I got some stuff printed out over the weekend. It's been a while since I created a new album, I THINK I've got it set for sharing, let me know if I remembered all the hoops I need to jump through so that anybody else can see the photo.
https://photos.google.com/share/AF1Q...l0RnQ5b3hWdnVR
What you are hopefully seeing is the front and rear halves of the diff housing screwed together, along with the pinion housing screwed on the front. I've lost track of the number of times I've printed the diff halves, definitely more than I can count on one hand, even if I was the 6-fingered man. I was having bed adhesion problems at first, it's been a while since I printed anything. But I DID dust the bed off first, that just wasn't enough. That was Round 1.
Then it JUST wasn't measuring up, too small. That was Round 2. Yeah, I forgot to scale it up in the slicer - it's been a while since I printed anything. I scaled it to 103% in the slicer and printed Round 3. Hoo-Boy-Howdie Round 3 measured at 120.18mm, close enough to 120mm for me. Do the guts fit....NOPE. How come, the ring gear has a 25mm OD and it's in a 26mm hole, it should fit. IF the ring gear was centered in the opening it would fit, but when the ring gear is offset from center - not so much.
Re-design the diff carrier space in the front and rear diff halves and re-print - Round 4. Things were looking up after Round 4, outside dimensions checked out OK, the donor diff guts and bearings appeared to fit in their respective pockets. Will the front and rear halves fit together? NO, the diff halves do not fit together!!!!!
I started measuring the bearing pockets, since the bearings are the only things that could be keeping the case halves from mating together. The bearing measurements and the model measurements match. I don't like either of the explanations that I was able to come up with; 1) either the slicer is doing something funky when it's scaling the part, or 2) the part isn't shrinking linearly.
The only thing I could think of was to start tweaking bearing pocket dimensions and see if that worked:
Round 5 - too small.
Round 6 - better but still too small.
Round 7 - WHOOOPS - over-compensated.
Round 8 - Sorta worked. The diff halves do clamp together, but the axles not longer turn as easily as they used to turn. I wondered if I was clamping the bearings too tightly? I backed off the screws and sure enough things started turning easier. It's hard to believe that a pair of M2 sheet metal screws and a 2 piece plastic clamp could apply enough pressure to load the bearing shells like that. I'll tweak the pocket dimensions one more time and try Round 9 tonight.
Don