It’s hard to know how beefy to build a disc-specific cyclocross fork, especially when you know it’s going to be ridden on trail, over big washboards, through winter, and with room for fenders.
You want to make it light and ride smooth but strong enough to last.
I first built a lugged-crown fork (Nova 7deg offset cross) and used Nova’s new fork blades that were drawn beefier specifically for disc brake usage. They are pretty heavy but serve the purpose (28 x 20 x 390 long, wall = 1.1mm top / 1.4mm bottom). The bottom of the leg is pretty big at 17mm diameter so I used a set of the 1″ Paragon hooded dropouts. Fitting tab dropouts would be possible but IMO would need to be done the “Iglehart” or “Potts” way instead of simply slotting the leg and brazing. Axle to crown is 395mm and it has 48mm of rake. I don’t think many would want to race on this fork, it’s just too much heft at over 2.3lbs (without eyelets for fenders).
Robonza Joe in Colorado is getting a Mountain Cross frameset and he wanted a Yo Eddy segmented fork so I built one using True Temper FB4 legs (1.3/0.9mm wall profile, round tapered legs, 1″ diameter at top, 14mm at the bottom). The crown pieces are 1 x 0.049″ 4130 and it’s a True Temper straight 1.125″ steerer. The dropouts are from Paragon and have an eyelet for fenders. Axle to crown is 400mm and it has 48mm of rake. I likely could’ve used the lighter thinner-walled FB7 fork legs but because I know where Joe will be riding and what he will be riding I decided to be safe, especially for disc use. This is really a MTB fork that only fits 1.7″ tires, or a cross fork that fits 45’s, you choose. It’s still a heavy cross fork at 2.29lbs with an uncut steerer. As comparison, both forks are over 3/4lb heavier than this random (non-disc) Bontrager carbon fork I have in the shop.
Forks take me a long time to build, but I do love the results. There’s just something about them that is very satisfying and they do top off a custom frame in a way a carbon fork just can’t.