How do I set a bridge plate in a new build?

[Brad Elbein]

I'm a mandolin player and neophyte builder, so why exactly I have the beginnings of an acoustic bass guitar on my work bench is unclear.  It must involve trying to impress my younger son. 

Anyway, I'm at the point where I need to set the bridge plate on the underside of the top.  But--simple question--how do I "mark" it?  I understand that the bridge should sit right about 1/2 way back on the bridge plate, and I know that I can approximate that by measuring nut to 12th fret, then 12th fret to bridge location.  But my question is much more basic: once I find that place, how do I mark it so it's "readable" from the top when it's put together?  Or do I just approximate and not worry?

Thanks in advance for a gentle answer to an undoubtedly stupid question.

[Ned Knepp]

Do  you have a hole in the center of the sound hole or, perhaps have the sound hole cut out? Measure from there to the center of the bridge location and transfer that measurement to the inside of the plate. You should be as accurate with the measurement on the bridge location as you can be but, unless you have very little margin on the bridge plate, you should be ok doing that.

This is a measure twice, or more and "cut" once process. It's no fun removing a plate you  already glued in when you realize that you didn't correctly position the bridge to begin with.

[Len Biglin]

I would probably copy an known instrument , but whatever you do , remember that the body/neck joint will probly be 14th or higher fret , so you dont just come back 12 frets from the body join . I think I would trust that if the inside is ok and the outside is ok , then no need to align more than that.

[Mike Kolb]

Are your pin holes for the strings in the top yet?  If so, take your bridge plate and lay it on the topside of the top (and, of course, just where you want it to sit when it's underneath)....  From inside, through the soundhole, mark the bridge plate through the two outside pin holes with a pencil.  Take the bridge plate off, transfer those pencil marks to the "up" side with a red marker or something readily visible.  

When you're ready to glue, just line-up the red marks to the outside pin holes and -voila'- you're there. Magnets for clamping and easy repositioning are helpful here. 

[Brad Elbein]

I think it's the "pin holes for the strings in the top" that I'm asking about.  Can you tell me more?  

[Mike Kolb]

Sorry, I thought the pin holes were drilled, and both the bridge & bridge plate were not yet installed. Are you looking for the correct location of the holes?  

In any event, the all-important placement is the saddle position (including it's compensation)  and everything else revolves around that. The bridge pad will probably be generous in size, so there's some "floating error" that's inevitable and shouldn't a big issue as long as you're close. 

Good to make sure the path is clear underneath when you determine where the pad goes, as it's easy to rub-up against braces and the like. 

[Brad Elbein]

Mike, I'm sorry, I'm starting to sound extremely stupid, I know.  My question is so basic it's embarrassing.  The guy who put together this kit ("Kit" in the sense that the sides are bent, and that's it) marked the string holes on the back of the top.  My question is: do I transfer them to the top by measuring, or by drilling pinholes through the top?  Your comment about "pin holes" and something I saw somewhere made me think that that's the right way, but before I go putting holes in my top, I figure I'd better get some advice.  

[William F.Eden]

Why don't you just send use a picture of what you have then mybe we can help you out.It is getting hard to tell what you are asking about a bridge plate or a bridge??????????? Bill............

[Jeff Highland]

Sounds like you need a plan to go along with this "kit"

As Len said, it is unlikely that the neck joins at the 12th fret, so you need to know things like scale length , compensation and the fret at which the neck joins the body to determine where the bridge saddle goes and hence bridge pins and bridge plate.

I measure everything from that neck/body junction.

[Ned Knepp]

Like Jeff said, you need to know the scale length of the guitar before you can properly position the bridge or the bridge plate. It's ROUGHLY twice the distance from the front edge of the nut to the 12th fret, no matter where the neck joins the body. BTW,  you need to pretty accurate with this measurement. I don't know if I would want to trust someone else's markings on the inside face of the top. It's a pretty important measurement to take on faith. 

 You need to know what scale length your kit was designed to use and you can figure it out fairly easily if your fret board is already slotted. Even if it's in the instruction for your kit, double check the fretboard anyway. 

[Ron Ellison]

It's not altogether clear how much 'kit' you actually have. Do you have a neck and fretboard? Is the fretboard slotted? Do you have a bridge and does it have a saddle slot and pin holes?

If you have to make these yourself then you have a lot of research to do. If you have a neck and a slotted fretboard then you can find the string length from that. The Stewmac.com site sells, among other things, a gadget to accurately position compensated saddles. It also has an article on how to use it. All in all there was enough information for me to make my own gadget and use it successfully. You may prefer to buy. Photos would help. Good luck.

[Steve Williams]

This guy had a good idea

http://www.13thfret.com/saddlejig.shtml