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Fix bed variance / warp using flat springs  

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Christizzz
(@christizzz)
Eminent Member
Re: Fix bed variance / warp using flat springs

No no the stock spacer variance was about 0.3-0.5..

the pictures here are both with the mod... one with a hot bed and the other with cold bed...

Respondido : 15/09/2018 9:11 am
Christizzz
(@christizzz)
Eminent Member
Re: Fix bed variance / warp using flat springs

So... here is my troubleshooting:

1) did new calibrate xyz --> rerun the whole process of getting a low variamce --> variance of 0.03-0.05 ---> bed always high on the Left when printing...

2) resetted everything ---> switched the Y smooth rods as well as their support from left to right ---> did 1) again ---> same issue...right is higher

3) tried to make the bed 2mm higher ( so i will be loosing 2mm)... just to check if it is an endstop issue...---> same issue

4) i am starting to loose hope... i mean i ve agot a replacement for BEd, carriage and smooth rods and bearings and i am still having the sam,e issue....

can smoeon pls print this file and check the left square : https://www.thingiverse.com/thing:1776031

here are my results: https://imgur.com/a/WCCqdzo

🙁 🙁 🙁

PS: i will post a new thread concerning this issue

Respondido : 15/09/2018 10:20 pm
Tiago
(@tiago)
Reputable Member
Topic starter answered:
Re: Fix bed variance / warp using flat springs

Try to post here on forum that problem, i had that before and still have a bit but not that severe like yours.
Send me the link of the new post

Respondido : 16/09/2018 12:01 am
Christizzz
(@christizzz)
Eminent Member
Re: Fix bed variance / warp using flat springs

https://shop.prusa3d.com/forum/assembly-and-first-prints-troubleshooting-f62/impossible-to-get-an-even-first-layer-all-over-the-t24557.html

Respondido : 16/09/2018 12:11 am
ron
 ron
(@ron)
Estimable Member
Re: Fix bed variance / warp using flat springs

Thanks a lot for that tip. I mounted my sping last week and it is great.
I designed an helper to mount the springs: https://www.thingiverse.com/thing:3102549
I bought the red spring at the end of august before any discussion about shorter spring. Then I designed and printed some guides (GuideCoupeRessort) to cut at 8mm with a dremel as it seems the good height to keep the bed at 5.5mm from its frame.

Respondido : 16/09/2018 12:35 am
OPK
 OPK
(@opk)
Trusted Member
Re: Fix bed variance / warp using flat springs

I got my springs (C0180-029-0310M) at amtec.nl and they are just perfect. Screwed in totally they are slightly smaller that the original standoffs and using the kitchen scale, each spring takes about 3kg to be fully pressed in.

I fully screwed in the center spring and then calibrated the others while the bed was heated at 70 degrees.

Fiddling with washers I got the variance to 0.123mm; with the springs I could improve it (almost) ten fold to 0.013mm (Im sure I can get it to 0.00x, but I ran out of patience).

Next I ran some Z layer test to get to the perfect 0.20mm layer and that is now consistent over the entire bed.

Respondido : 23/09/2018 10:10 pm
Tiago
(@tiago)
Reputable Member
Topic starter answered:
Re: Fix bed variance / warp using flat springs

I'm glad to see the people success with this mod 🙂
As proven here by OPK you don't need a super strong spring, like mine which does 3KG of force at first when start to compress and about 30KG when full. The number make the streng 😉
This should be standard with the kit! But well i understand is way more difficult to setup without a plugin or visualizer. As bonus this will flat your bed over time.

Respondido : 23/09/2018 10:18 pm
marto
(@marto)
Eminent Member
Re: Fix bed variance / warp using flat springs

done with red springs 6x3x40 , cut them to 8 mm with dremel and sand them to make straight
after 2 hours

Respondido : 13/10/2018 3:27 am
Tiago
(@tiago)
Reputable Member
Topic starter answered:
Re: Fix bed variance / warp using flat springs


done with red springs 6x3x40 , cut them to 8 mm with dremel and sand them to make straight
after 2 hours

Welcome to the forum, it seens this is your first post 😀
Glad it did the trick for you, keep it tunned :ugeek:

Respondido : 13/10/2018 3:30 am
marto
(@marto)
Eminent Member
Re: Fix bed variance / warp using flat springs

Yep
I am reading the forum since July, when I got my mk3
MY printer had 0.58 variance and in order to have good 1-st layer I was using bed corection up to 100 microns lef to right.
Now all this is gone .
I am doing 35 pinda now and go inside 0.06 variance .
Now XYZ wizard and final checks

Respondido : 13/10/2018 4:01 am
marto
(@marto)
Eminent Member
Re: Fix bed variance / warp using flat springs

Yep
I am reading the forum since July, when I got my mk3
MY printer had 0.58 variance and in order to have good 1-st layer I was using bed corection up to 100 microns lef to right.
Now all this is gone .
I am doing 35 pinda now and go inside 0.06 variance .
Now XYZ wizard and final checks

Respondido : 13/10/2018 4:01 am
Patrick McNamara
(@patrick-mcnamara)
Estimable Member
Re: Fix bed variance / warp using flat springs

I'll add my name to the list of people that have implemented some sort of spring based leveling. Just because I'm a glutton for punishment, I went with 2.5mm springs and 5mm spacers, with the springs undernearth the spacers so that the heat bed is sitting on the spacer and not the springs. I don't have have pictures, but I went from ~700um of variation down to ~15um variation. It made all the difference in the world. Prior to leveling with springs, I couldn't get a first layer print that was good, even with leveling compensation.

Now:

Respondido : 14/10/2018 12:52 am
andy.b15
(@andy-b15)
Active Member
Re: Fix bed variance / warp using flat springs

Are there any changes needed to be made after installing the 15mm red springs? Will this throw off the XYZ calibration?

Respondido : 14/10/2018 4:18 pm
Tiago
(@tiago)
Reputable Member
Topic starter answered:
Re: Fix bed variance / warp using flat springs


Are there any changes needed to be made after installing the 15mm red springs? Will this throw off the XYZ calibration?

Yes, don't go 15mm you will lose some Z. Only if you can cut them at size.
Better to buy the 10mm spring i said some posts ago OR if you can find good 8mm go for it

Respondido : 14/10/2018 4:51 pm
Patrick McNamara
(@patrick-mcnamara)
Estimable Member
Re: Fix bed variance / warp using flat springs


Are there any changes needed to be made after installing the 15mm red springs? Will this throw off the XYZ calibration?

Others have made comments on the length. You really want to find a length that is under 6mm when fully compressed, and over 6mm at its uncompressed length. Once you install the springs, tighten them down to about 6mm, insert the 6mm spacer beside the spring and tighten down, then loosed just enough to remove the spacer. The spacer will help you get all the springs at about 6mm. You will then need to re-run at least the Z calibration, and I re-ran the entire calibration from scratch. Once you have the basic printer calibration done, you start the G80/G81 cycle. For leveling the bed, I found it didn't matter what the PINDA temp was as long as it stayed the same throughout the process. You aren't setting live Z, just leveling the bed. Once the bed is level to your satisfaction, you run the live Z calibration prints to get your first layer to your liking. I stopped trying to get the bed more level at about 17microns variation. At that point, the high/low point just moved every time I tried to get better, and I didn't get better.

Respondido : 14/10/2018 11:31 pm
ron
 ron
(@ron)
Estimable Member
Re: Fix bed variance / warp using flat springs

I was disappointed that my fine tunings where gone after a Z calibration. In fact, due to design, the left and the right of the X axis don't got the same level after each Z calibration. That is my hypothesis.
So I tweaked the Prusa Mesh Leveling Octoprint plugin to be able to adjust the printer to my mind.
My idea:

  • I want a quite flat bed.

  • The bed may have a slope along the X axis as the height of the right and left may change after each Z calibration. And I assume the firmware handle well the linear interpolations.

  • Then I produce a second graph that correct the levels according to the points (X0,Y105) and (X250,Y105):
  • Those points are set to 0. They are my reference. Then I don't touch them when I level the bed.

  • All other points are corrected to those 2 points. It is corrected to a (ax+b) line. The parameters are displayed on the new plot.

  • Extra: the scale gives angle of M3 screw instead of mm.

  • First mesh bed leveling:

    Respondido : 15/10/2018 2:13 am
    ron
     ron
    (@ron)
    Estimable Member
    Re: Fix bed variance / warp using flat springs

    Second mesh leveling after Z calibration:

    You can see I have close to 0.1mm delta of variance between the two cases (0.728 and 0.633). But the values are the same (it is kind of luck that time) if the bed is corrected to a slope going through (X0,Y105);(X250,Y105).

    EDIT: I think next step I will go by decreasing the "raw" bed variance (original graph) too. At the moment the level of the point (X250,Y105) is done with a 5.5 mm height spacer, the same as for the point (X0,Y105). I will raise all the points on the rights and keep the points on the left at the same level.

    Respondido : 15/10/2018 2:18 am
    marto
    (@marto)
    Eminent Member
    Re: Fix bed variance / warp using flat springs

    After great printing for 2 days
    I got mintemp bed and My bed termistor cable had broken wires in the bed strain relief.
    Ordered new one and in the same time cut the worn parts and soldered connection put this under the table and had to use the reserve length .
    After that No way to make proper calibration ,1 I level it with dial indicator in 0.1 and then the mesh bed leveling results are terible 0.5 mm variance
    after 5 hour fight in one moment the nozzle hit the table during picking up Zero point Z. I tought faulty Pinda
    I happened that my pinda connector on the Rambo board was not clicked fully . I think I did this during getting the extra length of the bed termistor cable.
    :(((
    I did already ordered new PINDA , but wil see if I am going to need it
    I am starting from fresh factory reset now

    Done in 15 minutes now

    Respondido : 16/10/2018 9:17 am
    marto
    (@marto)
    Eminent Member
    Re: Fix bed variance / warp using flat springs

    and this is with pinda at 35 deg Cel
    I am not going any further as far this is better than last time

    Respondido : 16/10/2018 10:48 am
    marto
    (@marto)
    Eminent Member
    Re: Fix bed variance / warp using flat springs

    Been printing 24/7 Black PetG for the last 2 weeks.
    What I found is that on 85 deg C the bed is withing 0.07 to 0.115 and is different with each print. In the beginning with PETG i had a lot of troubles with first layer sticking to the bed , then found that 20 mm/s or lower for the first layer fixes everything . Now I get perfect first layer even the support base , that was worst

    Respondido : 06/11/2018 3:08 am
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