Arch top guitar to pin bridge conversion......

[Kerry Krishna]

 Has anyone here actually done this work? Out of the 14  Kay Kraft two points that I have right now, I have 2  that are both written off candidates for this work, and I have done the initial measurements and am pretty sure that I can pull this off. 

 I will have to make a neck for one of them also if I decide to go forward on that one.

I will be taking the backs off and rebracing them with Martin x style bracing, and will do a two bolt conversion to the neck, and replacing the endblock also. Before you ask, I have a pretty good idea what I am getting myself into. Some adult supervision from the Forum would be great.

 I will be doing a photoessay of all my work for the KK Facebook site, and I have a tendency to post both the dead ends and the successes of my work.  Thanks for any comments... 

[Kerry Krishna]

Anyone?

[Tim Mace]

What type inserts for the bolts are you using?Sounds like worthwhile excersize......neck flat to body?What neck angle?Solid carved top?

[Ned Knepp]

I've seen a few instruments with this configuration for sell on ebay and such but haven't played or heard any of them. It sounds like an interesting idea but I can't help  but wonder how freely the top will move in this configuration what with the reversal of forces on the top and all

I think I would consider using something like the bracing used on the Tacoma guitars. The Long "A" shaped bracing of the Tacoma would appear to be closer to what you will probably find inside of your guitars. and the cross brace they use to support the bridge shouldn't be too hard to do. 

[Ron Ellison]

Isn't bridge height a problem? Arch top guitars with floating bridges surely have higher bridges than flat tops. Maybe it could work instead of a neck reset though.

[Kerry Krishna]

 Tim, solid 'pressed' top, not sure about the bolts, probably what was posted on the 'floating bridge to pin bridge' discussion, and the neck angle will be dictated by the arch in the top of the guitar.

 Ned, I really am wanting to do Martin style X bracing, mainly because it is the bracing that is already in most of these Kay Kraft two point arch top guitars, believe it or not!  

Ron, the bridge height will not be a problem because I will likely be making a neck, so I will be able to figure it out... 

[Tim Mace]

X would appear to be the most likely to succeed.Check out Stefan Sobell's site for contouring the fit of a pin style bridge on an Archtop.Finger board extension float freely or supported?Here's a pic of the bolts

I believe work great!

[Ned Knepp]

If you already have an X brace It shouldn't take too much more to support the bridge.  Is it correct to assume that the ends of the floating bridge set on the lower legs of the existing X brace? If so, you should be able to fit a bridge plate in the same area. I think I would pre-bend the plate to match the interior arch. 

 

Do you happen to have any interior shots of one of them that would show us what you have to work with?

[Kerry Krishna]

Here is the bracing of the 12 fret one that I have Ned. The 1st guitar I will be working on doing this is a tenor, so a smaller body and quite different bracing than this. It is half and half ladder/X bracing, and is a horrid job resembling something that an architect would design, not a Luthier. It has to come out.  I would rebrace it with something even closer to Martin X bracing...

 Tim, I am thinking that the fingerboard extension will be glued down. I went to Stephan's site, and after navigating around a bit, I could not find any such pics. Could you send me a link?

 

[Tim Mace]

there's a lot more detail image wise...I found the news 2004 to be a good example...Martin Simpson model has a pin bridge fitted to a carved top though it's not f/hole.The more you look the more you find......

[Ned Knepp]

Well that's a lot closer to "flat top" bracing than I imagined. All of the X braced arch tops I've seen have an X and only and X. I think you have a pretty good grasp on what you need to do. Have you tried to mock up anything to assess the bridge to neck relationship?

[Kerry Krishna]

Ned, I have not done a mock up yet, still thinking about the bracing.

[Ned Knepp]

With that wide X you might consider a small brace under the bridge plate just to help support the back edge. I don't think it would need to be very large since the top is already arched but it should help distribute the pull over the arch and allow a much thinner bridge plate.