It was while…
It was while I was removing a particularly stubborn print from my glue-stick covered glass plate that I thought a better, less difficult, flatter and more consistent print surface was in order.
So after fitting a new aluminium heated bed, I set out to find one and very quickly found the clone PEI powder-coated spring steel sheets on Banggood.
These so greatly interested me that I asked Banggood if I could review one and here we are.
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These sheets are available in 220×220, 235×235, 300×300 and Mk52 (Prusa i3 Mk3) sizes in both powder-coated and smooth PEI sticker types(220×220, 235×235, 300×300, Mk52) with either a magnetic sticker or 6 20mm rare earth magnets.
Fitting it is as simple as cleaning your aluminium heated beds surface, sticking the magnetic sticker down and maybe running an M303 Gcode to recalibrate your heaters PIDs.
I know some of you will be wondering why the magnetic sticker and not the magnets?
Well, the main reason I originally chose it is because I use an inductive proximity sensor for my homing and (hardly used) auto bed-levelling so having an evenly distributed magnetic field is much better than having one with 6 holes in it, but it also stops cold spots forming when the bed is first heating up.
The magnetic sticker is not super strong but it is plenty strong enough to hold the plate without moving (the heated bed will move well before the sheet) and it hasn’t seemed to lose its magnetism at all in the time I’ve had it.
One worry I had about this product was that PETG, which I use a lot, would weld itself to the PEI and ruin my sheet.
Unfortunately(?) whatever amount of PEI they use it’s not enough for PETG to stick to it in that manner and most PETG prints require a brim which isn’t that bad but can be fiddly with detailed prints.
The PETG does stick enough to print but small prints without brims can simply be pushed off the plate without flexing or even removing it.
PLA, on the other hand, sticks much better, but still not enough to stop warping and subsequently also requires a brim for most parts.
As you can see this F47 glider by iClint, in Hobbyking premium transparent green PETG printed great but the nose and the front of the cockpit warped slightly, but once the Z-Offset is properly adjusted this print surface is set and forget, which is a big improvement over lumpy and inconsistent glue stick.
I also printed an F22 Raptor Glider by pcgear in PLA and although it did warp it was almost unnoticeable and much less than the PETG.
But the thing I like most about this product is the texture on the bottom of prints.
It leaves a very smooth, matte-like finish on the bottom of prints which blends the extrusions together so if you use a non-transparent filament and adjust the Z-Offset correctly you can barely see any extrusion lines.
So, should you buy one?
If you don’t mind using brims on larger models and don’t like the glossy finish that glass gives your prints, or having to scrape prints off of buildtak-like stickers then this is an excellent option, if you want better adhesion than this powder-coated one, mainly use PLA and want the flexibility of a flex-plate then I would recommend the PEI sticker type.
And yes, my printer is a custom RepRap, but more on that in a future post…
Have you ever wondered how they get the PEI to stick to the steel?
Well one of the first things I noticed about this product was that there was a ring of gold around the holes on the front, so my hypothesis is that they first coat the whole sheet in PEI (naturally gold coloured) and then powder-coat it, and the ring is there because that is where they hang it from while powder-coating it.