Well, that ate way more of my weekend (and this spool of white PLA) than I anticipated:
As you can see I went through quite a few revisions on these X axis upgrade parts! And these are just the variants I went through this weekend!
The two in the front right are the final versions - I may reprint them in raptor PLA before doing actual assembly - partly for strength partly because I'm just not big on this white. You'll notice in the closer photos that this white isn't printing very smoothly. Same things printed in other filaments come out much nicer so i think it's a bit of inconsistency in this filament causing that
Dimensionally they're good...but the surface finish just isn't up to what I know my machine usually produces.
The two behind the final prints I thought were going to be the finals...but I made a small mistake on them...more on that in a moment.
On the left you can see what got me to this point. The three little pieces were tests I did confirming that the opening for the lead screw nuts and their screws and the nut captures for the nuts on those screws were all looking good. I had to get this "just right" because once the spring and lead screw nut are in place there's no way to access the nut in the middle for attaching them. So that nut has to be captured by the print and held well enough to tighten without a wrench. Getting the nut captures sized just right and designing an opening to get that back nut in took most of the time.
Behind those are some earlier variants, and one that I thought was going to be a final...but the CHIP that runs my printer crashed mid-print (Never had that happen before and I've been using the chip to power this thing for over a year!)
One thing I did different on the final version is I added a bit more material that will go around the lead screw:
This is mainly there just to stiffen the part and add more material along the bearing enclosure. There's no real need to surround the lead screw like that but I felt the earlier revisions were getting a little too insubstantial and worried about things holding up. This adds a lot of stiffness to the part but does make final assembly a bit trickier.
It's kind of hard to see...but here's the problem with the "almost final parts" after all those tests with the nut traps the nut traps ended up being an issue when I printed the full part. Basically I had the nuts aligned so the edge between two flats on the part you put a wrench on was pointing towards the middle...but that meant it stuck out a bit further and interfered with the spring because there's so little room for clearance. As a result last minute I rotated those nut traps 30 degrees putting a flat towards the spring:
Well, that didn't actually solve the problem and ended up creating another. Even with the flat facing the spring the nut still rubs against the spring:
And with the nuts rotated that way the opening for the inner nut was now too narrow to press a nut into. So after printing what I thought would be the final pieces I had to reprint them yet again (a 2.5 hour print to do both at once) with the nut traps back to how they were (like the initial photo in this post.) Fun.
But...it all seems to fit finally!
I'm holding the lower part of the nut in place to show approximately how it should look when installed. These anti-backlash nuts are two pieces separated by a spring...the preload created by the spring is how these help eliminate backlash. But it makes them a bit tricky to assemble and install!
Once I let go it springs apart...but when the leadscrew is in there it will keep the two pieces close together. There's about -3mm of room for the lower half of the nut to be adjusted...I'm hoping that's enough.
As you can see I opted to follow Prusa's lead and eliminate the flanges for screwing the bearing enclosure tight. I have to gently pry it open with a flathead screw driver to get the bearings in and they seem to hold VERY well once I remove the screwdriver. And since I've never even installed screws on my current setup...I feel safe with this.
Since I had to redraw this entire part from scratch I did a few things to make it more like I envisioned it and eliminate some hard edges. I made the bearing clamp cylindrical (but then had to go back and add more material because I felt it was a bit weak.) and did a little fillet where it meets the square bracket. I had been hoping to do this before but the way I had drawn the earlier versions it wasn't really possible.
Most importantly for me...it's all designed so it can print with no supports. That's why the bit that encloses the lead screw below the nut is at that angle - so it's a nice easy no-support overhang.
Top view you can see that the flange of the leadscrew nut overhangs the opening of the bearing slot just slightly. This isn't really a big issue. if anything it will just help retain the bearings and keep them from being able to slide out this side. The shaft itself doesn't come near the flange.
So...these parts should be functional now! But I'm missing a few nuts and screws to assemble them...and still need to test everything dry fit before taking my machine apart to try and install this upgrade. I also need to finish designing a geared extruder that will mount to the V-rail or...rejigger my current extruder so it will mount until I get around to finishing the geared design.
Oh - I also printed these this weekend:
Not the yellow golf balls...the white plates under them. The golf balls are soft foam practice balls. The plates will mount under my printer and allow the machine to be supported by the golf balls. Supposedly this helps absorb a lot of vibration and both makes the machine quieter and reduces ringing in the print...we'll see.
A third upgrade from this weekend turned out to be no real upgrade at all. The 40mm fan I have on my RAMPS board to help keep the stepper drivers cool and the one on my layer fan are both dying. They still work...but they've gotten very noisy and rattle a lot. So I ordered some new fans a week or two ago. Finally installed the first one...and...right out of the package it's louder than the old fan I'm replacing
On the upside...it does seem to move more air than the old fan. But it's way too loud...and no point in putting one of them on the layer fan because if they're not held flat and level or vertical they get REALLY loud and the layer fan mounts it's fan at an angle
So...looks like I need to order some more fans. Kind of tempted to get more noctura fans like I used for the extruder...that thing is SILENT. But one fan for $15 it better be! I can't really justify $30 on two more fans...will take my chances on a few more $1 fans hoping to get more quieter ones like I did last year.