Kindness to Brush Motor Control Board

I recently purchased a Warco WM180 lathe. It has Start and Stop buttons, and a speed control.

I'm sure I've read somewhere that its undesirable to start the motor with the speed control set above minimum because it can fry control board components; can anyone confirm this?

Its a little tiresome having to keep winding the speed control back and forth if frequently stopping the spindle to take measurements.

Hi Andy,

I have a WM180 and never had a problem with the control board in 7 years of use. I usually switch on, then adjust speed as necessary.

Ed.

Thanks Ed, that's good to know.

Have my Sieg for five years, always turn speed control to zero before switching off and had no trouble with electrics so far.

I also had a WM180 and did have to replace control board for starting with the speed set fairly high, a large flash when it happened and not cheap. I have now up graded to a WM250 and have replaced the plug fuse to 5 amps as a precaution and must say the fuses do seem to pop frequently, no doubt due to my over ambitious cuts. I seem to recall there was a sticker on my WM180 warning about starting with the lowest speed setting. I would recommend changing the plug fuse and keep a few spare fuses as a precaution..

It depends on the design of the control board: it might do an automatic 'soft start', and be generously rated or it might not. Unless the instructions say otherwise, I'd always start the motor at the lowest speed. Better safe than sorry!

Dave

Hmm - no warning sticker, but...

I might phone Warco and ask - if I get any useful information I'll post it here.

That's because the 5A fuse is too small. The plug fuse is there to protect the upstream wiring, not the downstream electronics. A fuse is a thermal device and even under overload conditions can take tens to hundreds of milliseconds to blow. The semiconductor devices on the board will blow orders of magnitude faster than that if there is a fault. Using a smaller fuse doesn't achieve anything, apart from increasing the PITA factor.

Andrew

I have a Clarke wood lathe [seldom used ] which has a motor like that, and they clearly advise to reduce speed to zero when stopping or starting.

Dont like motors like that, but that,s the way it came !

Might be a P-I-T-A, but might be cheaper too.

DO NOT all burst out laughing at my ignorance ! All this talk of stopping and starting motors - I take it they do not have a clutch ? and little or no stepped pulleys to give speed change ? Now I understand why they can be so cheap ! and why machines with a clutch are so much more useable and reliable. Ah well, Noel.

The only one of my industrial machine tools that has a clutch is the horizontal mill.

Ah, just remembered that the power guillotine has an electromagnetic clutch.

Andrew

While this doesn't help the OP with his question regarding start up procedures for his lathe. The Chester DB7V that I have has a built in soft start and to date I have had no problem with the electronics even though I rarely set the speed to minimum prior to starting unless I require a high speed setting. The lathe must be over 10 years old now and hasn't missed a beat in that time, famous last words!!

As I said this doesn't help the OP but I believe that this illustrates the benefit of soft start procedures be they implemented either electronically or manually so if you are unsure whether your system has a soft start built in then starting at the minimum speed and ramping up to the required operating speed will do the electronics no harm and could well extend their life.

I wouldn't trust these dodgy modern clutches. I drove my industrial horizontal mill the proper way, via fast-and-loose pulleys (I made the pulleys from layered MDF, glued together, and after machining the diameters, painted with several coats of red oxide. They worked surprisingly well and didn't wear away despite my very inexpert use of that wretched alligator lacing stuff).

I tried phoning Warco today, but most of the staff seem to be off until next week.

My 7x16 mini-lathe throws a fault if I turn it on with the speed above zero. I guess others don't have this protection?

My Clarke CL300 mini lathe has interlock relays and a switch on the speed control pot which means you HAVE to start up from zero speed setting.

Warco emailed me today to confirm:

"Your are correct, these machines should always be started with the knob on minimum as the sudden surge in power when turned on can cause damage to the speed control PCB board."

Which means that the design is poor. You would think that for the price of a resistor and capacitor they would add soft start at least, if the power control is that flaky.

Which means that the design is poor. You would think that for the price of a resistor and capacitor they would add soft start at least, if the power control is that flaky.