Venatius
Posts: 3
Joined: Sat Dec 01, 2018 11:07 pm

Supports on print bed refusing to stick

Sat Dec 01, 2018 11:23 pm

Hello! I'm a relatively new S3D user trying, and failing, to get any parts to print with supports (or first layers more generally) that directly touch the print bed. Is this feasible at all, or are rafts an outright requirement to pull this off? In essence, the problem is that it goes through the following sequence: The print begins. The extruder "wipes its nose" with a single long line on the front of the build platform (which adheres 100% perfectly). After that, it draws closer to the middle to begin the print. However, its first few wiggles are accompanied by no extrusion at all most of the time. Afterwards a very thing, stringy amount will emerge and usually get immediately brushed off, or curl right up against the nozzle. After a while it seems to start to print normally, but the lines are very thin and tend to scuff away. It's almost as though the program somehow doesn't "try" to actually make its printouts stick unless it's doing a raft! Even using the exact same print settings with vs. without a raft have results as different as night and day.

Troubleshooting thus far:

* Even though rafts and the initial extrusion print perfectly, I've tried raising the initial extruder temperature a bit for the first two layers in case under-extrusion is an issue.
* Even though rafts and the initial extrusion print perfectly, I've made sure the bed is level, and used glue stick to increase adhesion.
* Based on advice in similar threads, I've increased the first layer height to 150% and the first layer width to 200%, and dropped the first layer speed all the way to 15%.
* I tried setting 1 or 2 support base layers, which the settings say may help with adhesion. I can't discern any difference with this option on versus set at 0.
* On the chance under-extrusion is responsible (though, again, it doesn't under-extrude on the raft), I set a higher temperature for the first two layers, up at 200 rather than 190 degrees.

Is support resolution possibly the issue? I have it printing them at 2mm, but I was under the impression this just increased the number of layers per support, not the thickness of the individual layers (and hence not how well they'd adhere, most likely). Am I mistaken in that? I wish there was just a checkbox that says "Work as hard on printing supports as you do on rafts" somewhere in the options! I'm looking over at a print in progress as we speak where the only difference was checking the option to include a raft, and it's chugging away without a problem.

User avatar
dkightley
Posts: 1788
Joined: Tue Mar 10, 2015 3:09 pm

Re: Supports on print bed refusing to stick

Mon Dec 03, 2018 10:10 am

* Based on advice in similar threads, I've increased the first layer height to 150% and the first layer width to 200%, and dropped the first layer speed all the way to 15%.
* I tried setting 1 or 2 support base layers, which the settings say may help with adhesion. I can't discern any difference with this option on versus set at 0.
Not that good an idea in my experience....

Set the first layer to 300% layer thickness...three times as thick as normal layers) and to 100% width (adjacent extrusions are laid at the same pitch as all other layers!)….and forget about more than one raft layer because of issues with the second layer not adhering to the first! You could also make a negative adjustment to your Global-Z value ( to lower the whole model down a tad).
Doug Kightley
Volunteer at the National Tramway Museum http://www.tramway.co.uk
Railway modeller and webmaster at http://www.talkingtgauge.net

Venatius
Posts: 3
Joined: Sat Dec 01, 2018 11:07 pm

Re: Supports on print bed refusing to stick

Mon Dec 03, 2018 10:39 am

dkightley wrote:
Mon Dec 03, 2018 10:10 am
* Based on advice in similar threads, I've increased the first layer height to 150% and the first layer width to 200%, and dropped the first layer speed all the way to 15%.
* I tried setting 1 or 2 support base layers, which the settings say may help with adhesion. I can't discern any difference with this option on versus set at 0.
Not that good an idea in my experience....

Set the first layer to 300% layer thickness...three times as thick as normal layers) and to 100% width (adjacent extrusions are laid at the same pitch as all other layers!)….and forget about more than one raft layer because of issues with the second layer not adhering to the first! You could also make a negative adjustment to your Global-Z value ( to lower the whole model down a tad).
Thanks for the input! Maybe I'm just underdoing it on the height. The "support base layers" I mentioned were for supports, not rafts. (NOT having to use the raft is the whole goal of this exercise) But that may be a moot point here. I'll give it a shot on my next print. Thanks for your input!

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