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PLA 0.4mm bottom two layers - outside edges delaminating

Posted by TAZ427 
PLA 0.4mm bottom two layers - outside edges delaminating
February 28, 2014 10:07AM
I'm in the early stages of printing on my MakerFarm 8" Prusa i3. I've done a few smaller PLA and ABS prints w/ 0.2mm (40mm cube, Control knobs, Z axis adjusting knobs, ...) and last night I decided it was time to make a spool holder (tired of sitting in front and constantly adjusting how much filament is out of the spool.)

I sliced it w/ 0.4mm / 0.7 infil. Set the hot end to 225 and bed at 70. (I had been using 225 and 100 but had some spreading on the lower layers on PLA - decided to turn the bed down.)

I calibrated the Z axis across the surface, it was pretty much 0.1mm all around, was a bit more than 0.1mm in the upper left of the carriage where nothing was being printed.

The results was the first layer put down had some curling (see pic - though it's blurry you can see the light shinning on the curls) and I let it go for another layer or two, and it seem to start smoothing out.

Here's a much better pic with it about 98% done. You can see separation between the bottom two layers and the rest on some areas.

When I let the glass cool and peeled it off the glass, the outer one or two sidewalls for two layers all wanted to delaminate. The rest seems stable and fine at this point (this being 12hrs later and letting it sit overnight.)

I plan on printing the second spool arm tonight, and I'm planning to re-slice it and bring the starting heatbed temp up to 85 or 90. I wanted to get the forums thoughts on this before I do, and also listen to any suggestions.
Re: PLA 0.4mm bottom two layers - outside edges delaminating
February 28, 2014 11:33AM
100 celsius is very high for PLA on the print bed. 60 is a better bet.

220 is very high for PLA at the extruder. Print PLA at as low a temperature as you can. Try 185 and go up if you get skipping at the extruder.

Calibrate your e steps per mm as per the reprap wiki calibration guide. Insufficient extrusion can cause delamination. [reprap.org]

To help prevent curling with PLA, paint your print bed with a diluted mix of PVA and water (it can be easily washed off with a damp cloth after the print completes). Other solutions include a layer of blue painter's tape or Kapton tape, acetone mixed with ABS (ABS sludge) for printing ABS, or a bunch of other solutions you can find with a little googling. I personally use PVA and it's worked wonders for preventing curling.

Edit: what's your nozzle size? Layer height should be no more than 80% of your nozzle size. Extrusion width should be greater than your nozzle size. Play with these values as per the calibration guide to improve your prints.

Edited 1 time(s). Last edit at 02/28/2014 11:35AM by 3dkarma.

[3DKarma.com] - suppliers of quality, affordable 3D printer kits and filament for the UK market.
Re: PLA 0.4mm bottom two layers - outside edges delaminating
February 28, 2014 12:16PM
Nozzle size is 0.5mm. I spray the glass with extreme hold hairspray (per MakerFarm recommendation) the nozzle speed is 30mm/s, 60mm/s infil, 120mm/s travel as per MakerFarms defaults.

I know those temps were high for PLA,but the default slicer config that MakerFarm had provided for the PLA had it at 225 and 100. I've done prints with it up to 225 w/o a problem, but I wanted to bring it down.

I have done some measurments on the glass of my bed, it it's actually reading about 20C lower than the thermistor mounted below. There's no hole in the PCB heat bead to put it in contact with the glass. So is it that the surface should be 60C? That's why I went with 70C when I did this print.

Re: PLA 0.4mm bottom two layers - outside edges delaminating
February 28, 2014 06:58PM
Well, I tried it with the settings that I indicated, basically the same, but with the bed temp up at 85C. I also, did a bit better job of leveling (smashing the plastic spacers in the back a bit so that it's level with the front.) I have some springs on order to make the bed level-able on the X-axis.

I'm about 8 or 9 layers in right now and no apparent separation in printing, but this point I had obvious delamination on the previous print.

Also, no curling of the PLA on the intial layer.

EDIT: Best print I've made so far.

Edited 1 time(s). Last edit at 02/28/2014 10:09PM by TAZ427.
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