My dodgy custom heatbed sheets  

My dodgy custom heatbed sheets

I've had the MK3 since about late March, so about a month now, I think. I've been printing non-stop on it. These forums have been a great help!

Anyway, after about 2 weeks prints stopped adhering to the heatbed. In the end I came back to the forums and found if I cleaned it with acetone, then IPA, and then re-adjust my live Z (thanks to Jeff I think for the 'life z' adjustment) properly, it came good again.

After reading about some who had damaged the PEI coating and had to replace it, and also those who are ... a little annoyed about the delay in new spring steel sheets, I thought I'd have a crack at making my own. You know, in case I broke mine and then would have to wait for x months to get a new one.

I bought two sheets off ebay (both from a steel supplier that was kinda local). One cold rolled steel sheet (1mm x 380mm x 300mm) and one stainless steel sheet (0.9mm x 380mm x 300mm). I remembered after the fact that stainless steel is NOT magnetic.

Took it round to my mate's shed and got it cut down to size. I got 2x 300x300mm PEI sheets from the official RepRap store on AliExpress, as well as a 5 pack of 300x300mm buildtak knockoff sheets.

Had to clean off a bunch of the rust on the steel sheet as it had lightly corroded in the week or so between getting it cut and receiving the sheets.

The spring steel PEI sheet as measured by my calipers is about 1.1mm. After putting the 'cheap' PEI sheets on both sides of the steel sheet, the thickness came to just over 2.5mm. So yeah a big difference in thickness. The PEI sheets measured about 0.7mm thickness.

It's taken me a few prints to get the hang of it (I write the live Z measurement on each side of the plate to remind me), but now it's going to be my go-to. While the original works fine, I am finding PLA just flat out adheres better to this 'cheap' stuff. With the OG spring steel sheet, I'd need 60C on the bed to get reasonable adhesion.

On the new sheet, 60C will make it adhere enough that I need to feed a razor underneath to get it to come off. I've found 40C is a good compromise, PLA sticks like glue to it (and importantly, doesn't warp), but is still removable at the end. The prints - somehow - are coming out even glossier than before. Like printing on glass, but with all the benefits of a softer material.

And while the steel sheet isn't a spring steel sheet, it still has enough flex in it to get prints off easily.

Only problem I've had so far is similar to someone else who bought the replacement spring steel sheet from BuildTak (I think) . The steel sheet doesn't have rough edges, but the cut on the back edge of the PEI is wicked sharp. When placing the steel sheet down or picking it up, the natural method is to lift from the front, rotating the sharp edge at the back over the copper traces. Quick sand over with some fine grit should fix it up though.

Uh and the stainless steel sheet ... I put the buildtak knockoff on it, although I think the plate may have a bow in it as the live z was waaaaay out. So my first test print made a mess of the sheet. I need to work up the motivation to scrape it off, level the plate out and put some new stuff back on.

(For reference, my OG spring steel sheet has live z of -0.925, the steel sheet has -0.597, and the stainless steel sheet was getting down to something like -0.300 or -0.250 before I terminated the print. The stainless steel sheet with the buildtak has a thickness around 1.5mm, so there's no way thats right)

I'll take some pictures later when the plates are free and post if anyone would like to see.

I know there's a lot of people who have been unhappy with the printer. I'm not one of them. I've only just recently started doing some multi-colour prints (through https://www.prusaprinters.org/color-print/ ), and the filament change is AMAZING. Is this what 3D printing is supposed to be like? I mean I've had some problems with the printer, but it's been nothing I haven't been able to work through.