Quote
uncle_bob
Scale up question:
The central axis of the machine is a hollow plastic shaft that's printed as part of hub_bottom. The shaft appears to be 15mm in diameter. I'm *guessing* that scaling up that shaft diameter would be a good idea on a 2X larger printer. 25 mm and 30 mm seem like pretty good candidates for a scale up from the standpoint of bearings to replace the 15mm 6702's.
So now the questions:
Is the shaft dimensioned based on the need to mount the hot end on the bottom or is it critical? (Do I need to scale it or not?)
If I need to scale it, is 1.5X (25mm) good enough or is 2X (30mm) the way to go?
Yes, I could go to something completely different. I'd prefer to go in as few directions at once as possible. The more I can retain from the original the better. At this point scaling is ok. Machining a different design from a solid block of tool steel - not so much.
Maybe the ubiquitous electric lamp fitting might work?
They are inexpensive, hollow, thin walled, threaded on the O.D, and are made of brass or steel.
Electric lamp fittings
[www.sizes.com]
1/4-27, Dia 6.35 mm (0.250"), 626 bearing 6x19 mm.
1/8-IP, Dia 10.29 mm, (0.405"), 6800 bearing 10x19 mm.
1/8-IP, Dia 10.29 mm, (0.405"), 6900 bearing 10x22 mm.
3/8-IP, Dia 17.15 mm, (0.675"), 6703 bearing 17x23 mm.
[www.bearingworks.com]