Big bed-leveling issues.

Topics around mechanical design, controller and electronics. Mods & hacks welcome.
wermy
Posts: 23
Joined: Fri Jan 20, 2017 1:49 am

Big bed-leveling issues.

Postby wermy » Thu Mar 02, 2017 12:59 am

My bed wasn't level from the factory - the back was much lower than the front. I didn't like how the leveling worked out of the box, so I did the 5-point leveling mod that others on here have done (this one specifically: http://www.thingiverse.com/thing:1992664 , using the same springs listed there).
Nothing is sticking to my bed (I'm using a PEI sheet from lulzbot, which works fantastic on my lulzbot mini), and I'm fairly certain it has to do with the bed being unlevel. I've tried with a 0.2mm gauge, 0.15mm gauge, and a sheet of paper, all different first layer heights, extrusion multiplier, speeds, you name it - MANY many times. What makes me think it's a leveling issue is when I heat up the bed and level it, I'll get the height set just right with a piece of paper so the nozzle just barely grabs onto it. If I sit there wriggling the piece of paper for a few seconds, I can feel it get much tighter, and then much looser, corresponding with when a fan kicks up a notch inside the PSU (so I'm assuming that's when a heating element kicks on and off). It's like the whole bed seems to shrink, expand and warp as the heating elements turn on and off. Is this a problem other people are having too? Is there ANYThing I can do? I'm going absolutely crazy and my printer is about useless right now.

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walshlg
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Re: Big bed-leveling issues.

Postby walshlg » Thu Mar 02, 2017 3:26 pm

try hairspray for adhesion

lami3d
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Location: Marseille - France

Re: Big bed-leveling issues.

Postby lami3d » Thu Mar 02, 2017 4:10 pm

if i well understood what you've explained, and that you're sure of the phenomenon you described, you have got a very strange issue. :?

When you level the bed, i understood that the bed is hot, is the temperature of the bed stabilised ?
is the nozzle hot too ? If the nozzle is hot, is there plastic inside or is it clean ?

I prefer level the bed with cold nozzle and bed, i have my marks and i offset in the software (depending raft or not...).
For me, if the bed is levelled, its attitude doesn't change... dilatation affects global Z (managed by the Z offset) but not the attitude.

If you have an original dual extruder version, the printhead is also very heavy and there must be a little bending when the printhead is in the middle of the shafts. Or it's possible that your shafts are bent (i've got this issue) ?

There are other parameters than can affect bed adhesion. Maybe, you can post a picture or a movie of a first layer ?

wermy
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Joined: Fri Jan 20, 2017 1:49 am

Re: Big bed-leveling issues.

Postby wermy » Thu Mar 02, 2017 6:11 pm

lami3d wrote:if i well understood what you've explained, and that you're sure of the phenomenon you described, you have got a very strange issue. :?

When you level the bed, i understood that the bed is hot, is the temperature of the bed stabilised ?
is the nozzle hot too ? If the nozzle is hot, is there plastic inside or is it clean ?

I prefer level the bed with cold nozzle and bed, i have my marks and i offset in the software (depending raft or not...).
For me, if the bed is levelled, its attitude doesn't change... dilatation affects global Z (managed by the Z offset) but not the attitude.

If you have an original dual extruder version, the printhead is also very heavy and there must be a little bending when the printhead is in the middle of the shafts. Or it's possible that your shafts are bent (i've got this issue) ?

There are other parameters than can affect bed adhesion. Maybe, you can post a picture or a movie of a first layer ?


I agree, it's a very strange issue. :)

I actually have a single bondtech extruder so there isn't much weight on the printhead.

I heat the bed up to 60 and the nozzle up to 150 or so, and let it sit for 20 minutes or so before leveling. It's clean, so there is no plastic oozing or sticking to the paper. The width between the nozzle and the paper will go from being just right to completely loose or far too tight. It seems like the whole bed is flexing slightly as it heats and cools (I can hear a fan turning on and off in I think the power supply, and it corresponds with the nozzle distance from the bed fluctuating).

Makes it VERY difficult to get a consistent level. I'll try leveling with a cold bed this evening, but I don't know if that will help given that heat seems to be making it flex in the first place.

I remember seeing others having a similar issue at one point, and someone suggested getting a thicker sheet of glass (so it won't flex as easily), but I can't for the life of me find it now. Anyone suggestions as to what a good thickness would be?

lami3d
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Location: Marseille - France

Re: Big bed-leveling issues.

Postby lami3d » Thu Mar 02, 2017 6:26 pm

I've done a bed level mod but i reused the 13 fixing points... 5 must be good but are the springs well compressed ?
if you've got the bondtech and your shafts are straight, it should stick...
I'll follow this topic !

Phenomenon motor/receptor : i'm about to finalize shafts replacement on my N2+ and i noticed that, with the printer power off and unplugged, it's possible to light the leds by moving fast the printhead :lol:

wermy
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Re: Big bed-leveling issues.

Postby wermy » Thu Mar 02, 2017 6:57 pm

lami3d wrote:I've done a bed level mod but i reused the 13 fixing points... 5 must be good but are the springs well compressed ?
if you've got the bondtech and your shafts are straight, it should stick...
I'll follow this topic !

Phenomenon motor/receptor : i'm about to finalize shafts replacement on my N2+ and i noticed that, with the printer power off and unplugged, it's possible to light the leds by moving fast the printhead :lol:


Well I started with 5 points and wound up adding the mid-points on the edges too (which helped some), so it's 9 points at the moment. Are you having good luck with the 13 points? I considered adding those as well.

How compressed are your springs? Mine may not be pulled down enough when I level it, so that could be contributing to it... Care to post a picture of your setup? :)

lami3d
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Re: Big bed-leveling issues.

Postby lami3d » Thu Mar 02, 2017 7:21 pm

Yes, i'm having good results but i'm not sure there's a big difference adding these points.
But, in all cases, we have to tighten until the bed can't move if we apply a certain pressure on it.

Printing bamboofill... with my new N2, it's perfect and tomorrow i hope my N2+ with its news shafts, will be able to do the same...

20170302_201423[1].jpg

wermy
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Re: Big bed-leveling issues.

Postby wermy » Thu Mar 02, 2017 7:27 pm

lami3d wrote:Yes, i'm having good results but i'm not sure there's a big difference adding these points.
But, in all cases, we have to tighten until the bed can't move if we apply a certain pressure on it.

Printing bamboofill... with my new N2, it's perfect and tomorrow i hope my N2+ with its news shafts, will be able to do the same...

20170302_201423[1].jpg


Thanks! This does look more compressed than mine, I'll compare when I get home but I have a feeling that's causing some of my issues. I see you have some sort of printed part on the bottom of the springs - what is that?

lami3d
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Re: Big bed-leveling issues.

Postby lami3d » Thu Mar 02, 2017 7:34 pm

I was teached by socke on this topic viewtopic.php?f=4&t=1003&hilit=yet+another
Just the fact that, if your printer is a recent one, the stabilizer located at the the center of the buildplate will need to be extruded a bit (about 2 mm, i don't remember exactly) to offset the panel under the bed that was added later. Socke didn't have this panel and so all the stabilizers are the same in the topic.

wermy
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Re: Big bed-leveling issues.

Postby wermy » Thu Mar 02, 2017 7:41 pm

lami3d wrote:I was teached by socke on this topic viewtopic.php?f=4&t=1003&hilit=yet+another
Just the fact that, if your printer is a recent one, the stabilizer located at the the center of the buildplate will need to be extruded a bit (about 2 mm, i don't remember exactly) to offset the panel under the bed that was added later. Socke didn't have this panel and so all the stabilizers are the same in the topic.


Thanks for this! I will read through that thread.

I've had so many issues with my N2, but I feel like I'm so close and once this is fixed it'll be a really nice machine. :)

lami3d
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Re: Big bed-leveling issues.

Postby lami3d » Thu Mar 02, 2017 7:42 pm

And, it depends on the stiffness of the spring you used... (don't compare with the picture if there are not equivalent)
Maybe, the picture is less important that your feeling when you'll apply pressure on the bed with your hand!

lami3d
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Re: Big bed-leveling issues.

Postby lami3d » Thu Mar 02, 2017 7:53 pm

you're welcome ! I understand because i had also issues and that was my first printer...
a picture of this afternoon, after installing the new shaft
i know what issue means :)

Axes.jpg

whoaa512
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Joined: Tue May 31, 2016 11:24 pm

Re: Big bed-leveling issues.

Postby whoaa512 » Tue Mar 07, 2017 6:46 am

Personally, I've had the most success with the 3-point bed level mod. It's much easier to calibrate since all you need are 3 points to define a flat surface. Adding more degrees of freedom actual just makes the leveling equation that much more complicated.

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geekhands
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Re: Big bed-leveling issues.

Postby geekhands » Fri Mar 17, 2017 2:38 pm

I've done the 5-point mod... my stabilizers were shorter than these because at the time my printer was so unlevel it struck the parts being printed and popped them off the raft. I used them anyway. I am re-printing them today with a nearly level bed. I can see some play in the springs. I've also noticed as I tighten down on the 5-points the center point has to be tightened way more than the edges. This prompted me to re-print the stabilizers to get full height and move from 5-points to 9-points.

Did I read your post right suggesting the center stabilizer must be higher than all other points on the bed?


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