FOLLOWUP -- Lathe and VFD -- Some results

Ignoramus30183 · 2008-07-17T04:22:37+00:00

I wired the VFD to the lathe. Not in the best way yet, but enough toexperiment. Toshiba VF-A3 3.7 kW VFD, similar to what I sold to PeteC, only bigger and with cracked top cover. (I have more for sale, 2.2and 3.7 kW) Here's one very encouraging piece of news (related to what Karl said):switching of the speed selector lever while the motor is running doesnot destroy the drive. It simply trips on a overvoltage error and letsthe lathe coast to stop. I am very satisfied with this behavior. It is as perfect as it gets. The drive can easily accelerate the lathe, even at the highestspeed setting, etc. Right now it trips when I press OFF, no doubt due to too ambitiousbraking that is the default setting right now.What I need to do is:1) A lot of settings need to be set such as no braking, fixedfrequency (60 Hz), one-two second acceleration, etc etc. 2) Wire it properly to turn on with the limit switch operated by latheON/OFF/BRAKE lever3) Place the VFD deep inside the lathe cabinet so that it would not bea hazard or distraction. There is no need to access the drive once itis set up. So I will put it away. This will be a single phase lathethat would be operated with its original control and no weird wiringoutside.The ONLY thing that I may allow to be visible outside is the FAULTindicator shown by a LED bulb. Maybe a FAULT with RESETpushbutton. That's all. I do not want switches, potentiometers, noneof that stuff is necessary.

Jul 17, 2008 21 Replies

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No! Motor - gearbox - spindle, no clutch, no brake, no varispeed drive.

Yes, the highest nominal speed is 1250 RPM, there is a version of the lathe with a two-speed motor, but I don't have that. I could take the motor up to 120 Hz and get 2500 RPM, but the idea of an 8.25" chuck at

2500 RPM scares me!

I think it is 5 Hz, I don't remember exactly. it is a programmable parameter.

Yes, works fine in high speed mode, but with the backgear engaged, it takes a lot of force to turn the chuck. I could EASILY live without it, but since the VFD supported the feature, I put it in, just a push button and one more wire.

Jon