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The biggest issue you'll have is validating alignment once it is built
Do you mean the frame or the jig? I'm puzzling over what adjustment I need to build into my jig design to bring everything into alignment before loading the tubes. I suspect that having a fixed feature (probably the bottom of the head tube) and then threaded lateral adjustment for the BB, seat tube top and rear axle will the best way to handle it.
That then got me thinking about making tube blocks for mitring on my lathe, and how I might make and fixture those...
hiraethus-
I think trying to build too much adjustment into it is a dangerous game. The jig i have at the moment is the LCFF. Its based around mild steel beams which are not straight. The jig has loads of adjustability so that you can move it, then realign everything.
In theory this is fine, in practice its a pain in the arse, a giant pain in the arse. Every time i want to adjust something, everything goes out, if you want to check how long the chain stays are mid mitring, your gonna have to realign it. Even when you spend 25 mins tapping stuff with a hammer to try and align it, its not always straight anyway. This becomes particularly apparent when working with through axle. Because there is no give in a through axle dropout, you have to be bang on out of the jig. If not the rim will sit off centre at the chain stays. Even when i have aligned it, i dont really trust it to stay straight, The alignment for the lcff is fiddly and annoying and i hate it.sorry rant over.
Biggles567
I've just lasercut a framejig from 5mm plate. The biggest issue you'll have is validating alignment once it is built. I did it via the long route using angle finders etc. for now. I'm currently figuring out how to make a laser aligner for this purpose.
I used wheels from a 3d printer on eccentric mounting nuts in place of a linear rail system. It holds alignment and has no slop. I'll update with photos of it assembled when I get into the workshop tomorrow eve.