MP Select Mini – Extended Bed (Part 3: X axis)

If you missed Part 2: Bed Wiring you can read it here.

Much to my surprise, this ended up being the hardest part of the extended bed mod. Mostly because you have to take a lot apart, and the original linear rods are installed in a way that makes them tough to remove. All you really need to do is swap out the old linear rods for new ones, but… unlike the Y and Z axis where the linear rods are bolted in, the X axis rods are pressed into plastic, and depending on your printer, possibly glued in place (as least I think mine were).

What I ended up having to do was put the entire X axis assembly in a vice and hammer out the rods with a punch. This means removing the entire X axis assembly.

It really feels like you are going to break that plastic block that the rods are in, but luckily it came apart without any damage.

Then you start reassembling everything, and get to the belt… This slot on the back of the print head that the belt runs through is my #1 most annoying design decision on this entire printer.

I had to take the shroud / carrier apart so I could feed the belt through the slots and pull it through with pliers.

It REALLY sucks. I want to design something better, but my printer was apart at that point, so I couldn’t just print myself a better system for holding the belt. Maybe I’ll come back to improving this…

You also have to extend the bowden tube. The old one just isn’t long enough. I moved the print head all the way down and out (the longest point the tube should have to reach) and cut a new length.

The stock wiring is also a little less than long enough (I think. I Just eye-balled it and it seemed a bit tight.) to run back out the hole in the top of the Z axis case. theres no way I was going to extend all those wires. I just “cut the corner” and left the wiring outside that hole which gives it more slack. However this means I can’t put the original front cover back on the Z axis.

I used the original end-cap on the rods, and one of the X axis limit switch holders that you should have printed. Everything is back together and works…

However I really don’t like the amount of play in the X axis now. That original black sheet metal holder around the rods seems to add a good amount of support. In trying to level my bed again I found that I could slide a sheet of paper under the nozzle, and when I remove it, I could hear the nozzle drop and hit the print bed again. This made it seem like the bed was level but actually the nozzle was touching the bed. I’m going to work on adding some bracing / support for the X axis next.

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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