Pm1340gt Lathe Threading With A Proximity Stop

[jeff_g1137]

Yes this is a very good motor for use with a VFD, probably the usable frequency range would be ~20-100Hz.

Hi Mark
Thanks i can buy the motor now, & get all the bits i need, getting ready for the VFD build .

Thanks Jeff

 

[Firestopper]

I can honestly say upgrading to a inverter motor makes a wold of difference when used in conjunction with Mark's system. I thought the new control system was awesome with the old motor, but with the upgraded motor (thanks to Mark's research) the lathe runs like a Swiss clock and stops on a dime with plenty of speed/torque range in short, its amazing. The PRM's do not fluctuate even during a heavy cut. The only time I see a slight RPM change +/- 1 rpm is during larger drilling operations but even this could probably be resolved by selecting a lower gear range and adjusting the potentiometer (speed).

Mark spent some time in the shop yesterday and we threaded a 1/2-13 utilizing the proximity stop and leaving the 1/2 nut engaged (like his video) and its worked like a charm. This will be extremely useful when boring/threading blind or to a internal shoulder. You really need to trust the system and with his micro switch mechanical back up incorporated to the carriage stop you can trust it won't crash in case of proximity failure. You'll need to practice/follow the sequence of operation when using the proximity by-pass, but its not complicated just different.

I should add the original motor on my lathe was not as good a quality as the ones that comes with the PM lathes. On hi speed it would cog a bit at run up and would growl as well at certain frequency. The new motor is silk, plain and simple. Replacing the drive pulley to a smaller one (under drive) also made a difference.

 

[Lonnie]

I used Marks threading technique yesterday and got my telescope spacer ring built with M48 x 0.75 threads.
Worked awesome! Now I just gotta give anodizing a try......

 

[mksj]

Neat, and impressive work for both internal and external threads, and amazed at how clean the threads came out. Great work, hope your happy with the system/lathe, the machine holds some very nice tolerances when turning. Always puts a smile on my face when using it.
Mark