So, I’ve just fitted the front wheel into my new Mastodon fork, with the Hope conversion kit already in place to space the disc outboard and with the new larger end caps in place.
The wheel fits into the fork snug & central but the disc is about 5mm or so too far inboard to match with the caliper, when it is pushed over as far as it goes.
Anyone know what has gone wrong with the compatibility here?
Do I simply need more than one Hope disc spacer? It’s like the ovalised bolt holes in the caliper don’t allow the caliper far enough across towards the spokes.

Sounds like you have an older rear disc spaced (RDS) front hub, where the disc mounts sit further inboard than the newer FDS hub the hope 150 conversion kit is designed for. I got round this by using the Superstar centrelock to 6 bolt adaptor as a spacer. Alternatively Hope do 2 and 1mm spacers you can use to further space out the rotor in addition to the black spacer. A bit of google will tell you the exact difference between FDS and RDS front disc spacing. Its about 5mm.

Are you trying to fit an RDS hub front wheel in an FDS fork?

https://www.tritoncycles.co.uk/frames-forks-c6/frame-fork-spares-c152/problem-solvers-fat-fork-disc-adaptor-p11825/s33072

Yes, to both comments, I reckon. I’ve ordered a pair of thin spacers to add to the existing large Hope disc spacer from their kit, already on the bike now- Just as well the original bolts provided by Hope are long enough to have enough thread for this task… Having all that ‘spacer’ in there is less than ideal, I’ll need to be canny about the amount of torque applied to the bolts to make sure it all stays together.

Thats the best way, the other way round where the disc is too far ouboard is harder to solve….