I Can Taste It « Team Seacats

I Can Taste It

by Jake on Jul.05, 2007, under One Meter

After seeing an “early show” of fireworks on the 3rd with Bonnie, the 4th provided a solid day of work on the one meter. I set out first thing to make the little pulley block I had dreamed up the other day. While I did save $10 by making this thing myself, after the first three tries, I had almost 1.5 hours invested in it…the next ones will be faster! I used some .030 aluminum plate and cut out a simple flat shape, drilled one hole, bent it, drilled the sister hole, cut a piece of 1/8″ aluminum tubing to fit the center of the sheave, and assembled with a 2mm screw and nut. It sounds simple but it took several attempts to get the bend right in the middle and I finally discovered that it bends perfectly around the end of a pair of forceps. A small hole in the middle of the bend provided room for another 2mm screw to fasten it to the deck. I suspect, however, that I will need the aluminum plate to extend beyond the top and further back to keep the line for shaking off the sheave and jamming.

Because the aluminum mold is a bit delayed, I also worked on getting the putty mold repaired to cast another bulb or two. If you remember, this mold was poured in two parts using a PVC plug in the middle suspended in a box with a screw. The first half that was poured saw the air bubbles suspend at the surface right against the plug. There was really no way for us to eliminate them. The second half did just fine since the plug was at the bottom of the pour. The air bubbles caused a problem when I poured the lead and the rapid expansion of the air in those pockets caused the mold to chip out. I used the old top half, without the air next to the mold surface, as a new bottom, and poured a new top – I put fiberglass in this one to help with some of the minor cracking that seemed to happen too but now I wonder if that didn’t trap some air bubbles near the mold surface again. We’ll see when I pour again. This time around, I attached a small section of the keel spar so I can maybe leave a piece in the mold to create the slot I need to attach the real strut when pouring the lead. With any luck, I’ll be able to extract the aluminum piece from the poured lead leaving a nicely fitted opening. I have some doubts that the aluminum will come cleanly out of the lead though. This way I could get more precision with the slot.

While that setup, I finally installed the rudder servo in the underside of the deck. I realize that most things need to sit down low, but this is a very small light-weight high-torque micro servo and it really reduced the amount of linkage needed to get it to drive the rudder.
Because the screws would be really difficult to get at for the servo arms, I made a fiberglass / balsa box that glued to the underside of the deck that had grooves for the servo mount flanges and a cover that screws on it to box in the servo. It works great and has no play. I also decided that I really didn’t like the ratchet action of the sail control stick on the new radio (usually intended for throttle on an r/c airplane) and wanted a smoother action. I discovered that if I take the ratchet detent spring and flip it over, that it gives a much smoother action and still provides enough resistance so the stick will stay where you leave it.

Next up was some filler on the hull half joints and a few minor imperfections. Before I did that though, I marked the location of all the holes and hardware and took photos to have documentation so I can find them later if they get covered up in the finishing process. Finally, a coat of primer.

3 Comments for this entry

Bonnie
July 5th, 2007 on 8:37 PM
I was just taking all of those close up photos for fun. I didn’t think they were good for anything or that you would keep them.
Nate
July 6th, 2007 on 4:56 PM
Jake,

It’s looking good. One Question,

Where did you get those tiny shivs?
Jake
July 6th, 2007 on 10:47 PM
http://www.mcmaster.com