Random Shut Down of Laguna Revo 18/36

[John K Jordan]

I haven't been able to read all the posts yet but David C. Roseman's comments on VFDs seem worth saving in my files.

I do find it odd to hear that Laguna may not have included the braking resistor with the Delta VFD. Although the VFD manual lists the resistor as optional, my three lathes with Delta S1 VFDs all have the braking resistors installed. None have had any problems spinning down heavy blanks with the default parameters including 5 sec deceleration times. (I certainly agree with locking the chuck or faceplate to the lathe spindle for heavy blanks, regardless of the lathe and circuitry.)

If Laguna did in fact omit the resistors I change my speculation design flaw to management flaw, to the person responsible for saving a few dollars by compromising function. And if so, I wonder if they could be convinced to provide the resistors. (The resistors are installed in contact with the heat sink and connect easily to two terminals on the S1.)

IMO, Jet and PM made a similar poor decision to opt out of the $4 VFD cooling fan in my three lathes.

JKJ

[Bill Boehme]

.... So, I doubt that I will add a resistor to allow me to stop more quickly. It already stops pretty quickly. Quick enough for me.....

It might be a common misunderstanding that the purpose of the braking resistor is to stop more quickly. That isn't the case at all ... unless that actually is what you want to do. The real purpose of the braking resistor is to dissipate the kinetic energy of the spinning mass in the resistor rather than in the motor windings. This is mostly important where there is a very large amount of energy that needs to be dissipated in a very short amount of time which isn't normally typical of woodturning lathes. Think of a heavily loaded conveyor running downhill and needing to stop in a half second as an example of where a braking resistor would be essential. However, if you're spinning a heavy piece of wood at high speed and making very frequent stops to inspect things the motor might appreciate being a tad cooler with a braking resistor.

[John K Jordan]

It might be a common misunderstanding that the purpose of the braking resistor is to stop more quickly....

The Jet and PM VFDs are programmed to decelerate over 5 seconds. I've sometimes wished it could stop a little quicker when turning tiny things. I looked at the Delta S programming once and two different accel/decel parameters can be set. One of the multifunction input terminals can apparently be used to switch between a slower or faster acceleration/deceleration. This is on my list of things to try in my spare time.

I didn't check to see if it's possible with these VFDs but a nice feature might be to vary the deceleration time based on the load - a massive blank would then take longer to stop than a pen blank.

JKJ

[Joe Frank Porter]

Thanks so much for the excellent discussion on the issue of "lathe shut down",when you stop turning large, heavy, wet bowls.
No company's customer service could have come close to the information given in this extensive dialogue.
Thank you Sawmill Creek Turners Forum!!

Joe Frank Porter