Saturday, August 29, 2015

curved trundlebed headboard surround iii

My next step was to veneer the curved panels. From my experience using cauls to hold down the second layer of 1/4 wig wood ply, it seemed that a different clamping scheme would be required. the cauls I made just never appeared to deliver sufficient pressure at mid span, and no manner of wedging/tightening seemed to deliver this without causing a gap to form elsewhere.

I posed the question to and the old salts there advised vacuum bagging. This made sense and so I grabbed a vacuum pump and bag assy from joe wood worker's website. I could have spent the time getting my own pump and bag setup done, but this guy's got the entire solution.

I'll begin with showing where I left off with the panels today, sanded to 180grit.

Here's a dry assembly of the piece
All this wood started from a reclaimed cache of redwood that I found at Earthsource Lumber, harvested from an abandoned water tower in Northern California. Lots of scrub planing and wood picking ensues.
I don't have the pics on hand, but essentially I took the planks at ~8" wide, and planed them on my machine. I then resawed into 1/8" sheets, and then sent these through the planer again to clean up the sawn edge. the final milled thickness was around 3/32", So I had to send these sheets through on a strip of 3/4 plywood. I used masking tape sandwich with hot glue to hold the sheet to the bed. Ben Crowe from Crimson Guitars on a youtube vid demonstrated this technique
Ellis Valentine at gave me the tip to use finishing nails like so to gather enough edge pressure to join the bookmatched veneers. The show side is face down here, and I used masking tape to pull the sheets together initially, as is typically done. I then folded along the seam,ran a bead of glue and then returned the edges together. The nails just provide an extra oomph to the clamping.
My ribs were too far spaced to handle the vacuum pressure, so I added extra ribs, at roughly 4,1/2" spacing and this helped prevent the panel from dipping under the vacuum pressure.
ON the short panel, after a few days of being in the hot garage, I noticed a few cracks in the veneer. I don't know why, perhaps I took it out of the bag too soon. The ambient temps were 70-80 degF in the garage and I had it in the bag for almost 6 hours. I filled the cracks with a slury of redwood sawdust and white glue. The long panel has yet to exhibit this problem, although tonight I heard a few audible split sounds in the panel, so i'm not sure where this will end up.
I used UniBond 800 Urea Formaldehyde glue which dries hard, but I don't want to inhale any of that dust while planing/scraping it off the edges.
My scraper plane worked magic on the rough sawn side of the bookmatched veneers, before using the palm sander.

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