Hi Dean. Cut the inserts out to fit easily into the cut-outs - don't worry about a perfect fit - you'll be using a good gap-filling high- strength epoxy anyway. Even if there are quarter-inch gaps here and there, no big deal. I'm not sure I understand the method of cutting you describe below, but it appears you routed out the pinblock cut- outs. Epoxy makes a mechanical bond with wood, so any roughening of the surface you can will be good. If you are applying thin epoxy resin to the wood, it would probably soak in enough that roughening wouldn't matter - but since we don't really know how far it will soak in, absolutely, IMHO, it would be a good idea to roughen the wood bonding surface. I cut my pinblock cut-outs with a saws-all saw - so it left me a nice rough surface anyway. Because of the stresses that will be applied to your pinblock, and the relatively small bonding surface area you will have, you really want to make sure you make the best epoxy bond possible. I used the West System Two-Step Bonding Method, which I strongly suggest is the best way to do this job. http://www.westsystem.com/ss/bonding-gluing-clamping/ Another good way to work thin epoxy into a surface that doesn't soak up much this epoxy (this is how West System recommends bonding metal), is described about half way down this page - point #3 http://www.westsystem.com/ss/bonding-hardware/ Basically, they recommend sanding (with very coarse paper) the thin epoxy into any non-porous surface to be bonded. I've even had very good results using this method when I wanted to bond a plastic pipe to something - and we all know that epoxy won't bond to plastic - or at least we thought it wouldn't! After wetting out the two surfaces, I highly recommend using West System #404 High Density filler - it is their highest strength filler. The method I used to align the inserts to the cut-outs was to first, make sure my inserts are the same thickness as the block. Then I used my pinblock jack (the thing you support the pinblock with when driving tuning pins into the block), with a piece of flat plywood (larger than your cut-out) on top of it and a piece of plastic on top of that. Put it under the cut-out, snug it up to the bottom of the block, and now you have an automatic insert leveling system and also something to prevent any low-viscosity epoxy from oozing out from the bonding area. Hope this helps. The last piano I used this method on I tune every few months - and it holds it's tunings wonderfully. Terry Farrell On Mar 30, 2010, at 10:16 AM, Dean May wrote: > This is the pin block from the piano tear down I just posted > pictures of. It is a rather complex shape with several different > levels- beyond my meager woodworking skills to duplicate. I could > have used plugs but borrowing from Terry Farrell, I decided to > router out the pin fields. I drew boxes around 3 pin field areas- > the two in the treble happened to come out so I could make them the > same size. I then transferred the dimensions of those boxes to a > piece of OSB board. I then drew a box 2.75” bigger all the way > around (6” router base, 1/2" cutting bit) and cut out the big box to > make my pattern. Since I was able to make the two treble cutouts the > same, I only had to make two patterns. Today I am going to a big > woodworking shop owned by a friend and I intend to cut out the > inserts on a good band saw. > > I plan on epoxying the inserts into place. I was wondering if > scoring the surfaces with a coarse rasp file, instead of leaving > them smooth, might give the epoxy better surfaces to bond. > > Dean W May (812) 235-5272 > PianoRebuilders.com (888) DEAN-MAY > > Terre Haute IN 47802 > > -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://ptg.org/pipermail/pianotech.php/attachments/20100330/e147bd71/attachment.htm>
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