Official Luthiers Forum!

hi
any tips or tricks to putting this kerfing on without it snapping on the upper bout curve, it usually breaks every time

cheers

Sent from my SM-G960F using Tapatalk

I've spritzed water on and lightly clamp it to the sides, let it dry, then take it back out and glue it in. It sort of holds its shape after it dries.

_________________
Insta - https://www.instagram.com/cbcguitars/
Facebook - https://www.facebook.com/cbcguitars

For especially delicate kerfed linings I lightly spritz with water, wrap in foil, place in a warm over for a few minutes - softens right up.
Lightly clamp in place, and allow to cool/dry.

Spritz with water, use the bending iron, bit of cloth on it. And some patience of course!
See from 4.00 onwards for a bit - https://www.youtube.com/watch?v=sAeXskZHC2o&t=889s

_________________
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.

talk nicely to it...

I soak it about 10 min and use spring clamps to set it on the side and let dry
should be good to go

_________________
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

All of the above regarding the outline of the guitar side. Get it wet, use heat, etc. That solves the problem in two dimensions. But there is another dimension to worry about: If you are using radius dishes, there will be some difficulty in getting the kerfed lining to go from head to tail and keep it at a reasonable amount of waste sticking up past the sides, which will get sanded off after you glue the kerfed lining to the sides and re-profile. It is worse for the back than for the top. In general, the waist curve is a fulcrum; the plane from waist to head is mostly flat, and the plane from waist to tail is mostly flat, but together, they are very much not flat. It often is easier to just cut the kerfed lining at the waist, and use different pieces in the two directions. Something to consider, depending on how you are building the guitar so far.

If using reverse kerfing, its helpful to do the initial bend with the kerfing around the outside of the perimeter so that the solid section of the lining is supported. Its not a problem for regular kerfed lining.

I usually have problems around the waist area. Is it shop made? How thick is the web?

_________________
Pat

This is brilliant! I've done the water and heat with decent results. still cracking a time or two. I'm going to give this a try. Many thanks!

_________________
Tony Thatcher
Bozeman, Montana

one more point try windex it works the ammonia helps to get the wood to bend

_________________
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 think the difficulty in bending kerfing derives from the angle generated at the gaps. The solid pieces ain't going to bend, so the faceted bending creates a tight angle at each gap. Or the gap gets taken up by the bend, and the bending forces the kerfing apart. And it breaks. My suggestion is that the kerfing be slotted in the middle of each 'cog', maybe by a jigsaw with a stop so's the kerfing doesn't get cut all the way through. Allows more bend without interference, too. I suspect that would help, although it's likely a big pain. Nice way to spend an evening. Bring along a cup of tea and turn on the ball game. And doing all those dampening things, too.

_________________
Peter Havriluk

You could put it in your side bender. I purposely make my reverse kerf linings rigid enough that they require heat bending. It makes for a more rigid side.

yes shop made don't have measurements to hand

Sent from my SM-G960F using Tapatalk

I've considered, to no great effect, whether putting my kerfing in the side bender would help, and I can't come to certainty. The kerfing breaks on the gaps at the same radius of bend when installing on the side as when bending with the heated steam of the bender.

I thought the kerfing picture showed a thicker continuous section than what I got from commercial kerfing, and maybe that will help OP's survive a trip through the bender. Won't hurt to try, I guess.

One suggestion to OP is go ahead and accept the breaks, and apply a strip of material to the outside of the kerfing, in effect making it reversed by virtue of the new layer added on top of the kerfing itself. I did that once with reverse kerfing that broke all over the place and I had some thin binding strips to contribute to the cause. An extra step but I thought it was worthwhile rather than spend a whole lot of time fighting the fragile kerfing. Worked out just fine.

_________________
Peter Havriluk

My guess is that the webs are either too thick (doesn't want to bend) or uneven (thinner sections breaking because of stress rising). Do you have a digital caliper?

Run out in the piece of wood could also be a factor.

_________________
Pat