Slipping/Skipping problem during auto calibration

dc42

If it's my mini IR height sensor that you are using, you must always use a P value of 500 in the G31 command. Otherwise the probing move won't stop when the probe triggers and the LED light up.

SM3D

Thanks deckingman and dc42 for your replies.

Regarding the P value, I think it was a mistake when I copied the file into system, otherwise it was P500. Just to be sure, I just now checked the value and ran the calibration again. It still stutters and behaves erratically.

I am a bit frustrated because I cannot pinpoint the error.

Here is a screenshot of the calibration I did yesterday after swapping the stepper motors. You can see that it progressively went bad.

dc42

Check that you don't have a G31 command in config-override.g that is overriding the one in config.g. Does the probe stop descending as soon as the LED on the IR sensor illuminates?

SM3D

I am sorry, this is a stupid question. By the way, how do I attach an image from my laptop to show you the calibration results.

Regards,
SM

SM3D

Yes the probe stops descending and I checked trigger height (1.45 to 1.52) which corresponds well with the actual height (1.5) I designed and measured.

Here is the config-override.g file:

; This is a system-generated file - do not edit
; Delta parameters
M665 L360.310 R163.319 H493.312 B115.0 X-0.186 Y-0.776 Z0.000
M666 X1.244 Y-0.947 Z-0.297 A0.00 B0.00
; Heater model parameters
M307 H0 A90.0 C700.0 D10.0 S1.00 B1
M307 H1 A175.4 C94.0 D4.5 S1.00 B0
M307 H2 A340.0 C140.0 D5.5 S1.00 B0
M307 H3 A340.0 C140.0 D5.5 S1.00 B0
M307 H4 A340.0 C140.0 D5.5 S1.00 B0
M307 H5 A340.0 C140.0 D5.5 S1.00 B0
M307 H6 A340.0 C140.0 D5.5 S1.00 B0
M307 H7 A340.0 C140.0 D5.5 S1.00 B0
; Z probe parameters
G31 T1 P500 X11.0 Y0.0 Z2.00
G31 T3 P500 X0.0 Y0.0 Z0.70
G31 T4 P500 X0.0 Y0.0 Z0.00

It has 3 G31 in config-override.g file, it is strange.

Regards,
SM

SM3D

Moreover, I have M501 S1 at the end of config.g file but when I issue M500 command to write the M665 and M666 values, it did not write and now I have 3 G31 commands here.

I am new to duetwifi so excuse my stupid questions

Regards,
SM

DjDemonD

Use https://postimage.io to upload an image copy the link it gives you for direct image then put and hey presto.

Just use M501 to load config.

I get issues as my bed.g has m500 at the end to save. If I get a bad calibration run then it behaves strangely on the next so I delete config_override (at least m665 and m666) and soft reboot.

SM3D

Thanks DJDemon for the help
Here is the calibration result working for the first and progressively going bad due to slipping.

OK, I will try it once my calibration runs fine. For the time being, I am stuck at this slipping problem. It is a bit frustrating. I am trying all the solutions. Since you have experience building a large delta printer do you have any suggestions for this problem?

By the way DJDemon, I read your reprap forum post about large delta print. I used flying struder after seeing your post but the swinging of extruder made me switch to direct drive.

If you remember, I am Vasan from Sweden who mailed you regarding the availability of piezo kit. Do you know when the next batch will be available?

Best Regards,
Vasan

DjDemonD

Hi I've not seen a skipping issue if there's a video I'll have a watch of it and see if anything springs to mind, if there isn't upload one to YouTube and link us up.

Subscribe to this thread http://forums.reprap.org/read.php?1,767998,773953#msg-773953 might have some more at the weekend.

DjDemonD

Cool, dealing with a 3 year year old and 4 month old who aren't much enamoured of the 30 deg + heat were having right now but will watch it when they're both 18 and have left home

AndreS

I had this skipping like in the video myself.
I changed from roller carriage to cheap chinese linear rails which were very bad. But I wanted to try them out: and got this skipping.
I went from 1A to 1,4A stepper current, but it got only slightly better. Somewere was some binding.
Then I changed the steel balls to G10 rated ones, and 2 of the 3 carriaged are now running much more smooth, but the third is not nearly as good. But: the skipping went away (at 1A stepper current). But because of the third one the print quality is not what I had. Interesting is that the calibration is better than with the roller carriages, but print quality is worse.
So my advise: take a look at the sliders from the linear rails.
While the print head moves they will be twisted and that should not produce any binding.

SM3D

Hi AndreS,
Thanks for the comments! I read about cheap linear rails so I bought from Germany, what I thought is a decent one

https://www.dold-mechatronik.de/navi.php?a=45382⟨=eng

It is actually from this company:

http://www.chieftek.com/product-arhr.asp

But as you say, I also suspect that it might be due to linear rail binding.

In that case, I want to lubricate the slider balls and see how it works. Did you do any lubrication? I also heard it is a pain to take the steel balls and put them back. Is it so?

Your suggestion is something I have not tried and I will do so. I hope it solves my problem.

Best Regards,
Vasan

AndreS

I did lube them, and the motion was better.

With the MGN12 I have its not that hard to take it apart, remove the balls and put it again together.

But your seems to be high quality ones and I wont take them apart.
From the datasheet there are lubrication pads built in. Go with the instructions on how to lubricate.

After my misery with these chineese crap, I took a look at quality stuff and had a look at dold-mechatronik.
If I go to by good ones, maybe from them (also because I'm from germany).

DjDemonD

I have cheap Chinese rails on 3 printers they all work fine. I removed the bearings, cleaned them, checked they were all round and the same diameter replaced a couple and literally drowned them in lithium grease.

Check they slide smoothly and aren't notchy.

I watched your video something mechanical is binding preventing smooth movement put your finger on a motor and move it around see if it's a motor skipping if it is its probably on a different tower and the skipping motor if fighting against the one that's binding. Are all the motors the same? Are they all wired correctly, are all the pulleys firm on the motor shaft (which should have flats on them if not grind some).

SM3D

Hi AndreS,
Thanks again! I am right now reading instructions to lube them. I asked for a lubrication kit from dold but they did not respond so far (more than a month). Since it is a new block, I assumed that they will be pre-lubricated but going by its motion, it seems they are not. I will try oil lubricating the pads. I lubricated the linear rails with good amount of lithium grease for many times but no use so far.

Anyways, I will try some lubrication oil and see how it goes.

Regards,
Vasan

SM3D

Hi DJ,
Thanks for your replies! Hope your kids turned 18 ; ) All the motors are same. I checked the wiring, tightened the pulleys, tensioned the belts and I have flats on the shaft. The only option for me is to infuse oil carefully into my carriages. I have to do it carefully. I will look into this lubrication issue and try to solve it.

Regards,
Vasan

SM3D

Hi All,
Thanks for your replies. I took the carriages and packed them with lithium grease for bearings. I used sewing machine oil for the linear rails. The problem has been reduced. At least, I don't hear the weird sound. Now I am doing my autocalibration.

I will post the auto calibration results in a separate thread.

In short, lubricate both the rails and carriages even if they come from high-quality vendors. It helped a lot.

Regards,
Vasan