Hey there. I found dozens of similar problems here but it does not fully help me with my problem.
I just finished building my MPCNC Primo. I already did my first test cuts and am very satisfied with what this thing can do. Now i wanted to level some pieces of wood (and resin) which i made.
For that reason i bought a leveling bit.
The thing that drives me crazy is, that i fo
und that my Z axis is not vertical / in a 90 degree angle to my cutting board. (In consequence that should mean that my leveling bit will not do a good job).
This is because my core itself seems to tilt towards the open side of the core. (Away and downwards from the x and y rails). It is not much play but enough that it gives my tool 1mm of room when i move/tilt the core by hand. It is almost as if the spinlde is too heavy and tilts the core inwards. I dont know how to describe this i hope it was okey enough to understand.
My question is, is there anything i can do about it ? I already tried suggestions from other threads by tightening or loosing the core and bearing screws and what not so ever but it did not help so far. There must be a thing that i am missing. I would be glad for your assistance.
Yes you can shim the router mount. I have tools on thingiverse and printables to test for tram or perpendicularity. With that tool you can add a few layers of tape or something similar between the mount and the mount plate to tilt it one way or the other. If you have any slight left or right tilt you can also move it a little more to one side or the other.
On the primo fine adjustments are done with the top and bottom Z tension bolts.
if it is play, probably not a good idea to shim it because it can still move. if it is solid and just offset, then shim it. the tension bolts are the ones that have plastic on both sides of the bearing and are behind the z tubes. When you tighten them, they will bring the other 2 bearings closer to the tube.
I’m putting in a new core as well and right now the z axis is very difficult to move and the bearings aren’t tight, so the core that was printed for the system is likely not quite right. This problem sounds like the opposite of yours.
The thing is that the z axis itself has no play at all sitting inside the core. The core itself has play. It tilts slighthly towards the open side of the core. All the bearings are in contact with the rails. So i dont know if it is good if i tighten the clamps anymore.
Take the core all the way apart and build it again. The second time around build it looser. I have not heard about this in a while now but this used to be a common problem when everything was tightened down far too much.
Read through the core instructions again while you build it. There are little tips like install tightened core clamps, then install the bearings.
If you printed the parts yourself you might really want to take a look at some XY XZ YZ calibration prints.
So it is the core to the X and Y rails that has play, not the Z axis? The bolts that adjust that are the four vertical ones that are on the opposite side of the tube from the core.
My system had play like that and the core was cracked and it wouldn’t tighten up. A couple of the clamps were cracked also. Since all your stuff is newly printed, that is not likely the issue…
I will definitely do this. However, I suppose this will have to wait until after my wedding because I suppose there are some other things that need to be done for this to work out, for example, fine-tuning my printer again. I have to make some presents for the people invited. To do that, I need to surface some things. So I suppose I will shim it first, then do it correctly after I finish this.
No nothing is cracked. And i dont want that to happen. It was a pain to put it together and it just got it running so im not very eager to crack it again. I can not really address the problem. I suppose your right … the core must have play against x and y, otherwise it would not tilt. Just to clarify, there is no horizontal play. I can not “rotate” the core towards x or y, but i can tilt it up and down between the 2 axis. Its really hard to explain. I tightened the x and y clamps a bit - which made it better. But im really really scared to tighten it even more. I dont know how tight is too tight.
Do you think it makes sense to tighten the bolts the clamps are mounted with ? (The 45 dregree tilted ones on the clamps ? )
The bolts holding the clamps also hold bearings, so they too should be tight enough, but not too tight.
The tightening procedure that Ryan mentions talks about starting with the bolts loose and then tightening a little at a time to get the x and y axis square. This assumes that it doesn’t have play in it. you need to get to where all the bearings are touching the pipes and then you won’t have play.
What do you do when they all touch and there is still play? Are the bolts too small or do the bearings have slop? A careful observation of where the core has movement is required. Most often movement is between the pipe and the bearing when the bearings don’t touch because the parts are broken or they were printed warped from a skewed printer.
I will try to observe where the peoblem is in the following days. I mean there must be something off. If it is something that is easy to fix i will do that before starting my planing operation. If not, and eg the core is garbage, then i will fix it later fully and just temporarily fix it by shimming.
Can you take a video of the movement and upload it to youtube and post a link here? With that it might be easier for us to help you. It sounds like you are adjusting the right thing since you made it better. Just go a little bit at a time until there is no more movement. 1/8 turn at most.
A core rebuild is about an hour and you would be surprised at how many times that magically fixes the issue. It is rare but if your printer is way off then yes, a reprint is needed. If you have never checked your skew on any axis, let alone all three it is really hard to know if you printed a leaning tower or not. Something like a Prusa tend to do okay without real calibration, something like an ender are all over the place.
Yeah a core rebuild is for me the last option. My machine is very cramped inside its space it has. This will be very complicated. But as Jonathjon requested i will make a video for further definition of the problem.
