JohnFox
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Posts posted by JohnFox
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You should be OK now.
I give the two pillars a wipe with a kleenex every two weeks or so, this removes any build up of oil from the ball races and keeps the friction between the balls and the pillars high.
Hopefully the final update on my z-axis problems.
My dropped layer issue returned after a couple of days. I contacted support again - they sent a replacement lead screw with attached servo. As I disassembled the leadscrew, I also removed the two vertical shafts and noticed oil on those shafts again. It appears when I put oil on those shafts some of it made its way down to the hole in the base and removing the shaft put more oil on it :(
I tried to remove oil from the hole, sprayed both vertical shafts with brake cleaner spray (which really removes all the oil and any grease) and reassembled.
In performing the vertical bearing alignment - I decided to try raising the buildplate to about half way up the vertical shafts and performing the alignment there instead of at the bottom of the printer. My theory was the shafts may be slightly further apart at the top of the printer, so trying the alignment in the middle might help.
After tightening the bolts on the bearings I raised the bed and lowered it manually and found it was much easier to move the bed up and down at the top of the printer - and it was a little more difficult to push the bed to the bottom of the printer manually.
I've been printing for a week and my z-axis issues have not returned.
Here is an example of printing four ABS models yesterday - about 4 inches tall.
Monty
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Whatever it was doesn't seem to be an issue now. Z travel is clearly slower during retraction but it's not a problem.
Obviously due to the little gremlin that lives in the controller section, I disturbed him
Hi John,
You can try setting the retraction length (not the speed) on the printer itself to 0.0mm to see if it makes any difference. If it resolve the issue then it may be related to the feeder motor.
The retraction is part of the feeder motor so if extrusion occur normally on a print not requiring retraction then it might not be related.
Do you know if your print uses z-hop? You can look in the gcode to see if it's the case. Between every G10 G11 code you will see a G0 with Z information. If that's the case then maybe z stepper motor is not connected properly anymore or got burned somehow and doesn't like to be used very often.
Please post a picture or video of the issue.
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Just changed the sensor, I became pretty sure that the wiring was the problem.
So far so good.
thanks
I had this occur multiple times and thought perhaps it wasn't plugged in tight at the circuit board. It seems it would go away and work for awhile before happening again. I finally replaced the temp sensor with the wiring and haven't seen it since. I am not sure if it was a problem with the wires or the actual sensor. The wires are pretty tiny and fragile. Just wanted to give you another scenario.
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I'm pretty sure the problem is with the bearings. Unless the rods are very marked and dented, they should be OK.
If you can undo the bearings, ( it's a real pain to do this ) and slide them up and down the rods, they should run smoothly with a slight 'whirring' sound. If the balls in the bearing get out of position they will suddenly lock and the whole thing jams. A slight twist and it will run again. In my experience, the more oil on the pillars, the more times the bearings lock.
Not sure of the advantage of the roller bearings over the slide bearings used on the X and Y axes, any mechanical engineers out there? This banding problem seems to be a pretty common fault.
Hi Markus,
yep, thats the one. Default 16,7mm/s. Just checked again, I changed it to 30mm/s not 60mm/s.
Try that and it should be OK.
Update on my case. I explained this behavior to igo3d and they want me to send the printer back. It is on its way there now.
I will keep you posted.
Thanks. But I wonder if this has any implication for the hardware? The help tooltip says
"Rapid movement speed for Z-axis when machine is not printing, should match actual Z-axis movement speed between layers for accurate print times"
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Dude
I did a system reset and things seemed to have improved, at least the object is now printing as it should.
What I have noticed is that during the layers when retraction is occurring, the Z motor speed seems to be about half the normal step speed, it's quite obvious. What I don't know, is whether this has always been the case. When the fault was happening, the Z speed appeared to get slower and slower until it didn't work at all.
The feeder retraction speed seems to be as it always was, so I don't think that has been affected.
Later on, I will check all the motor connectors, they are the most obvious source of the fault.
Not sure about Z hop, never been into the Gcode.
It almost looks like a processor overload.
thanks
Hi John,
You can try setting the retraction length (not the speed) on the printer itself to 0.0mm to see if it makes any difference. If it resolve the issue then it may be related to the feeder motor.
The retraction is part of the feeder motor so if extrusion occur normally on a print not requiring retraction then it might not be related.
Do you know if your print uses z-hop? You can look in the gcode to see if it's the case. Between every G10 G11 code you will see a G0 with Z information. If that's the case then maybe z stepper motor is not connected properly anymore or got burned somehow and doesn't like to be used very often.
Please post a picture or video of the issue.
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I have had to replace my nozzle sensor and did a nozzle replacement at the same time.
Normal printing now looks OK, a test print which did not require retraction looks perfect.
However, when I print an object where retraction is required, the Z axis motor slows down and eventually stops turning, killing the print.
I strongly suspect this is electronic as I had to undo the controller in order to get at the sensor connector, so worried I have upset something.
The print that failed has been made several time before without any problems, so the fault does not lie with the Cura file. Z travel looks perfect, no evidence of mechanical issues.
Any ideas?
Suspect I have disturbed something so that either the retract or Z motor is drawing too much power and the controller can't run both at the same time.
Just run another test on a larger object that needs retraction. Z axis is working now but it is clearly slower than normal while retraction is on. Just about to repeat the test with retraction switched off.
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Why didn't you try the Arduino 'Due'?
It's a lot faster than the Mega and you can run touch screens off it.
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I would stick to a glass plate. Can't see why bits should come out of it though, do you use a blade to prise the parts off while they are still warm?
With PLA and Prit-Stick, the models stay on the plate very well at 60C, just wait a bit longer for the plate to cool.
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Just gone back to the iakovs post. That sounds exactly like my machine, the Z step is a bit noisy but is working perfectly OK.
Don't think it is an issue at all, suspect the noise comes from the sudden start/stop action and vibration of the bed.
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It looks like a dodgy connector on the board then.
I'm printing at 210C
Can't reproduce the error at all, suspect it is due to the little gremlin that lives underneath the machine :-)
This is the head sensor error, when it's the bed it's mentioned explicitly in the message, don't remember the exact phrase anymore...
Check if you metal fan shroud is not touching the heater block, which is more likely to happen if you have the olsson block. Also turning the fan on more gradually might help.
This would help, if he got a "Heater error"...
Just to be sure: usually these error messages are showing
"ERROR - STOPPED"
in the first line... and the second text line looks like this?
"Temp sensor" (without the appendix "...BED")
This one is triggered, if the temperature sensor inside the heater block reads less than 5°C or more than 275°C. At which temperatures are you printing?
There's no connector near the head, the wire goes all the way down to the electronics board. You can check the connection there. Or can you reproduce the error if you wiggle the cables a bit?
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When I fitted the new ones they ran very smoothly up and down with hardly any friction. The old ones locked repeatedly.
I removed the top of the machine, ( I think ).
It's worth wiping the pillars from time to time to remove any oil that comes from the bearing themselves.
I printed out a 20mm high bracket last week and again got my ‘missing layers’ problem. This time it was at 14mm, rather than at the 10mm position as before so the position of these missing layers is showing some variability. So I decided to take a look at the z-axis bearings. First of all I manually raised and lowered the bed. It felt reasonably OK but it is difficult to tell what is ‘normal’ as I have nothing to compare it with and of course you have to back drive the lead screw and stepper motor. So I set about re-aligning the linear bearings. Before re-tightening the 8 screws, I removed them all and slid each of the bearings up and down the z-axis rods. They feel really rather bad to me. They are rough, notchy and stick/bind at various positions, sometimes needing a noticeable push with my finger to get them to slide further along the rods. They certainly will not slide down under their own weight. My printer has had this printing fault since new so maybe I just have a duff pair of bearings in my machine. I see that the bearings have a shaft seal at each end so I couldn’t add any lubrication to them even if I wanted to (I’ve never added any lubrication to the rods). I am familiar with how deep groove bearings feel when rough and how smooth they operate when new. Is this the sort of feel that I should be getting from the linear bearings (ie should they just glide freely along the rod?) Sure there will be a bit of resistance from the seals but what I am feeling is definitely not from the seals.
John, when you replaced your z-axis bearings with new ones, were they very smooth running on the rods? Out of interest did you replace the bearings by removing the top of the machine and pulling the rods up or remove the rod ‘stops’ from beneath and drop the rods down? I think I am going to contact Ultimaker sales as my machine is still in warranty and has never been right since new.
Thanks for your help.
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I suspect it is due to oil on the Z axis pillars.
The Z axis bearings are ball bearing races and I think that oil on the pillars causes them to slide and not roll, making a jam.
I had this problem for some time, new bearings and no oil fixed the problem. As an experiment, I oiled the pillars again, promptly creating the fault. Cleaned off the oil and everything was OK again.
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All it says is 'temperature sensor error', nothing to say which sensor it is talking about. The fans are normally off on the first layer, 50% on layer 2, then 100% beyond that.
The bed and nozzle are heating up for certain and pretty close to what they should be.
A loose connector seems the obvious cause but can't explain why only on the first layer. I am assuming that if the controller sees an open circuit on a sensor it halts immediately.
Does the nozzle sensor have a connector around the hot end area?
What does the temp error actually say? Knowing if it's nozzle or bed could narrow it down a bit.
Do you have fans come on during the first layer?
Could be a loose connection.
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I think the oil on the pillars is the real culprit, the bearings hardly get a lot of use, they only go up and down once in a print.
New bearings from the re seller seams to have solved the problem (fingers crossed).
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Just had some 'temperature sensor error' messages on my UM2. They are fatal, i.e. only switch off and on again clears them but then the machine works perfectly again.
Oddly, I have only seen these during the first layer.
No obviously incorrect temperatures on either the nozzle or build-plate.
Any ideas?
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Wonder if your PLA is a little over size and getting caught in the head.
Also cut the end off. If I do a 'filament change' I often get a small blob on the end of the filament which is quite a bit larger than 3mm.
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I take it you stopped the print before the end?
I think it was printing correctly but you should have either inverted the model in Cura or printed with supports, ( inversion is better ). All that mess on the rear of the print is due to filament being extruded into air without any support, ( it's the clip for the card holder ). Inverting the model would put the top of the object onto the build plate and give support all the way round.
Welp, seems I may have used the "Jump to Conclusions" mat on this. Doesn't seem to be a filament issue, but something is wonky with my printer. I just changed over to use the Colorfabb Blueish White filament, which I've used successfully before, and I came back to this:
I had JUST re-leveled the bed too, guess I'll have to sit down and try and figure this out.
I was trying to print a SD Card holder (this one), and I used the Normal Print settings in Cura, plus the default PLA setting of 190F from the Printer Materials type menu (that you choose after changing filament).
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I have printed this one:-
http://www.thingiverse.com/thing:177794
Fits onto the spool holder of the UM2. Coils can be a bit of a pain but the big benefit is that the filament isn't in tight circles which can increase the friction in the Bowden tube.
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Just downloaded Izzy's files. Thanks, that should sort it!
Looks slick Izzy! I'll give it a go when I'm back in the lab.
JohnFox - The youmagine page says you have to cut away plastic to clear the wires. Izzy seems to have come up with a better solution though!
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I agree with cloakfiend PLA is FAR easier to print than ABS. For my applications, the only reason to print in ABS would be its stability to high pH liquids. When I switched from ABS to PLA, the print failure rate dropped from about 40% down to zero.
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Hot end fan spacer.
Just printed the fan spacer but on my UM2 this spacer is far too thick. It pushes the fan back by about 5mm and thus prevents the heater and thermocouple cables from entering the black plastic bearing shell. If you force it, the cables will be damaged. I tried reducing the thickness to about 2mm but still the cables would be crushed by the bearing holder shell.
The air flow problem is not as serious as it sounds. Yes, there are only two full slots where the air flows in but those slots, ( at least the left one ) are in the perfect place to cool the PTFE coupler. It's is possible that by allowing the air to flow though all the slots instead of two, it may reduce the flow of air around the PTFE coupler. My coupler doesn't seem to get too hot anyway.
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Don't oil the pillars, that seems to be part of the problem. If they are oiled, the balls in the bearings tend to slide rather than roll and make them more prone to jamming.
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I used this one:-
http://www.thingiverse.com/thing:177794
then made a modified one which is bigger and wider arms. You need some 40mm M3 bolts.
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I got some new ones from Ulitmaker, ( under warranty ).
Very obvious that they slid up and down cleanly.
I would suspect the Z bearings if you saw the bed drop. I think the balls locked up in the raceway, then suddenly released again. It's a bit involved but if you can undo the bearings, try sliding them up and down the pillars. They should move smoothly but mine had frequent lockups. Changing the bearings solved the problem.
JohnFox - After some more investigation, I have found that this is exactly the problem. They move freely for the first 10mm then lock up as you say, when the balls reach the end of the race.
Did you change to a different bearing from what Ultimaker provides or the same bearing without that fault? I'm very keen to find out.
Thanks.
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Advantages of different types of bearings
in UltiMaker 3D printers
Posted
Are there any engineers out there?
What are the advantages of using the phosphor bronze slide bearings on the X & Y axes and the roller bearings on the Z?
The Z axis roller bearings seem to be quite a source of trouble yet the X & Y slides are problem free, ( although I shouldn't tempt the fates ).
Just curious.