Update on sherline CNC lathe


good stuff!


Mounted the drive in an enclosure for more room for potential upgrades in the future of a speed controller. Tied the CPC connector in on the outside, still have the inside to do. Obviously I still need to do cable management which I have a few different things for it.


Slowly forward progress.
I tied in the speed controller to the CPC 7 pin connector, installed a solid state relay, put in a fuse holder, & put in strain reliefs. I went to run the cable from the main control box to the motor drive & found that someone ran off with/moved/misplaced my SO cable.


Forward ahead.
I wired in the 120 into the fuse holder, wired the 120 to the motor controller( sorry for the EU wire colors but it was the only SO cord we could find at the space), re-ran & placed the manual speed control knob.

So what’s left you might ask.
Ground wire to the case, wire the pilot(low voltage) side of the SSR & cable management. We have all the cable management items at the space to tidy the exterior cabling going to the steppers & limit switches.


Good job! Proceeding forward with much Gusto


More progress this afternoon. One axis with wire management, ground done, however I could not find the right size screws for the SSR.


Am I the only one surprised you didn’t just make some?


I would have probably but the easy thread gauges being on a cable makes it difficult to be 100% on the size. Because of the cable, I could not easily turn the test gauge to verify the size. I think we have other styles but I forgot about them.


If you have a reasonably good guess on the screw size I could go by Elliotts and see what I can find.


Picked up a few different sizes of metric & its 4 mm. Finished cleaning the wiring up this afternoon.


So Saturday @Chris_Wischkowsky & myself got the lathe closer to the finish line. We were able to get the machine homed. We tested the first SSR, it was bad. The second was good. However we began chasing our tails with the spindle speed. At full speed in the current condition it runs 895 rpms. It should run at 1400. We weren’t able to find out why other than maybe it was just at that speed. We tried various ways of triggering the start but in the end it did not change the top end speed. We need a small piece of 14 AWG about 8-10 “ in Orange to tie the electrical back in for the spindle. We also just need to place the enable for the spindle start stop into the software. After those 2 & securing the case to the base it will be able to run.


So I was able to troubleshoot the motor today by using another speed controller from the “metric” Sherline. The speed controller on the CNC lathe is bad to where it does not want to speed up. So the max speed on it is 895 rpm’s or so until we get a new controller for it.


sorry to hear that. let’s do it.


The Sherline speed controller is from KB Electronics. Check the model number on the controller and download the Datasheet and User Manual. There are several adjustments for speed and torque. Suggest that you check this out prior to buying a new controller.


Pretty much went by what I thought, essentially I did mostly what the book says. We have the KBLC-240DS. I did not physically check the horsepower resistor however.

You will notice the CNC one has (3375A) vs the other (3375B) on the other, I did rudimentary searches but did not find any good results for the difference between the 2.


I see from your photo you have the KBLC-240DS Controller. The link I gave you above does not have that specific model, but it does have the KBIC-240DS Controller which looks similar. I can only assume that Sherline got it’s own model number. Check out the list of User Manuals near the bottom of the page. It should still give you information about the Max Speed and Torque adjustments on the Controller, those features should be the same from controller to controller. This is the motor controller and motor that came with the Lathe when I originally got it.


They are really close to being the same. I have previously turned the Max down then up all the way to see if it made a difference, pots will at sometimes develop a bad spot in them. This has been my experience with what I do for a living. When we get the new board & after I verify the speed, I will paint all the pots to make sure there is no movement in them.


If the speed control is in a box, use security Torx screws and put a label over one of them.


After more troubleshooting, it’s definitely the controller. I swapped the resistors after attempting to measure them unsuccessfully in elab. FYI the resistance is supposed to be .015 ohms.


LCR meter with its 4-wire mode should be able to measure that. The regular DMMs won’t be able to, most likely.