I have run the MPCNC for drawing for the last couple weeks doing 24x24" mazes etc. THEY have been fairly good.
BUT i noticed I had left the gantry loose. So i checked the square and it was out and the gantry had quite a bit of wobble.
SO as i go to tighten the gantry to the point of LITTLE wobble not NONE it really takes it out of square. At one point i had tightened the 5" bolt enough to remove most of the wobble and the z screw would bind. When the gantry is loose the majority of the wobble is back by the 5" screw between the bearings and the conduit (bearings are NOT making much contact there).
I am out of brain power on this one. Was even wondering if my bearings where slightly undersized the OD is 21.98
I read some of the others issues on gantry square⌠so take it apart and put it back together again???
I donât think Iâd go that far right away. First check the gantry spacers to make sure they didnât wiggle out of place when the gantry was wobbly. They can spin around the bolt a bit, but they should be seated into the depression of the neighboring pieces. If that doesnât solve it, but you have dual endstops or some other way to square the machine, I would probably just kick the can down the road unless itâs really bad. Iâve heard of people turning the tubes because they are out of round, and that causes some slop with the bearings, so you might look at measuring those, too. But taking it apart and putting it back together might be worth a shot if you canât come up with anything else.
I do have the duel end stops⌠When the gantry is tight (enough to take out most of the wobble, it goes way out of square) and I home the machine. The force created by g28 /home to move the x Y pipes into square is substantial. When I unplug the machine you had a âpopâ as the x Y pipes spring back to⌠Their non square state.
If I leave the gantry loose I donât think there is and chance at a good cut with a router bit. Just to much movement.
I will look again at the gantry as you suggest see if the parts moved. Thank u
Not sure how you are measuring âwobbleâ but for me a bearing that turns freely because it isnât touching means the assembly is less overconstrained than it should be. What I did is loosen everything all the way, and see which bearings turn freely, and tighten only the bolts that affect those bearings, and then just enough so they barely touch and then stop. The long tension bolt B affects those X/Y bearings in the back corner and I did that one last. This is not the official guidance but it hasnât been said to be wrong.
Differential tightening of the tension bolts can skew the machine one way or the other to get it more square but I prefer to just force it square.
If you do not want to take it all apart, at least loosen all the tension bolts and start again. Like Jamie said just making things tighten can actually make it worse. as it is is should be tight with no tension so adding more just makes it worse. Taking it apart and doing it again usually really helps, for a reason I do not understand but usually it is all good after.
Ryan, I took apart the entire gantry. Removed every bolt etc. I am double checking everything. I noticed that my bolt dia vary but most are about .5 mm dia smaller than the ID of the bearings. That would seem to be a pretty large compounding error. Is this normal? I am using standard bolts. Could this be an issue? Thank you
Try twisting the conduit. Push the gantry back and forth while twisting and keep an eye on the bearing contact. Conduit is not perfectly round, not a consistent diameter down itâs length, and not necessarily 23.5mm in diameter. Indexing it to the bearings will help take up some of the slack but wonât be perfect. There is also some slack in the bearings because a 5/16" bolt does not fit tightly in an 8mm bearing.
Ok sooooo I pulled the entire gantry apart bolts, bearings etc. I read the directions step by step and did the assembly again I got to the end of the assembly and was missing two bearings.
I checked the bearings needed total count for the project was 53. So I should have seven left over⌠Checked my bearings I had 9 left over. Itâs embarrassing to admit I must have left two bearing out of the gantry somewhere.
Installed the missing bearings and guess what⌠Itâs squared up no problem in 5 min.
Thank you every one that helped me I learned a lot of stuff to check and learned a lot on how to adjust the gantry.
