Pickup and bridge location

[ZippyKenny]

I'm in the process of putting together my first guitar, a semi-hollow dual HB with a hardtail fixed bridge, so excuse my ignorance and lack of technical knowledge.

I was hoping one of you learned people could help me out with dimensions for the appropriate placement of the pickups in relation to the bridge and neck. I purchased the neck 2nd hand (as for this version I still working out the building processed and to make one seemed, at this stage, too much like hard work) and have determined the scale length to be 645mm placing the bridge at 368.68mm.

I looking at a set up similar to LP or SG for the PU and was hoping to find out their position relative to these dimensions.

I am sure this will be the first of many questions so please be patient with me.

Cheers

[Nick]

Hi Zippy, firstly welcome to the ANZLF! A brief intro from you wouldn't go astray along with your christian name. User names are useful for logging on but we usually like to talk to each other using first names here, it's just that little bit friendlier and a more personal touch which is how we like to roll .
In answer to your question, there aren't any hard and fast 'rules' governing pup (pup=pickup) positions, what you have to think of is in terms of the type of sound you want from each pup position. As you probably already know, if you pluck the string with a pick close to the bridge then gradually move up the string and you hear the sound change (it mellows, gets more bass frequencies accentuated and overtones added to it) so you want to place the pup at the point of the sound you want. Traditionally the bridge pup gives a more 'trebley' thin sound so you want it as close to the bridge as is structurally possible, usually this means if I'm installing a 'tune-o-matic' Gibson or a Floyd Rose style where there are posts set into the body, I would be placing the edge of a humbucker's cavity about 12-15mm away from the front of the bridge so that I don't get any timber breakout between the bridge post bushing and the pup cavity. Fixed (Fender style) bridges can be closer as there isn't the same loading on the timber between the bridge and cavity. Conversely the neck position pup wants to be nice and mellow so it needs to be close to the end of the neck as you can get. If you are using a middle pup, that's where it goes, equally spaced between the two other pups, more from an aesthetics point of view than any other reason.
If you do want specific measurements of the 'major' brands (sounds like you want to reproduce Gibson styles), then you're probably better to either get some plans of a guitar 'of that style' from somewhere (try our own "instrument plans" section for links or do a guitar plans image search on Google, it sometimes kicks back drawings that are clear enough to read a measurement from) or go down to the local music shop with a rule, grab one of the styles/type you want to reproduce off the wall and physically measure it, never hurts to copy 'established' designs on your first one.
Good luck with your endeavour