I3 MK3 Clone (Haribo, Self-Sourced) by Achase79

Last crawled date: 3 years ago

This is a self-sourced I3 MK3 Clone. It currently is a near-exact replica of an I3 MK3 Haribo, with the following deficiencies:
No Power Panic
The filament sensor is a standard IR optical sensor, not the PRUSA laser sensor.
It is likely that these parts will be cloned at some point (the power panic board could easily be cloned, but the sensors Prusa uses for the filament sensor are hard to come by.)
It runs a (slightly) modified PrusaFirmware 3.2.1 (for modified axis length, filament sensor). It passes X/Y/Z calibration, and everything works perfectly! The Haribo frame is also incredibly solid, especially with the power supply and Einsy case rigidly attached to the extrusions. It has been printing very reliably for the last month. I have filament runout detection working, although it can be a little sensitive to ambient light changes.
Honestly, if I did it again I would either just buy the MK3 or buy the MK2S->MK3 upgrade kit and add the haribo frame. This really isn't much cheaper. But it's very solid, prints wonderfully (I haven't had problems with the dreaded extrusion inconsistency issues), and was a fun project. It makes the most sense for someone who already has most of the parts and specifically wants a Haribo-style build.
BOM
[Haribo 3030 Extrusions] (https://github.com/PrusaMK2Users/3030_Haribo_Edition/tree/master/BOM). Also get the rubbed feet.
60 or so 3030 T-nuts. Add a few 3030 hammer nuts for post-install additions and tight spaces.
I got some black 3030 L-plates to stabilize the base (may not be necessary). These could easilly be printed.
3030 Feet
GT2 Belts and Pulleys
LM8UU bearings x 10
Y-carriage and U-bolts
Smooth Rods: X 370mm x 2, Y 350mm x 2, Z 320mm x 2.
If you don't want to print the Prusa LCD holder, try this. New mounting holes need to be drilled, but it works (if you have rubber feet and the 3030 L bracket - bed clearance could be an issue if you don't have these).
The standard 2004 LCD smart controller display
Motors: Probably best to either get a set from Prusa or one that claims to be the same LDO motors (017 007 006 etc.). You want the same motors (especially on X and Y) if you're planning on using sensorless homing, since the thresholds are set for Prusa's high inductance motors, which will differ in other NEMA17 steppers.
Einsy Rambo (the Prusa version, not the retro version)
3 Pin 5V 5015 Blower. I used this one
Noctua or other 3 Pin 5V 40mm fan. I used this one
24V heatbed, Pinda 2 Probe (? and Prusa filament sensor) - best option is probably to buy the MK2S->MK3 upgrade kit from Prusa, but I bought a clone bed and Pinda 2 from 3dprintronics.com
Standard optical endstop (if you can't source the laser sensor). Its connector needs to be removed and replaced - you can either hack it off and solder directly to it or desolder and attach 90 degree header pins.
24V 17amp power supply if you don't get the Prusa MK2S->MK3 upgrade
Standard switched IEC inlet
Bondtech gears (real or cloned)
50 pcs M3 Square nuts (but see note below)
All necessary M3 screws (get list from Prusa build instructions)
50-60 PCS M6 12-14mm button-head hex screws
E3D V6 1.75 universal or bowden V6 clone (works in you unscrew the push-fit adapter)
If you want a spool holder, you can print one, use the Haribo one, or build one with 3 OpenBuilds black corner connectors, 2 ~120mm 2020 extrusions, and one small printed part.
Bag of Haribo gummies :)
A few notes:
Prusa uses M3 square nuts that are a little smaller/thinner than the typical Aliexpress ones. They can usually be fit in with a soldering iron/file/force, but get the smallest ones you can source, and some parts may need modification. If you read through the SCAD files in Prusa's github, you can see they are specing the square nuts as 2.1 x 5.6 x 5.6. The ones I found were 2.4 x 5.4 x 5.4. It takes a little force. Alternately, you can modify the SCADs and recompile them. [Update: Search specifically for DIN 562]
The standard Prusa fan shroud does slightly hit the Z-axis motors on homing, although it doesn't seem to cause any problems. I'm testing a narrower version of the shroud.
X/Y squaring requires a precise distance from the X-home to the first calibration point. What I did was leave the bed a little loose, watch it look for the calibration point, cancel, reposition the bed left/right and repeat. It took a couple of tries, but it worked.
X/Y/Z axis lengths are somewhat longer than on the original. Here are my settings:
X_MAX_POS 249
X_MIN_POS -6
Y_MAX_POS 232
Y_MIN_POS -4
Z_MAX_POS 210+28
Z_MIN_POS 0.15
If there's an interest in the optical endstop runout detection, I can post my hacky firmware. It seems to work, but has not been extensively thought out/tested.