Hey EG!
Mike has neck blanks tapered for both 17.5mm bridges and for 19mm bridges. You just need to specify which construction at the time of spec / downpayment. It’s NOT like Sadowsky, which only has the 19mm neck taper, but will put either bridge on the same taper.
My build a few years back involved a discussion with Mike, in which I told him that my actual neck taper pref was 18mm. So, he used the 17.5mm taper neck blank with no additional carving at build time. He did send the bass with the 17.5mm HipShot A bridge; which I adjusted to 18mm spacing with no problems. I’ve subsequently replaced that bridge with a HipShot B bridge; which is NOT adjustable, but is slightly lighter, and has a more open resonance than the A bridge.
In fact, I’ve replaced most of my bridges with HipShot B bridges. They don’t look very impressive vs the A bridge; but, they sound significantly better to me while playing.
Good luck with your build. FWIW, here is mine with the A bridge set at 18mm, before I swapped in the B. Guess it’s time for a photo update.
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