I’ve been trying to figure out a home-made unicrown fork mitering system for a couple of weeks now. It’s fun (and slightly frustrating) to make these things yourself since you spend HOURS trying things out to only get thwarted by a lack of knowledge or tooling to get it done right. But sometimes, things work out.
I could miter one leg at a time right now on the mill – which is a total pain in my opinion, wait for Anvil’s unicrown mitering fixture to be produced and pay upwards of $800 for it, or create something myself with what I have already.
With the addition of the large milling machine, the mini-mill had become just a glorified drill press. A good one at that, but not really working up to its potential. So, I dismantled it – unbolted it’s column and headstock from its table, welded a piece of C-shaped steel to my somewhat flat welding/work table, grinded it as flat as I could get it with an angle-grinder, tapped some 10mm holes in the side, and voila’! It’s pretty solid and the Anvil fork fixture lines up real nice on the table. The fork fixture is key – you can set up the forks rake, braze on the dropouts, and just remove the steerer tube attachment from the fixture which makes room to miter the tubes. Once the fork fixture is bolted onto the welding table, it’s pretty solid and hopefully will do the job. I have to use the long 6″ Paragon hole saw arbor, as well as an end mill holder, to get the reach I need, but it’s still really stiff and should be able to pull it off.
The fork legs are attached by the use of Paragon 1.25″ tubing blocks attached by longer bolts to a piece of 1/4″ steel plate. That unit is really solid and doesn’t allow any twist in the fork legs once tightened down. The weak part of this design is the fork fixture’s bar that the fork legs lie upon. Right now, I just have a toe-strap (or two) cinched down to keep the legs against the bar, but I need to figure out something better so there’s no shifting side-to-side of the legs while mitering. Ideas anyone…?