My Top Cracked!

[radrobgray]

so i carved the arm contour on my soloist, and then i bent my sub-top over the contour. every thing went smooth and it was fine after i clamped it. but when the it finished drying it cracked (see picture), the crack is 1/8" wide to nothing and about 8" long. how should i approach fixing it? it doesnt need to look good from the top, just the endgrain, beacuse im glueing on a flame maple top on top of the sub-top. is that a bad idea?

also the sub-top is 1/8" thick brazilian cherry/jobota.

the top is 1/4" thick flame maple.

***digital rendering***

[Drak]

If it's all glued down, there's really not much you can do less sand it all off and give it another try.

Or if you have any left, try and glue a patch into it where you need to see it and fill the rest in with epoxy or something.

[Jon]

Patch with veneer and sand. Will be tricky, but you can do it if you're dedicated!

[Prostheta]

Agreed. Either gain the experience of trying to repair it at the expense of time and maybe not succeeding, or sand it off quick sharp and chalk it up to experience.

On that note (so Rob isn't left wondering in fear of it re-occurring) has anybody got any tips on how to avoid this and why it happened?

[fryovanni]

How did you go about bending the wood to the contour?

If you try to fix it. The suggestions above sound reasonable(if the look is acceptable). If you do sand and re-do. Seems like more heat less water(1/4" is a tuff bend).

Peace,Rich

[Jon]

has anybody got any tips on how to avoid this and why it happened?

I've heard of a veneer softener, that may help with something like this. I had this same thing happen recently, except the veneer didn't split apart. It just didn't glue together side by side in one area. Patched up easily.

[spazzyone]

(1/4" is a tuff bend).

Peace,Rich

+1

and your contour has a sharp bend (at least in the rendering)

which needs a very soft transistion

this is a more common problem than some would like to admit

but ive seen it happen to 3 tops in two months

[radrobgray]

If it's all glued down, there's really not much you can do less sand it all off and give it another try.

Or if you have any left, try and glue a patch into it where you need to see it and fill the rest in with epoxy or something.

its not glued its just clamped on right now. i have enough for another sub-top or to patch it.

How did you go about bending the wood to the contour?

If you try to fix it. The suggestions above sound reasonable(if the look is acceptable). If you do sand and re-do. Seems like more heat less water(1/4" is a tuff bend).

Peace,Rich

its only 1/8" thick. im going to put another top over this one (the 1/4" flame maple). i used a cloths iron and water.

(1/4" is a tuff bend).

Peace,Rich

+1

and your contour has a sharp bend (at least in the rendering)

which needs a very soft transistion

this is a more common problem than some would like to admit

but ive seen it happen to 3 tops in two months

its not super sharp it drops only about 1/4" if that and is very gradual.

there were no problems when i bent it it was fine. i think it cracked from when the water evaporated.

[low end fuzz]

does 'veneer softner' exist because its better than steam?, or does it not raise the grain?, or maybe dosent interfere with glue?

i seen it for the first time on the weekend and took it as a scam; id have no use for it personnally, but the more i think about it the more im intriged;

i think i'll look it up

[Mickguard]

Any chance that, now that it's bent into shape, you can just glue the crack together? Since it's going to be covered anyway, I'll bet you'll never see the crack on the side once it's sanded.

[fryovanni]

If it's all glued down, there's really not much you can do less sand it all off and give it another try.

Or if you have any left, try and glue a patch into it where you need to see it and fill the rest in with epoxy or something.

its not glued its just clamped on right now. i have enough for another sub-top or to patch it.

How did you go about bending the wood to the contour?

If you try to fix it. The suggestions above sound reasonable(if the look is acceptable). If you do sand and re-do. Seems like more heat less water(1/4" is a tuff bend).

Peace,Rich

its only 1/8" thick. im going to put another top over this one (the 1/4" flame maple). i used a cloths iron and water.

(1/4" is a tuff bend).

Peace,Rich

+1

and your contour has a sharp bend (at least in the rendering)

which needs a very soft transistion

this is a more common problem than some would like to admit

but ive seen it happen to 3 tops in two months

its not super sharp it drops only about 1/4" if that and is very gradual.

there were no problems when i bent it it was fine. i think it cracked from when the water evaporated.

Try to use less water(seal the steam in as much as you can). The water is only to help get the wood up to temp because we generally do not have the best heat sources. If you had a very efficient system(maybe a heat blanket with a sheet of metal over the wood) I would say forget the water completely. The moisture in the wood is generally enough if you can get wood to temp efficiently. Since the wood is 1/8" I am pretty sure you have too much water not enough heat. I have bent a lot of wood in that thickness range and I rarely have issues(splitting-and generally only hairline) when I am frugal with the water. A 1/4" drop should is not too bad. This is a bend I did a couple days ago and the wood is in the 1/8" range, and just lightly spritzed with water-

Peace,Rich

[SwedishLuthier]

On Taylor guitars excellent ”factory Fridays” videos (c’mon Bob, some more updates please) they show the side bending machines. They use NO water what so ever. They seal the sides with plain brown paper and put it in the machine. When the sides come out the paper are slightly wet from the moister within the wood. Of cause they do this under extremely controlled conditions but it shows that we often over-use water when bending wood.