Official Luthiers Forum!

In the ongoing quest of playing action here is an idea that will...

1. Install extremely HARD hard fret material. Much harder than the typical stainless steel alloys used for frets.

2. Install and glue frets into their positions far more accurately predictably than any other tanged fret method could.

3. Eliminate any possibility that fret installation will cause a backbow to due imperfect gap sizing.

4. Provide COMPLETE contact from the vibrating string through to the wood. There is about 75%
of the fret surface area - totally contacted and thusly...conducting vibration through the various
materials, wood, steel and epoxy...the epoxy being chosen for its microcracking mechanical
properties and hardness combined. In this setup...the epoxy is musical....providing much much
more surface area directly contacting the metal than any hand installed fret could without using a highly controlled filler/glue.

Aside - if you use glue for fret installations study all the properties of the glue. A completely filled
gap of DENSE glue will be better than a badly filled gap of low density glue. This design more or
less eliminates the density issue because there isn't a wood to metal gap. The filler part is the most
critical aspect here. It needs density and the ability to give just a tiny bit (micro level) before
the bond breaks.

5. Eliminate the need for any caul, hammer, or any other amount of high pressure to mount.

6. Locks fret in position but with 200F...it basically falls out and takes the glue with it....no
tear out possible. Pretty easy replacement...on frets that will most likely never wear out to
need replacing. Even so...

Fact...if I can hold the bottom of these grooves to be mathematically perfect to the model
(I'm certain) the frets should mount and play without having to level at all. It won't...but it will
be VERY close to perfect right out of the gate.

Anyway...this is the next test that will prove or disprove the theory. This will be a flat
fretboard initially...the concept being easier to produce with a flat, rather than complex,
fretboard. the compound fretboard requires the initial step of precision bending of the
metal. Pretty simple...but an additional tool to make. Later. That will be the next thing
after proving this concept.

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I read Emerson on the can. A foolish consistency is the hobgoblin of little minds...true...but a consistent reading of Emerson has its uses nevertheless.

StuMusic

That's an interesting idea Stuart, let us know how it works out.

_________________
Steve Smith
"Music is what feelings sound like"

I’ve often wondered about using epoxy or HHG to hold down barbless frets. Then there’d be no tearout when replacing frets, and the fretboard could take infinite refrets…

Yours is a most interesting idea.

Sounds like a fun project Needle bearing pins are great when you need super hard and precisely ground short-length rods, since they're pretty cheap due to being produced in large quantity. 50pcs 3x60mm for $15 on ebay. Leveling them to the edges of the board and beveling the ends will not be easy, though. And they can rust.

It will be interesting to see how the board feels with such smooth bumps compared to regular frets, and the relatively large radius on top.

The idea of indestructible frets reminds me there was a place years ago that made frets out of quartz http://www.luthiersforum.com/forum/viewtopic.php?t=31165, but it looks they're out of business.

One of the things I failed to address.

The frets (hardened drill rod) will glue into place in one step...then the top fillets are added in a second step. Then the cnc will cut the glue fillets, skim the wood surface of the fretboard, and then also touch the fret tops.

So those fillets are really pristine looking after they are cut.

I'll do some measuring...but when it comes time to do that last operation...I can program the machine to just kiss off the tops of these frets to establish the final playing action. Any subsequent sanding or polishing only occurs with very fine grits. THAT'S the reason this is cool to me. But I'll look at the result without the kiss cut first....then employ it later. I'm very curious how effective this will be to produce a playing surface without leveling or crowning.

I've already used the cnc to level and crown nickel frets and it's worked quite well. The first time I EVER used the technique it produced the best guitar I ever played, action wise. Only possible with the carbon insert.

I can use the cnc to establish the playing action because the neck is so reinforced with carbon (plus I also use form fitted supports while I'm cutting) it doesn't move AT ALL when it's being processed. In other words, the perfect mathematical solution for your flat or complex contour fretboard is in there, there's zero stress in the neck itself, and it won't warp or bend....ever.

The ONLY thing you can do to screw up perfect action is to over-sand a single fret attempting to remove the residual machine marks....but those marks come out pretty easily with 1500 grit. You'd be TRYING to screw it up then.

_________________
I read Emerson on the can. A foolish consistency is the hobgoblin of little minds...true...but a consistent reading of Emerson has its uses nevertheless.

StuMusic

Richard Schneider used to do frets like you describe, although he may not of left a fillet. It's been a while since I've seen some.

_________________
Jim Watts
http://jameswattsguitars.com

Don Teeter came up with an epoxied fret method for refretting many decades ago, but it fell out of favor due to various reasons.

The most I can find about Don Teeter's method is that he simply cut the fret slots wider and glued in the frets with hhg. I'm going to guess here...but he probably was thinking about backbow due to very hard fretboards and too narrow slots.

If one cuts the fret slots wide and glues in the frets...all issues of backbow are decided there...and the species doesn't make a difference in how much backbow occurs.

BUT....doing that makes GLUE the variable in the transmission of vibration. You don't want that. Take it from a pro gluer (airplane propellers). IF THERE'S VIBRATION IN A SYSTEM...you don't want your glue transmitting
it. you want clean, mated surfaces with NO pockets of glue.....direct contact is the deal.

A three molecule thick glue line would be the ideal....lol...assuming humans could ever do that.

If you use glued to fill voids....with fret wire you really can't know how much pure contact is being made....and pure contact is the goal (again...just solid contact).

The objective is controlled, even contact fret to fret. So this design maximizes wood to metal contact as best I can do on short notice. If I were to come up with anything better it would have to come from a custom extruded shape of metal...but that could never really be hardened to the point of hardened drill rod.

Then...the epoxy filler for the fillets is also more pure contact....provided the glue was tested for its musical properties.

Honestly? if you pour out a large puddle of whatever epoxy onto a flat waxed surface and then peel it up....a tap test is enough. You know what you want to hear. The thing you won't know is the micro-stress capability of the glue. When you bond to metal you MUST use a "toughened" epoxy...which will take a GREAT deal more stress on the glue line...created by the ingress and egress of moisture in the wood. No off the shelf stuff is guaranteed to have this property.

Plus...custom epoxies can be formulated to have a SPECIFIC Tg (glass transition temperature) after which the glue lets go. VERY handy to make sure the specified temperature applied will release the glue evenly...cleanly.

_________________
I read Emerson on the can. A foolish consistency is the hobgoblin of little minds...true...but a consistent reading of Emerson has its uses nevertheless.

StuMusic

I have personal experience with Teeter's methods including having both of his repair texts in my library. His goal was to simplify and standardize refrets in old fretboards that had been refretted several times, worn, damaged, etc. I agree that it is not ideal for a fret tang to be bedded in epoxy, but this overlooks the fact that the underside of the fret was well seated on the fretboard surface. But I haven't used the technique in years due to the irreversible nature of it.

Good luck with your interesting project.

I've been making somewhat similar fretboards, at least in the outcome--mine are patterned on the old Fred Van Eps scalloped flush fret fingerboard. I use rectangular SS bars instead of round, and the filets are in the fingerboard material itself. I glue mine in with CA, but epoxy would work well too. These fingerboards play like buttah...

The fingerboards I remember of Richard Schneider used Delrin bars (they were nylon string guitars) and I don't remember any filets.

Dave

Nice, Dave! Do you scallop by hand using drum sanders? I can't imagine trying to fine sand that thing.

I have an original Van Eps board that Fred made with sanding drums, but I modeled mine in Rhino and cut it with CNC. Very little sanding left to do, but what there is I do by hand.

Dave

I love this concept Stuart.

It looks vaguely similar to what Emmet Chapman used to do with round steel fret rods, and now does with square steel fret rods, where he uses a shaped router bit to mill a slot which matches the shape of the rod and includes an undercut so that the frets have to slide in from the side and are captured by the fretboard material. I'm not sure what adhesive he uses, if any.
http://www.stick.com/about/innovation/rails/


Todd Kheen of TK Instruments has been using a similar slide-in rods method for a long time too.
http://www.tkinstruments.com/id17.htm



But I see that you're using epoxy to hold the rods in instead of sliding them in from the side.

Can you tell us more about how you are shaping the epoxy into a nice filleted curve?
Are you filling the entire area between frets with epoxy then CNC trimming the unwanted portion away after it has set?

Also can you tell us any more about the epoxy you're using and where you source it from?

Leo

I hope none of this rubs off on me. But I'm watching.

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Hutch

Get the heck off the couch and go build a guitar!!!!

On the scalloped fingerboard, how are the frets removed if needing new?

Heat with a soldering iron and tap from the side far enough to get an end to stick out, then carefully lift the end. In honesty, I've never had to do it on a real instrument, the wire is hard and wears well. Not nearly as hard as the rods that Stuart is using though.

Dave

Dave,
What type of material do you use for scalloped fingerboards?
I've considered using the stainless inserts from windshield wiper blades for bar frets, but they are a little narrow. I think they might be perfect for scalloped fingerboards. What are your thoughts on this?

Not meaning to hijack Stuart's thread--but I use rectangular stainless steel wire. Those wiper blade inserts might work out just fine.

Whether done by fileting round wire or by scalloping between rectangular wire (which results in basically the same final result IMO), the sensation of playing on fingerboards like these is like playing a fretless instrument, but it plays in tune. Very smooth action, and the action can be set very low. Nothing at all like the Malmsteen style scalloped boards, which lack the filets and result in the same speed bumps you get on a conventional fingerboard.

Dave

I've considered the stainless rod idea, too - I've just been too busy with life to even experiment with it. But since it's not my original thought, and others are giving it a go, then I conclude that it has merit.

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"Act your age, not your shoe size" - Prince

Go ahead and hijack your brains out. The internet can't offend me. Plus I like tangents.

I was going to add about my epoxy....it's not something you'll buy off the shelf....it being a designed epoxy meant to co-cure with other pre-preg materials. I bought it by the 55 gallon drum which was a small order to a company that sold engineered epoxies by the train car load. In other words....you can't get it. I only have any because it's left over from that....it has all the right properties but there a lot of other choices.

Epoxy sold as "toughened" will be fine for this application. The variables are mixed viscosity, optical clarity, open time, cure time, and absolutely Tg (glass transition temperature). That tells you at what temp it will release the bond.

The viscosity is important. I want to use a syringe to apply the first beads of epoxy along those fillet areas with de-gassed epoxy. So here I need a low mixed viscosity system that will open long enough to de-gas, get it in the syringe, and apply.

Look for a "toughened" epoxy that cures at room temp overnight. I want one that stays open for at least 45 minutes and releases at no less than 180F and no more than 250F. I want the mixed viscosity at about 1000. It could be 500-1500+ and still work. I also want it as clear as possible. Cause when it's polished up together with the frets....it'll look quite ich. People that look closely will have more to see.

_________________
I read Emerson on the can. A foolish consistency is the hobgoblin of little minds...true...but a consistent reading of Emerson has its uses nevertheless.

StuMusic

I use 17-4 stainless pins (they have to be made on a lathe) in my bridges...I've seen no wear enough to tell me not to use it for frets as well.

But then I thought, "I have some drill rod. High speed steel. Shiny. Can I dress it with a diamond file?" Yes.

"A HIGH quality file"? It's hard but...yeah.

Can you polish it? Oh yeah....all the way downtown.

What is the Rockwell C hardness of 17-4? 36. The drill rod? 64. I choose this initially because...why not try a different alloy on one guitar and then see how it feels and sounds. Then if I hate it I get to practice the thing I preach. I get to remove all the frets and re-fret with a new alloy. Beat THAT for a design feature....you can change fret alloys on a whim...lol.

_________________
I read Emerson on the can. A foolish consistency is the hobgoblin of little minds...true...but a consistent reading of Emerson has its uses nevertheless.

StuMusic

It's wonderful to see you posting again, Stuart. What you're up to is cool and I'll be following along. Actually, I'm following the forum in general, I just don't say much anymore. Those of you who know me in the real world, know that's out of character. :-)

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George :-)