Tonerider bridge pick up, scale length and cavity routing

[McCreed]

That looks good to me as you have enough thread left on the intonation screw to get the saddle within the margin. FWIW, the treble E strings on my guitars can intonate between 647-651mm. Some are bang-on 648. There aren't always hard and fast numbers with these things. As Simon detailed above, there are lots of variables.

Now, one thing I will say re: using a tape measure vs a steel rule is that the metal cleat on the starting end of a tape measure can have some play in it and vary the measurement depending on whether you're pulling or pushing the tape.

If you do not have a long enough steel rule yet (or can't get one) you can "calibrate" the tape measure by checking it against your 600mm rule. By determining the variable between the pull/push measurements, you can account for it in your scale length measurement. I know that all sounds a bit dodgy, and ultimately a 100cm rule is a better option, but sometimes we have to improvise.

I have a Stanley tape measure that is spot-on in both directions, so sometimes it's not an issue, but I still use a steel rule for critical set-out measurements.

Am I on the right track by sticking with the pre-drilled holes and dealing with the pick up problem by some minor (ie about a mm or two) routing?

That should be fine, but check that there is enough length in the bridge plate that it will cover the extended routing. You can position the bridge using the pre-drilled holes and scribe a line with a fine pencil at the neck end of the bridge. The line will show you how much wiggle room you've got from the edge of the pickup cavity.

[Johnny Bravo]

I re-measured, starting at 100mm and still got the same measurement. Whew.

So, here's my dilemma (apologies for the pedantry but this feels like a "cross roads" moment that I'm going to royally stuff up!).



The left picture is with the bridge in position (using the pre-drilled holes) which gives me my scale length. The second picture shows what I think I will need to route out.

I'm just triple checking but I think I just need to use the existing pre-drilled holes for the bridge and just route out the mm or so (I think this is the way I am heading and means that the front of the bridge lines up much better with the scratch plate). I'm going to use a sanding drum and take it very slowly.

The other option (ie making sure that the pickup is happy first and then fit the bridge relative to that) worries me because I'll have to set the bridge another 1-2mm back and I don't think I'll have enough play in the saddles (ie need longer threads) and have to fill and re-drill the bridge screw holes.

I'm pretty sure that I've answered my own question now but a "You got this, Johnny. I agree with the first option" would be appreciated

Please forgive me - I hope to be a little more adventurous/less needy as I go along.