Bearing cap broke on my AMS unit’s internal hub.
I think I’ll make one instead of paying $54 + shipping. As it is it seems it’s a fail point. There is room to make it more robust. The mating gear under it is spring loaded for pressure on the filament. Nothing to lose except time and filament.
And the list keeps piling up. 
Looks about right 
. Wait for my printer to finish the current job and I’ll give it a try.
Nice one, that block is a good candidate for a printed upgrade. A few things that have helped me with small load-bearing parts like this:
- Orientation: print it so the force from the spring-loaded gear pushes across the layers, not in a direction that would peel them apart. For a bearing seat that usually means the bore axis vertical.
- Bearing fit: printed holes come out a little undersized, and every printer differs. A quick test ring with three bore sizes (nominal, +0.1, +0.2 mm) takes ten minutes and saves you a broken part. Aim for a light press fit; if it is too tight, warm the part slightly rather than forcing it.
- Strength: more walls helps more than more infill here. Four to six perimeters around the bore and the screw holes, and 40% or so infill elsewhere.
- Material: PETG or ASA is tougher and less brittle than PLA, which matters for a part that is under spring load all the time and sits in a warm printer.
- If the original cracked at a sharp inside corner, a small fillet there will spread the stress and is probably where you can make it more robust.
Curious to hear how the first print fits.
Good points all 
And that spring load IS significant. I have used Polyterra version of Bambu’ Tough PLA. Bambu tough PLA is some very impressive stuff. I make springs with it and they can handle significant torture.
Draft angle. It was an injection molded part so there has to be some draft angle on it and it’s mate. 1% is common, I think ? A part this small 
?
I am at a junction where the parts works great on the hub itself. But doesn’t quite clear the placement in the housing/ body of the AMS. Without the 3D model of the body to help and the fact that I cannot see under the hub while mounted, I am going to have to do some measuring + guesstimation. 
I could carve out some inconsequential (IMO) structural fins/ gussets which is a risk I am willing to make on my own unit. However I’d like to upload it for others to print if needed.
This is the original AMS so there is no heat, so temp vs expansion should be a minimal concern. I can experiment with that.
Roll up my sleeves and chug some coffee, I’m on it. 
First print fit a bit too snugly without the bearing shaft. With the bearing shaft assembly did not fit all the way down.
I could use a very tiny digital caliper if they made one. 
And a very tiny helper!
OR dental goop for making denture molds. That would be handy! 
My X2D’ accuracy is pretty dam good. I made springs and sockets in the body for my needle chopper project. They press fit perfectly with moderate “dual thumb force”. I since loosened the tolerance and went with a keeper screw and slot. Getting a spring back out to replace it would not be easy.
Draft is usually given in degrees, not percent. 1 to 2 degrees is common on molded parts, and small parts often get 0.5 to 1. Your printed copy doesn’t need draft to release from anything, so you can model straight walls. The catch is the pocket it sits in: if the housing was molded with draft, it is narrower at the bottom than at the opening. That would match what you saw, where the part goes in and then stops before seating. Tapering the lower edges of your block by a degree or chamfering the bottom edge often fixes that.
For the clearance you can’t see, try the clay trick: put a small ball of modelling clay or Blu-Tack on the spot that hits, install the hub, pull it back out and measure how thin the clay got with calipers. That thickness is your clearance (or how much you need to remove, if it squashed to nothing).
To iterate faster, cut the model down to just the area that binds and print only that slice. It takes a few minutes instead of a full print, and you can try two or three offsets in one go. When you share it, noting the tolerance you used and the printer helps others who print on less accurate machines.
I’ll have to pick some up.
Internet was down for 24 grueling hours. Amazing the modern conveniences that do not work or work well without it. Wifi was fine. Bambu will not send directly without bouncing to their cloud first. Smart lights would not work. I see a market for “cloud free” home devices.
Anyhow, back up and running. I give you " the Bambu Hub Cap"
I got these buttons, installed directly into my walls! Completely air-gapped from the internet, hack-proof! 
On a serious note, I had some smart devices at home just running off a raspberry pi. There’s various smart home projects for them.
Nice solution for the AMS!
I would have like to use a longer screw by about a millimeter or 2 and lessened the depth they recess into the part.
I need a selection kit with those little screws with the blunted ends for plastic specifically. I have an assortment kit that is more general purpose screws with a point on them.
I should upload it after I run it a while for others to have if they need it.
