By Jove I think I've sussed it. Sticking to the bed.

Hi all..

I was having the same "sticking to the bed" problems as every one else. Necessitating the same hoops and jumping.
Then.. by chance I printed something where the first layer fill was at 90 degrees not 45 degrees.

The first layer fill now involves ONLY the X carriage moving left and right with a step from my Y carriage at the end of every row.
i.e. the bed is not moving while the nozzle is laying PLA down onto it.

I have no idea why, and I have no idea of the fluid dynamics involved, but this is DEFINITELY and I mean DEFINITELY making a difference.
I've never gone in for all the hairspray and washes etc etc, I've only ever used acetone wipes I bought from the chemist.

Now I am doing this about every 3 or 4 prints, just to be safe, but my prints are sticking like glue. (I must replace my Kapton tape, as I've lost some lumps out of it, trying to get prints off)

So..

anyway..

why do we fill at 45 degrees, sure.. it looks fancy, but if you want your prints to stick, fill at 90 degrees.
(I also use honeycomb inside the print, instead of rectilinear, everything has improved since I used honeycomb too)

Is this new knowledge, buried knowledge, unverified knowledge, or does everyone not mind using hairspray, washes, etc etc ?

What's everyone else's view ?

cheers

Dave

Are you printing to a heated bed? If so the air flow due to the movement of the print bed may be causing parts of the bed to get too cold. Otherwise, I can't see why it would matter unless your Y steps/mm were out of calibration.

I am still puzzled why some guys have trouble with PLA adhesion. I have never used anything on the glass, no glues, no Kapton, no painters tape, just a wipe of the glass surface with window cleaner before I start. There must be something magic in the glass I use coz' I can't explain it! The parts stick so hard, they will only release when the glass is cold. I've mentioned it before, its not so much an "adhesive" bond but rather a significant suction to the surface. ABS however does get the hairspray treatment,

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Waitaki 3D Printer

I agree with waitaki. I have a ReprapPro Mendel which has a heated glass bed and I have never had problems with the first layer sticking.

For PLA I run the bed at 57 degrees C and I regularly clean it by wiping it with a clean tissue dampened woth methylated spirits. I rub the bed until it squeeks, then dry it with another clean tissue, being careful not to touch the suface afterwards. Usually my items stick so well that I have to prise them off with a knife.

I have seen references here to using things like lemon juice, vinegar etc to clean the bed. As an ex (retired long ago!) industrial chemist I have been unable to see how these types of 'potions' could work. What you need is a chemically clean surface as near as you can get it. Methylated spirits is not ideal and acetone would be better, but I've not been able to source acetone locally. Lemon juice contains citrous oils which will leave a contaminated surface, household vinegar will do likewise.

I could believe that adhesives such as PVA, would work provided that the top surface of the layer is perfectly smooth (very difficult to achieve it you brush it on). Kapton tape and other similar ones would also work as would spray on lacqeurs such as hair spray, as they provide a smooth, grease free surface (PROVIDED of course that you dont subesquntly put finger prints on it!). But I can't understand why you would need any of these surface additions, when for PLA a properly cleaned bed works on its own.

Harvey