Please help! tos trencin type sv18ra

Does it have a metric or imperial leadscrew? Most imperial leadscrews on larger lathes are 8 TPI, so all you need is a 1:1 ratio between the spindle and the leadscrew. That should be easy to accomplish.

If the leadscrew is metric, only, then it gets more difficult. Some lathes have transposing gear sets that can be inserted in the gear train to make an approximate conversion between metric and imperial threads. But, because it is an approximation, and the basic leadscrew thread is the wrong pitch, you have to back up the lathe to wind the carriage back to the starting point. You cannot disengage the half nuts until you are done with the thread.

Jon

What is a tos trencin type sv18ra?

8tpi is generally a pretty easy setting for a lathe to do if that is what it is. You do need a cutter with the right shape tho.

-- Bob May Losing weight is easy! If you ever want to lose weight, eat and drink less. Works evevery time it is tried!

If the transpose gears are 127 tooth and 100 tooth, it isn't an approximation. It is *exact*. 127x2 is 254 which is the *exact* number of millimeters in an inch by definition.

Gary

Er, ah, decimal point decimal point, but it still is exact.

Gary

The thread will come out exact, assuming the QC box has the right selection, since the metric way is thread pitch, while us imperial types do threads/unit of measure. But, you STILL have to back up without disengaging the half-nuts, because the leadscrew pitch doesn't repeat every inch.

Jon

Sorry, it is a lathe. Made in Slovakia, sometime in the '70s. I have access to the right cutter, I just wonder if it is possible to set this machine to cut 8 threads per inch without modifying it and if so how.

Thank you

Jon