MonoPrice Select Mini Bed Expansion V2 (150mmx230mm) by iBigNTastyi

Last crawled date: 3 years ago

This is a revision of YourDrunkle's design. I've updated the bed holders to work with thumb-wheels. I've also included two versions of the thumb-wheel. Print 4x of whichever you choose. Photos above and the summary below are pulled directly from Yourdrunkle's design.
This is a modification to expand the MonoPrice Select Mini's print bed depth to 230mm on the cheap. I am able to utilize a printable area of 130mm x 220mm with just these modifications. The price once built was approximately $60 for me. This is nearly the same price as the unheated version of the "4th dimension modifications" "Maximus" kit but my build includes a heated bed. Note that you will need to upgrade the Select Mini's power supply to utilize the heater but I hope to be making a basic guide for that as well soon.
Some notes about this project:
No special tools (except a 3D printer) are needed for this project. I used a hacksaw to cut the aluminum, scissors, a drill with 1/8" and 5/32" drill bits, and a measuring device.
Most of the non-3D printer specific parts (8mm rod, belt, and the bed itself) were purchased from my local Ace Hardware.
I used a lot of Imperial sized (6-32) bolts instead of Metric (M3 or M4) bolts. Im in the US, so they are WAY cheaper locally. Seriously, like 1/3 to 1/2 the price. Sorry, I'd rather use metric too... M4 will PROBABLY work fine and allow use of the nut inserts.
Links to what I used:
Print Bed:https://www.amazon.com/gp/product/B01AAYY70Y/ref=oh_aui_detailpage_o01_s00?ie=UTF8&psc=1
Belt (note: this is WAY too much belt. You only need ~30cm and could save money by buying a smaller quantity):https://www.amazon.com/gp/product/B00F2IQNX8/ref=oh_aui_detailpage_o00_s00?ie=UTF8&psc=1
Rods:https://www.ebay.com/itm/300-350-400mm-8mm-Chromed-Rod-Parts-DIY-CNC-Linear-Rail-Shaft-for-3D-Printer/122850462999?hash=item1c9a754d17:m:m3bE2vd9IhcoeTMEq0XmC7Q
Everything else was locally purchased at Ace Hardware.
A REALLY REALLY BRIEF BUILD GUIDE:
Looking at your printer as it comes apart is crucial. This "guide" is very broad and skips a lot of stuff that you should be able to figure out on your own.

Printing
I printed everything with 100% infill and 0.1mm layers with PLA. Time will tell if the PLA holds up tot he heat from the print bed but I am confident. I am able to fit it all in 3 print files on the stock Select Mini. It took a long time but it is very rigid and looks good IMO.


Cutting Aluminum:
Cut aluminum to 150mm for the front and rear and approximately 2-5mm shorter than your rods for the left and right sides. Its ok for the aluminum to be a few mm short but not a few mm long.


Drilling:
Assemble and square the frame off of the printer. Ensure that the 8mm rods are against the aluminum and are the same spacing as on the printer. Use a 1/8" drill bit to drill through the holes in the 3D printer parts. Expand the holes shown in the pictures in the aluminum only. The expanded holes are to allow for some adjustability in the system.


Assembly:
When the frame is initially assembled on the printer, do not tighten the 2 screws in the front and rear that were drilled oversized. Push the frame to the farthest back point of travel and tighten the front screw and vise versa. This prevent binding.

Installing the bed
When installing the bed, I placed the connector for the electronics toward the outside of the printer. It will bind if placed on the inside.
Installing the belt:
The belt loops through this frame differently than the stock printer. However, it still goes through the stepper motors the same way and the layout in the frame should be obvious. The ribs in the belt will sit in the ribs on the inside edge of the frame.