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Author Topic: Print head scrapes against old hard layers  (Read 1515 times)

fiya

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Print head scrapes against old hard layers
« on: December 24, 2013, 04:08:06 AM »
I am using a Bukobot V2 with black PLA and Sclic3r 1.0. I have tried it at .1 and .2 layer height.

In the process of filling in the first layers, the print head will pass over the old layers, and audibly bump/scrape against the previous layers. I have tried most of the Bukobot presets, and I have tried variations of the settings posted here by James005 http://forum.bukobot.com/index.php?topic=3014.0. I have also used print head temps of 190-210. I'm not sure what settings to change, I think it's Z Lift, but I tried it and faced a 9 hour build time. What can I try?

One other troubleshooting issue, that may be related, is some parts won't stick to the build plate. The larger the footprint the worse the adhesion. I am using fresh 3M painters tape for every build. Along with bed leveling with a piece of paper so that the print head provides a little resistance.

Other than the occasional bumping, the prints are pretty good. I'm attaching a vase and multi part build examples.

Milo

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Re: Print head scrapes against old hard layers
« Reply #1 on: December 24, 2013, 11:20:25 AM »
It just sounds like your print head is too low. Raise it up a little by adjusting the Z-stop and try a few more prints.
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fiya

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Re: Print head scrapes against old hard layers
« Reply #2 on: December 24, 2013, 08:38:30 PM »
Thanks, I will try it. Can I use the 3 bed leveling adjusters to drop the bed instead of moving the z-end stop? And do you use a piece of paper to set the initial z-stop?

Milo

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Re: Print head scrapes against old hard layers
« Reply #3 on: December 27, 2013, 03:11:15 PM »
If the bed is already level, I find it's quicker to raise the head 20mm, adjust the Z-stop a quarter or sixth turn, then just home Z.
As for the paper thing, I tried that a few times and found it's not always the best. I prefer to have a couple of outer skirts before the print to see how well it's adhering, then just stop and adjust if it looks like there will be an issue.
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whosawhatsis

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Re: Print head scrapes against old hard layers
« Reply #4 on: January 03, 2014, 11:03:30 PM »
On the Bukobot V2, the Z endstop is not adjustable. This adjustment should be done using the adjustment screws on the platform.

It sounds to me like you're putting out a little too much plastic, causing it to mound up around the nozzle so that it bumps into it later. You should check your filament diameter, and you may need to adjust your flow rate.

Lwanmtr

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Re: Print head scrapes against old hard layers
« Reply #5 on: April 07, 2014, 06:20:45 AM »
Having the same thing...How do you adjust flow rate?

whosawhatsis

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Re: Print head scrapes against old hard layers
« Reply #6 on: April 09, 2014, 08:15:15 PM »
There is a flow rate multiplier slider in Repetier Host for adjusting while printing, or you can use the extrusion multiplier in Slic3r's filament settings, though if everything else is working properly and you have the correct diameter measurement for your filament in Slic3r, these should not be necessary unless you are using a filament like TPE, which compresses into the drive gear enough to reduce the drive gear's effective diameter while pushing it.

Lwanmtr

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Re: Print head scrapes against old hard layers
« Reply #7 on: April 09, 2014, 11:24:27 PM »
I guess ill need to get one of those caliper thingies to measure filaments each time...hehe

Yeah, I found the speed in repitier, trying different speeds to get the right speed, at least for the current filament.

cadmodeling777

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Re: Print head scrapes against old hard layers
« Reply #8 on: April 21, 2017, 08:11:42 AM »
It sounds to me like you're putting out a little too much plastic, causing it to mound up around the nozzle so that it bumps into it later. You should check your filament diameter, and you may need to adjust your flow rate.

 

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