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I plan to use epoxy to glue an Ebony board to a Mahogany neck.
I’ll be using Bob Smith #105 slow set epoxy.

How do I prep the surfaces?
Should clamping pressure be less than when using pva glue?
Thanks

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Surprised you're using the 105, thought it was for plastic. I have used the BSI SLOW-CURE™ 30 MIN EPOXY, and Devron 2 ton both work fine.
I've been using the Smith's OAK & TEAK EPOXY GLUE.
I sand both surfaces to 80 grit, epoxy both surfaces, let it soak a bit, clamp lightly is the advice.

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The name catgut is confusing. There are two explanations for the mix up.

Catgut is an abbreviation of the word cattle gut. Gut strings are made from sheep or goat intestines, in the past even from horse, mule or donkey intestines.

Otherwise it could be from the word kitgut or kitstring. Kit meant fiddle, not kitten.

Yes, I go less pressure than with I do when clamping with PVA. You want nice, firm clamping pressure but get it tight and stop when you start to feel a lot of resistance. With PVA glue, I get everything tight and in place and then I go back and torque it down a bit more until it is really tight -- so ideally, that's the part you don't want to do. From what I understand, it is quite difficult to glue starve the epoxy joint if you let it soak into each piece of wood and the long open time allows you to do that. SO don't skip that step. For what it's worth, West Systems is the gold standard in epoxy and is what I recommend to builders for pore-filling and gluing. Maybe give it a try after you've used up all your current epoxy.

My mistake, I bought #205
Thanks!

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I used West and I just made sure to not over clamp but I still clamped with decent clamping force.

Then our apprentice, Link Van Cleave who is one of the most experienced woodworkers I've ever known. He was personal friends with Jim Krenov so much so that Jim willed Link his hand made planes. Link taught woodworking at the Redwood school of woodworking that Jim ran and Link had his own woodworking TV show on the West coast. He was our apprentice for two summers and one of my best friends.

He took me aside and wanted to know why I would not use epoxy for a bridge because of it's high dampening and I would use it for a fretboard. We debated this back and forth with a few other well known, very well known Luthiers and then two of us stopped using it for fretboards. I was one of the ones who stopped and I went back to Titebond original for fretboards.

Apprentices can be as right about stuff as anyone else if it's well reasoned and we stop and actually listen to them and hear them. So just introducing a different view here and relating a story of the student teaching the teachers a thing or two. I can't use names here because he has hundreds of guitars in the field but the other Luthier who stopped using epoxy for fretboards is VERY well know and has many famous clients. He's likely a top ten in the world Luthier.

Something to think about maybe, maybe not and if I oxed anyone's Gore as Todd Stock once said here on the OLF (I'm big on attribution and that was a funny way to put it for sure) that's not my intent. It may be that you would be better off with a different glue for this application.

But as always do whatever you want I'm just relating what I did when I encountered a different view about epoxy for this application.

Most of my necks end up with a bow after using Titebond.
I want to take water out of the mix to see if it makes a difference.

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I switched to regular Titebond for my fretboards a short while ago. Didn't notice any tonal differences but just did it as a matter of convenience (epoxy is messy stuff and cleanup is easier with Titebond). I do notice more movement in the neck when gluing with a PVA glue... so if you are a builder that frets before gluing the fretboard to the neck, then I think epoxy is a really good option for you.

I don't recommend fretting before gluing the board to the neck either. A lot less movement when you fret a completed neck AND there are methods to glue the fret board onto the neck that factor in the backbone caused by fretting.

Simon I didn't notice any tonal difference either but who would? I'm not sure it's possible for either of us to have noticed. I agree on the a lot less messy comment it sure is.

Titebond Extend might be a good choice too although regular Titebond has the open time to do the job.

I use HHG for fretboards now. Doing restoration and repair work I've had to remove fretboards on several occasions so for me it's a service ability issue. I've heard about swelling problems but I honestly have yet to experience it. I use very stiff clamping cauls and clamp no less then 24 hours.

But anyway... That's not the OP's question so... Someone posted a link to a video about modern guitar finishes a while back but it had an intro piece about Titebond too. I'm not sure who the Titebond guy was in this video but I do believe he was like one of their lead chemists or something. Anyway I was quite surprised to hear that I have probably been clamping Titebond wrong all these years too because according to him you only need to snug the clamps down and they had done tests and it really does make a dramatic difference in the strength of the joint.

My understanding of epoxy is that it is similar. Just snug it down and let it cure.

The Oak and Teak stuff is really good on some applications I have used it. Plenty of open time and it soaks into the wood well.

I do epoxy (brand doesn't matter much to me) on fretboards and inlay only. My theory, borrowed from Greenfield, is the less moisture the better at the point that I glue the fret board on. When I do this step, I'm ~99% on the neck shape and only need final leveling on the fretboard. The last thing I need is some additional moisture to push things around. I've not done any scientific stuff to prove this theory, but I've made enough furniture with titebond to understand what pva glues can do to things.

As far as clamping pressure, I get it snug like I would for any other glue joint. I don't hold a lot to the idea that one glue needs this much pressure and another needs that. As long as you aren't white knuckling your clamps, it should all work out in the end.

Think of it this way. Go-bars seem to be universally accepted as plenty of clamping force for the most critical joints in a guitar (aside from the bridge) and they really don't provide much force, as compared to modern F-Style clamps that can generate ~2,000 pounds of pressure. So, maybe just get it tight and let the glue do it's thing.

when you look at the large glue surface area tite bond is plenty strong I used to use epoxy but got to see some acoustic tests at Martin. There is a difference and your better off with Tite bond or HHG .
elmers white glue is also usable dries harder than tite bond.

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John Hall
blues creek guitars
Authorized CF Martin Repair
Co President of ASIA
You Don't know what you don't know until you know it

I would be curious about these tests and what they proved, if you can share.

I should clarify ... I'm not talking about tightening clamps (when using Titebond) as hard as you can. I just get everything reasonably tight and then go back and toque things a bit more at the end. When using epoxy, I think about tightening things on the level of force applied by something like a large spring clamp.

I only saw the result in the Martin acoustic lab couldn't get a copy . They also had HHG and tite bond

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John Hall
blues creek guitars
Authorized CF Martin Repair
Co President of ASIA
You Don't know what you don't know until you know it

Hey Dan:

What I did to counter the back bow was to clamp the board and neck on the most rigid thing I could find such as a table saw table. I still got some back bow so I learned a method from StewMac.

In the StewMac method they suggest using two enormous rubber bands wrapped around and around the neck and fret board as the assembly is cantilevered off the end of a bench. A stick is positioned under the headstock to press up on the neck countering back bow as the glue dries. The method is detailed in the free for download instructions for a StewMac dread kit. I used this rubber band method on over 30 guitars and it worked great. Combined with a double action rod AND the belief that I will be leveling the board before fretting and fretting only after the board is on the neck Bob was my uncle and I had a repeatable process that always gave me good results.

Everyone else: I just got done pushing back against someone here for posting subjective bullcrap so I am going to be careful about if epoxy for a massive glue joint on a neck is a good idea or not.

But I will leave you with something that informs how I think about if epoxy is too dampening to use to construct an acoustic guitar. The question I ask myself is would I use epoxy for a bridge and the answer is no, heck no.

Incidentally, how do you all approach fretboards made of richlite or similar phenolic materials? I heard Martin recommends epoxy to their warranty shops, but the last one that I had in for reglue I used strong HHG …

If both surfaces are wetted with glue, I doubt you could over-clamp a neck with the clamps that can fit on a guitar or bass neck unless you allowed things to get truly out of hand. We used West 105/205 or 206 (depending on shop temperature) for any epoxy work such as synthetic fretboards. Slower cure is usually stiffer for epoxies, so no quick-cure stuff, and no 1:1 mix with fillers and bulking agents in the hardener. Whether epoxy and water-based glues, the neck saw 72 hour clamping, always with a trued I-beam strong-back.

We preferred 192g HHG for new construction or where we could heat the fretboard and surface of the neck. Where we could not, fish worked well if the joint edges were finish-sealed afterwards to avoid the usual humidity sensitivity of that glue.

My experience removing Titebond, HHG, fish, and epoxy-glued fretboards suggests fish was the most difficult to remove, followed by West and System 3 slower cure epoxies such as 105/206, then 192g or 251g HHG, and then Titebond. The one exception I saw was a 1920's fretboard that required a rout-off... not sure what happened to that HHG, but it would not let go even after the ebony was a few thousandths thick and water-saturated/heated (this was a board replacement - unfortunate but necessary). We ended up spending a crazy amount of time on getting the last few square inches of that wafer-thin board off the neck.

In terms of post-removal cleanup prior to reglue, worst was Titebond (more a contaminant than glue IMO), epoxy, fish, then HHG, which usually just wanted a wipe with warm water prior to glue-up. Epoxy is happy to bond to itself with just minor encouragement, so as long as the surface was flat (that can be a pain), a maroon Scotchbrite prep was adequate, given the huge gluing area and low average loads.

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For the times they are a changin'

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Dan I just went to StewMac and downloaded their dread instructions and yes they are still teaching the method that I mentioned and here is a pic of Dan the man using the rubber band and stick method to counter back bow from Titebond original. I did this method many times and it's works like a charm.

Mind you I always leveled the board on the beck and fretting on the neck too.

I do not agree with StewMac or anyone else who frets the board off the instrument. Might be easier for you now but you never will learn to fret an existing instrument this way AND we can take fretting much further when we do not fret the board off the neck. For example I can induce fall-away and relief specifically where I want it at the board level but I can't do this to the board once it's fretted.

Anyway it's a method, it's been taught for well over a decade on this manual and I've used it and countless others have too and it worked for me.

Good luck man!! PS: StewMac sells the 20' rubber bands too if you want to try them.

So that's all that is used to clamp is a rubber band then? Or does he add a clamps to that as well? I'm also surprised that simply hanging it off the vice like that is enough to counter act any warping.

I notice to that in Hesh's pic of Dan that he has the neck entirely finished. I glue the fretboard on to the unfinished square neck. That's perhaps why I don't see this back bow issue in my work, because the neck is so stiff at that point. Nonetheless I like double action rods for that purpose.

JF—

In the photo, look for the stick that is propping up the neck, right at the heel cap location.

I've always used a strip of rubber cut from an old bicycle tire. You just need to place a wrap of saran wrap or something to keep the "black" from the rubber from getting onto the wood.

Yep the StewMac kit comes with a carved neck so he's doing it on a carved neck.

Don's right the stick is the money point of the pic. He counters the bow with maybe 1/8" of forward bow pressure from the stick. It's been a while since I did so take my 1/8" with a grain a salt I don't remember what Dan recommended. The instructions will say though even though we are males, some of us and instructions are a bad word....

But around 30 of mine were built this way and they are out in the wild at this very minute, dang kids....

Anyway I was trying to help our friend Dan here with a way to counter back bow.

Todd Stock used to speak of a "strong back" too and that's a great way as well and I used my table saw until I gave it away to someone for never using it for Lutherie.

Oh ! I see the stick now. LOL! I love the simplicity of that. It's one of those "I know!" moments that works and you just 'stick' with it.

Thanks guys! I really appreciate the guidance!

I think I will use Titebond on my current build and change my clamping pressure.
I have been tightening the holy crap out of my clamps.
Caul against fretboard, no caul against neck (probably a mistake).
I reckon it’s possible that compressing the wood could lead to distortion.

Thanks again, you guys are the best!
Dan

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I install frets after the fingerboard is glued to the neck, the neck is carved, everything is finished, the neck/fingerboard are attached to the body, and the fingerboard is flattened lengthwise and arched laterally. So, the water in the glue used to attach the fingerboard to the neck, and any resulting bow in the neck, are distant memories by that time. Just my preference. For this particular glue joint, I would rather have the repairability of hide glue than the absence of water associated with epoxy. But different folks have different preferences. That's fine.