Last time I attached the threaded rod and guide rails for the Z-axis. With these in place, I’m now able to start building the X-axis.
A few notes on this post before I begin:
- I ran out of black filament while building this part, so I had to use the yellow filament I’ve been using for my other project.
- This was one of the trickiest parts of the project so far. The X-axis involves a few pieces being bolted together, and I had issues with ABS parts shrinking slightly – which meant that holes corresponding to each other on different parts sometimes didn’t line up perfectly.
- Because I’m using a regular M8 threaded rod (rather than a very accurate ballscrew) I had to design my own part. I’ve uploaded the AutoDesk 123D files to my GitHub repository.
First things first – I’ll talk about the parts I could print out from existing STL files.
Thingiverse to the rescue
Lulzbot have kindly open-sourced the designs for all the 3d printed parts from the Taz – however, not all of the parts are 3d printed, which means it’s a bit more difficult to build the Taz from scratch. Fortunately, a Thingiverse community member has re-designed and open sourced the left and right parts of the X-axis mounts in a way suitable for 3d printing. They aren’t perfect matches of the Taz-5’s factory parts, which are made from acrylic. If the same 3d shape as the original was printed out, it probably would be too flexible for my machine to work.
These are both really big parts – each of these parts took my Sintron Prusa i3 about 5 hours to print out. Fortunately they came out ok, with no delamination or noticeable shrinking.
Printing the double bearing holder
Each of the two X-axis ends have a double linear bearing mount – the STL for these is available here, and these fit onto the vertical guide rails. These printed vertically by default – obviously they could be printed in a flatter configuration, but I think printing vertically makes the part stronger, given that the linear bearings will be an interference fit (which means they are slightly larger than the printed part).
In order to attach these to the large end mounts, I used a soldering iron to insert 4 knurled M3 nuts into the mounting holes.
I found that printing vertically did give me a slight problem with shrinkage. I found that the holes in the double bearing mount weren’t quite long enough to comfortably line up with the holes. However, it was possible with a bit of careful coaxing.
Redesigning the nut holder for the threaded rod
Each also has a mount to hold the nut for the threaded rod. The parts which have been open sourced by Lulzbot are designed for a ballscrew – and I’ve elected to use a simple M8 threaded rod. I re-designed this part to hold an M8 nut, with a cover which bolts onto this piece and traps the nut in place. I’ve uploaded the AutoDesk 123D designs to my Github repo here.
Using a soldering iron, I fitted 4 M3 knurled insert nuts into the back of the piece, and 3 M5 knurled insert nuts into the bottom of the piece.
I then used 3 M5 nuts and washers to attach the cover to the piece, which encloses the M8 nut.
I then used 4 M3 nuts to attach the piece to the end mount, through the 4 holes. Obviously the above steps have to be carried out for the left and right sides of the X-axis.
Attaching the parts to the X-axis guide rails
Now that I had two fully assembled parts of the X-axis, I was able to fit these to the existing frame. I had to remove the vertical threaded rod and the guide rails, and then re-insert them with the assembled X-axis end parts. This was a bit tricky – I had to thread the rod through the nut quite a way before it was able to fit into the coupler.
I threaded 2 x 10mm x 600mm guide rails through the holes in the side of the parts, which proved to me that the two parts were aligned well.
I am pretty sure I’m going to have to disassemble this again, so I didn’t tighten up any of the nuts or bolts (actually I’m 100% sure because I need to get the actual print head onto the horizontal guide rails).
Attaching the Y-axis and X-axis motors
I decided to get all the motors attached, so I attached the motor for the Y-axis using 4 x M3 nuts (which I made early on in the construction process).
And finally for this part, I used another 4 x M3 nuts to attach the left X-axis assembly to another stepper motor.
This it for this part – next time I’m going to start ordering in the Arduino and RAMPS hardware to drive the motors, and test the movement of the X-axis in the vertical direction.