Build PLOG. ZenXY LACK hack end table

There is a big difference between 350mA and 1100mA. I have found it is pretty sensitive to the current and there is a noticeable difference between 750mA and, 700mA. I’m sure you’ve got a setting that will work.

Looks good though. I like the sharp contrast between the black and white.

I keep feeling that something is wrong, and probably my mystery motors.

At 1100mA it works – mostly. I know that it won’t take 1200mA – at least its counter part did not. I tried a web design, and it starts skipping steps again. The wiper works pretty well, but anything complicated and it’s anyone’s bet. Sometimes, it’s working fine, then starts chunking away randomly. It’s really getting on my nerves.

I’ve got a couple of new motors, and I’ll be heading out to Lee Valey tools tomorrow for magnets, since the stack of 3 that I’m using keep dropping the ball. I’ll try adding one more to the stack, since they don’t have one 1/2" by 1/2" magnet to replace it with. They have 1/2" diameter by 1/8" thick ones. Currently I’m using 3 of these. I’ll try adding another one. It might drag on the bottom, there’s about a 3mm gap, now. (I thought I had it shimmed closer) It looks like the only shot that I’ll have to replace the whole stack is to remove the belts so that I can pull the carriage out.

Maybe drop the acceleration? I personally like the acel really low. I find it more aesthetically pleasing.

yeah, reducing accel is on the list.

I did manage to add a magnet to the stack, and it doesn’t drag, so there was probab y a 3.5mm gap before. I seem to have miscalculated homing positions, I placed things so that the centre of the magnet goes to the edge of the table, when it needs to be a quarter of an inch into the table. Funny, I remembered that in defining the max limits. Sandify does have the minimum positions as well, so I’ll set those to 6.5mm, which should do the trick.

When cold, the motors don’t skip steps. Once warm, they’re pretty bad. Or maybe the drivers are getting too hot. Fans are more noise, but it’s a pretty small amount at this point.

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Sandify space filler, now that I’ve stopped losing the ball so much. I’ll have to change the end plate again, but that’s no big deal. I’ve got another full graphic controller coming, so getting rid of the 2004 controller. Also, a smaller PSU. Don’t need 360W, I’ve got a 12V/5A PSU coming too, much smaller, so it doesnt use the same mounts.

So much for using leftover or spare parts… but I think the end result looks pretty good, even if you can still see the rails. Glad I didn’t use bright colours for the printed pieces (though the v1pi case is raspberry red. You can’t see it normally.)

This might need some fine tuning, I may end up making a new top for the table to correct some distancing issues, and add LED lighting.

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Something ain’t right here…

Trying to diagnose the skipped steps. It looks like something happens to the center shuttle, and it gets pulled.out of alignment. I was under the table, and noticed that there is a ridge gouged into the steel tube along the side where the single bearing rises. There is another along the top that I van feel with my fingertips. This is pretty obviously a problem, which causes the machine to need too much power, thus the skipping steps.

Did I put the part in wrong? The long bolt where the belts are zip tied is facing towards the motors, along with the idler pulleys which are offset from the center of the trucks. It seems to fit correctly. I’m actually almost ready to go buy some 3/4" conduit and print new parts to see if that version works, but I don’t want to give in just yet.

The center piece seems to be able to yaw in between the rails, which I believe is the problem. It fit tightly when first installed, but now some bearings don’t seem to make contact sometimes.

I’m inclined to think this means I assembled something wrong.

A short video that might more clearly show the problem: https://www.youtube.com/watch?v=0frCRqq0uRI

Huh. I don’t know. @vicious1 ?

I know that it was tight when I first assembled everything. Now… not.

So maybe PETg is just too flexible, or somehow the stresses from earlier distorted it. I printed another center, using the same printer gcode that I used before, and verified that it’s nice and tight with the new piece.

Then I broke out the 3 year old bright yellow PLA that I have left over and printed another one using the old printer and reassembled. This way, if it is the PETg, I won’t be seeing the same problem next week. Tried it out printing a pattern that I never managed to finish before.

Nothing proved yet, but it did finish. I didn’t think that the plastic would disort that far. Maybe from when it was skipping steps for other reasons it hammered the 5/16" bolts into the plastic? Dunno…

Edit: Now I seem to be having a lot of trouble with homing. The X stop on the belt doesn’t want to contact the switch anymore. I’ll try re-doing the zip ties, I must have the angle wrong.

Re-did the zip ties, made sure that the block on the belt is turned towards the homing switch, which seems to do the trick. There are times when it seems like something is taking more power than it should, or maybe that’s just the noise from the steppers. It’s hard to tell, it seems to move as commanded, so it can’t be just slowing down, since the program isn’t going to wait for the steppers to catch up.

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So far so good, the center seems to have remained tight.

The second mystery stepper burned out at 900mA. I managed to turn the current down. I have a couple of good 84 oz-in motors in now. I also added noise dampers, which help more than I’d have believed. The motors arent getting more than warm now.

I replaced the 360W PSU with a 60W one. Much smaller. I’ll have to change the end board where it mounts, but also have a full graphic controller coming, so I’ll swap that when I remove the 2004 controller. I’ve got the CAM done for it, I just need to give the CNC a piece of melamine to do it.

Assuming that the center doesn’t go loose again, almost done. I don’t know what I’ll do if it does go loose. Maybe fit in a linear guide…

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Started getting crackling noises from it again. https://www.youtube.com/watch?v=ATkncKRLZLE

It seems to still be tight, but I can hear it trying to turn and scrape along the edge of the bearing again. Something just ain’t right…

While your accelerations are low those speeds are much much higher than I run.

I am going to start this with…I am working on a new version but it is tricky.

The zen is very sensitive to magnet and ball distance, that also means the surface nearest the magnet needs to be super flat and level for the ball to stick, and the magnet not to bind…but be as close as possible to the surface. I shim mine with paper. magnet strength is cube root of the distance (if I remember right so serious ever tiny bit helps.

The other part is the bearings on the rollers is super sensitive and the rails need to be perfectly parallel and start perfectly perpendicular. If this is off it will raise the magnet up and bind, hearing it clicking is a sign of this happening. This is the part I am working on. Gravity is not the best helper here, the rail needs to be fully captured.

That center problem you are having is bugging me, I don’t think something is right there. Any way to sneak a picture of the top single bearing where the zip ties connect, maybe that stack is backwards?


@vicious1 I’ll take all the pictures you want… I’m fairly confident that it’s correctly assembled. I am running it fairly fast, but found that it seems better behaved when it runs fast. It slows down a lot for curves, which is when it shows the biggest problems.

I 3D printed a shim for the magnets, which is further shimmed to just below dragging on the hardboard.

I’ve also been thinking the Y rails need to be fully captured. I’ve checked again for parallel on the Y rails and they are as close as I can reasonably measure.

My thought is to add a printed piece outside the bearings on the Y runners to hold one more bearing underneath, and use a zip tie to tension it under the rail. Sadly, this will increase the depth of the mechanism by that bearing’s diameter, but will fully capture the Y rails. I have some smaller bearings that I might use for my own use, but probably could not recommend for others in the “anyone can source these parts” philosophy

That looks fine. I am not sure how that piece can even wiggle so much without something obviously wrong.

Shoot.

While testing for the new build I have sources some tiny wheels. I like them so far. I am trying to make sure it will fit in anyone’s current build and actually use less space but that is proving to be the trick part while fully capturing the rails. That is why I am really interested in how that center is having an issue as I do not want to duplicate it if it is the problem.

Best I can say is watch the zen move (lay under the table if you can). See what is happening when it grinds. Maybe the pulley is slipping and that is making it crooked every so often?

I should point out that I’ve replaced the center print. The one that was moving htat much has been replaced by the bright yellow thing. It was tight when it went in. Lots of juddering while the motor was skipping steps, I think that basically jackhammered the threads into the plastic, allowing the bearings to move more and more. Now it’s started clicking again. This print is PLA (Previous was PETg) the bright yellow is because that’s the only PLA I had left.

The pulleys aren’t slipping on the motors, but when it has homing problems, it can pull the X rails askew. The belt will slip on the clamp at the center as it tries to pull the carriage further in the X direction than it physically can. I have many cut zip ties from fixing this… I’m looking at using a screw assembly to secure the clamp. It has also sometimes pulled a twist into the X rails, which I have to loosen the clamp screws in order to fix. (I could probably gorilla it back into alignment, but that’s never my preferred method.)

I can’t see anything obvious when it grinds. Something is pulling unevenly is the best that I can determine. The belts do not seem to feel excessively tight at the back end, but I can hear them catching somewhere. My intuition is saying that it might be under the bearings along the Y rail… Which brings me to a suggestion:

Perhaps the belt run that goes from motor to corner pulley can be moved to go through the tube. I think that it sometimes catches where the twist is tightest. This happens at both ends of Y travel. If instead the belt were run through the tubes, this twist would never need flatten at the point where it runs underneath the spacers on the trucks, and so could be left to always run the full distance between the motor and the corner pulley. The biggest trick would be ensuring that it only run a 1/4 twist along the length, which would take some careful planning when laying it out, but once done, it would be aesthetically and functionally simpler. It would also allow you to pull the rails a few mm closer to the table.

It should be zip ties to that clamp, no slipping.

Yeah… It’s zip tied, but with enough force, it still slips. I can’t imagine what it is that puts that kind of force on the belt, but it happens from time to time. Might be when it’s trying to go past the physical limits of the machine.

This is the reason why I have a bunch of clipped zip ties in a pile because it would go and pull the X rails out of square, and the only way I can (reasonably) put it back to square is to clip the zip tie, re-square it and put a new zip tie on.

Again, I could probably gorilla it back into place, but zip ties are cheaper than new belt.

Something else seems wrong. I drive mine with like 100mA on each motor and there’s no way it is jumping teeth on that connection. I wonder if we had the root problem earlier and we just increased the current and now it is just hurting itself when it binds.