Thompson Belly Reducer

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Thompson Belly Reducer

Item # 1380
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Thompson Belly Reducer

A lifesaving tool set for older acoustic guitars! Helps correct soundboard bulge caused by string tension, without replacing the bridge plate.

Excessive soundboard "bellying," caused by string tension, can make an acoustic guitar difficult to play. It can even damage the top, bridge plate and bridge. Replacing the original bridge plate to correct the problem is a time–consuming job that can unfortunately reduce the value of a vintage instrument.

Respected luthier and restoration expert TJ Thompson developed a simple tool set, the Thompson Belly Reducer, that can fix soundboard bulging without permanent alterations to the top or bridge plate.

The Thompson Belly Reducer is a set of five precision-machined aluminum tools: convex flatteners for vintage–style belly and rectangular bridges, and concave flatteners for the three most common bridge plate shapes.

Aligning the cauls is now easier—magnets are embedded right into the tools. Magnetic cauls stay in place (hands free!) while installing and tightening the clamps.

They're designed for use with the bridge removed from the instrument, and are effective for bridge plates that have been installed with hide glue, aliphatic (yellow) glue, or PVA (white) glue. Simply match the appropriate flatteners to your guitar, heat them to 150 degrees F, dampen the wood on the bridge area and bridge plate, and clamp the flatteners into place for a day or so.

Instructions included.

TJ Thompson recommends using three Ibex bridge clamps.

Trade Secrets!

Fixing a potbelly with the Belly Reducer

Dan Erlewine's got a Martin with a potbelly: string tension has pulled the top into a hump on this 1928 0-18. To make things tougher, the guitar top's encased in a thick layer of epoxy finish! It's an interesting puzzle...

Product Instructions

Thompson Belly Reducer Instructions

The Thompson Belly Reducer is a simple tool designed to get rid of the bellying without making permanent alterations to the original guitar top.

Customer Reviews

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(Customer's Reviews)

Tried it three times with no noticeable difference. By the time you get it installed it has lost all heat content. The guitar I used it on is not severely bellied. If you closely inspect the bellying on a guitar you will see that it is primarily behind the bridge, not under the bridge.

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StewMac PDF Catalog, page 30 See Thompson Belly Reducer
on page 30 of our StewMac Catalog PDF

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