lathe help

[cuesdefuentes]

not sure if this is the right place to ask but i need help with my porper model b.
the spindle will not turn. it still gets power and the power feed is still operational. i am fairly certain that the speed control dial is the problem. i have a voltage meter but not sure which wires i need to check or voltage that i should see. if the speed controller is the problem is it a simple fix?

thanks for the replies.

 

[Michael Webb]

not sure if this is the right place to ask but i need help with my porper model b.
the spindle will not turn. it still gets power and the power feed is still operational. i am fairly certain that the speed control dial is the problem. i have a voltage meter but not sure which wires i need to check or voltage that i should see. if the speed controller is the problem is it a simple fix?

thanks for the replies.

I haven't seen the speed control quit yet but it is more common that your forward reverse switch has a burn from going to forward then reverse without stopping it first. If switch looks like a flying saucer with a bunch of wires on it. It's easy eneogh to visually inspect it while moving the switch to see if it contacts or not. Not sure when your lathe was made. I know they switched some of the Components a while back. If your switch is as I described and you discover that's the problem. The switch is made by Electroswitch. Part #D4C0305N.
On the older Porpers. When you go from forward to stop. It should engage the break. If not, the ceramic block near the speed control is bad.

Hope this helps.

 

[qbilder]

It could be a bad switch, bad rheostat on your speed knob, or it could be a bad rheostat on the controller circuit board. I have had issues with all three. Radio Shack will have the speed knob rheostat and switch. Ebay will have a replacement circuit board. The board costs about $100, give or take.

edit: I have also had motor failure due to brush always burning out on one side. I replaced the motor with a treadmill motor.

 

[cuesdefuentes]

thanks for the replies.

The lathe came with a couple of spare boards, so i changed that out first. It runs now but has intermittent lapses of power (like it is stuttering). I also changed out the rheostat for the speed control but that did not help the stuttering problem. I guess my next step is to check the brushes on the motor, then change out the on/off switch if the brushes are good.

 

[Michael Webb]

thanks for the replies.

The lathe came with a couple of spare boards, so i changed that out first. It runs now but has intermittent lapses of power (like it is stuttering). I also changed out the rheostat for the speed control but that did not help the stuttering problem. I guess my next step is to check the brushes on the motor, then change out the on/off switch if the brushes are good.

Look at the pc board on top in the back. Look at the bottom section of the board. I think there's a row of capacitors??? Resistors??. Look for burn marks. Another is looking at the same board. Ceramic looking block around the middle. See if the connection is loose.

 

[qbilder]

thanks for the replies.

The lathe came with a couple of spare boards, so i changed that out first. It runs now but has intermittent lapses of power (like it is stuttering). I also changed out the rheostat for the speed control but that did not help the stuttering problem. I guess my next step is to check the brushes on the motor, then change out the on/off switch if the brushes are good.

Ok that's a good thing. There will be 5 tiny rheostats on the board. You'll see Accel, Max, Min, IR, & CL. Those need tuned. You need a small screw driver to turn them. The accel will dictate how fast your motor gets to speed. Adjust max to where the motor gets full power when the knob is turned all the way up, and min to where the motor just doesn't turn where the knob is turned all the way down. The CL is current limiting and dictates overall motor torque. The IR is where you are getting surges. It has to be adjusted up or down while motor is running until the motor turns smooth. You might have to adjust IR and CL both a bit until the motor is working properly.

Here's the manual. You'll want to see page 16. https://www.kbelectronics.com/manuals/kbic_manual.pdf

 

[Michael Webb]

Ok that's a good thing. There will be 5 tiny rheostats on the board. You'll see Accel, Max, Min, IR, & CL. Those need tuned. You need a small screw driver to turn them. The accel will dictate how fast your motor gets to speed. Adjust max to where the motor gets full power when the knob is turned all the way up, and min to where the motor just doesn't turn where the knob is turned all the way down. The CL is current limiting and dictates overall motor torque. The IR is where you are getting surges. It has to be adjusted up or down while motor is running until the motor turns smooth. You might have to adjust IR and CL both a bit until the motor is working properly.

Here's the manual. You'll want to see page 16. https://www.kbelectronics.com/manuals/kbic_manual.pdf

Tap. Tap. Forgot about those.

 

[qbilder]

Tap. Tap. Forgot about those.

Man I have replaced/repaired a dozen of those dang things. I had a bad motor to begin with, so it kept either burning brushes or burning circuit boards. Finally I swapped the motor with a treadmill motor, added a big outboard controller, and replaced all wiring & switches. That's been many years ago & no problems since. The KB boards are actually pretty dang high quality. Usually when they go bad, it's either because the motor was overworked or something is shorting out.

I sometimes run my routers off of them, too, for variable speed control. It helps a lot with controlling harmonic vibration.

 

[cuesdefuentes]

thanks for all the help. The IR adjustment fixed the problem.