Friday, December 22, 2017

The Slow Saga of Zip Frame #4 — part eight

For me, the pure madness of this holiday season has been tempered by the peace and calm of working on this frame during quieter moments of the day.

Sometimes, those quieter moments have been at 4:00 in the morning with coffee in-hand and my brain in a painless neutral, moving a sanding block back-and-forth.... back.... and forth.

Sometimes, those moments have been late at night after a long and hectic day, with the scent of sanded mahogany blending deliciously with good bourbon.

Enough rambling. Let's start with an epoxy problem I ran into.

Epoxy Problem

You may recall this photo of Frame #2...

This was during the last of the encapsulating process for Frame #2. I had sanded through most of the epoxy, as you can see. I only needed to mix a very, very small batch of epoxy to finish this.

By small, I mean VERY small. I mixed 5 grams of resin with 2 grams of hardener, for a total of 7 grams of epoxy. ( 5 x 1.44 = 7.2 ) My kitchen scale does not show fractions of a gram, so forget about 0.2 grams of accuracy.

Up until this point, the smallest batch of epoxy I'd made was 10 grams of resin to 4 grams of hardener. ( 10 x 1.44 = 14.4) These batches had always come out just fine.

However, I guess the smaller you get with these batches, the more critical the accuracy of proportions. My 7 gram batch just wasn't dead-on. The stuff took forever to cure. For. Ever.

So, if this was during work on Frame #2, how does it affect Frame #4? 

Even 7 grams of epoxy left me with a good bit of leftover, since I only had to cover this one spot on one gusset. Marine epoxy (I use System Three Silvertip) is expensive, and I hate to waste any. So, I took the leftover part and began encapsulating some parts of Frame #4.

Honestly, I'm not sure any of that batch ever cured... not fully, anyway. 

After a couple of weeks, it finally hardened to something usable... but it remained gummy up until that point.

When I sanded it, it was very messy.

My point is: unless you have extremely accurate and precise measuring instruments... be very careful with such tiny batches of epoxy.

Moving on...

Angled Dash Beam

All along, I have wanted to have my dashboard tilted at an angle, like the classic Rivas, Chris-Crafts, etc. I had seen other boatbuilders approach this in different ways... often attaching the dash to angled blocking on the carlings.

I approached it a little differently. A while back, using my planer-jointer, I had made a piece of blocking with a 10° angle. I cut this blocking in half, so that the angle on either side of the dash would be exactly the same. Then, I cut each wedge to match the curvature of the gussets. I sandwiched the wedges between the gussets and the dash beam, giving it a nice angle.

Once all this was fit, drilled, and screwed together, I began to trim off the excess. For most of this step, I used my Porter-Cable multi-tool to cut away portions of the wedges and gussets.

This wasn't really a problem in the areas where the mahogany wedge was solidly pressed against the plywood gusset. However, when cutting through the back of the gusset where it wasn't backed, the meranti plywood splintered badly.

I learned my lesson. On the other side, I sanded it instead of cutting. The result was much better.

With the dash beam set at a ten degree angle, the top aft edge was now slightly higher than the top forward edge. So, the next step was to sand that edge down, or "fair" it, so that the top of the frame was once again perpendicular to the side members of the frame.

So, here are photos of Frames 2 and 4, in their current state:

The next step is to disassemble the dash beam. I'm going to cut some of the height off the bottom of the wedges, to "hide" them behind the dash. I just think it would look better. Then, I'll glue-and-screw the dash beam, wedges and gussets back together.

It may be a while before I attach the dash permanently onto the rest of Frame #4. I still need to cut out an oval in the center for the instrument inlay. I don't yet have a router (ahem, Santa!) to round over the edges of that oval cutout, either. I'd prefer to do all of this work with the dash beam laying perfectly flat. That won't be easily accomplished once the dash beam is permanently attached.

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