Bed height drops frequently

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iPeel
Posts: 42
Joined: Sun Dec 06, 2015 8:32 am

Bed height drops frequently

Post by iPeel » Sun Dec 06, 2015 7:13 pm

Hi,

I've gone through about 5-6 reels with the Up Box now and generally haven't suffered any issues, but recently I am finding that the bed height is changing on more or less every print.

I found out pretty early on that the Auto Bed Height feature was always off by 0.2mm, if I took the level given I would get the extruder clattering against the bed so I always have to deduct 0.2mm from the height the sensor says. That has worked fine for a few reels but now I am finding that after detecting the bed height I get a good print by adjusting by 0.2mm then the next print will look like it's extruding too close to the build plate, then the next print will start grinding the filament and need to be aborted. I do a bed height check again and deduct 0.2mm and everything is fine but the bed height reading has reduced from the last by a few tenths.

I started the week before last at a stated bed height of 207.5mm and am now at a stated bed height of 204.3mm.

I find this a bit strange and am wondering what's causing this. I initialise the printer the same way all the time and the build plate doesn't have anything blocking it against the heater plate. My only idea is that maybe the levelling screws are unwinding a little under vibration? The only issue with that hypothesis is that the bed level stays good and it would be strange that the screws rise under vibration by an equal amount each.

The prints themselves are fine, no complaints there, but the issue with constant bed height changes doesn't seem right.


Has anyone else encountered this or does anyone have any suggestions?



Thanks.

pp3dp.nl
Posts: 252
Joined: Thu Jul 05, 2012 6:18 pm
Location: Holland/The Netherlands

Re: Bed height drops frequently

Post by pp3dp.nl » Mon Dec 07, 2015 9:57 am

The only thing I can say is to calibrate manually. I don't know how the latest version 2.18 handles auto calibration but I also had varying results with it. Support would be stuck on some areas of my models.

Just go the calibrate screen with the 9 points of height calibration and click reset. Now calibrate the table manually and adjust the screws untill it is level, set the height and see it that helps.

JWA
Posts: 13
Joined: Thu May 14, 2015 9:18 pm

Re: Bed height drops frequently

Post by JWA » Mon Dec 07, 2015 7:33 pm

iPeel wrote:Hi,

I've gone through about 5-6 reels with the Up Box now and generally haven't suffered any issues, but recently I am finding that the bed height is changing on more or less every print.

I found out pretty early on that the Auto Bed Height feature was always off by 0.2mm, if I took the level given I would get the extruder clattering against the bed so I always have to deduct 0.2mm from the height the sensor says.
Had same problem - falling bed and unpredictable nozzle height. I sent it to service, they repaired it .
Also Auto level works like in your one - nozzle always too low after autolevel, causing air printing during 1st layer.
The best practice I found is to check the heighest point ( marked "0") in 3d Print > Platform Calibrate. Check the nozzle height at that point and add 0.2 to this value. After that I,m able to do very big prints without issues.

iPeel
Posts: 42
Joined: Sun Dec 06, 2015 8:32 am

Re: Bed height drops frequently

Post by iPeel » Tue Dec 22, 2015 10:34 am

Hi,

Thanks for the comments.

There's no issue with the bed level, I have calibrated it manually from the start and so long as the nozzle height is set correctly I always get good prints. I'm now convinced it's an issue with the initialisation when the printer drops the build platform onto the microswitch at the bottom of the enclosure; I think that process is too vague. It's funny though that it has only started to happen recently. I have checked the build platform and the microswitch mounting and nothing is loose.

I'm OK with doing a nozzle height check every time I switch on now I know that's needed but may just drop a line to the UK distributor to see if they have seen this elsewhere.


Cheers,


Neil.

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