Is it possible that because the z axis is not all wheel drive (3 motors) but rather a single motor driving a belt to all 3 points plus a 4th added point from the auto tensioner that the z rods are not moving at exactly the same rate ?
That alone may cause some discrepancy in the accuracy of the 3 points of movement
You could use your leveling design that you graciously put together and install it on all 3 bearing tops as a test
It wouldn’t surprise me if you find the corner with the discrepancy is moving at at different rate than the other 2
At least it conducts heat, where silicone would be a bigger insulator than the air was. (despite what the link says, the pad linked is bigger than the bambu heat plate)
Thermal Pad is a great idea, but I already have everything on hand now. Silicone is not the best choice but I use it only as a glue, the layer will be very very thin
I dont think so. It looks like a headbed from my Creality and I tried it on a old defect unit - it was impossible to remove it. Its not a 110/230V silicon heat unit
I was hoping to find what model it was and get another and mess with a custom bed at this point. I’m not seeing a good way to get it off without damaging it.
Hello, so I have now a perfectly flat bed, still making testing (temp, weight, aux fan, etc…) to see if it does not have any downside, and I will post all detailed informations, maybe some will be interrested.
It is basically three layer on top of the aluminium bed:
double sided 3M 468 MP
3mm mirror (I wanted 2mm but local store did not have this thickness, I think it would be better)
magnetick sticker (quite thick)
@Nirin I have finally used a “3M 468 MP” double side sticker rather than silicone mastic, problem with that is that it let you only one chance, nearly impossible to adjust the bed position once sticked, but that’s worked very well, just not very convenient.
Can you also create a dedicated thread in the User Mods section? I think many will be interested in those details and it’ll likely get lost if you only post it in this gigantic thread.
Other than cost and easy access, any known benefits over using borosilicate glass?
Nonsense, silicone has quite good thermal conductivity compared to air, about 0.2 W/m·K on average for non filled types, air has about 0.025. Cheap white thermal pastes have about 0.8 W/m·K for comparison. It’s better to have silicone to fill all of the gaps than having nothing.
Thermal pads are only good if you have a thick gap to fill. Otherwise it’s better to have much thinner filler layer even if filler material has worse thermal conductivity.
The good thing about a thermal pad is that it DOES cancel out imperfection and unflat beds. It will prevent the glass top from slowly taking on the form of the warped bed below.
Nope. It will fill the gap with the least of distance but areas with the most of distance will have gaps remaining. Thermal pads are not something you can sneeze that easy. Even super soft types will not do the job of filling uneven gaps on area this large. As of gluing them, you may have some luck with very hard types which can be barely squeezed but not with soft ones. Not to say they will start leaking silicone oil after some time under high temperature.
You are forgetting that the air gap for most of the plate will be in the order of microns, up to maybe fractions of a mm at the thickest parts. Vs a layer of silicone which is going to be fractions of a mm at its - thinnest-.
So I assume by nonsense, you mean “yes, the silicone will indeed still be an insulator. You are correct sir.”
You’re right that the air gap is also an insulator, but neither of them will be good. While a thin layer of thermal paste or pad will be better than either option.
The solution he ended up using of an extremely thin layer of 3m adhesive is going to be better than the silicone, and was a good pick. Though I’d still have liked to see a thermally conductive metal option to make use of the magnetism, rather than a permanent glue fix (for a final product version I mean, for testing purposes he’s doing a fantastic job).
You are forgetting about uneven bed where you will have like 0.5mm or even larger gap in the middle. In any case, if someone wants to use silicone for a whole bed, usual RTV silicones will not work as silicone in the middle won’t cure as it will be sliced between aluminum and glass which do not pass moisture required for curing. Magnet rubber will pass some but not that far. So only two component silicones will do the job. BTW there are some silicones with high thermal conductivity like 2 W/m·K but they are very expensive.
“The solution he ended up using of an extremely thin layer of 3m adhesive is going to be better than the silicone, and was a good pick.”
But it won’t fill any gaps, therefore not better than air unless both surfaces are flat.
Until I got some time to write a full article here are some first results with the mirror+magnetic sticker bed :
I have used this sticker & PEI plate for my tests :
Temperature :
About temperature, it is almost ok, about 5°c less than the setted value (measured on the first layer of plastic once printed, so the bed may be a little upper).
Flatness :
The bed is almost perfectly flat, but as it can only be leveled on three points, the back left and right are not at the same height, so the bed is a little tilted about 250µm
On all the area of the bed, the ABL widget only move from one graduation (250µm), and it is mostly du to the tilted bed
Magnetic sticker:
Very strong, at least as much as the Bambulab original, maybe a bit more
First layer with Giantarm PEI textured plate:
I ony do a 0.2mm first layer test on full bed and it come out nearly perfect, only two little defect that are probably due to the bed was not perfectly clean
I tried a 0.08mm first layer test on a small area (10cm) and it came out perfectly, I will make a try on full bed when I got some time
Bed height:
The bed is about 4mm higher than the original, it is a bit anoying because the little hooks at the back that help placing the PEI plate on the magnetic sticker cannot be use, I will print and stick new ones in PACF
But this is interresting has it enable to use PEI plate that are a little larger 260mmx260mm wich was not possible on orignal bed
Measured the new bed with some good and suprising results.
The new bed was less banana (0,44mm instead of 0,86mm delta cold). A good start!
Then I followed the recommendation of heat soaking the bed for a day. So I printed some PLA with 35° and 55° bed temps. Inbetween I let the bed sit with 90° and 110° for 30 minutes.
Well, the banana became less of a banana. See for yourself. I consider this good enough in terms of what I can expect from a machine at this price point. What do you think?
… and when I find the time I will follow in DzzD’s footsteps. Until then some aluminium tape will bring it to 0,1mm delta
