Ken LeVan - Posted - 11/12/2022:  13:54:22

In the latest issue of American Lutherie, there was an article by Harry Fleishman about the sequential order of fret-pounding in a fingerboard to prevent backbow—I'm guessing he's talking about fretting a fingerboard that's already glued to the neck, but he doesn't say.

I thought it was very interesting.  Kind of similar to the order of tightening tension hooks on a banjo or bolts on a car cylinder head.

Mr Fleishman says this has prevented backbow on his and the guitars of hundreds of his students—don't see why a banjo wouldn't be the same.

I thought it was worth passing on and maybe some have experience with this and other systems.

Edited by - Ken LeVan on 11/12/2022 14:09:19

lightgauge - Posted - 11/12/2022:  17:51:41

Interesting for sure. I am not sure I understand his sequence, but I do not have a better one. It appears to be fairly even tightening.

Ken LeVan - Posted - 11/12/2022:  17:57:36

I honestly don't understand how it could work.  I keep forgetting to try it, but will next fingerboard I do.

Old Hickory - Posted - 11/13/2022:  06:14:27

Where's 22?

RB3 - Posted - 11/13/2022:  06:19:08

Presumably, the theory is that the interference fit between the fret tangs and the fret slots creates compressive forces near the top surface of the finger board and those compressive forces increase the probability of back bow of the neck. I don't understand why the timing of when the frets are installed would reduce the totality of compressive forces associated with the fret/fret-slot interference condition.

Edited by - RB3 on 11/13/2022 06:20:40

Ken LeVan - Posted - 11/13/2022:  07:44:39

quote:

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Originally posted by RB3

Presumably, the theory is that the interference fit between the fret tangs and the fret slots creates compressive forces near the top surface of the finger board and those compressive forces increase the probability of back bow of the neck. I don't understand why the timing of when the frets are installed would reduce the totality of compressive forces associated with the fret/fret-slot interference condition.

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I don't understand why the order would make any difference, either.

I always pound the frets in to the fingerboard, just 1-2-3-4 etc, and of course, it makes it backbow, but an even curve, tighter at the end with more frets,which is logical.. Then I epoxy-glue that onto a laminated substrate which flattens it and clamps the frets into the slots tighter.

I am therefore gluing a flat thing onto the neck.

I would guess that if you glue the fingerboard on the neck first, then fret it as many people do, you are subjecting the neck to backbow pressure.

Nonetheless, I can't see why the order of the fret insertion would have any effect, but the person who wrote the article swears by it.

Edited by - Ken LeVan on 11/13/2022 07:46:06

latigo1 - Posted - 11/13/2022:  07:45:28

I have never had a problem with back bow after installing frets. Has this been a problem for others? I wonder why he includes frets 16 to 24 in his sequence. The neck is so thick in that area that I don't see how back bow is possible there.

latigo1 - Posted - 11/13/2022:  07:49:00

I have never had a problem with back bow after installing frets. Has this been a problem for others? I wonder why he includes frets 16 to 22 in his sequence, The neck is so thick in that area that back bow doesn't seem possible there.

rmcdow - Posted - 11/13/2022:  08:19:14

quote:

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Originally posted by Old Hickory

Where's 22?

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21 frets

TreyDBanjoKS - Posted - 11/13/2022:  15:39:52

I've refretted hundreds of necks in a repair shop setting and simply fretting in order I've never encountered the problem of backbowing due to my fret installation. Careful attention to the fret slots, tang sizes, and how the truss rod works in each individual instrument are the most important factors to prevent this. I don't really see the point of this method when fretting in order works without problems. If it ain't broke don't fix it (instead refret it?)

That being said, I've built a handful of instruments but always glued on the fingerboard before the fretwork, I've never fretted a board then glued it on. 

Somewhat on topic and kind of silly- I like to start at the far end of the fretboard (22 for banjos, tongue for guitars) and work my way towards the 1st fret. The only reason I do this is because I like to mentally trick myself- when I start at the 1st fret and work up, by the time I've reached the 15th fret or so, it feels like the progress goes slower and It will take a lot of time to get to the final fret, but when I work the other direction, after I pass the 12th fret It's like the progress goes a lot faster and I can see my effort paying off with every fret I install It is silly to play mind games with oneself but these are the things that keep me in a good mood while I do monotonous & repetitive tasks like fretwork.

-TD

lightgauge - Posted - 11/13/2022:  16:34:41

Having been in the engine world for many years, I understand alternating tightening forces/torque back and forth as well as starting in the center to force things outward in both directions rather than cumulative in one direction which is what he appears to be countering.
It just seems odd that 1 and 2 are the ends, but as before, I have no better sequence to offer.

G Edward Porgie - Posted - 11/13/2022:  17:11:20

a car engine is subject to heating and cooling, so controlling potential warpage is important. I have never placed a banjo neck in a combustion chamber and doubt anyone else has. I agree with Trey Durkin that fret slots, tangs, and truss rods are more important.

If ever I decide to re-fret a guitar or banjo in a Bessemer converter, I might reconsider.

Helix - Posted - 11/14/2022:  01:26:11

lightgauge: I read that you are talking about tightening sequence. when I was splitting Schedule 80 8" pipe in the shipyard to make barge bumpers, we slotted both sides with the torch, but left the ends.
We then split the pipe from the center so we got a bow instead of a banana peel. The old guys knew why.

No banjo necks will be harmed after reading this. "I'm going down to the railroad, put my head on the track. And when that train comes rollin', I'm gonna pull my old head back."

I have read here on the hangout about frets being too tight to even adjust the neck. How? Why?

I'm sure any of us would like to avoid any adjustment problems in the future.
I make sure I check for relief +/-

Another neck builder here on the hangout told me of finally getting to the 22nd fret and blowing the end of the fingerboard off with a hammer. Start all over.

Personally, I don't pre-install the frets off of the neck. I like the way the neck "feels" and sounds.
I used to use the fret press in my drill press. I just found I had less QA to do when using the hammer. The vise grip version , no feel.

I use a single drop of water with a steak knife to prepare the slot. No superglue, nor anything else, just a clean slot and swelling shut on the tang. It shrinks back, but not enough to let go of the fret.

As one hammers, you can see the spray coming out from under the fret as it seats. I use distilled water so no calcium is present in the water.

Going on 15 years, I haven't had adjustment, nor maintenance problems, nor phone calls. I set my relief if needed when setting up.

More info needed on why the luthier does this.

lightgauge - Posted - 11/14/2022:  03:32:44

The only backbow I have encountered was on an old Fender Artist neck where the refret did introduce a slight backbow. These were thin necks with a one way rod. Frets were pressed in with a drill press starting at 1 and going toward the heel. I doubt I will do another one, but if so, I would try the alternating way just to see. I know it is not an engine, but wood has its own characteristics, sometimes making it more unpredictable.

Ken LeVan - Posted - 11/14/2022:  05:05:48

I recently had a bad back-bow—first ever and nothing to do with order of fretting.

It was on a mahogany neck made from 45 year old pattern grade Honduras mahogany, which doesn't warp. a baked ipe fingerboard with a three-ply under-laminate all epoxy glued—no water introduced.  It was straight as an arrow when I sent it out.

It went to Texas in the middle of August, and it was bloody hot.  When it arrived 4 days later it had a pretty bad backbow. The only explanation I could figure was that it was in some truck or warehouse headed south and the temperature was so hot it slightly softened the glue and the truss rod expanded lengthwise forcing it into a backbow, like a bi-metal thermometer. some of the frets popped out. Then when it cooled down, the glue hardened again and it stayed that way—just like heat treating a warped neck to straighten it.

The truss rod either broke or was broken to begin with.

I told the customer to send  it back, took off the fingerboard, and the neck went straight again—the fingerboard assembly was also straight. I put in a new truss rod and re-glued the fingerboard on to the neck, this time with a really thin shim on the caul to make it set with a slight relief curve—.004 at the 4th fret .008 at the 10th and .004 at the 14th.

It has stayed that way with the truss rod neutral. Once again, this had nothing to do with the order of fretting, but backbows do happen for odd reasons.

Wyatt Fawley always put the glue on the fingerboard, never the neck when he did a glue-up so water from Titebond didn't get introduced into the neck, which he said caused backbow, nowadays we have no-water structural adhesives, but who can account for shipping in hot trucks in hot places? Another reason I don't keep instruments sitting around in cases, especially in a car.

Quickstep192 - Posted - 11/15/2022:  19:21:06

I'd be curious to know how many fret the board before installing vs fretting the board after it's glued onto the neck.



I've only fretted a few boards, but for me, fretting the board off the is a whole lot easier, but it always bows the board as the frets are installed which makes me wonder if the tangs are really getting a good "bite" into the board since they're expanding the slot rather than being pressed in to it.



Conversely, I've not experienced any bowing when fretting the board installed on the neck.

Ken LeVan - Posted - 11/16/2022:  05:17:54

quote:

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Originally posted by Quickstep192

I'd be curious to know how many fret the board before installing vs fretting the board after it's glued onto the neck.



I've only fretted a few boards, but for me, fretting the board off the is a whole lot easier, but it always bows the board as the frets are installed which makes me wonder if the tangs are really getting a good "bite" into the board since they're expanding the slot rather than being pressed in to it.



Conversely, I've not experienced any bowing when fretting the board installed on the neck.

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I'll readily admit I have never understood why you would put the frets in the fingerboard after it's glued to the neck—so much more difficult, requiring fixtures, and seems wrong stepwise, but probably most people do it that way, even on the part of a guitar fingerboard that goes out over the top.  Path dependence?  but where does the path come from.

I'd love to hear an explanation of the benefits—maybe it has to do with the recent practice of oversized slots and gluing the frets in.

Quickstep192 - Posted - 11/16/2022:  05:29:49

Keep in mind that all of my comments are not informed by extensive experience or expertise!

The only reason I can think of to fret the board after gluing to the neck are the things I cited in my earlier post.

It seems to be that because the board can bow, the fret slots are not confined and can expand as the fret is pressed in decreasing the amount of “bite” the tangs get into the adjacent wood.

Does this make any sense at all?

My preference is to use an arbor press on a board that hasn’t yet been glued to the neck, but I’ve always been off put by the way the board bows while undertaking this process.

Eager for your perspective.

Ken LeVan - Posted - 11/16/2022:  05:45:20

quote:

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Originally posted by Quickstep192

Keep in mind that all of my comments are not informed by extensive experience or expertise!



The only reason I can think of to fret the board after gluing to the neck are the things I cited in my earlier post.



It seems to be that because the board can bow, the fret slots are not confined and can expand as the fret is pressed in decreasing the amount of “bite” the tangs get into the adjacent wood.



Does this make any sense at all?



My preference is to use an arbor press on a board that hasn’t yet been glued to the neck, but I’ve always been off put by the way the board bows while undertaking this process.



Eager for your perspective.

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My perspective, understanding the way wood laminations work, would be this:

If you pound or press the frets into slots of the proper kerf for the tangs to do their intended job,the fingerboard is going to bow up because of the frets expanding the slots a little bit.  Then when you glue that on to the fingerboard, it flattens the fingerboard and forms a 2-layer lamination with the neck, that keeps it flat and squeezes the fret tangs in the process.  You can put a caul with .028" relief into the glue-up if you want, which is what Stelling did,  and it will stay that way.

If you glue the unfretted fingerboard onto the neck, now it's flat—then put frets in and you will be either backbowing it or creating the same stress in that plane that was caused by fretting the un-mounted fingerboard (which you can see), now hoping that the string tension and tension rod will keep it straight.

It's just bass-ackwards to me.

Edited by - Ken LeVan on 11/16/2022 05:47:35

Quickstep192 - Posted - 11/16/2022:  05:56:02

Ken,

Thanks for that reply. It validates my preference for fretting the board before gluing to the neck (It’s sooooo much easier)

The caul with .028 relief sounds interesting, but I can’t imagine how one would make that without a CNC machine. I use a piece of manufactured marble and epoxy. As I said, I haven’t done a lot of necks, not the ones I have done come off the marble dead flat and seem to stay that way.

Joel Hooks - Posted - 11/16/2022:  06:41:21

Perhaps the special order of fret installation is based on some ancient numerology which unlocks the secrets to prewar tone? The old guys know what this is.

Ken LeVan - Posted - 11/16/2022:  09:08:35

quote:

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Originally posted by Quickstep192

Ken,



Thanks for that reply. It validates my preference for fretting the board before gluing to the neck (It’s sooooo much easier)



The caul with .028 relief sounds interesting, but I can’t imagine how one would make that without a CNC machine. I use a piece of manufactured marble and epoxy. As I said, I haven’t done a lot of necks, not the ones I have done come off the marble dead flat and seem to stay that way.

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You can make one with pieces of paper glued together with titebond—one piece of ordinary paper is around .003", feathererd towards the ends so you have about 7 thicknesses of paper in the middle, accounting for glue—you can measure it with a caliper or micrometer as you go as you go.

You could also use shim brass which would be more accurate. You want the thickest part to be at the 7th fret positioned on the flat gluing caul you would normally use.

Edited by - Ken LeVan on 11/16/2022 09:09:28

G Edward Porgie - Posted - 11/16/2022:  10:28:27

I never install frets before the board is glued because have yet to make a banjo. All my fret work has been done on old banjos, and I'm not about to remove their boards to re-fret.

I think some builders also do repairs and they simply learned to re-fret with boards already attached. I have to say that it can be an extra pain, but at least I have learned to do it. Guitars are particularly tricky because the frets must be installed, crowned, filed, etc. over the difficult to access portion over the guitar body.

I have only had back bow on one banjo, but that was due to the barbs on the tangs not aligning with the barbs of the original frets. The ebony was too hard for the barbs to bite into. After about a month of playing, though, it all settled in fine. I don't think fretting in any order would have made a difference.

If the guy who presented this sequence swears by it, that's okay with me. I personally don't see the point, but if others find a particular order works best for them, so be it. Not everybody does things the same way, and the more ways to get a job done well, the better.

Quickstep192 - Posted - 11/16/2022:  15:39:21

quote:

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Originally posted by Ken LeVan

quote:

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Originally posted by Quickstep192

Ken,



Thanks for that reply. It validates my preference for fretting the board before gluing to the neck (It’s sooooo much easier)



The caul with .028 relief sounds interesting, but I can’t imagine how one would make that without a CNC machine. I use a piece of manufactured marble and epoxy. As I said, I haven’t done a lot of necks, not the ones I have done come off the marble dead flat and seem to stay that way.

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You can make one with pieces of paper glued together with titebond—one piece of ordinary paper is around .003", feathererd towards the ends so you have about 7 thicknesses of paper in the middle, accounting for glue—you can measure it with a caliper or micrometer as you go as you go.

You could also use shim brass which would be more accurate. You want the thickest part to be at the 7th fret positioned on the flat gluing caul you would normally use.

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As usual, your information is useful and appreciated. It seems like building up 7 pieces of paper, each 5" shorter than the previous layer would build the profile, but...

Do you think it's worth it to build in that 1/32" of relief ?

Ken LeVan - Posted - 11/16/2022:  17:30:34

quote:

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Originally posted by Quickstep192

quote:

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Originally posted by Ken LeVan

quote:

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Originally posted by Quickstep192

Ken,



Thanks for that reply. It validates my preference for fretting the board before gluing to the neck (It’s sooooo much easier)



The caul with .028 relief sounds interesting, but I can’t imagine how one would make that without a CNC machine. I use a piece of manufactured marble and epoxy. As I said, I haven’t done a lot of necks, not the ones I have done come off the marble dead flat and seem to stay that way.

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You can make one with pieces of paper glued together with titebond—one piece of ordinary paper is around .003", feathererd towards the ends so you have about 7 thicknesses of paper in the middle, accounting for glue—you can measure it with a caliper or micrometer as you go as you go.

You could also use shim brass which would be more accurate. You want the thickest part to be at the 7th fret positioned on the flat gluing caul you would normally use.

---

As usual, your information is useful and appreciated. It seems like building up 7 pieces of paper, each 5" shorter than the previous layer would build the profile, but...

Do you think it's worth it to build in that 1/32" of relief ?

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Sometimes it can help, but normally it's not necessary with a 2-way truss rod.

TreyDBanjoKS - Posted - 11/17/2022:  05:53:47

I come from a repair background and I've simply learned to do all fretwork on glued on fingerboards. Although this way is slightly more difficult, I feel it gives me more control of the end result.

Good fretwork and optimal playability starts with a well planed board. I often string instruments up with no frets installed to see just how the string tension affects the relief in the fingerboard. This gives me an opportunity to plane the fingerboard to achieve ideal relief according to the individual instrument before installing frets. Doing this method, fret dressing after install is rarely necessary and if so it is very mild, just a couple thousandths here and there.

That being said, some of the most problematic necks I've ever seen/worked on have been instruments that are fretted before gluing on the fingerboard (I'm looking at you, Gibson electric guitars). Gibson uses a less-than-ideal clamping system which results in dips and humps in the fingerboard glue-up. They compensate for this by installing extra tall frets and using a plek machine to dress out any inconsistencies in the frets. I've seen new Gibson guitars with frets that vary in height up to .020" due to the terrible fingerboards.

Maybe this is thread drift but for me it's interesting to read about everyone's order of operations when it comes to fretting.

-TD