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March 28, 2015

Dashboard

One of the coolest things about the TR6 and some of the other British cars of the era was their fully instrumented wood grain dashboards.  Never mind the marginal practicality of this in a roadster with the top down most of the time, it was an important style statement that became part of the mystique of the marque.  The TR6 outer dash is a plywood base veneered with what appears to me to be walnut or something close to it.  

My dash, other than being grimy, was in pretty sound condition, althought the finish was not.  It was cracked and crazed from four decades of temperature and humidity extremes, not to mention frequent strong doses of UV radiation and the occasional dowsing from an unexpected shower.  




On close inspection of the dash from all sides, I determined that I could easily save the dash, but the finish had to go.  This is where I began to consider the range of options for either rebuilding or replacing the dash..  Many have commented on the difficulty of removing the factory finish, and I wasn't sure I could remove it without doing some unintended violence to the thin veneer.  In pressing on, I too was struck by the tenacity of the finish.  Wimpy strippers don't faze it.  A good strong methylene chloride stripper will remove it, but it's a slow, iterative process.




In the scraping required by the stripping process, I did indeed damage the original veneer in a few places.  It's very thin, and is very vulnerable in places where there is short grain between two edges.




Considering the damage, I deemed the dash unusable in that condition.  This started me running through the options.  There are aftermarket replacement dashes in many different veneers.  Some of the ones I've seen are beautiful, but expensive, and since my dash was physically sound, I didn't even consider buying a new one.  All I needed was to restore mine cosmetically.  All I needed was new veneer.

Once I got on the path to new veneer, I realized how wide the range of possibilities was.  Broadly speaking, a veneer surface doesn't have to be wood, but to my mind, using some non-wood finish would violate the spirit of the car.  Even limited to wood, the possibilities are many.  There are hundreds of types of wood veneer, domestic, exotic, and specialty.  I gave it a lot of thought.

Now I've been a hobby woodworker for decades, so I have at least a passing familiarity with quite a few kinds of wood.  When thinking of a dashboard wood, the first thing that will come to mind for many people is walnut burl.  It's almost a cliché for very upscale cars, and is widely cheaply imitated in lower class wanna-be cars.  I find walnut burl very beautiful, but a little too obvious, a little too pretentious, and also a little overdone.

I considered quite a few kinds of wood, mostly exotics.  I've worked with padouk and purpleheart.  They are gorgeous when freshly finished with strikingly rich colors.  The colors don't last well, though, tending eventually toward brown.  I considered several kinds of mahoganies and rosewoods.  Some of the rosewoods had such bold grain that it seemed too overpowering.

While I struggled with the veneer decision, I prepared the dash for whatever I finally decided on.  Mainly, this involved sanding the surface smooth and flat, and repairing the few voids in the old veneer.  I also filled in the five countersunk dash mounting holes.  The countersinks looked to be kind of hogged out, so I'll redrill and countersink after the final finish is on.




Also filled some voids and fixed a few stripped holes on the backside.




Enough stalling.  It was time for a decision.  In the end, I came back to one of my all time favorite woods--zebrano, or zebrawood.  When zebrawood is quartersawn (cut on a line that goes nearly through the center of the tree), it has a striking grain consisting of more or less straight lines of alternating tan and dark brown.  The dark brown is close to the color I plan for the interior.  I'm not totally sure how it will look in the car, so it's a bit of a leap of faith.

Raw veneer is commonly sold by the lot.  A lot consists of a number of consecutive sheets of veneer, meaning that they would have been adjacent to each other in the tree.  Sheets in a lot will not only have consistent color, but the grain pattern of adjacent sheets will be nearly identical, with only subtle differences.  I went on a website that posted photos of the lots they had in stock, so I could pick the one with the grain pattern I liked.  The lot I bought had four sheets, but any one of them was big enough to do the dash.




While there are a number of methods to attach raw veneer to a wood substrate, most of the better ones involve some serious clamping.  Just stacking weight on top of the veneer is often not practical since the 10-12 pounds per square inch needed for a good bond can add up to thousands of pounds for something the size of a dashboard.  Luckily, there is an easy way to provide this pressure that doesn't involve lifting heavy weights.  A vacuum press uses normal barometric air pressure to apply clamping force.  It does this by evacuating the air out of a sealed bag that contains the items to be clamped.  With little air pressure inside the bag, normal room air pressure provides the clamping pressure.

I fabricatred a bag out of heavy vinyl sheet (like what our rear windows are made from) that was big enough for the dash.  I did build a vacuum pump, but only because I can use it for other things.  A much simpler pump would have worked as well.  People have even used shop vacs.

I built a shallow frame to hold the dash and veneer.  On top of the veneer goes a flat panel that applies the pressure to the veneer.  The panel has grooves cut in it so no air can get trapped in cavities in the bag.  I decided to veneer the glove box door at the same time as the rest of the dash, so I taped it on the backside to keep it registered with the surrounding dash.  This guarantees that the grain will be continuous across the door, but would make cutting the door out a little more tedious and risky.




Then in the bag under vacuum for an hour or so.




Another couple of hours to finish curing, and I started trimming.  A very sharp Exacto knife worked pretty well, which of course meant that one of the biggest risks became blood stains on the veneer.




After sanding the edges flush.  The glove box door seemed to fit nicely.  All the exposed edges of the dash will be painted brown eventually.




The glovebox door gets veneered on its backside, too.  The factory appied the veneer vertically on the back, so I did too.  I was able to use a scrap from the dash and cut it in half so the door backside veneer is bookmatched, or mirrored.




While trying to decide what kind of finish to apply, I cleaned up and primed the metal sub dash.




For the finish, I obviously wanted something good looking, but also durable.  The environment for the dash is essentially outdoors, with wide swings in temperature and humidity, and strong doses of ultraviolet light.  I've used many of the products available to the mass market through big box stores, and most of them worked OK, but I felt there were probably better products available.  I researched true marine varnishes, and finally chose a European varnish popular with the higher end boat crowd.  It isn't cheap, but I was able to get a half-liter can which was plenty for the project.




Staying fairly close to the recommended application schedule on the can, I applied a few thinned coats, which tended to soak into the wood.  I followed this with unthinned applications for a total of nine coats, sanding between coats to level any imperfections.

I don't have a dedicated finishing room, so I expected the usual dust nibs in the finish.  This isn't a big problem since I planned to cut back the gloss anyway, a process that will remove those kinds of imperfections.

Here is the dash after the final coat was dry, but before any final leveling or adjustment of the sheen.  A good varnish finish suitable for outdoors takes time.  After nine days of one coat per day, the finish is dry to the touch, but is still soft.  It can take another week or more to get the finish hard enough to sand.  I waited until a finger pressed hard onto the finish would not leave an impression.  It was about another ten days of leaving it on a window sill in direct sun.




I glued the speedo and tach veneer cutouts to a substrate with the idea of testing finishing techniques on them first, before applying them to the dash itrself.  It gave me a chance to try various rubbing products and see various sheens before I committed myself to the dash.  I wasn't totally sure what level of gloss I wanted, or even how to get it.  One advantage of using a high gloss varnish is that it can be rubbed to just about any level of sheen from matte to high gloss. Even if I wanted a very high gloss, the rubbing steps are necessary to get rid of the surface imperfections of the raw varnish film.  

The pic below shows one of the test panels with the right half untouched after varnishing, and the left after a regimen of  fine wet sandpapers and a series of hand rubbing steps.  That was about the maximum gloss I was interested in, and I knew how to get there.  I could stop short of that level for a little more of a satin look.




Here is a section of the dash part way through the process.  I really like this look, but went on for a little more shine.




After a little more work, I had this.  I decided to back off on the sheen just a little from here.




Here are a few more photos of the glove box door raw, at sort of a semi gloss stage, and nearly full gloss.




Here is a view of the parts together.  I think I'll leave it at this level.




I then had to redrill and countersink the holes for the dash mounting screws.




Painted the backside and the instrument holes black just for a more finished look.




This puppy is done!




Postscript

The dash looks nice, but we can't really have a fancy zebrawood dash without a matching fancy zebrawood gearshift knob, now can we?

I believe this is the original shift knob.  I think it's walnut.   It lost its emblem decades ago.




I happen to have a chunk of zebrawood.  I cut a couple of little pieces off and glued them together.




I took a hardware store threaded coupler and cut some grooves in the outside for better grip, and epoxied it into a hole in the center of the zebrawood block, then sawed off the corners of the block to make it a little closer to round.




OK, still needs some work.




Put a cutoff bolt mandrel in, and put it in the lathe.




This looks better.  The badge is actually a tie tack I bought off the Internet.  The stock knob always felt sort of delicate to me.  The new one is a little fatter.




I resisted the urge to pot the whole thing in plastic, as is pretty common.  I didn't even use the same varnish as for the dash.  Instead, I used a simple oil finish, which I think feels better in the hand.




I didn't realize until this was almost done that the original knob had a rubber isolator inside, presumably to transmit less transmission vibration to the knob.  If I had known earlier, I might have tried to duplicate it.  Oh, well,  live and learn.


Please send comments to Ed at: elhollin1@yahoo.com

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