Iām not sure if there is a structured feedback process to determine the number of 48x30 users having this issue but add me to the list. On the X gantry, I have loosened the V wheels, the anti-backlash nut mounting screws and the clamping nut on the end of the lead screw to make sure there is nothing else causing it. It still binds and looses steps on the X axis. It seems to try to accelerate too fast and the stepper motor binds.
I have only tried two projects since hooking up the SLB and both were ruined because of this. I am afraid to try another project until this is resolved. I could go back to the old longboard but I was hoping I could make the SLB work.
@DaveR66 if thatās the case, change your X-axis acceleration value ($120) back to 750 instead of the SLBs default value of 1000 and let me know if that resolves your issue. I havenāt seen any tickets on this issue but Iāll conservatively put the count at 4 in case 2 other people have been missed and see how the results continue to emerge from there
If the fix works for you then Iāll discuss with the team to either add to the docs or do more from there
if I do a M122 on the console are all the divers meant to be set Identical? I wonder if boosting the X current to the motors would help with the X issue.
We had some issues in Beta testing that meant we needed to cap the current to the drivers so increasing it probably wonāt get much further since itās hard-capped. They can technically go further but we started to see diminishing returns since as the drivers get hotter their efficiency goes down
You can add another user to the list. New cnc user here and only used my 48x30 MK2 with the original longboard for a few cuts before my SLB arrived. That said I experienced the same x axis binding problem as well when I swapped to the SLB. I chalked it up to not knowing what I was doing and poor alignment. Was experiencing other issues as well so just swapped back to the longboard until I get more experience.
Iāve had a chance to disassemble the X-Axis and do some investigation since everything is pointing to an issue with the physical set-up of my Longmill.
While assembled, I had a hard time getting the lead screw slid into the coupler but no resistance while apart. I then took a closer look at where the motor attaches to the left Y-Axis gantry and couldnāt see any obvious problems with the alignment. I then looked at the right Y-Axis gantry and it seemed a little off, so I put a straight edge up to it and noticed thereās a slight bend to it where the X-Axis attaches and the leadscrew passes through. Using feeler gauges, thereās almost a 1/32nd bend towards the right side Y-Axis. Checking the left gantry with a straightedge, thereās a very slight bow in the middle but nothing major (pictures below). I currently have the right gantry in a vise with some shims to hopefully straighten it out a little, although itās so beefy Iām not sure it will actually do anything.
Am I just being pedantic here, or could that be a contributor? The Longmill as a whole isnāt presented as something that has to have super tight assembly tolerances to function correctly, but I can envision the gantries not being close to parallel might cause the leadscrew to be flexing in certain areas - especially by the coupler. My binding is typically worse closer to Home than any other spot along the X-Axis. Iāll give the vise some time, reassemble, and see what the results are.
I too am having those issues, but I am also experiencing it with the Y Axis as well. VERY frustrating!!!
That amount of variation should be tolerable Jon. You mention that your motion is the most impacted when close to home, to me this would point to your X-axis anti-backlash nut perhaps not being fully aligned that itās causing more noticeable friction as it nears the left bearing. What Iād recommend for that is to loosen the two M5 bolts, and then slowly alternate on tightening them when your machine is positioned right next to the left bearing to ensure theyāre as aligned as they can be. Let me know how you find that to be
Have you tried lowering your values yet? If so, what was the value you settled on that finally got it working for you?
Also can you let me know what size your LongMill is
I just tried to change the $120 value from 1000 to 750. It automatically revert to 1000 when I hit enter. I also had install the new Anti-Backlash nuts. My Longmill is the MK 2 and is 48 x 30. I just installed a PWNcnc spindle system 2 weeks ago as well.
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Ok thanks for the information that helps. Make sure when you change the settings that youāre hitting the āApply settingsā button in the bottom right of the window. If your machine is also currently in an alarm state like Alarm 14, make sure you unlock the machine so itās āIdleā instead
The cnc is stuck in the Home position, and when I clear the alarm and it tries to go to Home again it gets stuck again. I have not gotten it out alarm mode yet. I can get it out of the EStop and then it prompts to run Home again. This is the loop I am stuck in. Alarm 11 to Alarm 10
Before I disassembled everything, I wasnāt running anything on the lead screw just to eliminate the anti-backlash nut and the X/Z gantry from my speed tests. Iām trying to see exactly why my machine might be in the minority for having to lower speeds and/or acceleration from SLB defaults. If I canāt hit 5500/1000 in that scenario, then I definitely wonāt when everything else is connected.
When I do a full re-assembly, Iāll follow those suggestions for the tightening process with the new spring-loaded version and see how it goes. Thanks!
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I am in the process of uninstalling GSender 14.7 and will reinstall to seem if it will allow me to change values. The program currently did not give me the option to apply changes I made, but returned the values to default.
Ok gotcha. In that case then you might need to also try really tightening down on the ACME clamping nut when you install the lead screw into place. Any amount of excess whip in the lead screw can cause hindered motion at higher speeds. If everything is apart it might also be worth checking your lead screw rolling on a flat surface.
@Slvrbullit if you hit the yellow āpadlockā button on the left side when gSender asks you to home the machine, it will allow you to get out of the cycle youāre in and then make the settings changes
@Slvrbullit You may know this, Bob, but you have to click out of the field that you just changed for the apply updates box to be active. I missed this early on in the beta testing.
I did, and it never gave me an option to apply changes. I am not able to change any values, which is why I opted to reinstall GSender 14.7
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Thanks Chris, I will try that
I have reinstalled gSender 14.7 and still have no option to save changes, or get out of the Home - EStop loop Iām Stuck in. The Unlock Machine is not working either,
I am going to let it go tonight as my frustration level is rising.
Well, Iāve had some measure of successā¦ hereās what I did:
- Reassembly
- I canāt say for sure that fixing the bend in the vise was the solution, but Iād recommend anyone facing the same issue to reassemble and adjust everything to do with the two Y-axis gantries. In any case, it took far less effort to slide the lead screw into the coupler when the right side was held in place by the bearing. I also noticed less deflection while tightening the coupler and Acme nut, which hopefully meant it was better aligned
- Anti-Backlash nut
- When moving the Z/X gantry over the anti-backlash nut to assemble, I noticed the gantry bumped into the edge and deflected the lead screw by a small amount even closest to the motor where it should be the āmost alignedā. I sanded down the face so that the gantry just barely touched when passing over.
- I could not use the new spring-loaded version even when I removed the springs. The old version is very smooth but the new one feels like there is something catching in the internal threads. Iām not sure if I could have damaged something while putting it on or taking it off during all my testing but itās possible
- Lubrication
- I tried not to use anything on the lead screw, but I was getting random stalls up and down the X-axis. There was a lot of tweaks needed for the anti-backlash nut, but even when seemingly dialed in the stalls were inconsistent. I eventually used some white lithium grease and the issues (mostly) stopped.
Now Iāve been running at the new SLB defaults of 5500 mm/min and 1000 mm/s^2, just running from corner to corner for 5-10 minutes with just one random stall at the far end of the axis when it was returning home. Next step is to start running sample jobs and see what happens.
Iād still really like to use the spring loaded version so Iām looking to find the right tap in order to clean up the threads. The Sienci shop states that the lead screw has a threading of T12 12mm 4 start and a pitch of 2mm/rotation. Iām not familiar with Acme threads, but any T12 taps Iāve found are super spendy! Does anyone know where I can find a more affordable version?
-Jon