Longmill disconnecting from UGS

Running a program from a student and I come over to the machine and UGS has disconnected mid program. I cannot reconnect and resume. The only way to reestablish a connection is to restart the computer. Therefore I have to reset the zero and hope its perfect in order for the remaining cuts to line up.

This has only happened twice, but I am curious is there is something I am doing incorrectly or if it could be an issue with the computer that is running UGS.

Any feedback is appreciated!



@thompson.rtj There are many possible causes from static electricity, bad usb cable, electromagnetic noise, old ugs version, etc.

Rather than repeat a whole bunch of advice here, I suggest that you do a search in this forum for ugs freezing.

If, after trying all those “solutions”, you still have issues, come on back and I’m sure someone here will be able to help.

I really do feel your pain.


I have had this problem the last few days too. It’s very annoying.

I have recently started experiencing the same issue. The machine disconnects mid-job and the computer must be restarted to get it to reconnect. Even using the touchplate on the exact same corner of screwed down material, it is impossible to get the machine re-zeroed to the same point. I have changed nothing in my set up or equipment to cause this. When it do restart a project, it often seizes up again in a different spot. However, today mine went completely off course. In the middle of a clearing pass it just took off in the -X direction and couldnt be stopped with the software. I had to hit the emergency stop. I am not comfortable turning away from the machine or even using it until I get this sorted out. There is some information on UGS freezing, but none seems to be of much help. I will keep searching, but will probalby ditch UGS all together. Does anyone have any alternative sofware Recommendations?

@Torminater Welcome, Torrey.

A couple of things you mention are different than others who have had UGS issues. I’ve had more than my share of freezes, but I’ve never had the machine go nuts, as you have. I would look to some sort of electrical interference as being the cause, rather than anything going on in UGS. What are you running for dust collection, for example? Also, make sure that all power saving settings in windows are turned off, including the usb power setting.
I don’t quite understand why you cannot get back to XYZ0 using the touchplate. Are you saying that there is enough slop in the machine to make this impossible? If so, you may want to ensure that your delrin wheels and the anti-backlash nuts are properly adjusted. You should be able to return to your job with a high degree of accuracy when using the plate for all axes.
As to alternatives to UGS, the most popular here, I believe, is CNCjs. Several of the members use it with good success.

@gkilki Thank you!

When I first set my Longmill up I completely disabled my screensaver, and set my power option to have my computer never go to sleep. I used it almost non-stop for a couple of weeks with great success. My dist ocllection is the same Ridgid Wet/Dry Vaccum I have been using since day one. I used to use my table saw, miter saw, band saw, and lathe while the CNC was working without any issues at all. I was not using any of these when the problems started happening. With the exception of the machine taking off in the negative X direction mid-job, I was not even in the shop. I check/adjust the slop in the anti-backlash nuts, wheels and threaded rods daily. When I say I canot zero it back, it is always very close, but even a fraction of a milimeter is too much if you have to restart halfway through a complex 3d carve (not to mention frustrating to have to recarve two hours of air before getting to where it was).

I downloaded CNCjs but can’t get it to work and now something I have done is preventing UGS from connecting at all. I tried setting up CNBCjs but as soon as I try to connect to begin setting it up, it just gives me warning after warning about repeated commands and things I didn’t change/adjust and don’t fully understand.

"error: 1 - G-code words consist of a letter and a value. Letter was not found. [$$]

"error: 25 - A G-code was repeated in the block. [$l]

"error: 22 - Feed has not yet been set or is undefined. [undefined]

As soon as I click ‘OK’ on the feed error, it pops back up in a second or two. I am unable to even start trying to adjust the settings, and on the machine selection, there is no option for the Longmill and I assume I must use the ‘Custom Machine’ setting but I cannot set anything.

As you can probably tell, I am new to the CNC world. But I am not completely technologically challenged. However, when is comes to g-code and GRBL commands my knowledge is quite limited.

I am extremely grateful for your feedback and any assistance is greatly appreciated.

@Torminater What program did you use to generate the gcode?

Can you do anything in CNCjs - jog, zero, etc?

You don’t need to tell CNCjs that your machine is a mill, just be sure to select grbl in the Connection window.

What were you doing when you got the error messages?

Now, as for UGS, be sure to exit from CNCjs before opening UGS. Otherwise, CNCjs still has control of the com port and UGS will not be able to connect.

I know exactly what you mean about freezing a 3D carve after hours of work. I truly do feel your pain. This group will figure this out, though.

Thank you again Grant,

There error messages came immediately upon start-up. I have been unable to make any adjustment or changes because of them. I cannot jog or do anything at all in the software. The first time i tried to connect the machine to CNCjs it immediately started the gantry moving in the negative Y direction as soon as I clicked the ‘connect’ button. I hit the emergencty stop button when it approached the end (I haven’t installed limits switches yet, but it’s on my to do list). Since then it only gives the constant error messages.

I tried completely removing CNCjs when it wouldn’t connect back to UGS with no change.

@gwilki Forgot to answer your very first question.

I am using Vectric Desktop Version 10.512

@Torminater I have to go offline for a couple of hours, Terry, but I’ll think in this and get back to you.

Not to be flip, but I think your Mill is haunted. An exorcism may well be in order.

Now to get serious, I would start simple. Shut everything down - your PC, the router and the Mill. Replace the USB cable if you have one. Then, first open UGS, as you’ve had success with it in the past. Assuming that you can connect, run a job in air. Leave the router off and just let it run.

I’m out of here. Back soon.

@Torminater Nothing else has jumped out at me yet, Torrey. (Sorry about getting your name wrong earlier.) When you’re tried those few things, post again to let us know of any progress. If its still haunted, we can look at more difficult surgery.

@gwilki Grant, Thank you so much for your time in helping me. I very much appreciate it. You pushed me past seeing it as a software issue. Thanks to your assistance, I seem to have exorcised my machine’s demons. I think I may have a faulty USB port on my laptop. I have never heard of anyone having such a problem, but it seems likely to be the culprit. I ran the program/toolpath that it screwed up royally (when it took off in the -X uncontrolably) twice and both times it behaved as expected. The problem was somewhat transient to begin with, so at this point I cannot be certain that the problem is resolved; however, it looks promising.

I would like to thank you again for taking the time to help me. When a person is relatively green at this, it is nice to have someone else’s input. When you are standing alone in your shop wondering if you are just completely incompetent and missing something painfully obvious, it is extremely beneficial to have some experienced input.

Have a great weekend!


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@Torminater You are most welcome, Torrey. This group is all about all of us helping each other out. Pretty much everyone here is relatively new to CNC. I’ve stood in front of my Mill many times wondering what the hell I was thinking. :grinning: When everything works, though, it sure is fun.

Take care.Have fun. Remember to post pics of your accomplishments.

@Torminater , When I first put my long mill together I was using and old Dell laptop, wouldn’t want to run a nice one is the crazy dust environment, in moving usb cables suspected it was a little intermittent, when my system would freeze up I tried the cables etc route. As soon as I confidently (Chest out proud) believed I had found and resolved the issue, it proved me wrong. I replaced the laptop with a refurbished unit from ebay, again thought it was fixed, wrong again. Eventually @gwilki and @Heyward43 plus others provided info about grounding my dust collection hose, did all that and other than an occasional “Quirk” it is finally working, this forum has become my mental saving grace, I am starting to believe this stuff is not for the faint of heart!


@Torminater Torrey: If it acts up again, you may want to try using a powered USB hub between the Mill and your laptop. In a former life, I came upon laptop USB ports with weird and wonderful power outputs. Putting a powered - and the key word here is “powered” hub in the line fixed them.

Thank you. I will keep that in mind. I have been busy ay my other job, but have ran several programs since and have had no issues.

Anyone ever find a solution? My machine will connect, but won’t move unless I use UGS classic or gsender. Mine also freezes during a job even when I can get it to connect. Or even when I am simply jogging the machine. And I have to re-start the software. I have tried windows 7 ,10 and linux. 3 different machines, disabled sleep mode.

@hobbyhands Clark: At this point in this old thread, can you be bit more specific about “finding a solution”. In reading back,it looks like Torrey solved his problem, as did Bill.

Your problem seems to be a different one. If I understand you, you can run fine in UGS Classic or gSender, but you want to use UGS Platform.

Can you tell us what you have already done to address the issue, so that we don’t simply bore you with stuff you’ve already tried?

If you don’t mind, why do you want to use UGS Platform over gSender?