Uses two pretty robust DGBB's for the live spindle at the moment. I'll have to evaluate if they can sustain enough lateral loading. Radial loading generally winds up being the most severe in this application from forces at the contact patch being translated as a force and moment at the bearing.
For example, 700 lbf lateral force at the contact patch becomes roughly a 700 ft-lb moment at the bearings. Split that on two bearings with say an inch between centers and now you're talking about 8,400 lb (over 4 tons!) of radial load on the bearings. Now that I think about it I'll probably have to tweak the bearing spacing in the current design and make the upright a good bit fatter, and/or run even more stout of bearings. Maybe ACBB's. Still just a mock up now.
Billet aluminum design at the moment. Sending it out to be cast would be outrageously expensive for tooling. In theory I could have some cast at Dave's place, since he has his own damn aluminum foundry, but AL356 and AL357 (high strength casting alloys) don't have nearly the same mechanical properties as AL2024, Al7075, AL7x49, AL7068, etc. Plus there's porosity, etc. In any event the design is pretty simple and shouldn't be hard to setup on a CNC. Symmetric left to right so programming costs are reduced.
For grins I may draft up a welded sheet 4130 design. I could have all the pieces lasercut to almost snap-fit together before welding. My issue with 4130 weldments is that I feel they're hard to do stress analysis on. Even if your welder is consistent, it's hard to say what exactly the alloy percentage, microstructure, and mechanical properties are of your weld zone once the filler metal has been diluted into it. Then you've got distortion with heat treating, and you'll have to do spot machining afterward anyway.
Currently mocking up the front assembly with a 4-piston radial-mount AP caliper and ventilated rotor.
No comments:
Post a Comment