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Apparent Z-Banding Driving Me Crazy

Posted: Sat Jul 28, 2018 2:51 pm
by mikehill85
Is this amount of banding normal? It appears on all my parts and has ever since I got my machine. I even noticed that it is present on the 3d printed parts for the machine itself.

It is really tough to photograph and it only really visible if there is a light source shining down on my parts from above. I am try to decide if I want to replace my Z lead screws or not. I'm not convinced it would help.

P.S. I have no idea why this damn window shows so many copies of the same image. Yet another flaw with Lulzbot/Alephobjects.

Re: Apparent Z-Banding Driving Me Crazy

Posted: Sun Aug 05, 2018 3:48 pm
by Orias
Reach out to the support team, you may want to take a few more images if you can: LulzBot.com/Support.

Re: Apparent Z-Banding Driving Me Crazy

Posted: Fri Aug 10, 2018 1:16 pm
by RCBrust
I get the exact same thing. If you get anywhere with this issue, please let us know.

Randy

Re: Apparent Z-Banding Driving Me Crazy

Posted: Fri Aug 10, 2018 6:51 pm
by mikehill85
Orias wrote:
Sun Aug 05, 2018 3:48 pm
Reach out to the support team, you may want to take a few more images if you can: LulzBot.com/Support.
Some better pictures, for you reference.

Re: Apparent Z-Banding Driving Me Crazy

Posted: Fri Aug 10, 2018 6:54 pm
by mikehill85
RCBrust wrote:
Fri Aug 10, 2018 1:16 pm
I get the exact same thing. If you get anywhere with this issue, please let us know.

Randy
Thanks for the response Randy. I'm thinking it is a bent Z-axis screw. I'll be sure to let you know if I ever get this resolved. Quite honestly, the reason I got the Lulzbot mini was so that I could have a printer that just worked and produced high quality prints. My 1st printer was a heavily modded Da Vinci. Currently, this print quality isn't any better than that of my $350 printer, probably worse in all honesty. I'm seriously considering dropping my 3d printer hobby. I can't tell you how frustrated I've been with this. I tried upgrading the firmware, turning the leadscrews so that the software didn't have to compensate as much, tightening belts, looking for loose bolts/screws, nothing has helped and I can't even stand to look at the prints my machine produces, the "quality" is complete garbage.

I had read in another post in this forum that there is a design flaw in the mini that causes, Z-wobble. Apparently there is a design flaw in the mini and most Taz printers. The axis is over-constrained by the bearings at the top and bottom of the printer Z-screws, as well as the two metal rods which also guide the Z-axis up and down.

viewtopic.php?t=2716

Re: Apparent Z-Banding Driving Me Crazy

Posted: Sat Aug 11, 2018 10:04 am
by mikehill85
Turns out the original 3d printed parts that are part of my machine also show the same banding (example below). I wish Alephobjects would just admit this is a design flaw, refund my money and stop wasting my time.
IMG-1391.JPG

Re: Apparent Z-Banding Driving Me Crazy

Posted: Sat Aug 11, 2018 3:37 pm
by Keebie81
mikehill85 wrote:
Fri Aug 10, 2018 6:54 pm
RCBrust wrote:
Fri Aug 10, 2018 1:16 pm
I get the exact same thing. If you get anywhere with this issue, please let us know.

Randy
Thanks for the response Randy. I'm thinking it is a bent Z-axis screw. I'll be sure to let you know if I ever get this resolved. Quite honestly, the reason I got the Lulzbot mini was so that I could have a printer that just worked and produced high quality prints. My 1st printer was a heavily modded Da Vinci. Currently, this print quality isn't any better than that of my $350 printer, probably worse in all honesty. I'm seriously considering dropping my 3d printer hobby. I can't tell you how frustrated I've been with this. I tried upgrading the firmware, turning the leadscrews so that the software didn't have to compensate as much, tightening belts, looking for loose bolts/screws, nothing has helped and I can't even stand to look at the prints my machine produces, the "quality" is complete garbage.

I had read in another post in this forum that there is a design flaw in the mini that causes, Z-wobble. Apparently there is a design flaw in the mini and most Taz printers. The axis is over-constrained by the bearings at the top and bottom of the printer Z-screws, as well as the two metal rods which also guide the Z-axis up and down.

viewtopic.php?t=2716
You could take the top off and remove the bearings. Thats what I did.

Re: Apparent Z-Banding Driving Me Crazy

Posted: Sat Aug 11, 2018 3:41 pm
by mikehill85
Keebie81 wrote:
Sat Aug 11, 2018 3:37 pm
mikehill85 wrote:
Fri Aug 10, 2018 6:54 pm
RCBrust wrote:
Fri Aug 10, 2018 1:16 pm
I get the exact same thing. If you get anywhere with this issue, please let us know.

Randy
Thanks for the response Randy. I'm thinking it is a bent Z-axis screw. I'll be sure to let you know if I ever get this resolved. Quite honestly, the reason I got the Lulzbot mini was so that I could have a printer that just worked and produced high quality prints. My 1st printer was a heavily modded Da Vinci. Currently, this print quality isn't any better than that of my $350 printer, probably worse in all honesty. I'm seriously considering dropping my 3d printer hobby. I can't tell you how frustrated I've been with this. I tried upgrading the firmware, turning the leadscrews so that the software didn't have to compensate as much, tightening belts, looking for loose bolts/screws, nothing has helped and I can't even stand to look at the prints my machine produces, the "quality" is complete garbage.

I had read in another post in this forum that there is a design flaw in the mini that causes, Z-wobble. Apparently there is a design flaw in the mini and most Taz printers. The axis is over-constrained by the bearings at the top and bottom of the printer Z-screws, as well as the two metal rods which also guide the Z-axis up and down.

viewtopic.php?t=2716
You could take the top off and remove the bearings. Thats what I did.

Which bearing did you remove? Both the top and bottom of each of the two Zs? Any pics of surface quality you can share?

It's pretty hilarious, I asked support about the banding on their own 3d printed parts from the factory and they just said that mine is worse...Personally, I think theirs is probably worse (they are likely printing at higher speeds so it is to be expected). I asked them to tell me if this is a know design flaw which can be resolved but they kept on suggesting silly possible fixes which clearly couldn't be causing the banding. One was the hobbed gear...yeah...I'm sure it's a feed rate issue that just happens to occur at the exact same pitch as the z-axis screw.
IMG_1393.jpg
IMG_1384.jpg

Re: Apparent Z-Banding Driving Me Crazy

Posted: Sun Aug 12, 2018 1:59 pm
by kcchen_00
This will be happen with any printer with lead screws... unless heavily modified. Its the nature of the screw.

Try a sixteenth to eight turn of one lead screw (either right or left), not both screws. The idea is to get the screw contact point in the middle of the pitch opposite to the other lead screw. This would create a more consistent contact... no wobble due to the screws in phase. Anyway this is highly "trial and error"... YMMV

Re: Apparent Z-Banding Driving Me Crazy

Posted: Mon Aug 13, 2018 5:51 pm
by mikehill85
kcchen_00 wrote:
Sun Aug 12, 2018 1:59 pm
This will be happen with any printer with lead screws... unless heavily modified. Its the nature of the screw.

Try a sixteenth to eight turn of one lead screw (either right or left), not both screws. The idea is to get the screw contact point in the middle of the pitch opposite to the other lead screw. This would create a more consistent contact... no wobble due to the screws in phase. Anyway this is highly "trial and error"... YMMV
I've tried that before, it doesn't do anything. Also, I have no idea of the mechanism by which that is meant to work, given that the printer is trying to adjust for the bed not being perfectly level. It will be adjusting the different Z-axis screws by different amounts and end up at different positions along the Z-axis screws in different regions of the bed, in any case. Perhaps if your bed is relatively level to start with it may appear to help in a small area of the bed where there are basically no adjustments made.