DIY Workshop: Gretsch Anniversary to 6120 conversion (Part Five)

As our project to convert a well-worn Gretsch Anniversary into a 50s-style 6120 nears its conclusion, Huw Price re-veneers the body – with a little help from his friends.

With a roll of veneer big enough for four tops, this cut-out is used to select the area of figuring we like best

There are times in our lives when we need professional help. Fortunately, my friend Patrick Alexander is a professional and he offered to re-veneer the top for me. He owns a bag press and a vacuum pump, but I had to source the veneer myself and I wanted to emulate the quilted figuring of John Entwistle’s famous 6120 and the example featured in Stuart Walmsley’s Private Collection in these pages back in 2011.

The decision to re-veneer wasn’t taken for aesthetic reasons alone. The top had lost thickness from having twice been stripped and was covered in scratches, so I probably would have sanded through the surface layer if I’d tried to get rid of them. Acquiring quilted maple wide enough to cover a 16-inch body proved problematic. After trying and failing at every luthier supplier and veneer specialist in the UK, I found a company based in the Republic Of Ireland called Maru Wood Veneers.

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This specialised roller ensures that the Cascamite glue spreads as evenly as possible

They emailed sample photos of some suitable sheets, I chose the one I wanted and the veneer they sent was enough to do four tops. I cut out a body template and moved it over the veneer in order to select the area I liked best. Patrick placed the top over the chosen area, drew the shape onto the veneer with a pencil and cut the veneer with a very sharp knife, leaving an overhang of around 1cm all around the edge.

Some sources suggest hide glue would originally have been used to create the laminated top, but that seems implausible because Gretsch bodies don’t de-laminate as a result of steaming off necks. That rules out hide glue and aliphatic resin glues such as Titebond – both of which will ‘let go’ if you give them enough steam.

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This low-tack veneer tape holds everything in position as the top is placed into the bag press and the air is extracted

Patrick recommended urea formaldehyde glue (Cascamite) because it sets crystal-hard and cannot be dismantled, plus it has a much longer open time than some other glues. The key to success was to ensure a very even coverage, so Patrick used a specialist glue roller tool to apply the Cascamite to the veneer’s rear surface.

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The top was flipped over, positioned onto the veneer and held loosely in position with veneering tape. The top was quickly placed inside the press, sealed up and the pump formed the vacuum. There was no danger of the top being crushed because a bag press provides even pressure front and back – about 14lbs per square inch.

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It’s suck-it-and-see time as the top sits for eight hours in the bag press

The overhang allows for the veneer being drawn in, as it conforms to the top’s curve. However, if it’s too great, it can cause bulging up at the edges. It was a pretty thrilling experience to watch the veneer taking shape, but it was eight hours before the top could be removed from the press.

Trimming the top

Thanks to Patrick’s expertise, the veneering couldn’t have gone any better and there were no cracks or bumps to deal with. The top was noticeably heavier and stiffer, with a brighter and clearer tap tone replacing the previously spongy and lifeless thud. Trimming the edges had to be done carefully because I didn’t want to remove any material from the original top.

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The f-hole binding is attached with acrylic cement glue and held with binding tape from Rothko & Frost

The method I settled on was to score most of the way through the veneer with a very sharp blade from the back while holding the top firmly against a wooden board. I cut about 2mm outside the edge then snapped off the veneer by pressing from the front.

A file was used to shave the veneer even closer to the edge, then I trued everything up with a sanding block.For the f-holes and pickup hole, I held the top up against a window so I could see light through them, and I traced the outlines onto the front with a pencil. This time, I scored the veneer from the front and pushed the veneer through, then filed and sanded as before. With all of the excess veneer removed, the top’s tap tone was further improved with a clearer and more distinct ping.

The re-veneer had caused the edges of the upper bout to curl upwards slightly, but they pressed flat easily enough. Where the warped f-hole points had previously pointed into the body, they were now flush with the top arch.

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After 24 hours, the binding tape is removed to reveal a horrendous-looking mess

I also noticed how flimsy they were and realised it would take little effort to snap them.

Clearly, the binding adds sufficient reinforcement, so Gretsch may well have left the points wider and squarer on unbound f-holes because the potential weakness was understood. Gretsch tops from this era were three-ply, and therefore a lot thinner than those made by Gibson and others.

Binding begins

The tedious task of binding the f-holes has to be completed before reassembling the body. Rothko & Frost supplied the ABS plastic binding – a black strip 0.5mm wide and a white strip 0.5mm wide. The ivory white I had used elsewhere wasn’t an option, so the plan is to stain the white later.

The f-holes present some fairly tight curves, but such thin strips are easy enough to bend without heat treatment. Since I had never done any f-hole binding before, I did it in two stages – moving onto the white only when the black layer was complete.

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After much scraping, the binding is finished and – although not up to Terada standards – it looks vintage-correct

This time, I used some IPS Weld-On 16 Acrylic Plastic Cement from Small Wonder Music and some binding tape from Rothko & Frost. Previously, I have used masking tape, but the specialist stuff grips better and it doesn’t tear.

When doing binding work, it’s advisable to cut and line up as many strips of tape as you could need, because you have to work quickly and preparation speeds up the process. The glue took 24 hours to set and Stanley blades and sandpaper were used to bring the binding flush with the top.

Trestle bracing

Besides the Filter’Tron-style pickups, the most significant change in a 6120-style conversion is the installation of trestle bracing. We have covered the history in other articles, but in brief Gretsch responded to main endorser Chet Atkins’ request for more sustain and less feedback by devising a method to couple the front and back plates of the body together. The design evolved over the years, but by 1960 Gretsch was using two spruce platforms attached to the underside of the top braces with the legs glued to a thin strip of wood next to the neck block and two platforms or ‘feet’ under the bridge.

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Daniel Nicholas’ drawing provides the best documentation of 1960-style trestle bracing we have seen

Besides a CAT scan that Gretsch had performed, it’s hard to find online specifics on vintage trestle bracing. Once again, Daniel Nicholas came to the rescue with a fantastic hand-drawn diagram and several photos taken of the inside of his 6120.

To make the trestles, I wanted some old and thoroughly dry pine. My dad’s garage is full of old wood he has been hoarding for decades and I soon found a cobweb-encrusted length of Edwardian floorboard that rang like a bell.

I used my router to thickness it to about 15mm and made one edge dead straight with a bearing-guided bit – the same way I trued up the fingerboard edges. Finally, I cut out two rectangular pieces, each measuring 22cm long and glued a thin strip of spruce onto the back, just in front of the neck block.

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By making a simple sled and flipping over a DIY routing table, you can thickness timber easily and accurately

Having established that the bottoms of the braces were exactly in line with the tops of the neck and tail block, I clamped straight batons across the blocks to simulate the underside of a brace and positioned the spruce pieces on the strip so the front edges were making good square contact, then I clamped the pieces to the baton.

I drew a pencil line along the bottom of the baton, removed the spruce pieces and used a saw followed by the bearing-guided router bit to make a straight, square cut. Following the dimensions Daniel provided, I used a fret saw to turn the rectangular pieces into trestles then clamped them to the underside of the batons.

Fabricating the feet

The back has a decent arch, so while the front legs of the trestles were wedged nicely into position, the rear legs were floating about 1.5mm above the body. Again using Daniel’s dimensions, I cut two blocks and marked their positions onto the back of the body.

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A line is drawn along the underside of the baton to mark the top edge of the trestle brace

After removing the trestles, I placed small squares of sandpaper over the feet positions and sanded the bottoms of the feet to conform to the curve – like the concave equivalent of fitting a bridge base to an archtop.

Once done, I clamped the trestles back in position and used sandpaper taped to a flat surface to skim material away from the top of the feet until they just slipped under the trestle legs. I was looking for a tight fit, but it was important not to have the feet pushing the trestles upwards.

Back on top

At long last, the time had come to glue the top back on. Had it not been for the trestles, this would have been a very quick procedure because the frame I had made for the body had held the sides in position for the best part of a year and everything still lined up.

The procedure began with identifying the exact position of the trestles and gluing them onto the underside of the top braces with hot hide glue. Gretsch used hide glue, and one of its properties is it pulls together the pieces being glued.

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The cut trestle is clamped to the baton’s underside to ensure the leading leg sits properly on the spruce strip by the neck block

I applied the glue to both surfaces and clamped them fairly lightly. Speed is key because hot hide glue has a short ‘open time’, so you need to figure out your clamping strategy in advance and have everything ready to go. It’s generally advisable to have a dry run, too.
Having left the trestles clamped overnight, I removed the clamps, placed the top in position over the body and clamped it down to test whether the front trestle legs were the correct height for the ledge I had glued against the neck block.

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While the trestle is clamped to the baton, the exact position for the ‘feet’ can be marked onto the back

The top’s edges rested about 2mm above the neck block, so relatively little clamping pressure was needed to bring the top flush. In fact, a tight fit like this is preferable because clamping the top onto the sides will create enough pressure to ‘clamp’ the trestle to the ledge. Next, I fixed the feet to the back with ultra-thin double-sided tape and re-clamped the top to test the fit.

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After contouring the base and levelling the top, the foot squeezes into position

I had to sand a tiny bit off the front edge of the bass-side trestle foot, but I was pretty delighted with the way everything lined up. With the double-sided tape removed, I applied hot hide glue to the back of the body and the bottom of the feet. Placed in position, the hide glue quickly grabbed the feet and I dry-clamped the top once again to get some downward pressure on the feet as the hide glue dried. You don’t need much clamping pressure with hide glue.

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The trestles are offset because of the cutaway, but both sit squarely in the spruce strip and the feet

After a few hours, the big moment had arrived as I set about gluing the top. Although Gretsch used hide glue, I realised I wouldn’t have enough time to get hot glue onto all of the surfaces before it cooled down, so I decided on Titebond Original instead.

The Titebond was spread all around the rims, over the neck and tail block and on the underside of the trestle legs. To make alignment as quick and easy as possible, I kept the body in its frame and I used the same indexing pin method that worked so well when I glued the fingerboard back onto the neck. There’s no real secret to this – just use a padded clamp wherever you can find space, wipe off the squeeze-out while the glue is still wet and resist the temptation to remove the clamps for at least 12 hours.

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The frame does its final job as the body is reassembled with Titebond Original glue and copious clamping

I’m pleased to report that all the wood used in this restoration has been older than the guitar itself and hide glue has been used wherever possible. The trestle bracing adds less than 100g to the weight and the glued top makes a satisfying and encouraging ping when tapped.

Figuring out how to make and fit the trestle bracing wasn’t easy, and judging by the direction of the old glue drips, I suspect the Gretsch factory glued the top before the back. This old Gretsch is some body binding and a neck set away from being playable again, and you’ll be able to see how it turns out in our sixth and final instalment.

Check out the other parts of this project here.

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