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Not sure if I should thickness sand my new black walnut back plates then glue or glue them first? Maybe plane close, glue, sand? Glue, plane close, sand?

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Plane to about .030" of final thickness (.020" if glued face down, you feel confident and plates are flat), glue, sand. (Make sure show face is smooth)

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Pat

I'm a believer in the sand to just above desired thickness, join halves, cut rough to outline, finish sand to desired thickness method.

I like to have my top and back plates about .188 inches or so when I glue them. If it's a nice straight grained wood I will use my planer to bring them to that thickness, glue them and then to the sander. With highly figured woods I will joint the edges, glue them and start with coarse grits (30 or 60) and thin to around .188 inches and then switch to the finer grits (80 and 120) to final thickness.

I like to glue them thick simply because they're stiffer, although I 've joined them at final thickness and had no problems just scraping the joint smooth and then bracing.
Lately I like to sand them smooth, joint them, and then install the backstrip or whatever if the plan calls for it, sand it to final thickness in the sander, cut out the shape, brace it.

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Old growth, shmold growth!

All righty then. Looks like, as usual, there's as many ways to do this as there are people doing it.

Thanks for so many responses, not sure which way I'll go but probably glue, plane close, sand. We'll see.

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so far i´ve only glued rough plates - i might scrape them before jointing to reveal the grain if it´s too fuzzy. i find it easier to have a larger glue surface. then comes the plane, then sanding.

might try to thickness them a bit first, shouldn´t do any harm.

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Anyone who read my erased post please disregard....!! Quite obviously made before coffee and while my brain was half asleep.
Tom

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A person who has never made a mistake has never made anything!!!

I use the tape method of joining and it makes it difficult to clean of the squeeze out so joining at around .150" allows a good clean up with the thickness sander.

Fred

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Fred Tellier
http://www.fetellierguitars.com
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I like to join the plates as thick as possible. Room for error plus shooting the boards thick seems to work better. I cut the outline then thickness through the drum sander.

Thanks for all the ideas. I had one back plate at ~.155 and the other at ~.140 I sanded the thicker to match the thinner and glued them up (tape method as well). Today I'll final thickness to around .095 for this parlor sized back. Really helpful and another thanks to everyone for their input.

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Glue, then sand (at an angle to avoid glue line build up on paper). If incorporating a back strip, do a little sanding first, rout and install, then final thickness sanding. I use the Spanish joining system. I do not care about glue squeeze out (though I will do my best to clean what I can). It all scrapes off without a problem.

Thicker plates are easier to join, you can safely use more joining force. If you use final thickness plates, any uneveness (unexpected) will require more sanding and perhaps you end up with plates that are too thin. A backstrip that is routed into the seam results in a much stronger joint than a backstrip joined between two plates. DAMHIK. Finally, I don't fully understand why, but sanding joined plates results in a more "invisible" joint.

Mike

Should be mentioned (maybe someone did I didn't read that carefully) that you should only do just enough sanding/planing/ flattening as necessary on the show side . For stock removal or thinning do that on the non show side so you don't lose the pattern of your book match. How much this matters varies with different cuts of wood etc. but it is a good general rule to follow.
L.

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Cut to size.....Beat to fit.....Paint to match.

No, it wasn't mentioned Link, and that is a very good point.

Yeah cut the outline, then final thickness. Just makes that much less material to send through the sander. I cut the shape after sanding to final. Not the best way IMO.

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Thank You and Best To All