Official Luthiers Forum!

Well, I had always intended to eventually make some double side guitars, but I would have preferred to have tackled it at leisure rather than have the need thrust onto me by a set of expensive thin sides. But so it goes...

making mdf panels. Marine ply was not in budget...

20 panels to get two 5” molds. 3/4” mdf is 4x the cost of 1/2” at Lowe’s so extra panels it is...

bandaw and carefully create a master template...

make the copies and assemble, check fit...


Sent from my iPhone using Tapatalk

make the ‘inny’ the same way. I hate MDF dust, especially since the router table throws it everywhere. Anyway...I left space for the sides and a backer the same size as the heat blanket...

as it comes off the bender there’s too much tension to squeeze it together safely. This is fine with single sides but not with the double sides, so I heat bent the cutaway area overnight into more precise shape.

everything press fits nicely with no gaps.

add epoxy

clamp

hope like hell it works. I think I should have used more epoxy as there’s was basically no squeeze out.

Wish me luck...


Sent from my iPhone using Tapatalk

On to the non cut side...


Sent from my iPhone using Tapatalk

Looks awesome, Ed. You definitely don’t drag your feet getting to things like I do, LOL.


Sent from my iPhone using Tapatalk

Looks like a good first result...

Well done!

I have til Wednesday the 9th to get it strung up, so...no time to tarry. Still possible...

hi Ed,
If you find places where you didn't get the two layers glued together (found by tapping) you can cut a slit in the inner veneer and squeeze some epoxy in between the layers using a dental irrigation syringe. It's a little bit of a PITA, but better you fix it before the customer finds it.
I use plenty of glue on my lams. I don't mind the bleed through since I pore fill with epoxy anyway.

Hopefully it'll just be alright. The non cut side will definitely be juicier...

I like to leave the sides in the forms for a week to fully cure . It seems to help them stay flatter. If you're pressed for time you might not have that luxury, but leaving them as long as you can would be a plus.

They came out nicely in the right linear shape, but unfortunately there's a little bit of cupping. But I'll be able to cure most of that with some sturdy side bracing. As long as I can flat sand it without going through the .060 outer shell it'll be fine, and that should be doable...

You should put them back in the forms, which will hold them flat until the glue cures a bit more (at least a day or so). You may be able to accelerate the cure with slightly elevated temperatures. If they cure with the cup they may be difficult to flatten even with side braces (they may cause the side braces to cup). It might be better to work on other parts of the guitar at this time if possible.

from West Systems:
for curing west system at elevated temperatures
Final cure time depends on the hardener speed and the temperature the epoxy is exposed to. Generally, higher temperatures require shorter cure times. When applying heat to cure epoxy, don't exceed 140°F (60°C). Leave clamps in place until the epoxy has cooled.

Yeah, it's all gone back in the forms, will check in the morning. The epoxy should have dried in 1/2 hrs, hopefully I got the mix ratio right. I used Lee Valley for the second side...

With your sides laminated, do they have any tap tone at all, or is it tuk tuk tuk?

As to tap tones it seems to vary with the wood. I am relaminating the matched pieces back in the order they were cut and pretty well aligning the grain. BRW tend to be more lively and have a more defined "Bonk" tone than Lauro Preto. The veneers when glued up this way seem to be similar to non laminated plates in their tap tones. With some wood species I think the tap tones become a bit more "glassy" - probably because the epoxy hardens them somewhat.
I don't worry too much about tap tones on the back and even less on the sides. I once interleaved some carbon fiber cloth between the veneers in a layup and the result was the pieces had what I have described as a "tupperware" tap tone. The finished guitar sounded very good, and when I offered my son a choice of guitars he picked it over several others.
I would expect (speculation) that laminating dissimilar woods would kill most tap tones and somewhat impede the transfer of energy to the sides, which I guess is generally what is wanted in double side construction.
Most of my conclusions are empirically based, and someone with a more scientific bent might be better able to tell you how things work.
To me - Tuk, tuk, tuk, seems to work as well as Boiiiinng! when it comes to the back and sides.

P.S. with epoxy there is a difference between "setting up" and "curing". Epoxy takes about a week to "cure" (probably longer to fully cure) It is better to let it cure before sanding it because before it is cured it is still a sensitizer and can cause allergic reactions in some people. Most people rush the process a bit, and sand their epoxy pore fills before they are "cured". Working with it infrequently (as a hobbyist) it might never become a problem, if you do it on a daily basis you may want to adjust finishing schedules to allow for the cure time. Again, I'm no expert on this, and just offering what I've read.

Well, since the epoxy is between the lams, hopefully I won’t have to sand it at all...

I think I can tentatively claim success. A huge fuss and bother in an already stupidly tight schedule, but the sides are saved.

Overnight cure seems to be the trick. There is at least some tap tone now, the epoxy seems to be a shade brighter but not by much.

I am surprised quite a bit that they’re not absolutely dead flat, despite how vigorously clamped they were.

Pray I don’t go through the veneer sanding...


Sent from my iPhone using Tapatalk

There seems to be enough flex in the sides that they will conform to dead flat with robust enough side braces so that’ll be the program...


Sent from my iPhone using Tapatalk

If possible, I like to leave laminated sides in the forms for 2 or 3 days until the epoxy is really cured. Keeps it flatter.

No squeeze out is not unusual. In fact most clamping setups I have used do not create sufficient pressure to cause squeeze out on laminated sides and epoxy. So it is better to not go overboard with more glue which will just result in a thicker lamination due to embedded glue.

Early on I had a couple of failures where the glue got sucked into the wood pores and there wasn't enough to bond the layers together securely. With humidity changes the pieces developed "bubbles" - places where the veneer wasn't bonded together and the outside layer expanded away from the inner layers. So on my next attempts I dryed out the veneer and used more glue (not an excessive amount) and clamped the dog snot out of things, and not only got squeeze out but also squeeze through (bleed through) The finished layups are not appreciably thicker than the sum of the veneers used and after curing are very stable (they hold their shape for years).
Obviously it is the only method, or probably even the best method, but it is what works for me.

Ed,
Those are very nice looking laminations - much better than my first attempts (back then people looked with disdain on anything laminated, so it was learn by doing). They should make a fine sounding guitar.

All I can say is, I hope and I pray they don't separate as it's going to the UK...but to a friend at least so if there is failure it will b slightly less bad..l

"Obviously it is the only method, or probably even the best method, but it is what works for me."

Looks like I "cut around some nots". That should read:

Obviously it is not the only method, or probably not even the best method, but it is what works for me.

Other people have had good success with other methods - there is more than one way to skin a cat.

Ed,
I'm sure your layups will be fine. It was my own parsimonious nature that made me use too little resin and caused the failures. I only mention my pitfalls as a cautionary tale to others who may want to give it a go.
Once you become an old pro at laminating veneers it allows the opportunity to use some exotic woods in an economical way.

Well, the hard part is done, in that the forms are made, so next time will go plenty faster...

When I laminate sides I apply glue to both sides of the joint with a credit card squeegee to make sure the wood is wetted out with the glue. Then I apply a bit more glue to one side and put the two pieces together. If you are using a good brand of epoxy this will never come apart. The amount of surface area in this joint combined with the structural epoxy makes it a joint you never need to worry about.

Wetting both pieces make a lot of sense...

I’d say it turned out alright...

i finished the inside to mitigate the colour difference between back and sides



Sent from my iPhone using Tapatalk