Mendelmax 1.5+ y rail for A0-10x type printers

You will need:
4 Misumi 90 degree brackets (90-D-BRACKET
1 Mendelmax 1.5+ y rail and 4 cars: (
An A0-101 style solid middle heated bed plate (If you have an A0-100, ebay has easily modifieable ones, though shipping is a pain in the ass)
The printed y axis endstop mount and belt piece
the existing Y axis belt and y axis rod mounting hardware
your existing heated bed and mounting hardware (screws and springs, etc)
an additional Y axis 20mm extrusion, 380mm long
4 Flat Head Cap Screws, M5-12
5 Button Head Cap Screws, M6-12 (-16 possibly)
8 Button Head Cap Screws, M6-10
10 additional t-slot nuts
assorted washers.

The rail is pretty much perfect as is lengthwise, it will rest on top of the existing lower structure. The advantage to this modification is less mass on the y Carriage (the standoffs and the lower assembly), less possibility of rod defliction theoretically resulting in better repeatability. The bearings seem to move faster than the origional igus style ones too, but that could just be because I have a used machine and these are new bearings.

The trickiest part is the modifications to make your heated bed plate. I followed the lulzbot diagram to make the side cuts to reduce mass. To attach the Y belt, you end up using zip ties and attaching the belt against it’s own teeth. I was skeptical at first, but it seems to hold. There is an alternative screw clamp variant of the belt attachment available, but it seemed fairly flimsy as is, so I ende dup using the one attached instead. I haven’t got everything into the machine yet, but once it’s in i’ll post more pictures.

ohmeye_mm2_endstop_y.stl (40.6 KB)
beefy_y_belt_block3.stl (62.4 KB)

Just an update on this project for anyone interested. I eventually ended up swapping that rail out for a much easier to dial in and much faster single piece chassis rail I also ended up going with a new belt tensioner to get higher tension than the original Ao-101 piece is capable of.

The new rail is from Trinity Labs, and is a bit more spendy than the makers tool works one. it’s also about 4mm taller, so you do lose a bit more print area, but the increase in accuracy and higher possible speeds is worthwhile. You will need this belt mount for the rail:

The belt tensioner I ended up using is this one:
It prints easily, and it is stout as heck. He also has an internal motor mount that looks interesting, but it is clocked the wrong way to fit the existing motor wiring. I do have a Mendelmax 2.0 Y rail motor mount plate on order in theory so that will be the next project. For now my insanely beefy Y mount works fine for the motor. That belt tensioner also allows you to use your existing belt. if you don’t you will need to procure a longer belt.

The rail Kit I ended up using in the end is here:
If you get that one, be advised that the car does flex some, so make sure your bed plate is mounted flush and not tightened down too much or the car will flex and bind on the rail.

Overall I would rate this project as moderately difficult given that you will have to drill and modify a bed plate to fit. That’s really the only difficult part with the trinity Y rail. If you attempt the Makers tool works one, be prepared to spend hours adjusting it correctly. The accuracy boost I am seeing in the Y direction and in part thickness is minor, but my machine was pretty well dialed in before that anyways. This will come in very handy for repeatability though if I ever get an auto leveler fitted to this machine.

Great looking modifications! Keep up the great hardware hacking :smiley:


Minor update: I did go ahead and reverse that internal Y rail motor mount if anyone wants it. Haven’t printed it yet but it looks right.

So many projects… So little time… :smiley:

Final update to this particular segment of the project. I moved the Y motor inside the frame, leading to a shorter belt path and a smaller overall footprint. The shorter belt path being the main driving force for the last update. I put the internal Y motor up on thingiverse. The endstop is a custom pain in the ass to print support required bit that I am not 100% happy with. I’ll see if it holds up, and if so I’ll post that bit as well. Motor mount is here:


New endstop. It sockets into the rail with a capture notch, then strikes the Y belt anchor to trigger

Motor mount installed. Also the new Power and data interconnect backplate. The power supply is not quite ready to go in the frame, I’m waiting on some of the connectors.

Blurry picture of the new arrangement. Basically the motor mount replaces one of the metal angle clips. Ads stiffness to the frame and rail (not that it needed it) and lets the belt length be decreased by 100mm or so, allowing for better geometry and tension.

After the modification

You can also see the mounting locations for the Power supply, some of the side and back plates in there. The deckplates will go on next when I open up the front of the printer and get them drilled.

How does this affect your travel and build volume?

Is it long enough so if you put dual extruders in line with the y axis, you wouldn’t loose any build envelope?

It actually increases theoretical y travel by about 20mm if the bed itself was longer, but I lose about 10MM of Z travel in exchange. If you compare it to the rod style, the limiting factor in travel there is the lower plate assembly. with this, the limiting factor is the belt anchor and the zip ties that hold the belt to the anchor. The anchor is offset far enough that the width of the motor and mount or the idler is not a problem in limiting travel. I could go with an external motor mount and tensioner and get the full frame for travel if I really wanted, but I don’t want the mass of a larger bed for what I am printing.

It would definitely accommodate dual extrusion or one of the makerstoolworks longer beds though. Not quite enough room for a proper TAZ bed, but I’m going for accuracy, not print size so that isn’t a concern at this stage.