How far to scrape top wood underneath the bridge?

[Alexis Magni]

Hey Guys!

First post here in this community. First I´d like to say I´m a fan of Frank Ford and his ways to tackling issues on guitars. Real clever stuff.

I´m a beginner Luthier, learning from my own mistakes, as I have unfortunately no other way of learning.

I decided to practice on my own cheap Acoustic Bridge Removal, so I did. The finish pulled up, but that´s a question for another day.

The main question is, some wood stayed glued on the Bridg. So the top is missing some grain. How should I approach this? I know the Wood has to be flat before I reglue the bridge, but should I scrape the wood around until it´s all level, lowering the overall thickness of wood on the area, or should I fill the gaps some other way?

I hope you guys can help me on this one

Thank you!

Alexis

[Alexis Magni]

I would like first to thank for the engagement. I wouldnt have ever imagined so many useful opinions!

What I learned is that I will never Scrape the remaining Top Wood to even the area, instead, I have to fill the Gaps as best as I can.

I will study the different types of glue. So far, I have only access to Titebond. Hide Glue I have to buy from a special Luthier Shop.

And I confess, these being my first two bridges removals ever, I lacked not only experience, but patience. The first one, I did 3X as fast as I should have done. The second, the Classical with Cedar Top, I spent hours, because the instrument was much more delicate. But my Spatula I think was too sharp, because it sliced the bridge, and left Rosewood untouched behind. Also because the Poly finish was much thicker than I expected, so to get to the botton of the Bridge, Going 100% flat from the top didnt work so much.

I have a lot to learn, unfortunately I won´t have anytime soon more acoustics to try to remove bridges, since these are expensives, but I will practice regluing them for sure! With Plywood, maybe I use just Wood Dust mixed with Glue? Since there´s no point in using Hardwood splinters with that one, right? The other one won´t be done by me, but if it were, I get that you guys would try to remove as most of the original Top Wood from the Bridge as possible, to reglue. Tought Job, I Will try to practice that as well!!

Thanks guys

Thank you guys

[onewent]

Alexis, I think the acoustic guitar community, and especially the 'vintage' faction, agrees that correctly chosen and mixed hot hide glue (HHG) is the best glue for most repairs to older acoustics, and especially on a bridge.  Personally, I wouldn't reglue a bridge with anything but HHG, since removal in the future could be compromised.

My advice, and I've been where you're at, is to source some good HHG (LMI or StuMac is good for starters), mix up a batch and learn to use it .. you'll be glad you did.  There's really nothing mysterious about it, in fact it's really easy to use and very forgiving if you make a mistake and must redo the job.  

Check Frank's tutorial on how to use small batches.  I make a small batch, keep it in a container in the refrigerator, and tear off a small piece large enough to complete my glue job. I melt it in a small cup, placed in 140* water.   This glue in the fridge will last a good 2-3 weeks, and when it does begin to go bad, you'll know by the smell and gooeyness.

Regarding your particular guitar, since it's ply and likely glued with a 'modern' glue, I would try to get some thin plywood, similar to that of the top, and peel the layer you need, and shape pieces to fit the pulled out sections.  Glue them with HHG, then level, and glue the bridge with HHG.  For this you'll need to make bridge and interior clamping cauls, and source appropriate clamps (again LMI and StuMac are good).  The clamps and cauls will be reusable down the road.  Frank's site has a wealth of info on making cauls.

I'd also suggest that you go on eBay or some 'reselling' site and find some Harmony or Kay guitars made in the 50s & 60s.  These are usually decently made guitars, solid wood, and glued with HHG (but not always).  If you're in the USA, these can be had for $50-$100 at any given time, or scour Flea Mkts, you'll find them there, too.  Getting these guitars into playing shape ..neck resets, bridge reglue or remake, brace reglue, crack repair, and so on, will build up your skill set, and, as a bonus, you'lll be able to sell the guitar to recoup your money with some left over to buy more tools.

Don't forget to check Dan Earlewine's youtube videos, another great source of tips for anyone with a computer.

Lots of good advice here, too.  

Good luck, 

Tom

[jbbancroft]

I can understands Rusty’s thought’s now. This a cheap guitar with missing wood on the top under the bridge. Epoxy will fill gaps, so glue the bridge back on with epoxy and be done with it because if the bridge ever comes off in the future, into the dumpster box with the guitar.

My thought’s are, if you want to learn proper repair techniques, use the same repair techniques that you would use on a quality instrument. And that is to first repair the missing wood splinters, then level and clean the area for a nice solid bridge reglue. 

Jim

[onewent]

That's well put, Jim, since there are two ideas here in the responses: 1. learning the repair 'skills' and 2. repairing the guitar mentioned in the OP.

That's why I suggest to the OP to avoid the 'modern' guitar repairs, and focus on older but less expensive guitars, since said repairs can be carried over to 'better' instruments, if and when the time comes.  That is unless the OP wants to work on newer 'Pacific rim' type instruments.  They're different animals with often different repair approaches.  I learned the 'California' neck set method on a Japanese guitar, and it worked!  But I'd likely never use it on a quality 30s Gibson.

Tom

[Alexis Magni]

Amazing Inputs so far guys. Let´s not get into a Glue War Please! I understand everyone here has experience, and each situation requires a different approach. It was indeed a confusing situation, wether I Wanted to fix my Cheap Instrument, or learn the techniques to do to others.

The answer is the second. The instrument was perfect, I removed the Bridge to practice the whole drill. Remove, Scrape and Reglue. Unfortunately some Tearout happened, litttle but it happened. Im talking about my Plywood top, not the one from the Photo, that one had plenty of tearout, and being Cedar, I wouldn´t risk it.

I Want to learn to use Hide Glue for sure, since it´s being used for so many times on some of the best instruments ever made. But I don´t think I can do in time for this repair, because I have to buy it online, and it would be expensive with Shipping .So Maybe on this one I will use Titebond Original instead.

I´m thinking if it´s worth getting some plywood to fill the little gaps. But it´s on such a small area, that I´m not sure if I would cause more damage than good.

Another issue now is bugging me. The top has an arch, subtle but it´s there. The glue will rock if I place it in position. The issue is, first, I´ve been trying to make the bridge match the top arch, instead of making the top flat, to avoid loosing wood. But my lack of experience is definitely showing. ALso, the front of the bridge makes full contact with the top, it´s just behind where the arc if more pronounced. So it´s not a matter of just shapping an arch to the entire bridge, it´s like compound radius.

These are some of the stuff that someone shows you how to deal in 5min, but trying to find in books and videos, you come out hands empty.

[jbbancroft]

You can use any kind of scrap wood to fill in the voids. Also you can glue a flat bottom bridge to a top that has some arch to it. The top is flexible and under clamp pressure the top will conform to the flat bridge bottom.

Jim