Micromill spindle question

[milton d]

I've removed the top board from my SmartStep/3 controller and hooked up direct to the step/dir pins via parallel port & TurboCNC DOS software. All that's working OK now and the steppers are under control.

My spindle will not run now though. I downloaded the Micromill schematic but am not good enough electronically to figure out what the system is looking for that it's not getting now that I've removed the top board.

All the fuses check OK, at least the 4 I found. Both of the 2 relays pull in when the system is powered up, the spindle on/off rocker switch lights up when clicked on and the light goes on & off when the plexi front door is raised & shut.

My spindle controller is the KB KBLC-240DS. I checked the L1 & L2 inputs and it's only 17 volts with the wires unplugged. I think it should be mains voltage (110v here in the U.S.)

I'm guessing there's a signal missing somewhere. Anybody have any suggestions? If not, can I just unplug the existing power leads on the controller at L1 & L2 and just plug in 110v power to check and make sure it does run?

Thanks for your thoughts.

[angel-tech]

at the top of the case to the right, do you have two large relays and a smaller one to the left.

[angel-tech]

or is one of the relays marked "SGR"

[milton d]

It has 2 relays, I can't see SGR marked on either. Here's a pic:

[angel-tech]

when you turn the machine on does one of the relays click on.

[milton d]

They both click on; the one on the right clicks on/off as the front door is opened/closed

[angel-tech]

press the emergency stop and see which one goes off.

[milton d]

Both relays click off when the E-stop is pressed.

[angel-tech]

going by the micromill drawing it would look like the right one is the sgr relay, but the diagram is for 2000 models, is your machine that new. Unfortunately i don't have a micromill here to look at, but normally one relay is the e-stop and the other is the sgr (which powers the spindle/spindle board). On the spindle board is there a power on light.

[milton d]

Mine is a 1996 model. I don't see any lights or led's on the control board. Yes, I think the right one is the spindle power relay.

The white wire on the terminal that's hot when the relay is pulled in goes to the spindle motor. It reads 110v.

There's 4 more wires going to the motor.
Green, goes to chassis ground lug.
Black, goes to A- on the controller (Armature neg.)
Red goes to A+ on the controller (Armature pos.)
Orange goes up front to the rocker switch.

3 more wires on the controller go up front to the pot.

Last 2 wires on controller are L1/L2, AC line in.

I'm cornfused!

[angel-tech]

I'm suprised the sgr relay is on when you start the machine, is there any other switch for the spindle, maybe on the pot.

[milton d]

No, there's only the on/off rocker switch and the speed pot for the spindle.

[angel-tech]

on mills, a signal is sent to to the sgr relay which enables/supplies power to the spindle board, and the pot/analogue board varies the spindle speed. It looks like the next step is to check the motor actually works.

[milton d]

How's the best way to do that? I'm OK with DC circuits but no so much with AC.

Is this a brushed "universal" motor that one could just hook up to mains power for a quick test or should I try a 12v car battery?

[angel-tech]

Unfortunately i have no idea, but a pic of the motor may help. I would expect it's a dc motor, a datasheet for the spindle board would help

[milton d]

Here's some info on the controller.

[milton d]

Well, how 'bout that! I hooked up mains power to the L1 and L2 connectors on the controller and the spindle runs great! Amazing how it adds current to keep the rpm up when I grip the spindle to try to slow it down. Powerful little sucker.

Now if I can just figure out what's keeping it from switching mains power up to the controller like it should.

[angel-tech]

check the relays, especially the sgr

[milton d]

Allright!:D Finally got the thing running. It turned out to be the silly little rocker switch on the front panel.

I kept studying the diagram and eventually decided there had to be a voltage drop across the switch contacts. I popped the switch out and took it apart and found an oxidized spot on one of the contacts. I cleaned everything, bent a little more tension into the contacts and stuck it back together. Voila, success at last!

I can't say I know how the circuit works but I won't argue with success.

[angel-tech]

well done, but i'm still concerned about the sgr being energised at the startup. Maybe someone can enlighten us.