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Showing posts from June, 2017

Laser Cut RC Sailboat Mainsail Boom

Last winter I designed a crazy looking, laser cut mainsail boom for my Sun Wind II RC sailboat. The idea was to add a bit of high-techy, artsy, far-outness to an updated 1949 design... and in the process make a boom that was both lightweight and strong.

It's made of 8 layers of 1/32" plywood cut on the laser cutter and then epoxy laminated together.

Here are the laminations after being cut out.


Then I put some tape down on a piece of MDF so that the epoxy wouldn't stick. After that, I drilled three holes and put sticks in them to hold the pieces in alignment.


Then I mixed up some epoxy and brushed it onto all the inside surfaces. Before putting them onto the MDF though, I gently wiped them down with a paper towel to remove most of the excess. When I did a similar technique for the swing arm, I noticed that I had a lot of excess and that it looked bad. Hopefully I've avoided most of that issue on the boom. The amount of epoxy that remained on the laminations should be …

Wind Vane/Indicator

Took some time out from varnishing to make a wind indicator/vane that fits into the mast crane.

It's made from brass tubing of various sizes. The weight at the front is simply three progressively larger bits of tubing soldered together.

This is my first attempt and I'm not convinced of the strength of it, especially where it's bent. But was easy enough to make and if it snaps off I'll make a better one!

It's also a rough-draft! Yes, it looks pretty sloppy, but future ones will be better. And in a future one, I see no need to solder a second bar on using tube sections. Instead, I'll just solder the two bars themselves. 




Peace!



Finishing, part 7 - The Mast

While I'm waiting for the 6th coat of varnish to harden on the hull, I've started to varnish the mast.

Yes, I'm an idiot for not varnishing the mast all along with the six coats on the hull! But I managed to get one coat on so far.

Today I cut the slot for the mast crane, fitted the crane, and drilled two holes for through-bolts. Next, I'll remove the mast crane and return to varnishing the mast.



Notice too that I soldered a brass tube to the mast crane. It is to hold a wind indicator that I'll make shortly. Should work well... I hope!

More later.


Aloha!



Finishing, part 6 - Varnish

Today I did the first coat of thinned varnish on the hull.

Over the past four days, I've let the hull cure and harden. It then sanded quite easily. For the most part, I didn't completely remove the orange peel but just flattened it a bit. The varnish should take care of the rest of it after 5 or 6 coats.

Then wiped it down with mineral spirits.

I'm using Pettit's Z-Spar Captain's Ultra-Clear Varnish. The can says that thinning usually isn't needed, but I added some mineral spirits regardless. Will probably do so for the first two or three coats.

While I've always claimed that varnishing is a dark art practiced by masochists, it does have it's benefits. It can hide a ton of flaws; scratches, slight orange peel, etc... Once it's built up, it can look fantastic.

I'm part of the "roll and tip" school of thought for varnish. The idea is that you use a small, 4" disposable foam roller to roll on a thin coat, then you go back over it wit…

Finishing, part 5

Today the "tile red" went on! It looks good... at least the color looks good. The orange peel, not so much.



It started off well. I masked and prepped the hull, and then sprayed on a light coat of clear so that it would bleed into the tape edges and not show.

Then I sprayed on the first few coats of the red.




But then, on the LAST coat, I neglected to put the lid on the gravity paint cup and while spraying up under the bulb managed to drizzle paint all over the port side!!! God!!!

I gently wiped it up as best I could, and then sprayed on two more pretty heavy coats hoping that it would all blend in. It didn't. Shit. Now I'm committed to sanding and spraying on more coats of clear over the whole thing. That's not necessarily bad, but I'm sure that I'll always be able to see the mess. Can you see it?


It looks of slop... F@#&!!!! Oh well... I'll keep working on it.

However, when I took the masking tape off, the rest of the hull looks pretty good! To b…

Finishing, part 3 & 4

Wasn't able to post last night, but sprayed on my first coat of clear epoxy.

I'm using a new, gravity feed spray gun that I picked up at Harbor Freight for $14. It works pretty well, although you really need to run reducer through it or it will seize up within minutes of stopping spraying.



Pretty easy. Just sprayed on the entire hull, but especially on the topsides. Only did two thin coats... just enough to start to cover the hull. Didn't even need to mask anything.


Today, I re-marked the waterline as it dissolved when I wiped the hull with reducer yesterday.

After that, I masked the topsides at the waterline. Had to use a hobby knife at the sharp turns near the stern.

Then I sprayed on one thin coat of clear. The idea here is that you spray on the same color that is underneath the tape so that the bleed is the same color and you don't see it.

Finally, I sprayed on several coats of white from the waterline just about an inch or two toward the fin.




And here's how it…

Finishing, part 2

The epoxy filler on the Sun Wind II RC sailboat dried completely by the next day, and then I was able to sand it.

The Interlux Primekote 404/414 filler is wonderful stuff. It sands much more easily and finely than epoxy. It allows you to get a plasticy-smooth finish that when painted will look amazing.

You actually end up sanding most of it off. It may look a bit blotchy, but that's because it has filled some of the low spots and scratches. The scratches you see in white are actually scratches in the epoxy underneath that have now been filled and sanded smooth. Pretty cool, huh?

The pictures below are after the hull has been sanded and then wiped down with a damp rag to remove the dust.

(By the way, this job gets messy! Best if you wear a mask!!)





More later.


Aloha!



Finishing, part 1

Here we go... time for the finishing. Gulp... I get stressed out during this phase. Too much of a perfectionist I guess, but then I run out of steam and end up being satisfied with an OK job. Maybe this time I'll carry all the way through!

Tonight, I added a coat of Interlux Primekote 404/414 epoxy filler. It's a two-part epoxy compound that fills all the small scratches and such. I'm only adding it below the waterline as that part will be painted red. The topsides will remain clear, so I can use this product there.

The idea behind the Primekote is that you put on a layer or two, and then sand most of it off the next day with pretty fine grit paper. It should fill the scratches, low spots, etc... When you sand it fine enough, it should leave a smooth, plastic-like surface that will take epoxy paint very well.

Here is how it looks with a coat on. I'm only going to do one coat, and then sand it off. Should be good enough. Yes, you can see brush strokes... it doesn't …

Marked the Waterline

Got a few things done over the past few days.

Most of my time has been spent cleaning up the hull/deck joint with epoxy. Since I'm leaving the topsides clear, I can't use epoxy filler or thickened epoxy. Bummer. So I've made a few coats of clear epoxy just along the joint and have sanded it all smooth. There may still be a few gaps, but for the most part it looks good and ready for finishing.

Today I water tested the boat with the servo tray in it, and with about 12 oz. of lead taped to the deck where the rig will go. Was able to gauge the waterline pretty well both fore and aft.

Then I turned the hull upside down on a flat surface and leveled the fore and aft water line marks with wood propped underneath. With an Ultra Fine Sharpie taped to a sized piece of wood, I could then run the waterline. It got a bit tricky at the aft section where it has a high angle, but I got something marked anyway.


Next, it's ... GULP... finishing time. Yikes. Still not entirely sure which…