XY Calibration Sheet and Leveling

[Tigerbeard 4]

Hi,

I am sure the question has been asked before, but I did not find one using the search.

 

I found that my UM3 does not scale my models correctly, so I wanted to do a full maintenance including Bed Leveling and XY calibration. Since I lost the original support material I came accross some items that confused my. I used the officuial support articles for the UM3.

 

1. Calibration Sheet

I downloaded that sheet and tried to print it on DIN A4 paper, as described. But the PDF file only was 210mm x 268mm. That is not DIN A4, which is 210mm x 297mm. Can I really expect my printer to print this paper to 100% scale on DIN A4 if I supply it a PDF file that has a different format? 

Is there anything I can use to verify if my print is correct?

 

 

2. Bed Leveling.

This Support Procedure, tells me that I should to 3 adjustments

1. coarse with a rough 1mm distance - visually determined

2. fine for head 1 with a "calibration card". I lost that. The procedure does not say how thick the card should be.

3. find for head2 with the same card. It says I should adjust the same table screws.

I do not understand why the printer should work with a fine tuned mechanical adjustment for head 1 if I destroy this adjustment again for the 3rd step with head2? Doesn't any change I do to the screws directly throws off the adjustment of head1 (aka nozzle1).

What do I misunderstand about this procedure?

 

also lease can someone tell me how thick this calibration car need to be?

Or does the exact thickeness matter at all? Someone told me use a bank card. My cards are 0.85mm thick. If the origina was 1.0mm, I introduce 20% error here...

 

Thanks

 

 

 

Edited July 18, 2020 by Tigerbeard
typo

[Tigerbeard 4]

Ok, I can answer a part of my question:

 

 

2.

"The calibration card has a thickness of 0.15mm, which is exactly how much space you want between your nozzle and bed."

Maybe its useful to add this info to the official procedures. I would comment there, but the comments are closed.

 

I read somewhere else that the UM3 nozzles should be 0.1mm above the print bed, which would be a sheet of 80g copy paper - but I can't find where that was right now.

 

Also the procedure, I misunderstood that the 3rd step is using the "wheel" in front. I missed that this was talking about an electronic ajdustment now, compared to the mechanical one in step 2.

 

Open is that the procedure says

• 5 Adjust the knurled nut at the center back until you feel slight friction when moving the card
• 6 Press “Continue”. The print head will move to the second point
• 7 Repeat step 5 “place the calibration card” and step 6 “adjust the build plate”
• 8 Press “Continue” again. The print head moves to the third point
• 9 Repeat step 5 “place the calibration card” and step 6 “adjust the build plate”

  Step 5 talks about the "center back knurled nut". If I read carefully in steps 7 and step 8 I should change the same screw? Wouldn't it make more sense to change the other 2 screws in those steps? I find that confusing.

 

[Enigma_M4 121]

Hi Tigerbeard,

 

you seem to have solved two of your questions yourself:

 

2. The calibration card can be replached with a sheet of 80g copy paper, or a business card, if lost.

It's (or was?) mentioned somewhere in the UM3 documentations.

 

3. After levelling the print bed for core 1 with the thumb screws (note to not apply pressure on the screws while adjusting; adjust the screw that's directly under the printhead), the adjustment of the Z - OFFSET for core 2 is only done with the front wheel; keep your hands off the thumb screws after levelling core 1!

 

Now to the open question 1:

print the PDF with "real size" or "original size" (I don't know the exact naming, as my PDF reader is set to German).

 

Regards

Edited July 18, 2020 by Enigma_M4

[Tigerbeard 4]

@Enigma_M4 thanks for your answer,

 

I completed the procedure as you say. From that I would say the original description is quite missleading, The fine adjustments go through all 2 knurled screws one at a time. It think it would help newbies to adapt the description.

 

Note for 1:

after printing a few versions (which all came out a bit different) I found this very helpful youtube video. From that its not clear why I need to print out the sheet at all. Since the printer prints both line scales and even the scale ticks (just not the numbers) its quite trivial to find out the "0" line in the middle and determine the right number.

That insight is especially helpful for anyone who is using adhesion sheet/stickers. As they are opaque I would have needed to removen (=destroy) the current sheet just to put the paper below the glass bed. Now this is not required, because I can print the test print directly onto the adhesion sheet.

 

 

 

[Enigma_M4 121]

13 minutes ago, Tigerbeard said:

Note for 1:

after printing a few versions (which all came out a bit different) I found this very helpful youtube video. From that its not clear why I need to print out the sheet at all. Since the printer prints both line scales and even the scale ticks (just not the numbers) its quite trivial to find out the "0" line in the middle and determine the right number.

That's an interesting point and I agree. But the calibration sheet would make the procedure more comfortable and possibly reduce errors.

But for adhesion sheet users (like me) your suggestion is absolutely useful.

Thanks.