I think I screwed up and ordered a modular bed and magnetic flex bed for my Mini 1. The install of the modular bed, magnetic base and leveling washers went fine. But, when I was all ready to go and put the thin flex bed over the new magnetic base, the edges of the flex bed overlap the washers. The upgrade did not come with new smaller diameter washers (the current ones are 22mm).
I was thinking I could just make/buy some smaller diameter washers like 15mm and I might be set. Unfortunately, I put the old bed back in to watch the auto leveling run and a smaller washer would not work as the nozzle would not touch it. So, there seems to be at least 4 solutions.
Send the upgrade back and be bummed.
Find the smaller washer and hack the firmware to move the position of the bed leveling points
Drill the aluminum bed base to move the existing 22mm washers out far enough for the flex sheet to fit (and also hack the firmware)
Cut the corners of the flex sheet to fit my machine.
The forth solution seems the easiest but I’m not sure if it might shatter if I try to cut it with an abrasive cutting tool or a simple hack saw. I should point out that the magnetic base fits fine. It is only the thin flex sheet that does not fit. The magnetic base fits the modular bed and mounts just fine. The problem is that the washers sit too far into the bed area and do not allow the flex sheet to sit flat.
It seems like option 4 (cutting the corners of the flex sheet to fit your machine) is the easiest solution, but there is a risk that the sheet may shatter during cutting. To minimize the risk, you can use a fine-toothed saw or a plastic cutting blade on a rotary tool, and make slow, steady cuts while applying gentle pressure.
Option 2 (finding smaller washers and hacking the firmware) or option 3 (drilling the aluminum bed base and hacking the firmware) may work, but they could also potentially affect the bed leveling and calibration, and require significant effort to modify the firmware and test the results.
I used a metal file after the cut of the corners to make it smooth.
I did find that using a file on the spacers was a bad idea as the leveling spacers were no longer level so it was not possible to tune in the Z-offset over the entire print surface. The answer for me was to use my original 8mm spacers ( instead of the 10mm with the kit) and take the two washers from the bed rubber mounts and stack them below the big bed leveling washer. This created a 9mm spacer that was flat and now it is all tuned up and prints work great. The bed is nice and snug.