Printrbot Mechanics

This next printer build is necessary for an on going project and also it’s to act as a dedicated printer for future clay extrusion experimentation. I plan to highlight the assembly and make note of anything interesting as I move through the building process.

All of the parts were printed with my RepRapPro Mendel.

 I purchased the LM8UU bearings from an eBay seller and as the saying goes, you get what you pay for. I paid $5.27 USD for 10 bearings and got a poorly manufactured product. The tiny ball bearings pop out if extreme care isn’t taken. They still work, but I’m not sure if I’m getting a smoother ride than printed PLA bushings.

The base is a solid design and is easily leveled.

I found a lot of 5 used NEMA stepper motors with T2.5 pulleys on eBay. The shafts are short, but work well for the Y and Z axes.

I used a clear acrylic sheet for the bed. The only major design change I made was with the Z axis threaded rods. I swapped out the 5/16" rods with 1/4" rods. A similar feature of the RepRapPro Mendel.

There were a few problems which had to be solved to adjust the X axis carriage. I had a difficult time in lining the 2 bearings parallel on the X axis rods. I ended up cutting out the bottom end of the carriage and zip tying the bottom bearing in place.

I’m using an accessible Wades extruder that I made on my first printer. I switched out the hobbed bolt with the Arcol hobbed bar, Hyena 1.0.

Overall, the mechanical assembly was easy and much faster than a Mendel printer design.


Addendum 22July2013

Getting the mechanical functions tuned to perfection has been a pain. This has been primary due to imperfections in the printing of the plastic parts. I originally printed them in gray ABS on my RepRapPro Mendel, but they’re not working out. I'm not getting good prints because the X and Y belts on the  RepRapPro are slipping. This I plan to rectify once and for all which I’ll cover as an addendum to my last RepRapPro post. For now, I reprinted the parts in black ABS on my Prusa Mendel.

Next, the low grade LM8UU bearings have been replaced with better bearings. I think the cheap ones would probably be fine, but I prefer to keep the performance higher on this printer.

Next, I decided to ditch the Wades extruder and go with  the MakerGear Brutstruder and hot end. I have tested this system time and time again with no problems and I prefer to keep with what works. However, I did print the Brutstruder parts and assemble the hot end to be fed with 1.75 filament. I really believe that 3mm is better, but for the purposes of an on going project, I’ve made this decision.

Last, I decided to add the components needed for a fan. I printed the fan system designed by erossman and posted on www.thingiverse.com (thing:32605). I cut out the ducting which cools the hot end with some snips to give the nozzle full usage of the air.