how to make threaded rod using lathe machine

[chepot]

I have lathe machine at home, and I want to make acme or ball screw thread by my own, but I don't know how to do it.

can somebody give me a guide or a link? thanks

[Geof]

Ball screw you cannot make for yourself.

Acme threaded rod is possible on a small lathe but not easy. Do you have a Travelling Steady? This link shows a home made travelling steady:

http://iwr.ru.ac.za/~iwdf/lathe/travellingsteady.html

You need this because a long piece of material is too flexible and will deflect away from the tool.

Have you done any threading on short lengths? This what you should do first; practise threading the size and pitch that you need but only on a length of a couple of inches or so.

[chepot]

thanks for your reply Geof.

I a beginner on operating lathe machine.

I have practice to make a rod diameter to be smaller, make the rod's edge sharp like a pencil

then I tried to make simple threaded bolt and failed.
the thread seem to be overlapped.

the info / guide to make a thread is i'm looking for right now.
do you have any good link? I tried google it but can't find it.

btw what kind a machine suitable to make ball screw thread (2cm outer diameter)?

[Geof]

Originally Posted by chepot ....then I tried to make simple threaded bolt and failed. the thread seem to be overlapped. btw what kind a machine suitable to make ball screw thread (2cm outer diameter)?

To answer your second question first: Ball screws are either roll formed or ground; Google 'roll forming' to find out what this is. They are also made to much better accuracy than is possible on a small lathe.

Regarding your overlapping thread:

Did you get any manual with your lathe that explains setting it for threading and using what is called the chasing dial?

You have probably figured out how to change the gearing between the spindle and the leaddscrew for different thread pitches.

What you need to look for is a little worm gear that engages with the leadscrew somewhere near the lever that engaes the nut on the lead scre for cutting the thread. This worm gear is connected to a dial with numbers and a little pointer.

If you cannot find what I am talking about can you take some pictures of your lathe and attach them?

If you do find the dial make sure the worm gear is engaged with the lead screw. Now turn the machine on with the leadscrew engaged so it turns just like you would for threading.

You will see the dial rotate and when threading to make sure you don't get overlapping threads you engae the nut always at the same position on the dial. There will probably be numbers so if you engage the nut when 1 is by the pointer for the first cut always engage at 1.

You need to practise a bit and start engaging the nut just before 1 gets to the pointer.

Sometimes you can engage at other numbers; often it is 1 and 3 or 2 and 4, but don't worry about that just use the same number for your first tries.

[chepot]

thanks for your guide Geof.

I'll practice soon as i got the material.