Status update:
I bought some NEMA motor mounts with the idea that it would save me some time. I may have spent more time altering them to fit than I would have fabbing from scratch from square tube, and I forgot to adapt the model for the slightly thinner metal (about 1mm) and it left me with Z screw alignment issues that took a while, and some shimming, to resolve. I’ll know whether I got it perfect when I install the Z motor.
I needed a stop to make sure I don’t run the Z nut off the top of the Z screw, so I made a knurled knob that will let me adjust Z when the printer is off that also functions as a stop.
I used a crosscut saw with a good carbide blade to cut the v-slot. It made nice clean square cuts, and the frame assembled square with no “convincing” or shimming; I can’t see light shining through when I hold my machinists square to the corners. My youngest drilled all the base frame holes. I showed him how to set up a jig on the mill, and the square fit shows that he did a good, careful job.
I should have included spacers in the design between the Y carriage and the “frog” to leave more room for bed adjustment screws. I’m using some 6mm openbuilds spacers right now to give myself a little more space. I’ll see if that’s enough; if it isn’t I’ll have to source longer screws as that has me using the longest flathead M3 screws I own, countersunk as deep as I dare.
I decided not to cut the tower piece down to 500mm. It’s tall, and I can hang the filament spools on it, above the print area. I gave myself about 15mm extra room on X and Y vs. what I modeled in case I forgot something, and it made it possible for me to put corner brackets inside the frame. I didn’t cut any of the 450mm MGN12 rail, so it sticks about 20mm behind the printer, so in retrospect I should just have designed it to be 450mm long. I also made the X beam longer than needed, because I used the offcut from cutting the shorter frame pieces out of a 1m section and didn’t cut it further. That way if I need to slide it around (say, to accommodate a second tower as discussed above) I don’t have to trash it and start over.
I didn’t model how to attach the tower to the side before I started. I used a piece of square bracket, screwed to t-nuts in the frame v-slot (the thick slide-in kind, not drop-in) and to a custom double t-nut in the 4040 t-slot that I’m using for the tower. Both use M5. I put a few extra T-nuts in the frame before putting loctite on the screws to hold it together. I’ll see whether that’s sturdy enough or not.
Not yet done, at least:
- Electronics: nothing done yet; no wires, no routing, not even much planning, no electronics enclosure design
- Mounting any motors
- Fabrication:
- Y idler pulley tensioner mount
- Y belt clamp for saddle
- X idler pulley rod
- Extruder mount
- Heated bed (planning to use an old heated bed as a heat source for a new cast aluminum bed plate)