I built my MPCNC Primo F (25mm) following the instructions, but obviously, I went wrong somewhere !
I printed the parts on a calibrated Bambulab X1C, following requirements (Infill & PLA) so I don’t think 3d parts are the issue.
Here is a video of my issue :
youtu.be/kwftcTOxF0k
As you can see, there are some sides where it slides well, but on one side, if i slide it from the left, the opposite doesn’t stay aligned so it get stuck (the plastic touches the tubing).
Parts are for 25mm tubing, my tubing is 25mm stainless steel, I measured the outside diameter of them at 24.86mm.
This issue was already there before putting the core (I hoped it would solve itself…)
I followed the squaring instructions and it is OK.
My bearings are aliexpress ones, can it be the issue ? I am in France so I didn’t find good ones that are not really expensive skateboard ones.
If someone has an idea, I would like to try it !
Sorry for my English, I did my best to be understandable
Thebasic designof the machine has quite a bit of slop in it. When youre moving it manually the axis tubes can pivot inside the truck which allows it to bind. When its powered up its moved bythe trucks themselves so the pivot isnt the same.
Try sliding it by holding onto the trucks instead of the core.
Your video seems at odds with the assembly instructions that specifically tell you to square your trucks. I really want you to be right as I’m stuck on that step and can’t get my trucks’ rest position within a 1/4" of each other as measured from one edge.
Possibly. It’s just the advice I was given when I asked a similar question and so far it’s working. I was pretty skeptical at first until the first time I homed it successfully and it was “yep, that makes sense.” I just had to see it in action as I was used to a machine that only ran single end stops and the process in my head had to adjust. As long as the machine is squarish, it just needs the stoppers positioned correctly and it will take care of itself.
Using the endstops you can set the blocks where-ever you want so the measurement from post to truck became less critical.
Letting the switches trigger is more accurate than I can be with a tape measure. I struggled for a while to get the last 1/4 or 1/8th (I don’t remember which) inch out, unsuccessfully, and was told to basically forget about it and just square it with the stoppers/switches. Doing the tightening on the bolts didn’t fix anything for me and looking at how everything is assembled, I can’t honestly see a way that it would.
One of the nice things about this machine is it’s very tinkerable. Worst case you just loosen a few things and you’re set to experiment. Or break something and you just print out a replacement and put it back together.
And this advice may have been totally wrong when it was given to me, but if so it’s wrong in a way that works, which is close enough to being right as far as I’m concerned.
I’ll check the squaring video as soon as I am in front of my CNC to check everything.
I will use endstops but I want to avoid possible failures as much as I can.
I’ll follow the instructions and finish the electronics.
You are right, I can change whatever I want even after I finished building it. (I had an Ender 3 as my first 3d printer, changing parts is something i’m used to… )
I’ll update this thread to inform you what worked for me as soon as I finish it.
Hello Nathan,
I couldn’t watch the video with sound on before, thank you very much for your explanations !
I now understand much better what you wrote.
I didn’t find anyone talking about this when I was looking for squaring issues on the forum.
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