MendelMax 1.5 Build docs

Assembly Instructions

MendelMax 1.5 Build docs are available on Google Drive. Many, many thanks to Theo Deyle for his hard work on these outstanding docs!
Nathaniel, AKA PointedStick has written up a outstanding build guide at TechPaladin

There are a few things that need to be done in the correct order, so it is best not to just try to put everything together randomly.

If you want to build your bot before I post the instructions, please post to the Google Group or ask in the #mendelmax IRC channel on

In the meantime, here is a rough draft of the instructions, that should be enough to get the basic frame assembly complete.

VERY IMPORTANT: The assembly is very easy and most people can complete at least the main frame assembly in a single evening, but only if you do everything in the right order. There are several small details that must be completed in the proper order, or you will need to partially disassemble the bot and redo steps you have already done.

These instructions are brief, I highly recommend you take the time to read all the way through them before starting to get a quick overview of the process, then read through them a second time as you assemble. Taking the extra few minutes up front will save you more time in the end.

  • Important: Any place where you use a screw through the plastic, be sure to use a washer on the screw to spread the load.
  • Tap both ends of the four 300mm extrusions and two of the 420mm extrusions, and one end of each of the 340mm extrusions.
  • Use the Top Rod Jig to drill holes to drill holes through one side of the two 420mm extrusions with the tapped ends. You want to drill from the same side on both ends. You will drill through the center of the extrusion, so later you can reach a screw head behind the extrusion (see the pic in the lower left corner here: (also available here).
  • Partially screw the self-tapping blind joint screws into the non-tapped end of each of the 340mm extrusions. Leave them about 4-5mm from fully seated.
  • Find the four Lower Vertex Middle pieces, and attach each one to the opposite end of the 340mm extrusions. You will use 1 M5-10 screw and T-slot nut in one of the slots, and one screw through the hidden hole in the printed part into the tapped end of the extrusion.
  • On two of the four 300mm extrusions, insert 2 T-nuts into one side of each extrusion, and one nut into the opposite slot. These will later be used to attach the motor or belt idler and the Y rods
  • Use t-nuts to attach the two 300mm extrusions to the two diagonals. Be sure that the side with one inserts T nut is on the outside.
  • Attach the two Lower Vertex pieces. Use two T nuts to attach to the diagonal extrusion first, then screw into the ends of the 300mm extrusions
  • Repeat the previous three steps with the other end.
  • Insert two t-slot nuts in one slot each of two of the untapped 420mm extrusions.
  • Loosely attach the two ends together using the two Top Vertex Y pieces. These should be right at the top of the extrusions.
  • Attach the two ends together using the untapped 420mm extrusions. The two inserted T nuts should be on the lower outsides of the bot.
  • Insert the four Top Vertex X pieces into the diagonal extrusions. Insert the screws and nuts in the other end, but leave them loose.
  • Insert the two remaining 420mm extrusions (these should be tapped and have holes drilled though them). These will slide over the blind-joint screws and the nuts already inserted in the Top Vertex X pieces above.
  • Line up the holes drilled in the extrusions and the blind joint screws, and tighten the screws, as well as those on the Top Vertex X Pieces.
  • Insert two T slot nuts into the top slot of the top extrusions. These are not needed for the included parts, but will be used to mount a filament spool (I have not posted this parts yet, but will do so soon).
  • Attach the Z motor mounts, with two T-nuts and two screws into the ends of the extrusions.

Smooth and threaded rods

X ~445mm depending on your X ends.
Y 420mm
Z 405mm

In all cases, it is okay to use longer smooth rods, not shorter.
If your smooth rods are 1 meter long, you can just cut them however you want. If you have 36″ smooth rods, you will need to cut one 445mm rod and one 405mm rod from each of two rods

If you use the thrust bearing, the Z leadscrew will be about 365-370mm. Place your Z motor in the motor mount and measure from the bottom of the motor shaft to the bottom of the lower Z rod mount, and make the threaded rods about 5mm shorter than that. If you do not use the thrust bearing, approximately 300mm should be fine.

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