what type of wood for action plates

[Marien]

I am trying to completely replace a the wood of 2 action plates in an old 30b Lachenal concertina. It looks like a kind of pine. I am wondering - would it be appropriate to use willow (it does not split easily), (good quality) spruce for the basic plate? What would be the best wood to use for it?

[alex_holden]

Traditional is quarter sawn European sycamore. American hard maple is similar and may be easier to obtain. Or perhaps some sort of mahogany.

[Frank Edgley]

Baltic birch aircraft grade plywood would work for your Lachenal. It won't warp or split...ever.

[Marien]

1 hour ago, alex_holden said:

Traditional is quarter sawn European sycamore. American hard maple is similar and may be easier to obtain. Or perhaps some sort of mahogany.

 

Thanks, I'll go for the sycamore...

[Geoffrey Crabb]

1 hour ago, Frank Edgley said:

Baltic birch aircraft grade plywood would work for your Lachenal. It won't warp or split...ever.

I argree with Frank, plus it won't shrink.

The desk also of the same material attached with the face grain at right-angles to that of the base plate.

 

Geoff

[Dana Johnson]

The European sycamore (not the flaky barked patchy stuff in the US) should be easy to get.  The wood I use comes from Austria anyway.  I have to look through the pile for the best quartered material and the least figured.  But it is excellent.  

[Marien]

Thanks for the tips everyone.

 

Problem with the sycamore is it has to be the right dimensions, quartered and dried for about 12 years (or artificially). So it is not that easy to get it for use today.

 

The original plates with the holes for the pads are 4.2 mm thick and is solid wood, possibly sycamore.

When using the birch plywood, would it have to be about the same (4.2 mm)?

 

 

[alex_holden]

1 hour ago, Marien said:

Problem with the sycamore is it has to be the right dimensions, quartered and dried for about 12 years (or artificially). So it is not that easy to get it for use today.

 

The original plates with the holes for the pads are 4.2 mm thick and is solid wood, possibly sycamore.

When using the birch plywood, would it have to be about the same (4.2 mm)?

 

Most hardwood you buy from a reputable large timber dealer (not a little backyard sawmill) will already have been kiln dried. In my experience you do need to cut it oversize and let it acclimatise to indoor conditions, ideally for a few months. Weigh it regularly and write down the measurements. Once the weight curve flattens out, you'll probably find that it has warped a bit, so you will have to plane it flat and parallel again before you can use it.

 

If using commercial birch plywood instead, I wouldn't recommend going thinner than the original, and it's not ideal to go a lot thicker either. You could start with 6mm ply, which is probably actually about 5.5mm, and plane it thinner. When I do that I always seem to find patches, knots, voids and other crap (one time I even found woodworm tracks!) hidden in the internal plies.

[Dana Johnson]

Plywood, birch or otherwise tends not to warp because it is balanced in its layup.  If you start planing off the plies, that ceases to be the case.  Even numbers of plies 90 degrees offset,  tend to twist in warping as humidity changes.  Because it is trying to assume the shape with the lowest area.  Odd numbers of plies stay flatter.  In the small sizes concertinas use, the small tendency to warp is not hard to constrain.  Given that you would be changing the wood anyway, using plywood slightly thicker or thinner than the original won’t make any more difference to the sound than the change in wood will.  

[Chris Ghent]

18 hours ago, Marien said:

Thanks for the tips everyone.

 

Problem with the sycamore is it has to be the right dimensions, quartered and dried for about 12 years (or artificially). So it is not that easy to get it for use today.

 

The original plates with the holes for the pads are 4.2 mm thick and is solid wood, possibly sycamore.

When using the birch plywood, would it have to be about the same (4.2 mm

 

 

 

Marien,
look around for a violin (or any member of the violin family) maker and they will have scraps you can use. Personally,  I think there is a tone penalty for using plywood.

Edited June 22, 2020 by Chris Ghent
Stupidity

[alex_holden]

1 hour ago, Chris Ghent said:

look around for a violin (or any member of the violin family) maker and they will have scraps you can use. Personally,  I think there is a tone penalty for using plywood.

 

If they don't have a single board wide enough, it should be possible to glue two narrower ones edge-to-edge like they do with violin backs. That is a bit more of an advanced woodworking technique though.

[Theo]

I've been able to find a nice piece of 100+ year old mahogany for Marien which should do the job nicely.

[Marien]

3 hours ago, Theo said:

I've been able to find a nice piece of 100+ year old mahogany for Marien which should do the job nicely.

Thanks Theo, looking forward to receive the wood.

I think that considering the age, the mahogany wood stopped working... seems to me that it is very suitable for the job.

Easy woodworking and If there is no pressure it will keep its exact form and it won't crack. 

[Dana Johnson]

Mahogany, especially The 100 year old sort was often used for larger instruments pad boards because of its excellent stability.  It is too bad that as usual it was over harvested and the best varieties are on the CITES list.  Sometimes Old  large pieces of furniture like display cases can be found and can be quite a prize.  Once upon a time, you could paw through the Martin guitar company’s reject pieces for some great wood.  Not these days though.