I can wiggle my core in both x and y. I thought i had overly tightened done of the bearings, and found i had 1 that was cracked. so i Re printed the core and all 4 clamps and went very gently as i put it together but with all new parts the problem remains. I even did the new core on a different printer.
It takes very little pressure to rock the core.
Looking down the rails i can see a slight gap opening up between the rail and the bearing when it’s wiggled.
The assembly info mentions using inch pounds of torque during assembly so I’m guessing really tight isn’t the route to take but I’m not sure what the fix is.
I had a similar issue but it was cracked core clamps and you have already replaced them so that doesn’t help. Beyond that here are a few things to check.
Are your printers calibrated and printing the correct sized parts?
Did you check that you printed the correct version for your tubing/EMT size?
Have you measured your tubing/EMT to make sure it’s within spec?
Is the tubing/EMT round? You may try rotate it to see if the gaps close.
I thought of some of the same potential issues over the last few days so I can eliminate these. The tightness/crack was from some crappy parts. Some of the lock nuts I had needed a full on guerrilla attack just get them on (thanks amazon! :laugh:) I ordered a new batch and everything went together smoothly.
I measured the tubes before I printed again and they’re at 23.5 according to my digital calipers.
I’ve moved the core to different spots on the bed so it would be in different spots on the tube and the problem remains. I still rotated the tubes and saw no real change.
I then thought maybe I printed the wrong core somehow so I downloaded again to make sure I had the 23.5 version. The rest of the parts were printed on the same machine from the same bulk download from thingiverse and everything fit well. I haven’t run any specific calibration checks on them, but the 1st one I printed on my ender 3v2, the new one I printed on the makerspace cr10. They both basically feel the same wiggle wise. We do have a new Bambulabs printer I can try just in case the other 2 are out of whack the same amount. Probably what I will do is a couple circles on each one to see if there is a difference before I commit to printing a 3rd core. I guess a small error wouldn’t be really apparent on the less complex pieces but there’s a lot going on at the core…
I took a video of the wiggle but the site won’t let me upload it, looks like pictures only. I’m not sure how to capture it in stills but I’ll give it a shot.
If the problem persists, the recommendation is to take the core clamps off and then first tighten the screw that remains (the one squishing the bearing), then screw it back on. This often helps.
Videos have to be uploaded to an external site, Youtube etc.
Once there is contact between the nut and the plastic, you get maybe 1/2 turn with the 5/16" bolts.
This isn’t about torque, it’s distance. It ought to take very little “tightness” as you can fully crush sllid PLA before you get anywhere near “tight” with those bolts. Most of the resistance should be coming from the nylock nuts.
I like to put those clamps onto the rail with all 3 bearings on, and tighten the clamp bolt until all 3 just touch the rail. Remove the other 2 bearings and bolt to the core. Sometimes I don’t need to unbolt the bearings from the core to adjust.
I find I get 6-10 months between tightening, but I check the core and truck bearings each day I use the Primo.