Longmill CNC Control Board very hot

About 3 hours into a carving my Longmill stopped, I found the CNC Control Board was very hot to the touch. The temp in my shop is about 88 degrees F. Tried to connect to the Longmill (using Gsender), showed connected but can not move X, Y or Z. Waiting for the Control Board to cold down before trying again. Does the Control board Rev 1.4.3 run hot?

Waited 2 hours and now can control X, Y, and Z. Put a small fan by the control board case blowing over the heat sinks.
Is the control board damaged?

Bob McNanley


I would say probably not since you are able to control the axis motors now.

However, continuing to operate at those temps will definitely shorten the life of the controller. Computers like to run in as cool an environment as possible…they generate a LOT of heat themselves. If you have the means, I suggest having the ambient temperature of the room in which your computer and controller located to be no more than 75 degrees F in order to not only prolong the life of the units but help eliminate random errors and glitches that may be caused by over-heating the chips.


Thanks for the feedback Don. There is no A/C in my metal 30x30 shop. I would guess the average temp during the summer will be between 80-90 degrees F. The best I can do is a small fan blowing across the heat sinks. I truly help the fan will keep the chips cool enough.
Thanks again,

I had a similar issue and did burn up a controller. Sienci assured me it wasn’t from the heat, but I know it was. They replaced my first controller as it was in the first week after buying it. My shop gets 100 degrees+ in the august sun, and the replacement controller started doing the same funny stuff but went back to normal when it cooled off, just like the first one before it died. I made a 3d printed riser that directs air up to the heat syncs from a small usb desk fan. It’s doesn’t do anything funny as long as I remember to put the fan on it on the hot days.

Yeah, I’m with Stairguy on this one. If you can also do something to improve the overall ventilation and bring down the ambient temperature in your shop (instal a fan in the ceiling of your shop and have a window open a bit to bring in fresh air?) and the small fan looking after the heat sinks, things should improve.

Let us know how things work out for you.

Marty from Kingston

Thanks of all the input. I tried both Gsender Rev. 1.06 and 1.1 on two different carvings. And each time somewhere between 25 and 60 minutes into the tool paths the control board loses it’s location on the carving board. The control board moves Y axis from 0 - 4 to 10 cm ---- the control board also loses the X axis - I don’t know by how much — because the X carriage can’t go farther to the left.

I believe the control board is wonky. How do I get a new one under warranty?