Originally shared by Brandon Satterfield
I have been playing with many different materials with respect to filament on TSP. This is partly related to the bed. I’ve tried a grouping of different materials for the bed, one has me puzzled.
An aluminum printed bed. A number of manufacturers use it on their printers. I am having a hard time getting certain PETs, ABS, and NinjaFlex to stick to it, bare.
My question, for those that run an aluminum print bed:
Do you have to apply anything to it?
Glue, tape, ABS juice,…
What surface finish do you have? Brushed, polished, machined…
How high a temp do you typically print at?
Have you seen deflection due to the heat cycles?
I have 3 printers that I built and I use glass beds cut to size from window glass purchased from Home Depot.
I then apply a thin coat of hair spray when it is cold and the another thin coat when it reaches about 60C.
My other printer is a FlashForge Dreamer the bed of which is covered with Kapton tape and a couple of coats of hair spray.
Kapton. Sometimes hairspray on kapton, sometimes scrupulously cleaned with an alcohol swad.
I run with Kapton on my Rep1dual. Running at 110 for ABS prints, 90 for PET+ and 60 for PLA. I’ve also got the sides covered to limit airflow.
My solution: mashined aluminium bed+mega strong hairspray (Morfose for example) for ABS/HiPS or blue painter tape for PETG, UHU stick on blue tape for Nylon.
Thanks all. So I’m gathering no one prints directly on aluminum. @Eclsnowman @Thomas_Sanladerer ?
Surface is 1200grit sanded with glue stick on top. Sometimes PET tape. 120°C first layer, 110° for the rest of the print.
I’ve been using this config since what feels like forever - i’ve never really questioned my settings, so there might be something better out there. Just works for me.
@Thomas_Sanladerer I’ll give the 1200 grit a try. I have been a Garolite and glass guy forever, but noted most manufacturers and those I consider mature builders use Al… Back to the drawing board.
The sanded part isn’t terribly important when using glue stick, but having a smooth(ish) surface helps tapes stick. If you have a smooth/milled surface, that’s going to be at least as good.
Yeah, not liking the brushed finish, which is smooth, err, semi-smooth.
I could wet sand it with 2000 and polish it but…
Ok, this is just my thought, I believe this (smooth surface) would rely on an actual surface tension based on both material properties rather than sticking an adhesive between both layers (glue stick, hairspray… ). The rough surface would go a little beyond that by creating slightly more surface area, off axis stresses,… .
I could be totally off on this thought. I will try it with a rougher finish.
I really don’t want to use adhesives anymore; but a 180 degree bed is just not a great idea. 
I knew both you guys ran Al. beds with a lot of surface area. Thanks for the heads up I’m going to continue to play.
I made a bed for my Printrbot out of Mic 6 aluminum tooling plate. I left the fly cut mill finish on top. I’ve had great success with Kapton. I wanted something on there to limit scratching when prying prints off.
I went to Mic 6 because: 1) I wanted more uniformity in the temp compared to the bare PCB. 2) I wanted something that would start out flat, and wouldn’t distort too much when heated.
I bought a 1/4" piece and milled away a 1/8" pocket in the underside, leaving a 1/8" flange around the perimeter. I also milled a small pocket and slot for the thermistor (0.030" below the top surface in the center of the bed) and potted it with Arctic Alumina. PCB heater is held up in pocket.
On the issue of uniformity of temp, it’s a total win. the entire bed is within 1 degree C from edge to edge. I had +- 10 degrees with the bare PCB.
On the issue of distortion, sadly, I’m seeing some doming after about two years of pretty regular use. something like 0.05 mm at the center of the bed.
I have read a bit about slabs of tooling plate doing this when repeatedly heated from below.
if I do it over, I might try to make the bed flippable.
@Robert_Swarner
Do you find that you get any doming from having a thinner center section and a (presumably cooler) thicker, stronger rim?
I’ve never compared to a thicker bed. But I did see some complaints of thick slabs of cast aluminum doming after repeated heat cycling from one side. Wish I could remember where. If I could stress relieve it in an oven, that would be nice, but my temp sensor wiring harness is potted in. If I find the article I’m remembering, I’ll copy the link here…
@Robert_Swarner this is great feedback. The topic of stress relieving has come up, and I’m looking into this now. Thanks again for the feedback.
