Side bending fault help

[misterg]

I've bent the IRW sides for my OM build using a hot pipe, I thought, successfully. However when sanding the sides, prior to installing the linings, I have found a 'divot' in the side that seems to be associated with a funky area of grain. The areas either side of the divot are pretty straight and true.

I have had a couple of tries at re-heating the area and trying to clamp it with a caul, but it has not been completely successful, and I am conerned that it might move in the future

This is the area (click the photos for full sized versions):

Outside



Inside



This is how far out of flat it is after my last attempt at heating / clamping it:

Outside



Inside



The area becomes very pliable when heated, and will clamp flat; it just doesn't seem to want to hold its shape.

Any advice appreciated on how best to deal with this would be appreciated.

My instinct is to double the area using an IRW patch on the inside, roughly as shown in the photo below. I would be inclined to align the grain at an angle to the sides (maybe 30°) to try and guard against splits going through both.



Should I persevere with heating / clamping? Fit side braces (there are none in the plan)? Go with a patch of some sort? Something else?

Thanks in advance,

Andy

[Fathand]

Do you think if one of your side braces was glued over that area it would hold it in shape. I'm thinking Quartersawn spruce about 1/8" thick, 5/8" wide? Something a little more substantial than a usual side brace but shouldn't look too out of place on the inside of the guitar.

[misterg]

Originally Posted by Fathand

Do you think if one of your side braces was glued over that area it would hold it in shape.

I really don't know - I think it would help, but I suspect it would have to be a bit thicker than 1/8" - more like 3/16" maybe.

(To clarify - there are no side braces shown on the Grellier plan).

Thanks,

Andy

[Bruce Sexauer]

I call that “potato chipping”. It is not uncommon. Some makers use extra thick sides so that is can be sanded flat. Others make the sides the thickness they should be for optimal performance and accept the purely cosmetic issue for what it is. Side braces glued to an uneven surface are trouble waiting to happen.

[misterg]

Originally Posted by Bruce Sexauer

... accept the purely cosmetic issue for what it is. Side braces glued to an uneven surface are trouble waiting to happen.

Thank you - What do you think to adding a patch to the inside? (The distortion is quite localised over an area about 15mm high x 60mm long - not the full height of the side)

I've had another try at bending it flat on the hot tube and it's currently clamped up and cooling / drying.

[misterg]

I had a few more tries at heating / steaming it, but I couldn't really make much difference, and I was worried that I would split the side if I carried on.

So, for better or worse, I've glued a patch to the inside so I can move on with this.

The patch made of the same material as the side, planed to a similar thickness with the edges feathered out a little.

I clamped it into place quite aggressively while the glue set:







It has got rid of the worst of the 'divot' to the extent that I think it will now sand out - I'll let you know how it fares...