MP Select Mini – Extended Bed (Part 1: Y axis)

I’ve been loving my Monoprice Select Mini 3D printer, but after a few months I started to find the print size very limiting. I decided to follow this guide and upgrade my bed to a larger one.

The stock print area is a 120mm cube (120mm x 120mm x 120mm). After this upgrade, I plan on having a 200mm x 200mm x 120mm build area.

The linked guide on Instructables says “Under $50” … I found that guide omits a few things yo will probably want to have (power supply, mosfet, a handful of M3 bolts, materials to build the print bed carrier, longer bowden tube…) I found my actual cost to be closer to $150.

Shopping List:

I stuck to Amazon and my local hardware store (ACE Hardware) for all my purchases.

Total: ~$150

Print List:

This Instructable has a list of items to print for the bed mod. Depending on your exact printer, you may or may not need some of this stuff, but it’s safest to just print them all.


Here is most of the “stuff” laid out. You can see the massive size difference of the new print bed.


I started by building a new print bed carrier using some angle aluminum and a few rivets. I considered using steel and welding the corners to make it nice and rigid, but figure it would have weighed something like 3-4x as much as the aluminum version. I decided not to put a bunch of weight on those linear rods. I used a 90-degree clamp to hold things together, and used a single piece across the middle to firm up the frame.



Then I used the original print bed as a template to mark the linear rod holder and belt locations on the new bed. You should have printed 4 linear rod supports, which then get used to attach the linear rods to the bottom of the bed carrier. Here it is reinstalled on the printer, where I could then slide it back and forth and check for clearance issues:


Once I was sure that nothing would hit when sliding the carrier all the way fore and aft, I powered up the printer and “home”d the printer. This let me align the print bed’s leading edge with the hotend nozzle.

I then marked and drilled holes for the print bed itself into the carrier. I re-used the spring adjusters from the original bed to support the new bed and set it to be exactly where the original bed was. I did not have to adjust my z-axis limit switch at all.


Yes, I know… painters tape… should have glass… blah blah… I’m an oddball and actually prefer the tape. I can do dozens of prints on it and it lasts really well, PLA always sticks to it without any adhesive, and prints release nicely. Anyway, at this point I have the printer re-assembled with a 200mm Y-axis print area:


Right now I can print PLA without a heated bed, so this was a good point to test that I could still print at all…

Next steps:

Posted in 3D Printing

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CodingWithSpike is Jeff Valore. A professional software engineer, focused on JavaScript, Web Development, C# and the Microsoft stack. Jeff is currently a Software Engineer at Virtual Hold Technologies.

I am also a Pluralsight author. Check out my courses!

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