Monoprice Mini Delta GT2 Carriage

thingiverse

My second GT2 carriage for the MPMD, first not being released to the community as had too much play and the geometry differed too much to the stock machine. These carriages are identical in geometry to the machines standard carriages, keeping the rose joint pivot in exactly the same place relative to the optical homing switch breaker both vertically and horizontally. Bearings are slid into the carriages and are supported around the circumference by the carriage, with circlips holding them in place vertically. Whilst I've not literature to show it, I believe the tolerance on linear bearings is set by the outer diameter of the housing (in our case, the 3d printed carriage), so I used a 15 mm hand reamer to open the holes in the 3D print to exact size and this has given me perfect fit on the sliding rods. The black carriage with the LM8UU photographed was opened up with a 15 mm drill and is sloppy, along with another I opened 0.2mm undersized being a too tight a fit on the sliding rod. The correct sized reamer was £7 on amazon for me, so well worth it. Rose joints are assembled in the same order as stock. My machine had motor pulleys and tensioners that took the GT2 x 6mm belt fine, but check yours. The belt will go into the loops when all swarf is cleaned, it is deliberately tight! I installed my threaded inserts cold with a smooth jawed vice (the holes are toleranced exactly for my inserts) but use your favourite method. Hardware required: Lock washers and nuts from your original MPMD carriages M3 threaded rod (take a measurement from your original carriages, the geometry is identical) (3 off) M3 x 12 mm countersunk socket head screws (6 off) M3 press in threaded inserts (these need to be thru, not blind) (6 off) GT2 x 6 mm belt. (a reel of 5m will give you plenty of spare, it is something like 680mm per tower) Your favourite 8x15x24 mm linear bearing (photo shows LM8UU, I run Igus DryLin - RJ4JP-01-08 on my machine) 15 mm External circlips (12 off) 15 mm Hand Reamer (I'm tempted to say optional, but actually I don't think it is. I really do think it will affect your final print quality) To print, I was having to deal with my old loose fitting carriages, so raft and support with the sliding rod in the Z axis and upside down to how they are installed on the printer (longer protrusion up). I'm tempted again to say a raft gives your machine a surface that is perfectly square to the machine's working axes and the best chance of good bearing alignment. Support is needed as there is a small protrusion facing the bed (which will become the top of the carriage). Belt joiners I printed with the belt loops facing the bed, optical beam breaker upwards.