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PLA not Sticking to Bed

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Colin Heseltine02/01/2019 15:39:01
336 forum posts
82 photos

Using a Prusa I3 MK3. Having an issue with PLA. Been trying to print ER11 collet block from Thingiverse. The first design tried printed end on, so quite narrow section to hold down on bed. It came loose at about 6.5mm high. Cleaned bed and repeated. Same problem. Found another design which printers the holder flat on the bed. First attempt got to 2mm high and broke loose. Did a bit of reading and decided to up the bed temp from 60 to 70 degrees and also add a Brim. This looks to be better but the front edge has lifted slightly and depresses as the hot-end moves over it. As the rest has not broken loose am going to let it continue and see how it goes.

The bed has been cleaned each time with Isopropyl alcohol.The first attempt was made suing Prusa Control. The second using PRUSA Slic3r as this gave the ability to alter the bed temp.

If this completes okay I will lower the hot-end a little further before next attempt at any prints.

Anyone have any other suggestions.

Colin

Mark Simpson 102/01/2019 15:58:58
69 forum posts
20 photos

Hi Colin

wipe some dilute PVA over your bed everytime you print, looks messy but works like a dream...

start printing whilst still tacky!

Strange but it's better not clean!!!!

Journeyman02/01/2019 16:07:33
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620 forum posts
97 photos

I too use 50/50 diluted PVA white wood glue on the bed, paint it on and let it dry. Only needs a very thin coat. The other thing to try is to increase the thickness of the first layer so it squeezes out slightly, should be a setting in Slicr, I use Cura so not quite sure on that. You can also decrease the speed for the first couple of layers. It is all a bit of guesswork to start with but it will come together after you have wasted half a roll of filament cheeky 60deg should be fine for the bed temperature. when in doubt slow down the print speed. Unfortunately once the print has started to lift it is 99% likely to fail. By the way my bed uses glass so check in the Prusa docs to make sure PVA is OK with their fancy bed surface.

John

Edited By Journeyman on 02/01/2019 16:14:17

Neil Wyatt02/01/2019 16:15:05
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Moderator
16655 forum posts
687 photos
75 articles

Dilute PVA and consider using 50-60 degrees for the first layer then dropping by ten degrees.

A brim is a good idea for shapes that 'curl' at the corners.

Check the bottom layer is fully bonding, not just discrete filaments. If not reduce the starting z-height.

Neil

Richard -02/01/2019 16:31:58
45 forum posts
6 photos

Thumbs up for dilute PVA, you'll have trouble getting it off it's that good!!

Richard

jason udall02/01/2019 16:33:37
2011 forum posts
41 photos
I use"pritt" stick other brands available and also work

Neil Wyatt02/01/2019 20:05:59
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16655 forum posts
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Posted by Richard John 1 on 02/01/2019 16:31:58:

Thumbs up for dilute PVA, you'll have trouble getting it off it's that good!!

Richard

I use a borosilicate glass bed, and PLA virtually unsticks itself if you let it cool long enough.

A sharp sideways tap with a plastic handled screwdriver is a good way to get PLA to unstick, but always allow some cooling first.

Colin Heseltine02/01/2019 20:15:50
336 forum posts
82 photos

Thanks for the quick answers. I checking on whether PVA can be used on the PEI bed. Will try lowered the Z-height as first option.

Colin

Colin Heseltine02/01/2019 21:22:45
336 forum posts
82 photos

See photos below of ER11 collet holder. Picture 2 shows the amount of lift which occurred and made the shape somewhat distorted. Picture 1 shows a closeup of the base. From the look of it would I be correct in saying that the Z-height needs lowering.

Thanks,

Colin

At least its still usable.

colletresize2.jpgcilletresize1.jpg

Neil Wyatt02/01/2019 21:38:03
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16655 forum posts
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Yes, reduce z height by about 0.1 to 0.2 mm in the first instance.

Neil

Andrew Johnston02/01/2019 21:41:03
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4893 forum posts
552 photos

I use a pritt stick, plus a wide brim, at least 5mm and preferably more. Generally I find that once the part, and baseplate, have cooled to ambient the part comes away with minimal effort. I wouldn't expect to get any noticable lift on a part with PLA.

Andrew

Bandersnatch03/01/2019 02:10:17
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1263 forum posts
40 photos
Posted by Colin Heseltine on 02/01/2019 15:39:01:

The first design tried printed end on, so quite narrow section to hold down on bed. It came loose at about 6.5mm high. Cleaned bed and repeated. Same problem. Found another design which printers the holder flat on the bed.



Could you not just have rotated the first design in Slic3r? A genuine question btw I'm not familiar with that program but most of the ones I am familiar with allow you to rotate the model.

Brian G03/01/2019 06:14:58
603 forum posts
25 photos

If Slic3r has an equivalent to Cura's "Z Hop When Retracted" option it might be worth trying as it may stop the print nozzle banging across the infill whilst travelling.

Brian

Colin Heseltine03/01/2019 08:52:36
336 forum posts
82 photos

Neil, Will look at lowering Z height

Andrew, Waiting for an answer on whether can use Pritt or PVA with Prusa PEI sheet.

Bandersnatch, I have not looked into options with Slic3r. I will look and see if possible.

Brian. Will need to investigate.

I'm sure lots of filament will be used (wasted) before get regular good prints.

Thanks All

Colin

Colin Heseltine04/01/2019 16:10:32
336 forum posts
82 photos

Well just had my answer back from PRUSA. DO NOT use PVA or anything else on the PEI bed when printing PLA.

So looks as though need to try the Z height.

Colin

.

Steve F04/01/2019 16:59:17
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60 forum posts
22 photos

Hi

I you have a PEI bed you shouldn't put anything on it to aid the stick. My robox has PEI and everything sticks to that.

I would try raising the bed temperature and see if it makes a difference after all that's why it normally is used for PLA. The Robox likes 70 for the 1st layer and 65 for the rest. The Ender 3 i use 65. Your printer / filament combo may need you to alter it a bit

regards

Steve

Colin Heseltine04/01/2019 17:43:40
336 forum posts
82 photos

Steve, You have just confirm what PRUSA said.

I have just played around with first layer calibration. The prints above were done with Z height set at -.500 and you could rub your finger nail along and it felt a bit like a nail file. Just tried at -.750. The filament came out very flat, could feel no roughness at all. the bottom of PRUSA badge was smooth as a babies bum Tried again at -.600 and possible filament still too squashed (with magnifying glass). Took it to -.550 and tried again. Let the PRUSA badge part print enough to get 1/2 dozen or so layers down then stopped it and looked to see what the bottom looked like and how it sticks to the PEI bed. Not as smooth as the -.750 but lt smoother than the -.500. Finger nail can feel the ridges of filament but nowhere near the roughness of the -.500. Now letting the badge print fully.

If this is okay will try something a bit bigger.

Colin

Steve F04/01/2019 19:04:14
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60 forum posts
22 photos

Hi

I've had a shower and it gives you time to think.

Maybe stick is not your problem.

I cant gauge the size but it looks like a big "slab" of plastic. What you seeing is the same as the problems you get with ABS. This is caused by Hot Bed-Hot new filament-cooler filament in the middle sandwitch, The print is sticking to the bed but is being pulled off by the cooler layers above.

Maybe you could also try reducing the infill %.

There's a good troubleshooting guide here **LINK**

regards

Steve

Colin Heseltine04/01/2019 21:22:32
336 forum posts
82 photos

Steve,

That's a good troubleshooting guide. I think could prove quite useful.

The slab of plastic was 114mm long, 30mm wide and 15mm high.

Colin

XD 35105/01/2019 03:29:52
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1356 forum posts
113 photos

For my first prints i had same issues , i found that i was setting the nozzle off the bed 0.2mm and had the initial layer height set in cura at 0.2mm as well so i ended up with 0.4 mm height and no amount of glue will fix that so i adjusted the settings in cura to as low as it would let me go to zero .

I found a lot if info on makers muse youtube channel and Thomas sanladerer chanel also .

Did you built the printer or get it pre built ? If it was pre built i should have come from prusa pre calibrated so i would say your settings in your slcer programme are to blame .

**LINK**

This manual has all the set up and calibration settings for your printer , you can do a lot of fine tuning via the lcd and control knob on the printer and they have way more features than my geeetech i3 !

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