Orac / 2024

[Neale]

Specifically, if you still do have the original Denford-fitted VFD, then this is a pointer to the manual for it (pointer to PDF in second post).

The Parajust VFD was a fairly early VFD, and from what I have read does not have the greatest reputation for reliability. However, when working, it does do the job. If you are going to use it, read the manual very carefully about connecting to it as some of the input terminals might carry dangerous voltages. Certainly you would be OK switching the forward/reverse inputs via a relay which would provide isolation, but I'm not clear about the 0-10V control voltage input. The manual describes how to use this, but as I say, I'm not sure about isolation from high voltages. In any case, you are going to need a PWM to analogue voltage converter, the same way that I did. The P-CNC board has a PWM output, not analogue, which seems a bit silly as almost everything wants analogue. However, you can pick one up for around a fiver off eBay. I used one of these but there are plenty like it. I didn't need to look for high-voltage isolation so didn't bother to check if these cheap little boards would do the job in your case.

If there is any doubt about the Parajust VFD (if that is what is in there), then replacing it with a modern equivalent is very easy.

Sorry for slow reply - the site seemed to be unavailable for a couple of days.

[addy]

Hello,
Not sure what happened with settings here, I got a notification regarding the first reply, but nothing after.

Thanks John, I will read through.


Brian,
Steppers: I went for nema 34 only because the original steppers have the 34 frame. Without much guidance, I was trying to limit the number of modifications to a minimum.
But very soon, I ran into a "problem" : the belt profile is 100XL037, the original pulley has 12 teeth, and the new motor has a 14mm shaft. Can't find a pulley with such a spec.
I ordered one 12T XL profile, but I have to open the bore and cut a key. I could have bought a nema 23 but only recently I found an adaptor frame 23 to 34.
After your post, I ordered DM860H drivers and a 60VDC source to use the original motors. I will play with the 34 closed loop once more knowledgeable.
Do you have an wiring diagram for the motors/wire color combination? I found a discussion about parallel and serial connection. I am planning to use the original wire combination.

The encoder on my lathe is a 5V (four wires : SYN, +5V, SPD, GRN). I been advised by the P-CNC tech support to buy opto isolators for all inputs and outputs. There were some questions around the encoder being PNP or NPN that I could not answer. I will updated with the progress once my 5V source will arrive.

VFD - If easier/ safer , I will buy a new one. No point of taking the risk of grilling the board. Any recommendations for a decent modern one? What should I look for? 1 phase to three? 750whats?

thanks,
a