2groggy's 2021 Brotherhood Experiment - laminated archtop

[2groggy]

Those that have seen my build threads know that they are usually, in some way, experimental. This time I will try making a hollow archtop. The front and back panels will be laminated out of maple veneer by vacuum forming them over a solid mold. I'm still shaping the mold, so it will be a few day's before there is anything to show.

I will reclaim a neck that I built for a previous experiment that had mediocre results. The neck is 6 string, 30" scale and takes a string set designed for a Bass VI.

The vacuum bag kit and veneers are from Roarockit.ca .

The outline of the shape started from an acoustic bass design, except I have removed the single cut, so the same mold could be used for front and back. The original design, by L. Mottola, can be found here.

I'll make up the rest as I go along.

 

[RiversQC]

Very cool... I checked out the vacuum setup and now I'm anxious to see this one in action!

 

[erix]

That is going to be awesome and thanks for the link to that site!

 

[TenaciousP]

Those that have seen my build threads know that they are usually, in some way, experimental. This time I will try making a hollow archtop. The front and back panels will be laminated out of maple veneer by vacuum forming them over a solid mold. I'm still shaping the mold, so it will be a few day's before there is anything to show.

I will reclaim a neck that I built for a previous experiment that had mediocre results. The neck is 6 string, 30" scale and takes a string set designed for a Bass VI.

The vacuum bag kit and veneers are from Roarockit.ca .

The outline of the shape started from an acoustic bass design, except I have removed the single cut, so the same mold could be used for front and back. The original design, by L. Mottola, can be found here.

I'll make up the rest as I go along.

This should be a very interesting build! I’m excited to see how it goes. I have actually done some experimentation with making laminated arch top plates myself. I am no expert on this type of construction, but if you don’t mind, I feel like should share some of what I have learned from my own experience. As they say, it’s better to learn from someone else’s mistakes than it is to learn from your own. Haha!

I used the roarockit 1/16 maple veneer as well and I have to say it’s rough. And it’s thick. I found that it needed to be sanded a lot to make the surfaces suitable for laminating. Also depending on how drastic your top arching/recurve will be, it may be too thick to form to your mold. I ended up having to thin mine significantly with a drum/thickness sander. My first attempt was with the veneer at near full thickness and it didn’t form very well at all. I was attempting an ES335 style top that has pretty drastic arches/recurves on the horns. That is where I had most of the problems. But even in the recurve areas of the lower bout I had a few areas that didn’t form well. Some of my problem may have been that I used too much glue. In the recurves, glue would be forced in to those areas because the don’t press down as easily, so I ended up with thick glue lines in these areas. My second attempt which came out very nice, I only applied glue to one of the mating surfaces between each layer. It also consisted of thinned veneer versus my first attempt. Another helpful idea I did the second time around was, after I had my layers all glued and stacked, I used a dry hard rubber roller on the top of it all to work as much excess glue out to the edges as I could. It helps press everything together well and makes for nice thin glue lines. I assure you the vacuum bag will not squeeze out much excess glue. So I recommend doing it before bagging.

What type of glue are you planning to use for the laminating? To avoid spring back, I recommend something that cures very hard and rigid such as Urea Formaldehyde glue. I think I used something called UltraCat that I got from some veneer supply site.

Anyhow, that’s about all the useful info that I can think of off the top of my head. Feel free to ask me any questions you might have, it may jog my memory of something else helpful.

Here are a few pics of my experiments.
Bagged glue up:

This was my second attempt. It came out pretty decent I think. I’ve had it hanging on the wall in my not so climate controlled shop and it has remained nice and flat for nearly a year now.

My first try, not so good:

and it warped after a day or so for some reason. Too much glue moisture possibly...

 

[Freeman Keller]

I'll be watching. I've built three laminated top/back/side guitars but I cheated and bought the plates from someone who did all the work of making the mold and laminating them.

 

[E-miel]

I'll be watching too. Vacuum forming with veneer is something I want to someday try too. Good luck with your build!

 

[2groggy]

It's about time for some pictures.

The shape is likely to be a one-off, so I decided to try steaming and bending the sides with the simplest jig possible. I've got a total of two layers of 1/16" veneer clamped in place but not glued. I'll see how the pieces holds shape tomorrow and evaluate if this is good enough to glue up or if process changes need to be made.

The mold for vacuum bagging the face and back panels is ready for sanding and sealing.

There is minimal recurve so far. I will sand some in. I don't want a lot of recurve, just enough for a flat around the edge as a gluing surface.

 

[2groggy]

Update - the shortcut on pre-bending the side veneers failed - they just sprung back most of the way. I'm starting on making a better perimeter mold tonight. When I'm ready to start bending and laminating the side veneer pieces, I will boil them instead of steam them. That has worked in the past. I just make a long narrow trough out of a steel stud channel for the boiling vessel.

There probably won't be pictures for a couple of days.

 

[2groggy]

The sides mold is getting close to done. Here is the first level. The 2nd and 3rd are rough cut and need final routing against the level 1 pieces.

 

[2groggy]

Work continues, albeit in slo-mo.

Yesterday, I completed a beefier side mold and glued up a test perimeter using the cheap veneer.

This morning I vacuum bagged the first two layers of an arch panel. I'm building from the inner to the outer layers with the middle layer grain running across, like in plywood. I will only add one layer a time, hoping for better results. It will take one day per layer, but I'm not in a rush.

 

[gitlvr]

Nice work!

 

[CapnCrunch]

For those of you that didn't realize that there was a recent Winter Bass build off in the "Bass Place" section of the TDPRI. Several really cool basses were made.

@2groggy, participated and built a mind boggling Tbird inspired bass. I still have a hard time getting my mind around it. Here is a link for any who might be interested in the bass which is his/her avatar.

2021 Winter Build Off - Thunderbird 5 | Telecaster Guitar Forum (tdpri.com)

 

[2groggy]

The test panel came out well - a small but manageable amount of twist and it holds shape. now I am confident enough to build panels with the show surface in the bird's eye maple veneer.

I still don't like the laminated sides. They seem to twist and leave voids. I'll test something else using left over bead and cove cedar strips from unrelated projects.

 

[2groggy]

BTW, does anyone have suggestions on how to cut slightly oversized sheets of veneer? The jig-saw was causing splitting.

 

[TenaciousP]

BTW, does anyone have suggestions on how to cut slightly oversized sheets of veneer? The jig-saw was causing splitting.

This probably isn’t much help, but I cut my maple veneer with a heavy duty utility knife using multiple passes along a clamped straight edge. But I also did my laminating with the pieces still in rectangular form. But if you are wanting to cut your veneer to a rough body shape first, that’s gonna be tough to do without using a jig saw or something similar.

 

[2groggy]

This probably isn’t much help, but I cut my maple veneer with a heavy duty utility knife using multiple passes along a clamped straight edge. But I also did my laminating with the pieces still in rectangular form. But if you are wanting to cut your veneer to a rough body shape first, that’s gonna be tough to do without using a jig saw or something similar.

I used a utility knife for some of the plies. I don't like the sharp corners. I'll probably try using the template that I have for the body shape and a different collar to see if I can rout a slightly oversized shape without splinters. I'm still hoping to learn of a silver bullet.

 

[TenaciousP]

I used a utility knife for some of the plies. I don't like the sharp corners. I'll probably try using the template that I have for the body shape and a different collar to see if I can rout a slightly oversized shape without splinters. I'm still hoping to learn of a silver bullet.

Now that you mention it, using a template and a router would probably have the best results. I’m afraid any type of saw would cause chips or cracks in the edges of your veneer.

 

[10orgtr]

A bandsaw with a fine tooth blade is probably your best bet.
Cheers,
Woody

 

[2groggy]

A bandsaw with a fine tooth blade is probably your best bet.
Cheers,
Woody

This is working quite well, thanks. I'll glue up a panel tonight.

 

[2groggy]

I've got the first bird's eye maple panel in the vacuum bag