Question about Delta inverter used on Grizzly lathes..?

[Doug Rasmussen]

At a shop sale yesterday I picked up an S1 or SL01 (?) .75kw Delta inverter that had been on a new Grizzly G0632 lathe. At 2 bucks it was too good a deal to pass up. Hopefully it's still functional.

From the owner's written notes included with the inverter it appears Grizzly replaced the inverter, display, display driver and speed sensor on the lathe without any attempt to actually diagnose whatever problems might have existed.

From looking at the screw terminals on the unit, besides the power input and output, there may have been an external speed potentiometer hooked up. If so, there would be parameters set to indicate the potentiometer which I'll need to unset.

My question is, are there other connections besides the external potentiometer that might need to be disabled in the parameter settings?

[Bill Boehme]

I'm surprised that you would want to disable the external potentiometer input. That's generally the preferred method of setting the motor speed.

Small inverters of that size typically have more than one method of controlling the motor speed, but for woodturning lathes the external pot is normally the preferred way to go. Other typical ways to control the motor speed include:

• A tiny knob on the inverter that adjusts an internal potentiometer. These are usually pretty cheesy parts and not very satisfactory for constant adjustments that is typical for woodturning lathes.
• Use the numeric keypad. This is also an inconvenient option.
• Some inverters have a current sensing input such as 4 to 20 mA. This might be useful in an industrial environment where there is a lot of potential for electrical interference.
• Fancier inverters will have provisions for digital input using an RS-422 or other interface. Ok for an automated factory, but not so useful otherwise.

You can find the instruction manual online at the Delta site and it will give you all of the set up instructions. There are probably just one or two soft switches to select your choice for speed control.

[Doug Rasmussen]

Bill, thanks for the reply.

I didn't make it clear, this VFD will not be used on a lathe. The key pad will be fine for my use.

I found the inverter manual online and there is an option to reset everything to factory default values, that should cancel any parameters that were preset for lathe use.

As I said, this inverter was replaced by Grizzly without diagnostic work to see what the real problem was (if any). Based on the previous owner's extensive notes it appears a problem with the lathe may have been related to the spindle speed readout, hopefully the inverter is good. The original owner was a good customer with $20K+ in new Grizzly equipment, my assumption is Grizzly did a shot gun approach to correct whatever problems the owner was having by replacing everything related to spindle motor control.

[Doug Rasmussen]

An update on this situation...

To refresh the story...at a shop estate sale I picked up a Delta inverter that had been replaced under warranty on a Grizzly lathe. For 2 bucks too good a deal to pass up. My intention is to use the inverter on a three phase bench grinder provided the inverter is functional.

The challenge was to disable the parameter settings specific to Grizzly's lathe setup for use with the lathe's remote control panel. Turns out not so easily done. The inverter's parameters are factory set and protected by a "secret" password for lathe user safety. The reasoning is Grizzly doesn't want users to be able to run the motors beyond a reasonable rpm. The inverter is capable of running the lathe motor at over 11,000 rpm. The factory setting of this inverter limits the motor to around 3600 rpm.

To work around the unchangeable factory settings I built a remote control panel using an easily sourced potentiometer and a couple momentary contact switches. This is all explained in the Delta inverter's online manual.

I did call Grizzly support to ask if they might know the password to unlock the inverter's settings. They don't have the password. They don't fool around with the inverters at all, if there's suspicion of a problem during the warranty period they simply send out a new one. That's what happened in this case, the inverter is good, but they replaced it because the original owner thought there was a problem. Presumably, with the cost of labor these days it's less expensive to replace an under 200 buck part rather than trying to diagnose a problem.