Prusa MK3.5 / MK3.5S X-Carriage and 10mm Z-axis Upgrade

About this model

The Goal of this upgrade is to move the MK3.5 on to the point where it is a MK3.9 minus the Nextruder - i.e. everything beyond the X-Carriage is MK3.9/4 Spec only the MK3 Extruder remains. I wanted to add the 10mm Z-Axis Rods but using all MK4 Frame parts (I also updated the Y Axis to use the MK4 Printed parts but that is not the focus of this package). So I have remixed the PRUSA MK4 X-Carriage parts and the MK3S Extruder Body to facilitate the mounting of the Mk3 Extruder onto a MK4 Frame. All this is needed because the MK4 printed Parts for the Z Axis changes the geometry - X axis rods 5mm closer together and X end stops 14mm further apart as well as bringing the MK3S extruder nozzle 4mm further away from the Z axis and around 12mm higher relative to the upper X-Axis Rod. I wanted something specific to the MK3.5 and I wanted to use as many MK4 Parts as possible - there didn't seem to be anything that did this out there so I've remixed the published Prusa parts to give me what I wanted. Certainly this solution for the MK3S was close and I took some inspiration from it but I wanted a starting point that used the MK4 Parts themselves - I wanted to keep as close as I could to the PRUSA design choices and see if I could achieve a MK4 build in all other respects. This model replaces 4 original Prusa parts MK4 x-carriage MK4 x-carriage-clip MK4 x-carriage-back MK3S+ extruder-body The X-Carriage, clip and back are remixed to remove the extruder specific parts and provide fixing points for the MK3 Extruder Body. The MK3 Extruder Body is remixed to mate to the X-Carriage and to account for the geometry changes in the MK4 Nozzle positioning. To carry out this Mod Use the MK4S upgrade assembly Doc to strip your MK3.5 of its X and Z axis (and if you wish upgrade the Y axis too). The build the Frame as per MK4 Until you come to adding the X-Carriage when you substitute the parts for this model. Then continue to build the Z-Axis as per the Doc skipping over the Nextruder parts. Then switch to the MK3S+ Assembly guide to build the extruder using the new extruder body. Note - this needs 2 x M3 Heat inserts in the X-Carriage as shown in the pictures. Here assembly is slightly different because of the new X-Carriage essentially the PINDA cable and the Part Fan cable need to be routed into the channel behind the extruder body before you fix it on. I have included a cut down Carriage Back to keep the carriage fixed to the X upper Rod whilst MK3 Extruder cabling is routed (you can't do this with the full carriage back in place). Route remaining cables to the rear of the X carriage via the Slot in the left hand side ensuring none are pinched - the cables route as with the MK3 the Heater and Thermistor cables joining the bundle from beneath the ext-cable-holder, the remainder join the bundle as they exit the x-Carriage. Once complete to get the 220mm Z height you need to access the "Experimental Settings" Menu (Long press from within the settings menu) and change "Z-axis Length" to 220mm. I have 2 of these up and running and have been using them for a couple of m months now - no issues - not significantly better than the standard MK3.5 but a big step on the road to MK3.9 although these are good enough now that I'm not in any hurry to incur the cost and effort of the Nextruder - there seems very little between this and a MK4 in terms of print quality now as far as I can see! Hardware Required (including the Z-Rod upgrade): X-Carriage mods 2 x M5 Heat Inserts 3 x 20x10x1mm Rubber Pads Z-Axis Mods 2 x 325mm x 10mm stainless steel rods 2 x LM10LUU Linear Bearing 4 x 20x10x1mm Rubber Pads Sundries M3 Bolts various sizes as listed in the MK4 assembly guide for X-Ends and Z-Axis Assembly (as they are not the same as the MK3.5) The list is not exhaustive so you should review the various assembly guides to ensure you have all the correct hardware before starting out - especially the nuts, bolts and other metal parts! Printed Parts: Printed parts in this model are all remixed from the following Prusa MK4 or Mk3S+ parts: MK4 x-carriage-r2 MK4 x-carriage-clip-R2 MK4 x-carriage-back-R2 MK3S+ extruder-body-r6 I have kept the Prusa Part Number on the remixed and added an "A" serial so I can keep track of the parts I have remixed should any changes be needed. Print settings same as PRUSA printed parts. NOTE: X-Carriage does require supports - the .3mf includes these as paint on supports. I will also add a .pdf file with more build detail in due course. Feel free to ask questions/clarifications.