Z axis torture test?

I hate asking any questions here, but I’ve been searching for days. I have this slight wobble in my z axis. Sometimes I’ll see the z jump down, it seems to be in the same locations. I’ve disassembled the core probably close to 10 times. It seems like the core clamps bolts come loose during an operation. Its driving me off my head. It doesnt seem like alot of people have this issue. I’ve seen mention a few times by Ryan of a z axis torture test. I’ve found his xz yz test, that’s for a printer.

Everytime I see any movement on the z I lose my mind a little bit.

Things I’ve done trying to solve this
Reprinted my core due to a very slight layer shift
Dismantled and reassembled the full machine at least once and the core and attached pieces at least 10. I truly thought I did something wrong during the build but am beginning to wonder. I’m usually pretty good at building things and troubleshooting. I’ve reassembled the machine at least 10 times. I should have gotten it right at least once lol.

One more thing. Where is the universal mount file? I’m talking about the plate that sits on the tubes I’ve seen here many times. Every one of Ryan’s mounts works fine for me thankfully yet when I go onto thingiverse.com all the mounts have the holes facing the wrong way. I know I’ve even seen one of Ryan’s machine using the plate in the pen mount article yet I can’t find that file anywhere.

I must be really dumb. I see mention and photos of these things but cant find them anywhere…

Please ask here!

It was a gcode script that just went up and down. It didn’t print anything. I am not sure where it is now. I haven’t seen it mentioned in years. You can write your own easily enough:

G1 Z100 F300
G1 Z10 F300
G1 Z100 F600
G1 Z10 F600

Just like that.

Hmmm. I think it is from the Burly. Here is the C version:

Maybe someone else knows. I don’t have a primo. It should probably get published with the primo parts.

As for the Z issue, I don’t have a primo, and I won’t be much help. What kind of wobble are you talking about? Does it skip steps (and not make it all the way) or does it wiggle in x,y while moving in Z? Do you have some example work pieces that show the problem?

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Thank you that’s exactly what I was looking for. It wasn’t included in my zip of parts. I’m a little confused tho I printed the 4mm version figuring that 4mm indicated the nuts on the back. Which it did but it also was for the screws that screw into the 2 z rails. Primo nut traps are for m5 not m4. I had to drill the holes out and countersink them a bit to get the screws to fit.

So I’ve been ripping my hair out the last couple days trying to figure out the z issues. I’ve realized its 2 separate issues.

I’ve uploaded a short 2 min video here

I’ve messed around with the bearing for hours it never sits right.

I think the holes did move. I have not built a primo, so I am not sure. I know Ryan was trying hard to get the router tucked in as far as he could to make it more rigid.

I know some people (even on previous versions) have made entire second Z assemblies and swap them out for different tools.


Sorry **[quote=“jeffeb3, post:4, topic:25776, full:true”]
I think the holes did move.


Which holes moved?

Was there anything you were able to determine what was happening. In that video I had everything as tight as possible I should have shown a video when it wasn’t that tight.

Is there anything you know of I can do to stop the issue?

I’m not a vain or proud man, but with this I’ve never felt such pride. Every time I see it shake, it’s like a dagger in my heart.

Sorry, I think was confused. I thought the screw locations moved between the burly universal mount and the dw660 mount. But I may be making that up.

I try not to answer the primo core alignment questions. I just don’t have a good sense of it.

Maybe it wasn’t doing it because there was no tool mount in there. Maybe they are binding when there is a tool mount in there?

If it sounded like crunching gears, then it was probably skipping steps (which isn’t actually any mechanical grinding, but the stepper quickly jumping between magnets. If it skips steps, then if you jog from 0 to 50 and back to 0, it won’t end up at zero. If it does end up at zero, then something is flexing and not giving.

If it is skipping steps, then it might be because of an intermittent wiring issue, or maybe a wiring mistake. It could be due to the stepper drivers not properly configured. It could be because the gcode is sending it too fast (steppers lose torque at higher speeds). It could be a power supply issue.

A slipping coupler also looks like skipping steps. Check the grub screws again. Making a mark on the motor shaft and on the coupler will help see if they are slipping.

My guess is that the Z electronics are normal, and the leadscrew and coupler are working fine (but they should be checked). My guess is that something is binding up. The likely candidates is something with the core alignment (and I am no help there, but more tightening is not always the right direction) or… The leadscrew nut is over constrainted. That leadscrew can really bind if the nut isn’t hitting it straight on. Using just one screw to secure the nut will leave it enough slack to align itself right, but not let it turn. The screw also needs lubrication.

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Thanks, this solved one of the issues.

I dont understand why its wobbling at the 45 of the x y meet.

I dont think it’s the core cause this is the 2nd one I’ve printed. That leaves only the clamps. My printing is typically accurate.

This is starting to frustrate me like my idiocy of having one of the xz mains on backwards of my LR.

There is also this if you want to keep more meat around those bolts:


Keep working at it and I am sure you will get it soon enough. Maybe it is a fundamental problem with the z pipe alignment. I take special care to make sure those pipes are perfectly parallel, and the burly style mounts do help with that. To give a sorta baseline, when I power off my Vmotor supply with my little bosch colt router installed, the Z on my primo will fall on it’s own until the bit hits the spoilboard. It really can be that smooth, and still have no z slop if the top bearing/shaft-adapter fit is done just right… or xy wobble when the bearings are snug on the pipes. The inner z pipe bearings may or may not engage hard, which is fine as the structure is fully determined with just the outer 4 bearings engaged.

If you’re getting z wobble with the z bearings being snug, you may have issues with your clamp fit. There is enough slop in the holes of the core and clamps to give a little give and go, which can make the diff between win and fail from my experience. Maybe playing with pressing the bolts too and fro while tightening might give you the mojo you need for a good fit.

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I measured the distance and I got 94mm on top and bottom.

I then played around with the wobble and noticed that it was mostly on the x so I removed the y clamps and then reattached them. It’s very solid now.

I dont like how the LR2’s z axis(sp?) drop when the motors disable. I wouldnt like my mpcnc doing the same. It couldn’t have been the coupler issue as my motor and rod are attached as one unit. The advice that Jeff gave me seemed to solve the issue, thankfully.

I could almost kiss you for your advice. It’s really late here, I’m not going to start cutting anything until tomorrow. I cant wait to see the improvement!!!

I can finally move onto completely figuring out my laser and pwm spindle control of my 500w spindle. The laser I think I finally figured out I’m just waiting on some resistors for the pull up and voltage divider. The spindle I’m still struggling with.

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