Cleats

[rocket]

I haven't thought of the need before but am just considering the addition of cleats to the centre join of arched plates in guitars, if only as a little insurance for that join as the guitar ages.
Makers of instruments belonging to the viol family add cleats to the centre join of their plates for extra support of the join but i haven't seen any evidence of arch top builders adding cleats, even though an arch top belly may have an Xbrace crossing the join, this is only in one area and if parallel bracing is used there is no cross join support,and although the gluing area of the centre join of an arch top is greater than that of a flat top, the latter does have a series of braces and a bridge plate to help support that seam.
Any opinions aired on this subject will be appreciated !!
Cheers,,
Rod.

[P Bill]

I don't know much about the viol family but the preforming clothes are interesting.

http://en.wikipedia.org/wiki/File:Barbara_Strozzi_1.jpg

[kiwigeo]

These are the cleats I use...

[rocket]

Helpful

[peter.coombe]

Have never used a cleat on any of my mandolins. Only one failure so far and that was my own fault. Left a mandolin in the workshop and went on holidays. While away the temperature went up to 38deg and the humidity fell to 8% so no wonder the top seam failed. A cleat(s) would not have saved it. Not necessary IMHO.

[Nick]

I would have thought the shape (being a 'self supporting' structure) and thickness of a curved top instrument would reduce the risk of a joint popping. The only time I could see it doing so would be as Peter pointed out, during times of large humidity changes. I can't remember exactly (and I could be waaaaay off base here because my memory is deteriorating at an alarming rate these days ) but I seem to think Bob Benedetto made mention of Jimmy D'Aquisto adding cleats in his DVD series? But he didn't and doesn't to this day.

[kiwigeo]

Helpful

I actually use cleats along underside of centre seam on my guitars where a significant length of the seam is not crossed by a brace. Seems like good insurance for little effort to me.

[Dave Stewart]

FWIW, John D'Angelico sometimes used cleats (.. so the D'Aquisto reference wouldn't surprise me). They show up periodically during restorations.

[rocket]

Far be it from me to criticise such accomplished builders but, in the example you've shown Dave i can't see the point of fitting a cleat so close to the neck and tail blocks and none along the rest of the seam and to me those " cleats" look more like blocks, I think that if supportive cleats were to be added to a soundboard they would be spaced at equal intervals along the seam, made as small as possible so not to hinder the performance of the plate but shaped in such a way that it is strong enough for the purpose it's being added for.
Cheers,,

Rod.

[jeffhigh]

It would seem to me that the F holes would provide a free edge to avoid the plate being restrained laterally, so the centre seam should not be a troublesome area.
Most cracks seem to occur running into the f holes.
Agree on the location of those large cleats, they seem pointless.

[Dave Stewart]

Yeah, what did they know!?
Seriously, I think you have consider of how bridge downforce tries to distort & break apart the plate. Forget about the viol family ...absence of a post changes everything IMO.
I think Michael Lewis had the best explanation ...."my guess at the center seam reinforcements near the blocks is that those areas are most prone to separation due to plate deformation from constant string tension. When the strings push the bridge down on the top the top responds by pushing up somewhere else, like between the bridge and tail block. The cleats have fairly large surface area so they have a lot of shear strength holding the seams together."

[peter.coombe]

Under the tailpiece is a common failure area on archtop mandolins. I know nothing about archtop guitars, but the forces are the same, so it should be similar. The pulling force of the strings is rotating the tailpiece into the soundboard, so a bit of re-inforcement under the tailpiece may be a good idea. However, the force is lengthways, so the sensible arrangement would be to have the reinforcement placed up against the tailpiece with the grain in the same direction as the top. I have done that on King Billy Pine topped mandolins. The failure is usually a break across the gain, not failure of the centre join, so a cleat with the grain going across the grain of the top makes no sense to me.

[jeffhigh]

Yeah I did the same thing on my last build, selmer style guitar, for the same reason
I left out the last transverse brace before the tailpiece (as per Djanjo's one) but used a centre joint reinforcement long grain from tailblock to the next brace.

[rocket]

Interesting topic this, got a bit more than i bargained for, some really good information coming out of those posts, thanks y'all.
Cheers,,

Rod.

[Patrick Hanna]

It's an interesting topic. In his book, Benedetto mentions that he frequently saw cleated D'Angelico guitars when he was doing repairs. For a time, he followed suit with his own guitars. Then he came to believe that perfect joints, well dried wood and optimal building humidity eliminated the need for cleats. However, Benedetto sometimes does install a nearly full-width cross brace near the tail in the lower bout. From the photos I've seen of the D'Angelico shop, it is very doubtful that he was able to control the humidity in the space. It's possible that he cleated some instruments as a safety measure after having just a few joints fail. Obviously, he's not around to ask, but two of his cleats are right there in Dave's photo. I frankly don't know the correct answer to this question and I suspect there will be many differences of opinion. However, if it works for you, I see no reason why you shouldn't use it. I don't cleat. If I did, I'd probably do it near the ends of the f-holes.
Patrick