Slipping/Skipping problem during auto calibration

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