcutting on the lathe is a new one for me, enabled by having a lathe with a banjo and set of changewheels. Useful pointers and I stand a much better chance of success next time. I generally do use HSS, although I can't say that sharpening it is a pleasure, but it does work well.

 

Alec