Screwcutting with AL320G

[Bidgee]

Wondering if anybody with an AL320 can help me with this. If I try to cut a 1.25 (or 20 TPI) thread using the chasing dial I cannot get the tool to track in the same thread ie I do the first pass and the second pass will usually be half a thread our effectively wrecking the thread. This occurs whether I use the same number on the dial or not.

If I leave the half nuts engaged and reverse the motor there is no problem.

I can cut 1mm and 1.5mm using the dial with no problem.

Got me stumped why there is an isuse with just the 1.25?

I raised this back a while but I thought the extra info might help.

Any thoughts appreciated.

Scott

[pipeclay]

dose the thread Chasing Gear cover all the pitches you listed or do you need to use another gear.

[Bidgee]

It only came supplied with one gear but I will check. Thanks.

[pipeclay]

If it only has 1 Gear you are either missing 2 or it maybe an Imperial leadscrew.
The Metric Leadscrew machines are normally supplied with 3 Gears,you interchange for the appropriate Pitch.
Did you get the Lathe new,if so the manual should explain what you need to do.

[Dave J]

As Pipe Clay said they usually have different gears for different pitches for a metric lead screw, this maybe your problem.
Unless it's a imperial lead screw but I don't think they come with one.

See if you can find out from H&F's if they come with extra gears, if not just keep reversing the lathe to cut those threads.Sometimes I just reverse the lathe on short threads and it gives me time to put a few drops of oil on it for the next pass.

This posting shows the different thread chasing gears on the next size up lathe.
Chester UK Ltd :: View topic - Crusader screwcutting drop in dial (http://www.atfreeforum.com/chesteruk/viewtopic.php?t=383&mforum=chesteruk)

Dave