Before you begin the MK2/S to 2.5S upgrade - some tips and caveats  

Before you begin the MK2/S to 2.5S upgrade - some tips and caveats

I hope this will help someone avoid some of the mistakes I made. Most of it is common sense but hindsight is 20/20.

The original MK2/S was also a kit but be warned that my experience is limited to these two builds: the original and this upgrade.

The kits:

- MK2/S to MK2.5 upgrade with self printed parts (some parts printed, not installed)

- MK2.5 to MK2.5S upgrade with pre-printed parts

Duration: ~12 hours. This includes time for:

- setting up the work area, prepare the kits contents, storage bins etc.

- lunch, dinner (with some cooking time) and bathroom breaks

- firmware upgrade, wizard calibration and first layer print with passable results

- light cursing at times (but enjoyable overall)

Below are a few tips which are better known up front, before you start the upgrade.

- BEFORE you take the printer apart, purge as much filament as possible if you plan to also change the nozzle at this time.

- If you need to print some parts, print them with whatever black PETG you already have dialed in. Save some calibration time. If you don't already have any, calibrate for the filament you'll use. It's worth the time. Make sure you have all parts for whatever kit you have.

- While the printer is disassembled and after the old parts are removed, take time to re-tighten all nuts & bolts using the tools provided. This is part of the regular maintenance but it's easier now than with everything assembled e.g the printer has better balance and you have more space for tools. Turn the printer on its power supply and work your way through all accessible nuts & bolts.

- While the extruder is disassembled change the nozzle. You have better grip on the heating block and less risk of damaging the wires.

- Dust the PTFE tube housing while it's completely exposed. I wish I'd remembered.

- If the print fan doesn't fit when mounting, loosen the other two parts and thighten them back after the fan is in position. This is pretty generic advice but wort mentioning as the plastic is frail and can break/crack easily.

- When a square nut fails to insert cleanly into a printed part slot you can use a tool that looks like a steel needle bent to 90 degrees to carefully scrape the corners of the hole from inside out a few times until the inside has less rounded corners. If you don't have such a tool try to inprovise one using a very thin nail or a bent needle. A blade won't work though.

Then use a flat electrical screwdriver tip (bigger than the included one) to push the nut. There is a size which is almost perfect, you'll find it if you already have some tips.

Remember that the printed parts can break so grab them on the strongest/thickest volumes when doing this operation.

- When inserting the pin for the Bondtech secondary, if the fit is too tight, don't force it! You'll break the printed part. Instead use a smaller diameter drill bit held between the fingers to SLOWLY enlarge the holes. Or if you have a conical needle file use that but rotate it instead of using linear motions.

ATTENTION! Both of these techniques will produce holes which are irregular and NOT cylindrical. Proceed slowly and measure often. Stop while some effort is still needed to push the rod through. When using a file this operation will enlarge each hole's exterior more than the inside. Keep in mind that the rod will always encounter the smaller diameter when hitting the second hole. Don't enlarge too much.

- When working on the X-axis belt (after you cut it to the proper length) if you struggle to push it into the X-carrier slots, unscrew the motor and rotate it as you did when installing the belt. An untensioned belt is easier to push. Rotate it back and tighten after the belt is in.

- When you adjust the pulley on the X-axis motor to center the belt, move the extruder SLOWLY so it doesn't generate power which will power up the electronics (you'll see the LCD screen light up). This is documented in some other place but it's worth mentioning in this context. You can use a flat screwdriver to push the pulley away from the motor in small increments.

- Both kits include a plastic piece used to zip tie the cables as they exit the X carriage. The second kit include a bigger piece with a different design not yet in the manual (Jun 24, 2019). The first kit piece you have to print yourself.

If you use the second kit piece, rotate its top sligthly to the left when tightening the screw. It will allow the X end stop to make contact. Probably a newer, slightly longer end stop piece is needed.

Also keep the last two ties' "heads" (the ones around the heater and thermistor cables) under the cable bundle as they will scrape against the electronics box while th Z-axis moves up and down in the X-zero position. Make sure they're both higher than the extruder's lowest part so they don't drag through your fresh print.

- Use the screw pulling technique to insert (4) hexagonal nuts into the new electronics box you printed - where the cable bundles are entering - but do it BEFORE you assemble and mount the box or electronics(PCB). Use longer (20mm) screws if the 10mm can't reach the nut or if you forgot to do this before mounting.

If the extruder bundle doesn't close completely or you struggle even when you have the correct part, use longer (20mm) screws instead of the recommended 10mm.

- Ground yourself every time when you come back to work on the electronics. Avoid ESD.

- Probably mounting the upper hinge and the door of the electronics box is better left off until all cables are plugged in. You'll have much better visibility.

- Using a zip tie for PINDA positioning (as recommended in the Preflight check Step 3 PINDA adjustment) was too much for me. Two business cards were still on the plus side. Using just one is probably to little but if PINDA calibration should be done without the steel bed, pay extra attention so you don't drive the extruder into the bed.

- Do NOT install any steel sheet on the heated bed until after the firmware is updated and the wizard asks you to do so.

Good luck!