The Bentside and the Bottom

Continued fairing the first side of the bent-side jig. The first side is extremely close to the drawing. I used the first side as a guide for the 2nd side, then cut the 2nd side out, screwed both together and used a router to trim the 2nd side with a flush cutting bit. Then I flipped them over and used the 2nd side as a guide to smooth the 1st side to be an exact copy. Screwed on the lower braces and the form was wracked by about ¼” so mounted the entire form to a ½” piece of Baltic birch plywood to make sure it was level. This adds weight but it is more important that it be flat and square.

Installed the upper braces in the bent-side jig.

Installed the 3 pieces of hardboard covering on the bent-side jig and trimmed and sanded the sides. Cut the slots in the ends of the clamping bars and ran all of the pieces through the drum sander to clean them up and make them all consistent.

Here is the bentside jig, complete and ready to bend the harpsichord sides.

Harpsichord - Completed Bentside Jig

Harpsichord – Completed Bentside Jig

I built the “jack-cutting” jig out of scrap maple and rosewood. This jig is used to cut the jacks to length. I just love making all the ‘tools’!

Jack Cutting Jig

Jack Cutting Jig

Purchased the poplar material for the case sides at Anderson McQuaid, a local supplier of every kind of wood imaginable. Ripped 3 narrow (1 x 4) strips for bent-side liner to 3 inches, and planed them to a bit less than 3/16” each in order to laminate them into a ½” part. Laminated first 2 pieces in bent-side jig.

After removing the 2-ply lamination for the bentside liner from jig there was a fair amount of spring back. The third piece had been put in the jig overnight not so much to bend it, but to take some of the spring out of it. Laminated the third piece and put back in the jig and clamped it down. Removed bent-side liner from jig. Aligned with plan, the liner now only has ~1/4” spring back, which is significantly better than the 2-ply lamination was. It lines up almost perfectly. This is the same approach that will be used for the bent-side itself. The bent-side pieces still need to be planed to thickness.

Cut all of the poplar pieces for the bent-side to length and width and used the hand power planer to begin planing one of the pieces to ~3/16”. Also tried using the Delta planer. Piece got rather torn up by the planer and has developed a decided ‘curl’. Will have to try to finish this piece with the thickness sander. If that works I’ll finish at least the poplar pieces with the thickness sander.

Finished milling the first piece with the thickness sander, 36 – 80 – 120 grit. Flattened out the ‘curl’ considerably.

Completed the planing/thinning of the subsequent 2 pieces of poplar for the bentside. Used the hand power planer to get the thickness down to as close to ¼” as possible and finished using the thickness sander. But this time I used 60 – 100 – 120 grits. Sanded to just under 3/16” each. Laminated the first two pieces in the jig, and left for 24 hours.

Removed the first 2-part lamination from the jig and aligned it on the plan. There was some spring back, but it aligns well. Returned to jig and laminated the 3rd, wider piece in the jig. Hopefully will remove much of the spring back the same way the liner lamination did.

Harpsichord - Bending the "Bentside" in the Jig

Harpsichord – Bending the “Bentside” in the Jig

Removed the laminated bentside from the form and checked it against the plan. It fits about as perfectly as one could expect. I’m relieved that the bentside is finally done, and if I build another one in the future I will consider buying thin sheets of Italian bending plywood to make just the bentside. It is thin and can be easily laminated together without all of the prep. Alternatively I’ve seen a video on YouTube where Kevin Fryer, a Harpsichord maker in San Francisco bends his bentsides from a full thickness blank using a custom made metal jig, which would be a significant investment.

Purchased three glued up wood panels (pine) that will be enough to create the harpsichord bottom. They aren’t particularly attractive, but it is for the bottom, which is not seen.

Today received a new edition of the Harpsichord Project 2.0 which is visually nicer and the navigation is much better than the previous version.

Trimmed the bentside and other case side pieces to 9 inches. Will trim to final 8 ¾ before starting to fit them to the bottom. Planed the bottom pine sections to ½” and began to join them together using pocket screws as clamps.

Once the joints dried removed all of the screws from the bottom and plugged the holes with special pine KREG plugs. Planed the plugs flat. Laid out the bentside outline on the bottom and trimmed along the edges, leaving enough wood to be able to flush rout the bottom to the sides, except along the spine.

About npcarey

Amateur Luthier, music enthusiast, software enthusiast
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