Tuesday, June 19, 2007

Some primer, finally

I have been waiting for a nice warm day to allow me to apply multiple coats of primer in succession -- if you wait too long, you have to sand between coats. This past weekend was quite unproductive due to more crappy weather. The PNW is like this every year -- just when you think you've made it to summer, it goes and rains for weeks on end.

I have made a little bit of progress on the daggerboard case. Here's the foam side pieces, with the HD foam cutouts done; you can see the HD pieces stacked off to the left as well:

Here's something that is kinda cool. Obviously the tops and bottoms of the case sides are angled - but they're not the same. And the plans only give the side length dimensions, not the angles. How to cut this accurately and straight? After some thought, I remembered I could use a little high-school trig (inverse tangent) to calculate the angles, then just use them to configure the angle guide on the table saw:

I'm not claiming any brilliance here; what's cool about it is that this is the first time in my memory that I've ever been able to use high school trig for a practical application. Maybe I need to get out more. :-)

My method of edge-gluing foam, is to slather some putty on one edge with a popsicle stick, clean off the gross excess from top and bottom, join and position the pieces on a piece of plastic, scrape off any excess that squeezes out the top, lay more plastic on top, then set something heavy on top of that to keep both foam pieces flat. You do get some squeezeout on the bottom, but the top is usually in pretty good shape as far as not needing much sanding. Sometimes there will be some gaps in the joints on the bottom, but that's easy enough to fix on a second pass. Here's the case sides after gluing in the HD foam:

On Sunday I set up some chains, so I could hang my floats for priming\painting:

I am not worried about the tent frame being able to support it -- 100+ pounds (I haven't weighed the floats yet - will do so after final paint) isn't that much. The attachment is just a threaded hook bolted to a 2x4, then hung from the chains with a s-hook:

Today was a beautiful day, 75 deg F after work, and I decided it was my chance to finally get going on some primer. First thing to do was open up the cans of primer and converter, and mix them up. The material in both cans had settled to an extreme degree; at first it looked like I had bought two cans of sludge (bottom 6-8 inches was solid material):

The can of white primer above is shown post-mixing; I've just gotten started on the converter on the right. By the way, those yellow clip-on can spouts in the picture above are awesome -- what a awesome mess-saver.

After much mixing, I finally had transformed the sludge in both cans back into a homogenous mixture (I wonder if a paint or hardware store would let me borrow\use their mechanical agitators?). I then used a high-quality 7", 1/4" nap roller to start applying primer to the starboard float:

This is Alexseal's "high build" primer; they say it is comprised of 57% solids (after seeing the sludge, I believe it) and getting the fairing compound covered up was pretty easy. I applied three coats on before it got dark. Here's a couple pictures of how it looked right after I got done:

And from the rear:

Applying primer while having the float hung up like this wasn't as easy as I thought it would be -- the float wanted to swing all over the place. Spraying would not have such an issue, but I'm not willing to spray this poisonous stuff in my backyard.

There are only a few imperfections that the primer didn't fill in. Next step will be to mount the float horizontally in the frames again, fix the imperfections with fairing compound as needed, sand this primer coat down, and get it ready for the "finish" primer coats.


Anonymous said...

Hello Jay,

Here's a suggestion. Instead of hanging your float by a single line, try hanging it by two ( v ) or possibly four lines to minimize swaying side to side and front to back.

- John

Jay said...

Good advice, thanks John. I already primered the port float today before seeing your comment, but I'll try it next time.