When refretting old fretboards the radius can be dodgy. Not exactly a set measure and it may vary over the fretboard. With a compound fretboard that's the rule! I love the Jaws2 press, but the cauls are firm and don't always follow the shape of the fretboard.
Today I came up with this tweak to a 16" radius brass caul. I made eight cuts almost all the way through the caul with a small metal saw to make nine somewhat movable parts (with the set screw on flat metal in the middle). To make it even more bendable I drilled a 3 mm hole in the end of the cut. To give the caul a chance to bend in the Jaws2 tool I put a shim of a soft but hard enough material in the bottom of the groove for the caul. I tried cork and it worked, but settled for raw rubber from the yoga mat I have on my bench. An old fretboard with 7.25" radius was used as an example.
Making a one-size-fits-all adjustable caul is aiming for too much I think. Unless there is some heavy duty design going on, hydraulics sounds like the way to go!
What I know is that my variant works better than the standard one I've been using if you have a good enough match between the caul and the fretboards radius. The leather shim will distribute the force pretty even, the fret itself will help even out the pressure. Not perfect, but good enough for me! I will do the thing to all my standard Stewmac cauls and happily use them and get better results.
When testing I can see the caul seating itself over the fret when adding pressure to the clamp. Next time I will try the nearest lower radius, that way I will get some extra pressure on the fret ends and probably get a bit more even pressure on the fret and better seated fret ends too!
And I have a bunch of supermagnets in the mail, I hate that set screw!
Rodger, the correct placement of the magnets is important relative to the shoe slot so they pull the caul into the right position.
When I was at Collings we pressed mandolin frets into a compound board with a mini leaf spring caul. It was just like the springs on a p/u truck axle. It worked because it was always the same wire, slot width, fingerboard wood,etc. Too many variables in a re-fret. Especially when the wire get's skinny and can be pushed into the board.
I always wondered if the cascading caul pieces could be taken up a level. It must have been pretty finicky to make.
Another Swede has made something too :-)
Long dark winters maybe? :-)
I wonder whats going on inside that mechanism.
I worked on a Stranberg 8 string last year. It came in because...................the frets were loose. The neck shape was a flat angle on the back and wider than standard brass cauls. I can see the motivation to come up with a system. The beauty of the set Dave Collins came up with is the sequence of radius's are an even progression of fit along the neck instead of the big gaps between the set Stew mac puts out.
I started down the adjustable road once with a design like a cross between a capo and a hacksaw where the caul was thin and under tension in a fork. I might stil have parts of it in my junk somewhere.
I think a series of fix sizes that can be changed quickly already ticks almost all the boxes for re-frets.
They provide the most important part to me, knowing when I press a fret, it will be down correctly without any doubt.
One can wonder! A caul in hard plastic instead of brass is interesting. Never seen any of his guitars, looks like he is doing inventions for electric guitars and trying to make a living that way. Loose frets was a bummer though. Didn't find much else of interest for me on the site, the neck shape I'd like to feel sometime.
The set of small increment cauls and magnets to hold them is a sure solution to compound radius fretting. Even better with my fix taking care of small differences between the caul and fretboard :-)
i hope i'm not being rude by having my very first post to this forum be a "yeah but check this out" response to a pretty slick creation, especially when i mostly call myself a "tech" rather than a "luthier", but for several years now i've been exclusively using my own answer to the adjustable fret caul question, one that doesn't need any swapping because it conforms to any radius flatter than 6":
after seeing an idea by one dan kelchack:
i took a regular 6" caul and chopped it into two "teeth", then put peaks on the back of those teeth so that they could take the full force of the clamping arbor while being free to swivel and conform to any fret radius
i rounded over the ends a little and put little magnets in the teeth so that they would stay put in the channel of the fret arbor but still let me slide them around for the right spacing
installed, they press on the fret at each end while swiveling to conform to whatever shape the board happens to be, so i get full pressure at the fret ends and in the middle regardless of board radius:
it's a little bit of a pain to slide them into position such that they just cover the fret ends, but it's been years since i've even thought about using any other kind of fret press solution!
(i was hipped to this thread and forum by a link posted in my own thread about this subject over on TGP.)
That's a great one. Food for thought and something I think I will try. Thanks for sharing!
Hey walter, welcome! I had been intrigued by your caul ever since you first showed a photo of it. I noticed the parallel conversation on the other forum and thought you might be interested in this one. I owe you for turning me on to the little magnets in the shoes. Thanks!
Did you see the 6 point version David Collins tried on page two of this thread?
man, i need to work on my "reading before posting" chops; i didn't notice the david collins post or the link to nate clark's version!
yes i've seen both the david collins prototype and the version that nate's using, and as far as i know they both were sparked by my idea in the old TGP thread.
i take david c's point about the drawback for this idea being really small or soft wire, where the four points of pressure may not be enough to prevent slight fret deformation and uneven seating, but with regular modern wire and especially stainless i've had no trouble.