Help with new custom printer - Prints have ringing around them
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@jumpedwithbothfeet Good suggestion. I will check this.
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@siam Can you recommend a reputable place to purchase these? I may be willing to invest in some. Thanks!
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@mrawesome987 I don't think that this will help you because is a German supplier I have my three ballscrews from https://www.dold-mechatronik.de/SFU1204-Standarbearbeitung
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@mrawesome987 I noticed your using a flex coupling on at least one of your z stepper motors, good possibility that z belt of yours might be pulling the leadscrew out of alignment, worth checking with a print and the belt removed?
6HC Voron Trident based, 6XD CNC, Mini 5 polar printer
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@jumpedwithbothfeet said in Help with new custom printer - Prints have ringing around them:
@mrawesome987 I noticed your using a flex coupling on at least one of your z stepper motors, good possibility that z belt of yours might be pulling the leadscrew out of alignment, worth checking with a print and the belt removed?
This is a good idea... I have not tried this, so I will do that! Thanks!
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I think your Z linear rods are not suitable for this or may get out of aligment easy. I would use full cylindrival bushings and roind rods
Muldex IDEX Duet2+Duex5
Custom CoreXY 600x400 Hemera , Duet3
Sapphire Pro with Duet2 , with closed-loop motors
voron v0.1,2.4 ,cr10s all running klipper; stock Bambu X1CC, X1C and P1P,A1,A1 mini
custom high temp E3D toolchanger with Duet2+Duex -
@mrawesome987 there could be additional reasons than discussed before
- leadscrews being bent as discussed
- the 4 supported shafts may have too high load, so pressure is built up and moves the bed sometimes
- leadscrews can have different pitch (1/100 mm differences), so the bed is tilted a bit and builds pressure and releases it
A test would be to loosen 3 of the 4 shafts a bit (or the screws between organge part and aluminium extrusion) and check whether ringing is less then.
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@martin7404 said in Help with new custom printer - Prints have ringing around them:
I think your Z linear rods are not suitable for this or may get out of aligment easy. I would use full cylindrival bushings and roind rods
I had not thought of this. Could you explain your thinking? The bed frame feels tight, and does not have any noticeable play in the X and Y axis. Thanks!
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@jumpedwithbothfeet said in Help with new custom printer - Prints have ringing around them:
I noticed your using a flex coupling on at least one of your z stepper motors, good possibility that z belt of yours might be pulling the leadscrew out of alignment, worth checking with a print and the belt removed?
Just printed the same file but removed the Z sync belt. Results are MUCH better! Here's a before and after in the same lighting:
I'd say the issue is almost completely resolved, however, I think I am going to make a few adjustments to my design for permanent use.
- Replace the lead screws with a better quality screw. Researching this now to find the best cost effective option. I looked at ball screws, but I don't think I can fit 1m ball screws in the budget right now. I am currently looking at Misumi screws. Are these of good quality for 3d printing?
- Replace the flexible shaft couplings with solid couplings.
- Design some sort of bearing mount for the top of the shaft that will allow the shaft to move slightly incase things aren't perfectly lined up.
Does anyone have any other suggestions or advice? Thanks again for all your help.
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If haven't PID tuned your bed heater yet, now is the time. Bang bang controlled heating can cause enough expansion and reduction of the bed heater that you will get z banding artifacts.
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@mrawesome987 well this type of linear guide uses C shaped bushings and as far the rods are mounted on Aluprofile that is not straight in terms of hundreds of millimeter , so they can go slightly out of alignment .
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@mrawesome987 glad you found the problem, it is looking a lot better
do the lead screws still appear bent as they move on the machine? or has that gone now? as @oliof has suggested a bed PID tune is next it`s easy and most importantly free to do! -
@jumpedwithbothfeet said in Help with new custom printer - Prints have ringing around them:
@mrawesome987 glad you found the problem, it is looking a lot better
do the lead screws still appear bent as they move on the machine? or has that gone now? as @oliof has suggested a bed PID tune is next it`s easy and most importantly free to do!The lead screws are definitely still looking bent. I'd like to replace them.
I am looking at the Misumi lead screws, but I'm having a hard time speccing what I need. The lead on my current screws is 2.54 mm, which is probably a bit low, right? They offer carbon steel and stainless. Any advantage to carbon steel?
Edit: I did PID tune the bed when I first configured it, although I PID tuned it for 60C, and I've been running it at 90C. Is that an issue?
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@mrawesome987 now check this video on fixing the Z surface smoothness:
https://www.youtube.com/watch?v=a3oQy6v3MrA -
@mrawesome987, here is a printer that also has that Z sync belt so probably the idea is feasible if you make it right.
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That z sync belt is interesting, but I'm not sure why you'd want to use that instead of a single motor driving both screws, which would eliminate any potential problems with the motor interactions. If getting sufficient torque to lift the bed is the issue, one higher torque motor would probably cost less than two smaller motors, and then you'd only need one cable and driver.
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@mrehorstdmd said in Help with new custom printer - Prints have ringing around them:
but I'm not sure why you'd want to use that instead of a single motor
Lower backlash since each motor holds on the exact microstep?
Possibly could keep the belt loose and use it to avoid large skew when the motors are off, with automatic two points bed leveling on print start to get the motors in perfect sync.
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@zapta I have a machine with two Z screws that uses a single drive motor to lift the X axis. It absolutely never tilts. Over the last 6 or 7 years that the printer has been in use I've had to re tram the X axis two or three times after taking the X axis off the machine for modifications.
If you use two motors and leave the belt loose, you're allowing the motors to move independently, a small amount (a backlash amount?). If you have to run a sync routine to force the screws back into sync, what did you gain by adding the belt?
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@mrehorstdmd I agree with this I think.
My original thinking with the sync belt and two motors was that it would be beneficial in two ways:
- More torque to move the bed frame
- Sync the two lead screws so that they can't skip steps (or at least can't skip steps individually)
- Remove the possibility of turning one side without the other accidentally
The more I think about it, the more I am interested in moving to a single motor setup, with a much smaller pulley on the motor. Mostly for the reasons below:
- Probably more consistent that two motors?
- Remove the weight from directly on top of the motors, as it is now. Is this a huge issue? I'm not sure. Does anyone know what kind of force a Nema 23 can withstand long-term directly on the shaft?
As for the bent lead screw issue, I have reached out to the supplier I purchased them from a few months ago, and they seem to be willing to replace them. If that doesn't work out, I'll purchase new ones from a different, more reliable source.
While I wait for the issue above to resolve, I have been working to try to tune it to print decently. This has been causing some headache, but that's expected.
I have been testing by printing an XYZ 20mm cube, and the extrusion seems to be inconsistent. Most obviously is the corners.
The block on the left had PA set to .025, and the block on the right had PA set to .075. This produced a noticeable improvement, but does this sound like too much? I'm using a Hemera with Volcano, at .8mm nozzle.
Of course, I forgot to get the config.g and I'm at work now. I'll try to upload that later this afternoon.
Thanks for your help guys.
