Leveling problem?

Leveling problem?

Postby jrnyfan@nc.rr.com » 2014-Jul-Tue-17-Jul

levelissues.jpg


I've had my printer for almost 2 months now. Got some really great prints with almost no tweaks.

I must have had a bad roll of filament - it got clogged. So, I took the tip off, took the hot end off, and made sure they were clean. Check. I reattached, and followed the "setup leveling probe" home location as directed on the Printerbot site - just to make sure I hadn't thrown anything out of line when I cleaned the extruder. Since then, it's been all down hill.

I'm now facing this problem, and I don't know what to do next...

As my first layer of this large object is layed down, the right middle/back area of the bed won't seem to stick. The area pictured close to the "front" of the unit sticks very nicely. So, I've adjusted the negative Z probe number all over the place. I got it to a spot where it layed down a nice first layer (pictured in the bottom pic). However, as that object builds upwards, the nozzle tip scratches the top layer of the object as it moves around. Raising the -Z probe value back up causes the first layer not to stick. So - I'm stuck. No idea what to do next. Would it mean the sensor isn't detecting the metal bed correctly in the areas where the first layer doesn't stick?

Advice and help greatly appreciated, as I have a $600 paperweight right now. I've only been 3-D printing for 2 months, so consider me a close to total newbie.
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Leveling problem?

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Re: Leveling problem?

Postby jrnyfan@nc.rr.com » 2014-Jul-Tue-19-Jul

PS - It's a Simple Metal. Bought it fully built. Repetier Host & Slic3r for software used.
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Re: Leveling problem?

Postby RetireeJay » 2014-Jul-Tue-20-Jul

jrnyfan@nc.rr.com wrote:However, as that object builds upwards, the nozzle tip scratches the top layer of the object as it moves around.


In Slic3r's "Printer Settings" in the "Extruder 1" section, try setting "lift Z" to a small positive value. Start with half of your layer height and increase from there if necessary.

I can't tell you how to get the multi-point bed leveling to work right, but it's clear from your picture that the clearance from bed to extruder is not consistent over the full area of your print. It may be that your print bed is warped, bowl-shaped. I THINK the bed leveling software assumes a flat plane - but I'm not sure of that. In fact, Mach-Chris with a 9-point compensation in his firmware may be correcting for non-flat beds.
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Re: Leveling problem?

Postby thawkins » 2014-Jul-Wed-00-Jul

RetireeJay wrote:
jrnyfan@nc.rr.com wrote:However, as that object builds upwards, the nozzle tip scratches the top layer of the object as it moves around.


In Slic3r's "Printer Settings" in the "Extruder 1" section, try setting "lift Z" to a small positive value. Start with half of your layer height and increase from there if necessary.

I can't tell you how to get the multi-point bed leveling to work right, but it's clear from your picture that the clearance from bed to extruder is not consistent over the full area of your print. It may be that your print bed is warped, bowl-shaped. I THINK the bed leveling software assumes a flat plane - but I'm not sure of that. In fact, Mach-Chris with a 9-point compensation in his firmware may be correcting for non-flat beds.


You are correct, 3 point leveling assumes a flat plane, however since the bed is held on with 4 fixing points, there is always the chance that the bed is stressed in one diagonal or the other.

The best bed fixing scheme is 3 point too, arranged in a triangle, with only one fixing point on one side and two on the other, then if the bed material is truly flat, the fixings cant possibly distort it, and the bed will always be flat. 4 point fixings cant guarantee that.

Just think about what would happen to a bed plate if you screw TL and BR to min and TR and BL to max.
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Re: Leveling problem?

Postby thawkins » 2014-Jul-Wed-00-Jul

RetireeJay wrote:
jrnyfan@nc.rr.com wrote:However, as that object builds upwards, the nozzle tip scratches the top layer of the object as it moves around.


In Slic3r's "Printer Settings" in the "Extruder 1" section, try setting "lift Z" to a small positive value. Start with half of your layer height and increase from there if necessary.

I can't tell you how to get the multi-point bed leveling to work right, but it's clear from your picture that the clearance from bed to extruder is not consistent over the full area of your print. It may be that your print bed is warped, bowl-shaped. I THINK the bed leveling software assumes a flat plane - but I'm not sure of that. In fact, Mach-Chris with a 9-point compensation in his firmware may be correcting for non-flat beds.


You are correct, 3 point leveling assumes a flat plane, however since the bed is held on with 4 fixing points, there is always the chance that the bed is stressed in one diagonal or the other.

The best bed fixing scheme is 3 point too, arranged in a triangle, with only one fixing point on one side and two on the other, then if the bed material is truly flat, the fixings cant possibly distort it, and the bed will always be flat. 4 point fixings cant guarantee that.

Just think about what would happen to a bed plate if you screw TL and BR to min and TR and BL to max.
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225mm x 200mm - Heated Bed
RAMPS 1.4 running Marlin 1.1.0
Full Graphic display.
-------------------------------
Zen Toolworks CNC/3d printer
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Dual j-head hotends.
Dual heated beds.
RAMPS 1.4 running Marlin 0.98
-------------------------------
Flashforge 3d Creator Pro
Dual Extruder
220x143x150mm
Mightyboard rev e, runnimg Sailfish 7.7r1234
-------------------------------
Photon, self designed printed printer.
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Re: Leveling problem?

Postby Jdublu » 2014-Jul-Wed-07-Jul

You can check the flatness of the build plate by laying a flat edge perpendicular to the bed surface and looking for gaps. You might be able to modify the gap by loosening and re tightening the mounting screws for the bed. In the short term, Retiree Jay's solution of using Z lift, will solve your scratching problem.

In the longer term, upgrading your X and Y axis with the Matrix 8x8 build plate will give you a flat surface to start with and 2 additional inches of build volume.

No affiliation with Matrix, just a happy customer.
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Re: Leveling problem?

Postby Mach-Chris » 2014-Jul-Wed-08-Jul

RetireeJay wrote:
jrnyfan@nc.rr.com wrote:However, as that object builds upwards, the nozzle tip scratches the top layer of the object as it moves around.


In Slic3r's "Printer Settings" in the "Extruder 1" section, try setting "lift Z" to a small positive value. Start with half of your layer height and increase from there if necessary.

I can't tell you how to get the multi-point bed leveling to work right, but it's clear from your picture that the clearance from bed to extruder is not consistent over the full area of your print. It may be that your print bed is warped, bowl-shaped. I THINK the bed leveling software assumes a flat plane - but I'm not sure of that. In fact, Mach-Chris with a 9-point compensation in his firmware may be correcting for non-flat beds.


After some digging into the firmware I have found that the leveling doesn't correct for warp, regardless of how many points are in use. Its using all the point data to compute a least-squares calculation. Essentially it is finding the best fitting plane between all available points. So that being said; a waped bed will still be problematic even with more probed points. The way I initially thought it worked (and maybe this would be a better way to go about auto leveling...or maybe something called bed mapping) would be to break the table down into smaller sections, each with their own tilt coefficient.

example, 9 points
0----0----0
I
0----0----0
I
0----0----0

with the information given by these 9 positions, it would then be possible to break the table into 4 quadrants. Each having their on tilt coefficient. So if you were to have a dip in the middle, the two left, and two right quadrants would be tilted down towards centre to compensate. Just my thoughts on the subject. Unfortunately that type of programming is beyond me, but perhaps some of the marlin developers can look into this solution. The amount of memory required to perform the task properly might eliminate this as an option on the printrboard, but who knows. Worth a shot I think. You could print on pretty much anything given enough points with a system like this in use.
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Re: Leveling problem?

Postby evanalmighty » 2014-Jul-Wed-10-Jul

Why would you want the software to compensate for a warped print surface? If each quadrant is different then wouldn't the Z plane also different? How would the part move upward in a unified Z plane? If the plate is warped, fix it or get a flat one. I just don't get why you would want to engineer around a problem instead of just fixing the problem.
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Re: Leveling problem?

Postby Mach-Chris » 2014-Jul-Wed-10-Jul

evanalmighty wrote:Why would you want the software to compensate for a warped print surface? If each quadrant is different then wouldn't the Z plane also different? How would the part move upward in a unified Z plane? If the plate is warped, fix it or get a flat one. I just don't get why you would want to engineer around a problem instead of just fixing the problem.


I agree with you, a flat plate should always be the priority over band-aid type fixes. The z plane would remain the same as it does now with current bed leveling as the hotend maintains a uniform distance from the bed at all times. Bed mapping would just make that warp-following action more accurate. The only reason I see to have something like bed mapping would be cost. As it seems quite a few people get less than flat beds right out of the box, this solution wouldn't hinder their printing abilities and would also allow manufacturers to utilize more cost-effective means to produce the beds. At the end of the day, the end user saves money as well. Granted, the bottom of any print you make will take the same shape as the warped bed. For some parts that's unacceptable, But it really comes down to how bad the bed is.
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Re: Leveling problem?

Postby Munson » 2014-Jul-Wed-12-Jul

There is no way you will ever get a perfect print surface,But if you can probe enough points,have that info to PRINT a flat surface on top of the bed that would support your desired print.
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Re: Leveling problem?

Postby Mach-Chris » 2014-Jul-Wed-13-Jul

Munson wrote:There is no way you will ever get a perfect print surface,But if you can probe enough points,have that info to PRINT a flat surface on top of the bed that would support your desired print.


I wouldn't go as far to say there is "no way ever". It just comes down to how much you want to pay. Geometric dimensioning and tolerancing makes parts more expensive to manufacture right out of the gate. Things like flatness and parallelism become increasingly difficult to conform to when the plate gets larger and thinner. But this is why you see PB opt to use MIC 6 cast plate for their upgraded tables. Cast alum plates have less inherent stress than that of their rolled/extruded or cold formed counterparts. Coupled with the fact that the cast plates are then machined (ground on blanchard grinders). It is basically as flat as you can get for an off-the-shelf flatness solution. The more expensive route (completely off the rails for a desktop hobby type machine) would be to get precision ground granite surface plates. Lapped to varying flatness tolerances (some in the micron range) and build a gantry that rolls around and prints on that. Again, horribly impractical, but not impossible. Although you can pick up some of these surface plates roughly 9"x12"x4" at busy bee tools and probably harbor freight, for like 20-30$....so maybe it's not THAT impractical. The printer would just have to move around it, it's too heavy to have it move under the hotend.
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Re: Leveling problem?

Postby Defy » 2014-Jul-Sun-21-Jul

In the same boat but with a 1405
ImageUploadedByTapatalk1404698520.538799.jpg


I am going to play with the leveling a bit. Seems like my left side is higher. My metal drags some too but its more consistent so i think the z lift will help.

Been seriously thinking about going back to a z end switch.
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Re: Leveling problem?

Postby Feenix » 2014-Jul-Sun-23-Jul

On the 1405, I ripped it apart and replaced the zip ties on the y-axis. This corrected a good portion of the issue. I'm still about .5mm low on the far y extension vs the near.
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