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centerchannel68 · May 10, 2007, 10:49 PM

K. I mentioned this before, but here's the basics: We had to design a towable submersible that could house at least two transducers, and we had to do drafting style drawings, make a buck, then pack clay, then carve the clay, smooth it, cast it in plaster, and then use FRP, most people used fiberglass.

Here are some pics of the process:

Pretty rough. After about... oh... maybe another 5-8 hours, I was around here:

It still wasn't close. I probably have about 15-20 hours into trying to iron out all the bugs in the clay. It was fun. Luckily I had some booze to help numb the pain of such tedious work.

Oh, to carve clay, you need a rake. I made mine myself. It's a nice piece of walnut I turned on the wood lathe, then french polished with walnut shavings, and I made the rake itself outta diamondplate polished aluminum. Oh yeah.

After you have the clay where you want it, you cast it in plaster. I did something kinda funky with mine, I cast it with an overlap of about 1/8 of an inch. Why? Well, in one of the molds, I put a 1/8" piece of styrene all the way around, so hopefully, after I made my fiberglass pieces, they'd snap together, because of the lip. I also found some plastic just a bit thicker than the plastic I wanted to make fins out of, so I used clay to fiberglass a slot into the back of the form, allowing the real fin to fold into it... kinda hard to explain: Pic:

Here's a pic once I epoxied the fiberglass pieces together, with the dorsal fin just shoved into the slot. Oh yeah, the front of the piece is dark, because I decided to use carbon fiber.

No reason really, I just found some scraps and threw them in instead of fiberglass. The resin was too yellow to let me use it aesthetically though, so there wasn't really a point. I did learn how differnet it was to work with though. It's a lot stiffer. Anyway:

After about 2-3 coats of massively thick primer, a bit of bondo, spot putty, and one RUINED paintjob thanks to the compressor not turning back on to maintain pressure, then having to sand the whole thing back down and respraying it with white laquer, and a clear coat with some green pearl, it looked decent. The decals were designed by me, and printed onto testors decal paper with my inkjet printer. After the decal sheets dry you spray them with 'decal fixative'. Then you simply cut them out and apply them like any model car decal. It turned out pretty decent, I think:

centerchannel68 · May 10, 2007, 10:51 PM

Hope you guys enjoyed learning about the process. Please keep negative comments to yourself. I've already had a real critique by people in the field, so I don't need your armchair critique.

mduell · May 11, 2007, 12:06 AM

Looks like some positive camber there... was it too heavy to be neutrally buoyant?

Also why the cutouts on the bottom/aft corners? Seems like they're just going to generate a lot of seperation.

SirCastor · May 11, 2007, 12:23 AM

What kind of plaster did you use? I cast in ultracal30, but that's for latex stuff, usually I cast in a softer material and then a mother mold for the mold to maintain shape. You went plaster to fiberglass, any reason? And did you have to break the plaster casts to get the fiberglass out? Did you have a release agent of some kind?

You said it has to carry transducers. What kind? And how do you get them in there? I think it looks very nice.
What are the dimensions. I had a hard time finding a good reference point in the pictures.

G4ME · May 11, 2007, 01:19 AM

dremal tool wasn't enought?

Looks cool, so what you drag it behind a boat like a gaint lewer? and what do the transducers measure? Also was there any testing in the shape of the design or was it just what ever looked good and easist to mock up in clay?

umm my final project this semester is designing a control system for a printer ink cartridge, doesn't sound easy but **** is it a crap load of work.

This summer though, gonna dive into a class D amp, start to finish, now that is going to be some fun.

residentEvil · May 11, 2007, 07:35 AM

in the very first photo it looks like the "standard" starting point for a gas tank on American Chopper...

sorry, no...that is not a negative comment. just what it reminded me of while waiting for the rest of the photos to load/resize.

peeb · May 11, 2007, 07:40 AM

Looks nice - interesting process - but I'm interested in how you fixed on the shape too - is there any science in that, or did you just make something that you thought looked right?

Mastrap · May 11, 2007, 07:46 AM

Originally Posted by centerchannel68

Please keep negative comments to yourself. I've already had a real critique by people in the field, so I don't need your armchair critique.

Sweet looking project. But what's up with the touchiness?

andi*pandi · May 11, 2007, 07:49 AM

not knowing what this project is about, I'd love to know what the experts said.

Looks cool to me though. Nice logo!

centerchannel68 · May 11, 2007, 08:55 AM

Originally Posted by mduell

Looks like some positive camber there... was it too heavy to be neutrally buoyant?

Also why the cutouts on the bottom/aft corners? Seems like they're just going to generate a lot of seperation.

Weight didn't matter. It's just a model. The side fins fold into those, the dorsal folds into the slot. My idea was that you could just retract all the fins and haul ass to another location without reeling it in all the way, since the form is pretty hydrodynamic.

centerchannel68 · May 11, 2007, 09:01 AM

Originally Posted by SirCastor

What kind of plaster did you use? I cast in ultracal30, but that's for latex stuff, usually I cast in a softer material and then a mother mold for the mold to maintain shape. You went plaster to fiberglass, any reason? And did you have to break the plaster casts to get the fiberglass out? Did you have a release agent of some kind?

You said it has to carry transducers. What kind? And how do you get them in there? I think it looks very nice.
What are the dimensions. I had a hard time finding a good reference point in the pictures.

Ultracal something or other. We went from plaster to fiberglass for reasons of time restraints, and that we only have to make one model. If you were making many, I could see why latex would be more durable. Also, can latex handle the heat generated by fiberglass resin? I had to break my molds, because I had some undercut areas thanks to the styrene lip, and the fin slot. For release agent, yeah, we used lots of floor wax, and this green liquid.

The transducers I picked up at science and surplus. I hot glued them into my mold, then fiberglassed around them. It's about 18-22" long somewhere, I think.

design219 · May 11, 2007, 09:57 AM

A couple of treble hooks and you could catch Nessy.

olePigeon · May 11, 2007, 11:58 AM

You shoulda put a mini Apple sticker on it.

IceEnclosure · May 11, 2007, 03:44 PM

Jawbone54 · May 11, 2007, 04:12 PM

Originally Posted by design219

A couple of treble hooks and you could catch Nessy.

On topic: really good job, Rob. The finished product looks very nice.

analogika · May 11, 2007, 05:09 PM

That thing looks really, really nice.

Only problem is, it takes about five minutes until anyone can see it, because you appear to be hosting the images via a dynamic DNS service from a home DSL line - to a forum with several thousand members.

One has to wonder.

centerchannel68 · May 11, 2007, 05:44 PM

Luckily those forum members don't view it all at once. Thanks for the compliments though, Analogika and Jawbone. It's nice to hear positive comments from you two.

Visnaut · May 11, 2007, 06:47 PM

Wow, that looks awesome! I wouldn't know where to begin to critique it. I really dig it. The spit and polish you put into it is evident.

Good work, Rob.

I'd love to see a pic with the fins folded in.