Official Luthiers Forum!

Hesh here tends to be a guy of action and we've talked enough about the need for serviceability. As such I thought that the next step is to give you a specific view from the trenches of how you can begin to build more serviceable instrument right now, today. There's more too, lots more but this is a good start.

Nuts: Only glued in with one small drop of glue, CA is fine for this, one drop, only one drop.… Nut channels should be flat or hollowed a bit and uniform in width the entire length. Nut channels should not have the head plate create a dovetail burying the nut. Nuts need to remain removable so they can be serviced and/or replaced. One of the most common thing that we are asked to do with small builder instruments is replace the nuts and saddles for cosmetic reasons and if the material was not bone.

Truss rod access area. We often see truss rod access difficult on small Luthier built instruments. Either there is not enough wood removed for the tools at the headstock end or the adjustor is submerged in the bottom side of the top for sound hole adjusted rods. Truss rod adjustments especially on new guitars need to happen and should not require a Luthier with a tooled up shop to make it happen. Build for easy access and adjustability.

Frets: How are frets serviceable? Moreover how are frets not serviceable? Some builders who have difficulty with fretting may enlarge the slots on the extension and ep*xy the frets in. This is not uncommon and it destroys the fret board for future, proper work. Ep*xy is a poor choice for frets as well for it’s dampening properties and it’s a bear to clean out of slots making the instrument less serviceable.

You may not care the hoops that a repair person has to jump though but I guarantee you that we will charge the client and tell them why they are being charge additionally too….

Bridge plates: Believe it or not bridge plates need to remain serviceable. Slotted pins, poorly fit pins and string combinations can destroy bridge plates as can a crack in the bridge from the same poorly fit pins. RH swings, loose braces, top distortion, creases in the plates formed by deteriorating pin holes usually from slotted pins all can require a bridge plate to be replaced or at least capped. Bridge plates with coupled braces, tucked edges, finish on them all make the process of removing a bridge plate with careful application of heat more difficult AND more dangerous to the instrument. I don’t care if Somogyi does couple his braces to the bridge plate it’s a nightmare for the guitar owner and repair people if that plate ever needs to be serviced. What can go wrong and does it really happen? The top center seam can come apart and yes it happens, sadly….

Bridge pins: One of the simplest things you can do to keep your guitars serviceable AND avoid repairs all together to the bridge plate is to use unslotted pins. Lots in the archives for you to find out why. I’ll add that 3 degree pins without slots although hard to find are superior to five degree unslotted pins. All my guitars were built with 3 degree unslotted pins.

Truss rods and CF reinforcement: Necks need to be adjustable via the truss rod and string tension. Some small builders see value in an immobilizing the neck with the application of CF rods. It’s a bad idea and I wonder what problem someone is attempting to solve with any CF in a neck at all…. Players may want strings that have way more or less tension than you anticipate, drop tunings, etc all require adjustability for the neck. Double action rods are a God send and have saved countless guitars form the scrap heap. Wood moves, guitars are abused and we need to be able to adjust things back to where they should be. Double action rods often save the day especially in our business. If a neck is also too stiff because of CF rods it impacts adjustability for no good reason and at additional expense and I wonder why the hell anyone would go there….

Bridges: Bridges lift for a variety of reasons including loose braces, bridge plate damage, poor gluing technique, not clearing enough finish, poorly fitted bridges and RH swings that exploit any of the other reasons and combine to lift a bridge. As such bridge should always be glued to the instrument in a manner that remains serviceable. Some examples of unserviceable gluing techniques are clearing finish to the bridge perimeter, not clearing enough finish, using unserviceable glues that will not release with heat low enough that it will not bubble the finish.

When finish is all cleared out under the entire bridge come bridge reglue day any error will be visible making this unserviceable. We clear to around .010” of the perimeter.

A common issue that we see with small builder instruments and bridge related is that the saddle slot is not flat. When a pup (pick-up) is installed and the bridge saddle slot is not flat the UST if present, under saddle transducer will have differing amounts of downward pressure from the saddle and strings causing balance issues for the performer/player. Even if your saddle slot was once flat and you “smashed” the bridge which is flat onto a domed top of a guitar you just made the saddle slot no longer truly flat. Beyond routing the saddle slot on the guitar after the bridge has been glued and installed there is not much that a builder can do about this but I did exactly that, routed my slots after the bridge was installed on the later guitars that I built. The result is a truly flat saddle slot and no issues with pup balance.

Recently some f*ctories have been inlaying… the bridge in a pocket carved into the top. Very poor practice in so much as the top fibers are now cut and compromised and when that bridge lifts, and it very well may lots of them do it will tear up the top… bigly…

Finishing the inside of the guitar. This was started likely by the classical guitar crowd and with a good intended reason. Classical guitars have always suffered from poor projection and low volume that results from nylon strings and less torque on the bridge. As such it’s much more important to classical producers to compensate and do what they can in a variety of ways to enhance projection. One way to do this was to build on the edge with thinner plates and less massive structures.

What resulted was also guitars that may be more prone to cracking if abused and not properly humidified when need be. As such classical builders learned that finishing the inside can enhance projection although I’ve never seen any hard evidence of this and it’s also thought that the interior finish belays the ravages of RH swings for a few hours.

Most of the cracks that we see…… developed over months of low RH and any interior finish would not have helped one bit. Time can compensate tor severity of an RH swing with an extended duration. Or a dry guitar for months is going to crack regardless of interior finishing and I would even make the case that equalization when the instrument is exposed to decent humidity will now take longer extending the risk of cracking.

We don’t like finish on the interior and it creates other issues with finish that may have to be removed to service various parts of the guitar.

In the past year out of over 1,000 guitars that we were inside of we likely didn’t see more than one that was finished on the inside.

Other issues: There’s more but I have to work for a living and don’t have more time to share preparing this stuff for you. If you subscribe to what I’ve suggested here though you will have eliminated around 90% of the serviceability issues that we frequently and commonly see.

Again don’t feel bad I did some of these things too until I learned about repair. What’s important now is what are you going to do about it now that you know?

Thanks

You mean use unslotted pins [GRINNING FACE WITH SMILING EYES]

_________________
Steve Smith
"Music is what feelings sound like"

God I'm a dotard... Thanks Steve my friend. Not getting any younger here. I've been called Blind Mellon Luthier before too with good reason...

None of us are getting any younger You and Dave made sure there were a number of things I would NOT forget and using unslotted pins is just one of them.

_________________
Steve Smith
"Music is what feelings sound like"

Thanks Hesh, I am guilty of just a couple but will consider changes to my process. I clear the finish to the edge of the bridge. I understand your point as I have spent a lot of time cleaning up the finish after gluing on bridges that were cleared to the edge, I just never put that serviceability aspect when evaluating how I wanted to both mask and clear the finish on the bridge.

_________________
http://www.Harvestmoonguitars.com

I guess we have some different ideas of what is service and what is a repair.....

To me service is routine cleaning and adjustment. Anything that would be done at a set up is service. I would go as far as to say level and crown frets is service work.

But bridgeplate wear from string balls, lifting bridges... these are repairs. These things are not meant to happen and they are not part of routine maintenance which is what service is actually about. By that rational broken necks are service work as are gluing cracked tops..... But most would agree those are repairs.

So I have a distinction between serviceability and building better guitars. One includes the other and the other does not. If one strives to build better guitars than easier serviceability will follow. But simply making things easier to service , as I have said before, becomes planning to fail at a certain point. For example I can make the truss rod easier to adjust by moving it 2" closer to the soundhole. But that impedes function at the other end.... what was needed was a longer rod or other change in actual design. And if given a choice between proper function or ease of adjustment I'm going with function every time. Cause if it don't function it don't matter.

So to me it is more than just point of view, more than semantics. I have long held and taught all my apprentices that approach is everything. The outcome is determined before you ever pick up a tool by your thought process and approach to the task. First question to every new guy was "Do you do wood work or do you work with wood?" Their instant off the cuff response often told me all I needed about them and what to expect of their work.

_________________
Brian

You never know what you are capable of until you actually try.

https://www.howardguitarsdelaware.com/

Yes.

Actually I'd probably get confused and ask what exactly you mean by each of those terms, since they're so similar yet you must have a clear difference in mind or you wouldn't have asked.

Blind Melon Luthier...

You had me at “bigly”


Sent from my iPhone using Tapatalk

So one should never use carbon fiber bars ever? I will continue to use them sparingly when necessary.

Bryan I am not talking about what a service and what a repair is. Instead I speak of building, engineering, crafting instruments in a manner that the things that are known to require service in the future that this service is not impeded by the builder or how it was built.

I don't understand what's difficult about that to understand. Or, in other words we know that a car will need new tires one day so we make wheels that can come off and wheels that can have new tires installed..... Strings need to be replaced so tuners, some tuners are engineered to accommodate string replacement. One tuner is capable of cutting excess string.

Bridge plates require servicing at times so keep the stinkin braces and finish off them..... This is not difficult stuff unless you simply want to be difficult.

For Christ sakes the very glues that we use are intended to be serviceable with HHG being a stellar example. Access is often restricted when say regluing a brace so we use a glue that can be added to without being cleaned out and also reactivated with heat and moisture precisely to support future servicing if needed. That's serviceability.

Maybe it's useful to talk about what's not serviceable such as ep*xying a dovetail neck joint.... or bridge plate or even a bridge for that matter. We don't use CA for braces because 1) we are not building model airplanes..... and 2) it can't easily be released nor can we just add to it for a reglue.

This is the second time that someone is pushing back on the very definition of the word "serviceability" and there are now several of us shaking our heads over this. What's the point of NOT encouraging builders to build in a manner that their clients can have things serviced in the future without having to pay more than necessary or even be denied service because serviceability was ignored by the builder originally.... That's a rhetorical question.

"Never" is a powerful and specific word. Use them all you want and wherever you want...

My point is that over stiffening necks when only about 20,000,000 necks were made in the last decade without CF may... make adjustments and even saving a dried out instrument impossible.

It's too bad that some here have to get defensive about a very simple concept that is commonly taught in Luthier schools. This is not intended to be personal and if you end up getting any on ya I have put myself out here first admitting to having used poor... practices... myself until I learned better.

This thread is intended for folk who are interested in learning AND are keen to know how their work would be vetted by industry pros who see the ravages of poor practices every day.

This is a great thread. Thanks very much for sharing your experience Hesh.

Thanks Mr.B!
I feel better about my work since the majority of the issues you consider good building practice are methods which have been gradually adopted into my last few instruments.
This is only possible by the great information shared by the members here.
Thanks to all who generously impart their knowledge.

_________________
My memory is so good, sometimes I remember things that never happened.

Hesh, I am only Guilty of one sin on your list and that is clearing the full area under the bridge.
You made me a convert to unslotted pins a long time ago, never looked back....
I figured the rest out on my own in the last 45 years...

[quote=

Finishing the inside of the guitar. This was started likely by the classical guitar crowd and with a good intended reason. Classical guitars have always suffered from poor projection and low volume that results from nylon strings and less torque on the bridge. As such it’s much more important to classical producers to compensate and do what they can in a variety of ways to enhance projection. One way to do this was to build on the edge with thinner plates and less massive structures.

What resulted was also guitars that may be more prone to cracking if abused and not properly humidified when need be. As such classical builders learned that finishing the inside can enhance projection although I’ve never seen any hard evidence of this and it’s also thought that the interior finish belays the ravages of RH swings for a few hours.

[/quote]

May I say WTF? Hesh, how many classical guitars have you worked on? Where do you get these ideas? Ignacio Fleta is the only famous classical builder I know of who finished the inside of his instruments. "Poor projection", "Low volume"? I guess all the world's classical guitarists are just idiots, struggling along with inferior instruments. I'll add that neck angle adjustments on a traditional Spanish heel are no more difficult than a dovetail neck-reset. Maybe the trenches you've been in are a little narrow.

Hey Brad! I've learned a lot from you though the years and you've been at this longer than I have too. My personal OM is built with BRW that I got from you back in the day and it's doing great. She says hello

One sin is not much (or I had better be stockpiling sun screen...) and you know none of this should be considered inflexible or always how to proceed. I can think of several of the top repair shops in the country that clear all the finish out from under a bridge making this a pretty minor offense and at least there is clear benefit to doing this too by expanding gluing surface.

The only place where it may compromise a future repair is it's easier in the removal or reglue process to have the cleared finish show and/or some finish touch up will be required. No biggie and I'll admit that the rabbited pocket thing that we and Collings do is not all that easy to do and you have to be tooled up to do it too.

With these considerations in mind I'm likely in the camp of clearing nearly to the perimeter, not rabbiting unless you can and do meaning you are tooled up for it and going for a decent, non-forced fit.

Anyway again no biggie and glad to hear that you use unslotted pins, that's huge and slotted pins are a very common cause of damage to guitars AND a major reason for a guitar to lift a bridge when the damaged pin holes attempt to connect and cause a crease that throws the bridge topside. We see it every day.

Thanks for your comments Brad.

Thanks for the comments from folks here interested in providing more value to our possibly mutual clients and/or who are just into doing the highest quality work that we can. Much appreciated.

Regarding Mr. Reid.

Not sure where you are pulling the subject of Spanish Heels from, I didn't mention it you did.

Regarding trenches not to be comparing endowments although I would win there too my two man shop serviced around 1,167 instruments last year of which 90% were guitars and 4% were classical guitars. We don't sell any products, not even strings anymore and all of our revenue comes from our labor. About a year and a half ago our business crossed over and beyond the $1,000,000 mark for our earnings exclusively repairing guitars. We continue to grow and our biggest problem these days is our following is so very large now it's difficult to manage everyone's emergencies.

We have famous clients, folks fly in from even out of the country to reserve our talents for a day or so because they want us and only us to work on their guitars. We keep their confidentiality though as they expect and we would anyway. I'm about to post a pic of Frank from Florida who let me take his picture. Frank teaches guitar including classical guitar in Florida and every year he drives around five guitars to us since we won't accept shipped in work. Frank does not want anyone else working on his stuff and he's said so too.

The vast majority of the guitars that I see with interior finish are classical guitars. We do and have worked on some of the top names in the classical world too in so much as we have 50,000 university students within ten miles of our repair shop. I've never seen one of yours or even heard anyone else talk about a Reid so I can't comment on your trench and think it was a stretch to disrespectfully comment on mine. You don't know.

But our trench may not be all that wide and that's intentional you have heard me in your trolling likely say before that one of the most common reasons why Luthiers fail in the commercial market place is trying to be all things to all folks. We don't try to do that and reject around one out of three guitars that come our way for reasons usually associated with the builder be it a f*ctory or small builder didn't have a clue about serviceability or just didn't give a *** about it or their clients.....

Our trench since you like my metaphor is very deep though. We have proprietary tooling that many others have built now that Dave Collins invented. Our repair volume is so very high that in a single day I may work on more guitars personally than many shops see in a week. My attitude has always been bring it on I can take it and just like my early days here on the OLF I remain very hungry for knowledge and hopefully always will.

I know there are others here who are interested in learning and growing with their building (or repair) and that's who I'm hoping to help as I was once helped here long ago when we had more real pros here. My PMs have lit up considerably over this topic too and I'm always happy to help people who are legitimate and honest.

I do want to thank you though, Eric even though I didn't bring up the Spanish Heel you just reminded me of something that I should bring up and I will do that in my next, following post. Thanks. Got to get back to our deep trench.

Here's yet another way your instruments may be more serviceable and this one will likely strike more nerves. I'll offer again that I did these things too until I learned why I might not want to be doing this. To be clear I'm am offering what is considered useful information to those who want to learn and not trying to offend anyone.

WRC tops are in our experience problematic with bridges more commonly coming off and even worse when a bridge does lift on a WRC top it often takes a considerable amount of wood with it AND can breach the bridge perimeter in the process making for a major repair effort that's also costly and may show.... I'll add that we see WRC tops on classicals where the tension is lower torn off with reckless abandon (always liked that phrase "reckless abandon...." ) often damaging the tops.

This is so common a problem in the industry of actual working in the trade Luthiers... that we have a joke about it.

The word "Cordoba" means bridge reglue in Spanish......"

Although I've not personally experienced a Redwood top throwing a bridge there has been lots of talk about it here on the OLF over the years.

For the record out of the around 54 guitars that I built two had Redwood tops with extreme figure and four were WRC.

Lastly on this topic be sure as a builder to learn about top runout and why it matters. Even a spruce top with excessive runout can be an unserviceable top and poor choice to build with if there is excessive runout. When a bridge lifts it can tear things up considerably and that's what we are trying to avoid.

Thanks

I would certainly consider using a CF rod to straighten and stiffen a neck that doesn't have an adjustable truss rod. Older Martin guitars used non-adjustable rods or in some cases no rods at all. Classical guitars are another example of necks without truss rods. CF can stiffen the neck where needed without altering the outward appearance or balance of the instrument. It won't affect the performance of the adjustable truss rod because there isn't one.

Hesh—

I was one of the mob (that’s me in the group photo, the one on the right with the pitchfork) that nudged you toward writing a stand-alone publication with this info. Since you don’t want to do that (for good, sound reasons), this thread will have to do, and I am super grateful for it!

My sins to confess (I’m a Protestant, so this is normally a private experience):

I do clear under the whole footprint of the bridge, but it is for exactly the reason you and Brad discussed. I make smaller footprint bridges, and I feel I need all of the gluing surface I can get.

I often take a tiny, tiny amount of wood away when I clear finish, but I do it because I am VERY careful to remove any wood with cut fibers. I think you and I discussed this in a thread a few years ago. If you mark the outline of the bridge for removal of the finish underneath, and you cut wood fibers while marking that line (in other words, you cut too deep), it is very important to remove the wood inside the footprint that is attached to the cut fibers. Leaving that wood on the guitar, with its disconnection from the rest of the top, due to the cut fibers, makes a bridge lift more likely. So, this might commit the sin of cutting a little bit of a pocket for the bridge, but it is in service of the higher goal of lowering the chances of a bridge lift.

Anyway, I appreciate all of your imparted wisdom. I am benefiting from it right now (since I follow all of your advice except for the above), and will continue to do so. You’re a generous fellow for taking the time to do this for us.

It's very common, every couple of days for someone to bring in an instrument that was dried out and went into severe back bow or even forward bow. Not having any truss rod is a huge mistake for builders today and I would be very careful to make this clear. Regardless of what Martin once did 50 years ago they went with truss rods after that and with good reason, they can save a guitar.

Today's double action rods are even better in that respect and highly recommended from the trenches AND while we are at it Martin uses the double action rods now too. I think that they know a few things don't you....

To be more clear we have had several small builder guitars where the attraction to CF was strong enough that it was employed, deployed in a neck and was overkill. The truss rod would not move the neck and in one case the client broke the adjuster on the truss rod trying to get some correction that wasn't happening because of the massive in this case CF rods. It was not well thought through and we encouraged the client to take it up with the builder. The builder reluctantly acknowledged that the neck would not adjust and offered to build a new neck without CF.

Once that was done and installed by the builder the client sold the guitar and didn't want it anymore, the thrill was gone and all because someone, the builder was not thinking in terms of serviceability that necks will need to be adjusted and truss rods should not have to overcome CF augmentation when there is too much stiffness added.

As to minor CF augmentation what problem is it that folks are trying to solve? That'a a rhetorical question I know that they are actually seeking a better mouse trap and stiffer neck.

It's important to remember that this forum is mostly catering to acoustic guitar builders there are electric guitar builders here too. Electric players may not be limited to the same tunings as the acoustic crowd and are known these days to tune to low C effectively eliminating much of the string tension on the neck. For this reason and the seasonal changes that impact many new guitars at least for the first few years not to mention an accident where a guitar dried out truss rods are a Godsend and double action rods are even better.

Not saying don't use CF but don't use it to the extent that the truss rod has even more work to do to adjust a neck. And again not having CF augmentation never stopped a killer guitar from being crafted, enjoyed and even coveted.

Lastly if folks would learn how to shape their fret planes (fretboards) on the instrument after it's been glued in place and do proper fret work the idea of needing CF for spot corrections is moot.

Really lastly there are exceptions that our friend Dan E. refers to as "rubber necks" and I can see CF being added to an instrument for an ongoing and identified issue. But I also can see builders being careful to select only suitable woods in the first place that will handle the tension of the strings AND the shape of the necks being utilized in the first place.

Toward the end of my building before I got bored with the slog I was using CF augmentation sparingly on some specific braces. I'll let you know if it worked in another 85 years. . Oh yeah I used the Blanchard double action rod nearly exclusively and have never had a single issue or failure and this is a pretty structurally stiff rod not benefitting from CF in my experience when proper timbers are selected as well.

If I was building today the Martin DA rods look like a great choice.

Hi Don: I really appreciate you reminding me that this at times thankless task with zero benefit for me or my business is actually helping someone do what they want to do. That makes me happy!

It also makes me happy that if you give or sell your guitars to others their enjoyment of the instruments won't be ruined by an unnecessary failure in the structures.

Your reasoning about the complete clear of the foot print and smaller bridge foot prints all together makes perfect sense and that's when none of this stuff is hard and fast or even a rule, it's case by case. You have good reason to clear to the perimeter and even good reason to make a bit of a pocket too.

About a year or so ago John Hall who also does Martin certified repair work like we do posted a pic IIRC correctly of a pocket bridge on a new Martin. We've not seen any of these yet and maybe, just maybe because it's working to reduce the number of lifted bridges. I can't know of course but this does occur to me and of course Martin is very well respected.

Don it's a sincere pleasure to discuss this with you and to know that you value excellence in what you do. Thanks for the thanks too.

Here are a few more to consider:

- Truss Rods:

o Avoid oversized peghead excavations for truss rod access (removes wood from where it is needed most)

o Body truss rod access without access hole in UTB (at least produce a specialty wrench that actually fits...many do not). A 5mm truss rod does not need a 3/8" access hole...1mm oversized is usually enough to address minor alignment issues with ball-end hex wrenches (we drill ours 1/4" diameter)

o If using an odd-ball truss rod design that needs a specialty wrench, supply it with the guitar, or at least make it available on website

o Avoid using home-brewed rods with weird adjustment wrench requirements (e.g., ancient wrench types labeled in cryptic increments or something really creative like a T-25 tip, double-Z bend, articulating adjustment wrench)

- Bridge design:

o Leave adequate wood in front of the saddle slot to support the saddle (0.100" is not even remotely enough)

o Space pins back far enough from saddle to allow ramping and slotting and use of unslotted pins without excessive break angles

o Unless slavishly duplicating Gibson's deeply flawed bridge designs for replica instruments, space the pin holes as far in from the back edge as possible, while still providing enough space between saddle and pins to address correct break angles with expected saddle heights. The highest stress area on the bridge-to-top joint is along the rear edge of the joint...interrupting that joint with multiple bridge pin holes per some of Gibson's rectangular bridge designs promotes early failure.

o (Micro rant) When you create a bridge design that fails, don't dismiss your customer's concerns and offer some paltry amount for someone else to fix your screw-up. Person-up and make it right.

- Correct neck set with corresponding bridge thickness avoids very low or very high saddles; don't ship it if the saddle is higher than 0.200" or lower than 0.080" at what the customer will see as playable action

- Nuts should be glued with just enough adhesive to keep them in place during string changes...preferably a single, tiny drop of thin CA between the fretboard face of the nut and fretboard. If a light tap with block and 5 ounce hammer does not break the bond, there is too much glue. A file is a better tool for adjusting nut fit in slot than fillers or gobs of Titebond

- Always glue traditional through saddles once adjusted to correct height

- Never, ever glue in a through saddle with CA. Never. Use 192g hot hide (or lower gram strength) and allow time for the joint to fully dry before applying any string tension

- When adjusting scale length on a model, remember to relocate the bridge plate

- Super-narrow and stepped bridge plates can be the devil when it comes time to install bridgeplate-mounted transducers or microphones...anticipate that your customer will eventually want sound reinforcement and provision for at least a basic system like a K&K Pure....this means at least 3/4" of plate in front of the forward-most edge of the pin holes

That is enough - time for a 4th of July bike ride before it gets too hot and muggy to bear.

If in the States, enjoy our birthday party!

_________________
For the times they are a changin'

- Bob Dylan

Terrific post Woodie many, many thanks!!

Lots of great stuff there folks pay attention Woodie has the most comprehensive list of suggestions yet. Very cool.

Happy 4th Woodie.