Robo3D R1+ / Bigtreetech SKR Pro Adapter Mount by rodsmith

Last crawled date: 3 years, 4 months ago

This Thing exists to facilitate mounting a BigTreeTech (BTT) SKR Pro 1.2 in a Robo 3D R1+ printer. (It will probably also work with the SKR Pro 1.1 and the non-Plus Robo3D R1.) See my writeup on the entire replacement process:
https://www.rodsbooks.com/robo3d-upgrade/index.html
In addition to this Thing, you'll need:
1x 3x6 screw
1x 3x16 screw
3x screws of intermediate size
(Optional) glue
There are two .stl (and associated .scad source code) files included in this Thing:
skr-pro-mount.stl -- This file describes a mount adapter plate for the SKR Pro board itself
micro-sd-mount.stl -- This file describes a mount for a micro-SD card extension reader (described shortly)
This mounting adapter plate fits over two small standoffs in the base of the Robo3D, roughly where the original 8-bit control board went. It's not clear to me why those standoffs exist, but I use them in this design as mounting points; the board is held to the bottom of the Robo3D using a combination of one screw directly through the plate into one of the standoffs; one screw through one of the board mounting standoffs, which fits over the second Robo3D standoff; and glue. I used Elmer's white glue, which should be easily removable should I ever need to replace the board again. You might be able to do without glue (or to use glue without screws), but a belt-and-suspenders approach seems best, given the fact that the two screw points are both on one side of the board, so gravity will tend to pull the board away from its mounting location if you use just two screws.
Very helpful items include:
1x USB extension cable, similar to https://www.amazon.com/gp/product/B071P2BGK5/ref=ppx_yo_dt_b_asin_title_o01_s02?ie=UTF8&psc=1
1x Micro-SD extension cable, similar to https://www.amazon.com/gp/product/B085HGTJWT/ref=ppx_yo_dt_b_asin_title_o01_s01?ie=UTF8&psc=1
The micro-sd-mount.stl Thing is designed to work with the second of these extension cables; the reader end slips into the hole in the Thing, which then mounts where the printer's original SD card slot went. (Insert the reader into the mount adapter with the icon of the micro-SD card facing up.) The fit of the extension reader in the mounting adapter is quite tight, so I felt no need to use anything but the friction fit to secure it; but if you use a smaller or larger adapter you might need to redesign the Thing using the micro-sd-mount.scad file, or possibly just secure a smaller adapter with tape or glue. The micro-SD card is recessed deeply enough that you may need to use tweezers to retrieve it.
Note that using the mounting plate will require cutting bits out of the Robo3D printer's plastic case to provide sufficient clearance for the USB and micro-SD extension cables. Mounting the USB port on the outside of the case will require drilling two screw holes so that the adapter can be secured with its screws.
There should be room to mount a WiFi module on the SKR Pro board -- either the one sold by BTT for use with Marlin or the more sophisticated design needed by the gloomyandy port of RepRapFirmware to LPC/STM boards. My photos show the latter in use. The USB extension cable may make for a tight fit when using an RRF-style WiFi module.
The design of the SKR Pro boards more-or-less necessitates the use of extension cables for USB and micro-SD cards, if those components are to be accessible when the board is enclosed.
I recommend printing both parts with supports. Both will print without them, but the main SKR Pro mounting plate's two screw holes will sag a lot without supports, and the bridge on the micro-SD mount will also droop a lot, necessitating more cleanup, without supports.