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Can't figure out why I'm printing like this...

Posted by jbenedetto84 
Can't figure out why I'm printing like this...
January 18, 2018 05:51AM
Hi All,

I'm hoping someone can help me. I have a HICTOP 3DP-12 that I purchased about 2 years ago. I've done some upgrades (bowden, bltouch, boro glass, v6 extruder, custom x carriage, reprap champion y carriage plate) and I've printed relatively decent from the beginning. My pillow blocks on my Y axis started to grind a month or two ago, so I ordered new ones, and while I was at it, a spare hot bed, 2 new Y linear shafts, and new glass that matched my hot bed size. The original shafts seemed straight but I had read people had better success by replacing them, so I found some on amazon with good reviews on quality so I figured I'd give them a shot. I replaced the stock y carriage which was bent to all hell, added my new glass on the original heat bed, swapped the Y axis shafts and pillow blocks. I also printed new Y axis shaft mounts as the originals are acrylic and I was concerned about them cracking. I did a test print and the nozzle seems to get closer to the bed on the back left and front right side. Pic is attached.

I checked the bed against the frame with a level and its level. I checked the flatness of the glass and it seems good.I checked my X axis with a dial indicator to make sure its level left to right on the bed. I used this: https://www.thingiverse.com/thing:1562189

The glass - https://www.homedepot.com/p/AFINIA-Borosilicate-Glass-Printing-Surface-for-H800-AFINIA-H800-BORO-GLS/206653633?cm_mmc=hd_email-_-Confirmation_STH_BOSS-_-20180101_PP_ET_Merch_Confirmation_STH_BOSS_3091372-_-product_image__W913164727

The Y carriage plate - https://www.amazon.com/gp/product/B01FV17EL0/ref=oh_aui_search_detailpage?ie=UTF8&psc=1

I use the auto bed level feature as well, but it doesn't seem to make a difference. I'm having a really hard time trying to figure out what could cause such a drastic change in height on the back left and front right of the bed.

The test prints initial layer height is .25 so it seems like it's at least a .25mm variation. IMO it's more like .5mm because some areas don't print at all because the nozzle is ON the glass, and other areas it doesn't squish at all and pops right off.

Has anyone experienced this? Any suggestions are greatly appreciated. Thanks in advance!
Attachments:
open | download - File Jan 18, 8 37 28 AM.jpeg (228.7 KB)
Re: Can't figure out why I'm printing like this...
January 18, 2018 07:44AM
Just that the dial holder you use is bad.
Unless you are lucky, there is no way the holes in it match exactly the rod diam and rod center to center distance. Therefore they will bend when you place the dial and the distance you measure will not be correct.

The ABL should correct it and may be it doesn't work too ?
You may also have excessive play somewhere (The "grinding" bearings may have ground the rods badly if they are not the correct steel as often.

Ensure everything is tight and try the simple method, a sheet of paper to make sure all is flat. Recheck to make sure your adjustment really work. A plane is 3 points and here you adjust with 4 screws.

If //, squareness ... it is pretty bad, you may simply not be able to adjust.

Edited 2 time(s). Last edit at 01/18/2018 08:03AM by MKSA.

"A comical prototype doesn't mean a dumb idea is possible" (Thunderf00t)
Re: Can't figure out why I'm printing like this...
January 18, 2018 12:44PM
which ABL method did you try there are several...

One common ABL only compensates for bed tilt not irregular surface Like lit looks like you have there
Re: Can't figure out why I'm printing like this...
January 18, 2018 01:23PM
Quote
MKSA
Just that the dial holder you use is bad.
Unless you are lucky, there is no way the holes in it match exactly the rod diam and rod center to center distance. Therefore they will bend when you place the dial and the distance you measure will not be correct.

The ABL should correct it and may be it doesn't work too ?
You may also have excessive play somewhere (The "grinding" bearings may have ground the rods badly if they are not the correct steel as often.

Ensure everything is tight and try the simple method, a sheet of paper to make sure all is flat. Recheck to make sure your adjustment really work. A plane is 3 points and here you adjust with 4 screws.

If //, squareness ... it is pretty bad, you may simply not be able to adjust.

Thanks for the tip. I'll try other ways to verify the bed level besides the dial indicator tonight. I changed the rods when I changed the bearings so I'm thinking that shouldn't be an issue.

You make a good point with the paper method. I'm getting too complicated; need to bring it back to simple. I'll hopefully give it a go tonight or this weekend and I'll keep you posted. Thanks for your help.
Re: Can't figure out why I'm printing like this...
January 18, 2018 01:27PM
Quote
Dust
which ABL method did you try there are several...

One common ABL only compensates for bed tilt not irregular surface Like lit looks like you have there

Because I have a BLTouch, when you enable it in the firmware there's only have one option for bed leveling which is mesh (from what I've read in other forums). I tried enabling a different method and got an error on compiling.

It currently is hitting 4 points on my bed. Maybe I'll step it up to say 16 points and see if it helps.

Will keep you posted. Thanks for your help

Edited 1 time(s). Last edit at 01/18/2018 01:27PM by jbenedetto84.
Re: Can't figure out why I'm printing like this...
January 19, 2018 04:14AM
Quote
MKSA
Just that the dial holder you use is bad.
Unless you are lucky, there is no way the holes in it match exactly the rod diam and rod center to center distance. Therefore they will bend when you place the dial and the distance you measure will not be correct.

The ABL should correct it and may be it doesn't work too ?
You may also have excessive play somewhere (The "grinding" bearings may have ground the rods badly if they are not the correct steel as often.

Ensure everything is tight and try the simple method, a sheet of paper to make sure all is flat. Recheck to make sure your adjustment really work. A plane is 3 points and here you adjust with 4 screws.

If //, squareness ... it is pretty bad, you may simply not be able to adjust.

Good morning! So last night I did the old paper method, expecting things to be WAY off, and to my disbelief it wasn't bad at all. I had to make one or two 0.05-0.10mm adjustments to the corners to get the paper to grab exactly the same all across the bed. Tried printing again and I get identical results. I was stumped, however I did notice that the Y carriage was slanted quite a bit compared to the heatbed, and further noticed that the right side pillow blocks seemed taller than the left. I removed the Y axis and replaced the pillow blocks with LM8UU's and zip ties (what reprap champion actually recommended to me over pillow blocks for their plates). While I had it apart I double checked for flatness on the rods and making sure there was no damage from the old bearings. All seemed good. I put it all back together and noticed much more symmetry between the carriage and the heatbed. I recalibrated everything and ran a new test. The results were almost identical to the photo in the first post.

Now I'm stumped. My X and Y are level and yet i still get unlevel first layers. I also checked for warpage on the glass and it is dead flat.

Quote
Dust
Dust
which ABL method did you try there are several...

One common ABL only compensates for bed tilt not irregular surface Like lit looks like you have there

I bumped my ABL up to 16 points and that doesn't seem to effect my results, either. I double checked and it doesn't seem like I can use a different method besides mesh because of the BLTouch.
Re: Can't figure out why I'm printing like this...
January 19, 2018 03:32PM
I would bet that while you were replacing bearings and rods and beds and stuff that you just torqued the whole frame a little and it has a twist. The reason that you can't see it is that the gantry and/or bed have to be in certain places to put the strain on the bed that twists it.
Find a flat surface, really flat, and loosen all the screws holding the frame together. Get it all to sit flat and go through and tighten screws and nuts in the order in which you built the printer. I think that one or more of your rods or posts are not quite square any more.

DLC
Re: Can't figure out why I'm printing like this...
January 20, 2018 11:44PM
I agree with DLC,
the best way to keep a Prusa frame level is to clamp it down on a thick MDF plate. ( not plywood )
Make the plate big enough to be able to add an enclosure later.
Re: Can't figure out why I'm printing like this...
January 21, 2018 12:20AM
Did you carry the paper shim test with the bed and hot end powered and at the T° used for the print ?
Your bed may be "level" enough at room T° but deform when heated.

Could even deform during operation if everything is not tight, too much play ....


"A comical prototype doesn't mean a dumb idea is possible" (Thunderf00t)
Re: Can't figure out why I'm printing like this...
January 21, 2018 05:46AM
Hello;

I have two Hictop 3DP11 an 3DP12. I use an TL-W3MC2 proximity Sensor that replaced the SN04-N. Would like to see how you connected the BL-Tough and the configuration.h settings that you used.

I have setup most Marlin 1.1.X firmware thou I am using Marlin 1.1.5. I use Bi-Linear bed leveling including the save & restore bed leveling data feature. Maybe the settings I use for bed leveling will help you.

Here is a link to Marlin 1.1.5

Quote
auggie246
Before I used Unified Bed Leveling (UBL), I was using bilinear leveling with BLTouch. everything was fine and calibrated. a 20mm calibration cube would come out ~20mm.

Edited 2 time(s). Last edit at 01/21/2018 06:15AM by Roberts_Clif.
Re: Can't figure out why I'm printing like this...
January 22, 2018 05:12AM
Just wondering if the ABL is working the wrong way round since the paper test shows a good setting.
Try without ABL - dont know if you have to clear the settings somehow.
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