Indian Rosewood Bridges coming off Cedar and Pine tops

[kiwigeo]

Yep some like these - could even make some wide pads to spread the pressure across the bridge and straddle over the fan brace under.

Make up a caul to fit under the bridge. Stic a bright light inside the uke and trace the position of braces onto a piece of tracing paper laid over top. This can be used to make up a caul that fits against the underside of the top/bridge plate and clears the braces. A caul is useful to spread clamping pressure on top of the bridge...depending on the topography the bridge. I usually fit a few pieces of cork on top of the bridge wings

[Bruce McC]

Hi Jorge

I live in Canberra. Happy to help if I can. Have sent you a PM with contact details.

[joel]

Here's some pictures of a vacuum clamp I made.

Frame is 19mm MDF.
Silicon membrane is a 2mm or 3mm silicon cutting mat I bought from an art supply store.
Sandwiched together with silicon sealant.
The vacuum generator, tubing and compressor connections are from guitartemplates.com.au (A local Brisbane business I can recommend. They also sell more professional versions of this clamp in large and small sizes. Check them out.)

The vacuum tube is simply a friction fit in the clamp hole. Worked very well for my build.

[NotTheMama]

Here's some pictures of a vacuum clamp I made.

Frame is 19mm MDF.
Silicon membrane is a 2mm or 3mm silicon cutting mat I bought from an art supply store.
Sandwiched together with silicon sealant.
The vacuum generator, tubing and compressor connections are from guitartemplates.com.au (A local Brisbane business I can recommend. They also sell more professional versions of this clamp in large and small sizes. Check them out.)

The vacuum tube is simply a friction fit in the clamp hole. Worked very well for my build.

Wow that is really good. And you've added a valve so that the clamp will hold its vacuum without a pump. A commercial one I saw didn't have that. Thank you for this post. I started a cam clamp today and ordered the Titebond, but I might have a go at a vacuum pump one day.

[NotTheMama]

If you're using straight PVA in your workshop......grab every bottle of the stuff and chuck it in the bin. For luthiery use modified PVA such as Titebond...Titebond I for joints where moisture in the joint isn't an issue. For bindings and other applications where the glue joint will get exposed to higher temps..use Titebond III. For joints where a non water based glue is required (eg fretboard/neck join, headstock veneers) use epoxy.

For bridges hide glue is probably the best choice..it has a higher shear strength than modified PVA and clean up is also a lot easier.

As Alan the oils in Rosewoods can interfere with a good glue joint. I always wipe the underside of my bridges with acetone to leach out some of the oil before gluing onto the soundboard.

Gentlemen,

You are right and I was wrong. I have not yet gotten around to repairing the bridges, but I had need to make 2 mitred corner boxes and the bond using Titebond even on end grain is quite strong compared to Aquadere and other PVAs. (I'll still be fitting splines on these corners just in case).

So thank you for your advice - It's had a positive effect on my woodwork.

Regards

Jorge

[NotTheMama]

I thought I would show my appreciation for advice given by providing an update.

1- Made a small cam clamp with purpose made 3D printed clamp pads - this ensured that the pressure was spread evenly over the bridge while the glue set. Note the groove on the bottom pad - This groove straddles one of the braces that runs under the bridge. Two M4 screws ensure that there's pressure at the thin ends of the bridge.

The clamp bar is made of hardwood (VIC ASH). I tried steel but it was too slippery, and the weight distorted the top while in use. The 5 mm wooden bar strong enough and makes a considerably lighter clamp.

2- Cleaned up the back of the bridges (2 ukuleles), re-sanded the top both around the bridge area and generally, masked the bridge area so that squeeze out was not a problem.

3 - Glued using Titebond original. left the clamp on over-night. Restrung several days later.

All of that occurred several weeks ago... so far so good.

I am now convinced that the No-Name PVA that I was using was either poor quality, perished or both, but I thought that I may as well eliminate any other problems by being careful with sanding, clamping etc.

Thank you for taking the time to provide advice.

Regards

Jorge

[Mark McLean]

OK, now you are a luthier.
Thanks for the update.

[NotTheMama]

OK, now you are a luthier.
Thanks for the update.

Thank you for anointing me, Mark!

Luthier: a person who spends a lot of time building jigs that will help them build other jigs that they can use to help them build stringed instruments.

[Bob_H]

I live in Canberra - I reached out to the local woodworkers guild but I have yet to meet a luthier here.

Hi Jorge - it could worthwhile following up further with the Woodworkers Guild. I left the ACT 12 months ago, but at that time the Guild had an instrument maker's "special interest group" that met monthly, and which included several luthiers. They also have some very useful power tools, such as drum sanders, which are a big investment for a home workshop.