Prusa Mendel build update #3

Figured it was time for a build update on my Prusa Mendel 3D printer. I had some friends over this past weekend from our RepRap user group and we ended up spending the whole day tinkering with the printer.

Prusa Mendel build update #3

With huge help from Brad and Eugene, we were able to get everything wired up and the motors moving.
It was pretty cool to finally get to this point and have things generally work as they were expected. The only issue I noticed was that the Z axis was inverted so it was simply a matter of flipping the connector around.

It wasn’t without some casualties though…we managed to break off 3 different PLA bushings while testing things.

Prusa Mendel build update #3

If I was doing this from scratch tomorrow, I’d definitely skip the PLA bushings and go for LM8UU or brass bushings…the PLA bushings plus the epoxy is just a pain in the butt.

When testing out the Z axis motors, it became apparent right away that that original couplers weren’t going to work. The threaded rods wobbled like crazy and I may have stripped the plastic parts when assembling. Fortunately I had a set of the updated couplers printed which worked really well after a quick trip to Home Depot for some tubing.

Prusa Mendel build update #3

At Brad’s suggestion, I swapped out the original belt clamps for the new ones in the 2nd Iteration of the Prusa files as it’s taller, has grooves for the belt teeth to hold it and helps the belt line up better with the motor and bearings on the Y axis.

I had printed some M3 nut thumbwheels for use elsewhere and they came in handy for leveling the build area on the aluminum thick sheet I have.

Prusa Mendel build update #3

Brad also soldered the wires to the heated build plate PCB (Mk1) after my failed attempts…seems my new soldering iron tip wasn’t heating up enough but Brad was able to make it work. The PCB works great and gets toasty hot pretty quick.

Prusa Mendel build update #3

The RAMPS 1.4 board almost fully wired up…just missing the extruder and thermistor connections:
Prusa Mendel build update #3
Note the fancy fan with blue leds – everyone seemed to like it and wanted to get one for themselves. It’s an Antec SpotCool Fan with 3 speeds and is SUPER quiet. It’s mounted to the Prusa frame via this simple mount.

We also had quite the adventure figuring out how to make a usable hot end out of the parts I had from Mixshop. The brass barrel was too short so we cut down the PEEK block and also milled out the heater block with a drill bit and some fancy dremeling by Brad.
Prusa Mendel build update #3

Modifying the heater block

Not a lot left to do: mount the endstops, clean up the wiring, finish building the extruder/hotend and check everything is tight and level. Hopefully this weekend I should knock those off the list and possibly even get to the point of extruding some plastic! I can already tell that I’ll have lots of calibration to do…it’s definitely not as solid yet as my MakerBot is so the fine tuning will be critical to getting some decent prints with it.

Also have to say thanks again to Brad & Eugene…they were a huge help and I’m not sure where I’d be without their assistance at this point. One of the things that’s good & bad about RepRaps is that there are an infinite number of ways to build them…having Brad & Eugene share their wisdom was awesome and really sped up the build since I didn’t have to make some key decisions because they’ve already been through the process.

UPDATE: Here’s a couple videos of the motors running. The extruder is just clamped in place (for now) for testing purposes. Yes, it’s a printed clamp :)

I’m currently running the Sprinter firmware on the RAMPS and using PronterFace (running on Mac OSX) to control everything but it also works with Replicator G:

So much quieter than my MakerBot! Although the motor speeds in the videos are pretty low…it can go MUCH faster.

UPDATE #2: Success! Last night the bot extruded it’s first plastic (PLA). The hotend worked perfect right out of the gate (once I had all the wires properly connected), it just needs to be tidied up with some kapton tape. Next step is to calibrate and actually print something:
It's not pretty but my Prusa Mendel is finally extruding PLA! #reprap

I was a little disappointed though. I had read that PLA (which is basically cornstarch) smelled like candy when extruded in this manner…sadly it doesn’t…in fact it doesn’t smell like anything although I haven’t had it printing for hours…perhaps it will be more noticable once I start printing objects.

Greg's Accessible extruder

UPDATE #3: Printing! Sort of!

Had an issue with the Z-axis voltage being too low to move the whole extruder (now properly installed), the whole X-axis fell down and the filament was sliding off the hobbed bolt teeth (results of which are in the video above). I’ve printed a filament guide that should help with this so I hope to actually be printing something recognizable tonight.

My original plan was to use Replicator G but I’m quite liking PronterFace with SFACT installed instead of the regular Skeinforge. It’s almost like the Print-O-Matic settings options I have for my MakerBot and aside from my filament issue, the above print is done with no calibration at all! It definitely looks correct when it’s going thru the motions.


  1. VancityAllie says:

    Argh, that is SO SO cool. Can’t wait to see it in action! Been following along….

    • John says:

      Thanks Allie! I just added a couple videos of it all moving. Finishing the extruder is all that’s left…followed by a lot of calibration.

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