Kossel 220mm Hot Bed Spacers / Mounts

by peaberry Dec 20, 2016
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Hi, looking at the picture you attached, I don't think these would fit your T1.

Do these spacers/mounts hold the heat bed down when the printer is turned upside down? I'd like to have access to the controller board without having to remove the bed or worrying about the bed falling off when I flip the printer over.

If not, would the bed holes align to the mount pads if the bed were rotated 30degs or so in the install picture? Maybe I could drill some screw holes to use for holding down the bed.

These don't hold the heat bed down if the printer is turned upside down.
I think the bed holes probably would align with the pads if rotated (but I haven't tried it). Ideally you would want a captive nut in the mount (possible remix!) There are some other bed mounts on Thingiverse so you might find some elsewhere on here with screws or clamps.

I've just uploaded a new version which includes a clamp to secure the bed.

Did you ever get around to implementing an external TO-220 packaged MOSFET?
I would hate for mine to burn up and I'm all for preventing it if at all possible by going external.

Hi there, yes I've made a start on fixing this. I bought one of these boards (https://www.amazon.co.uk/gp/product/B06W5RJ9LY) which are based around the HA210N06 MOSFET. This board is widely available under lots of different brand names (maybe cheaper in some places).

The control input for that board can just be connected directly to the original hotbed screw terminals on the Ramps board, so it's pretty straightforward to wire up. I've already tested this complete set up with some test leads and it works fine, I just need to print a bracket to mount the external MOSFET and wire it more permanently.

It was a bit more complicated in my case, since the original MOSFET on my Trigorilla 1.4 board (STB55NF06 MOSFET) burnt out, so I had to repair that damage first. It actually caused the copper heatsink pad to de-laminate from the PCB, and melted the connector nearby! To fix that, I bought another STB55NF06, seated it on some copper tape, and soldered to the old pads, then stuck a small heatsink on top. This poorly heatsinked 55NF06 is never going to run a hotbed directly again, but I just wanted to restore the output screw terminals so I could connect them to the new external HA210N06 board. It only takes about 1mA to switch the external MOSFET, so that will be fine.

In conclusion: if you are running a hotbed at 12V, the MOSFET on the Trigorilla 1.4 board is completely unsuitable for the resultant current, as the heat-sinking is seriously inadequate. It really needs an external MOSFET board to drive the hotbed safely.

I just took delivery of this, I will try to wire it up over this weekend.
Thanks for your speedy reply.


Looks like a good choice Dennis.
I'll probably get around to finishing mine this weekend also!

Comments deleted.

Which paper Size is the pdf?

The PDF paper size is A3 which can be printed on a regular A4/Letter printer from Acrobat by selecting "Poster" to print two overlapping pages at 100% scale which can be glued to some board and used as a cutting template.

After printing, you can check it came out the right size by measuring the width of one of the three flat tabs which should be 70mm wide. Hope this helps!

yep helps me a lot Thanks!