November Holiday

[He Who Shall Not Be Named]

Funky? It seems that America is learning the metric system one millimeter at a time!

… I got your millimeter right here, pal!

David
From the Land of Inches, Feet, Yards, and Miles

[HardRock]

Funky? It seems that America is learning the metric system one millimeter at a time!

[He Who Shall Not Be Named]

Waiting for more rubber to arrive (Friday) so I've been casting the rear planes.

Those look good. I'm casting up propellers with the 3mm bores needed for those funky metric propeller shafts of yours.

David

[HardRock]

Waiting for more rubber to arrive (Friday) so I've been casting the rear planes.

[He Who Shall Not Be Named]

Nope. I'd need a 1.2 metre long pot to do that. I've found that the best practical method is to brush on the first two coats of goop to pull the bubbles out. I missed the bit near the bottom sonar dome and it set up before I could get back to it. Hopefully the bubbles are in the matrix and not on the surface of the plug. More glooping tomorrow.

Yeah, I think you'll get away with it. You do hand lay-up without a pressure assist, so internal bubbles will not be an issue. Looking good! And shoot for a very thick glove with this tool, up to 3/8" to 1/2" thick!

David

[HardRock]

Nope. I'd need a 1.2 metre long pot to do that. I've found that the best practical method is to brush on the first two coats of goop to pull the bubbles out. I missed the bit near the bottom sonar dome and it set up before I could get back to it. Hopefully the bubbles are in the matrix and not on the surface of the plug. More glooping tomorrow.

[He Who Shall Not Be Named]

Do you vacuum the mix before application? If not, the alternative is to slip the work into a pressure pot and take it down an atmosphere and keep it there till the rubber changes state.

David

[HardRock]

That was the top; this is the bottom.



I'm having a small problem with trapped air bubbles. They are small but persistent. I'm using a brush to paint over the rubber to release the bubbles but if you miss a few and the rubber goes off, you're done.

[HardRock]

I wondered how you did that. Meanwhile the first layer of gloop is on!



Its a crappy photo. I had to shut the shed doors to keep out the sunlight. The moulding clay interface between the plug and the splitter board kept melting. Have to wait a few hours while this skin coat goes off before adding thickened gloop to make up the full thickness mould.

[He Who Shall Not Be Named]

I hope I have the correct photo. The dowel is an extra push?

The dowel is inserted at the top of the sprue channel to displace a bit of the liquid metal. As the opening of the sprue channel is beveled. Failure to dump the metal at the top would result in a plug of frozen metal that would prevent removal of the propeller and attached sprue piece from the tool.

David

[trout]

David

I hope I have the correct photo. The dowel is an extra push?

[He Who Shall Not Be Named]

Insanely good stuff. Can't wait to see that how that sail comes out. Silicone should arrive today, in which case I will get on with making the hull moulds. Onward!

Just popped the sail master from the intermediate tool. Usual exceptionally fine glass job. However, measuring the wall thickness, it's only .050". I want .125"! I'll build up the inside with chopped strand matt till I get what I want, damnit!

ONWARD!

David

[HardRock]

Insanely good stuff. Can't wait to see that how that sail comes out. Silicone should arrive today, in which case I will get on with making the hull moulds. Onward!

[He Who Shall Not Be Named]

David,
more info, this is great. The third from last, is the clear silicon to seal the smaller tube to your mold? That tube is to get more weight or casting metal up high?
last photo is showing what? Coating with epoxy to make thin shells?
really good stuff you are showing, thank you for taking the time to do this!
peace,
tom

Yeah, the clear Lexan flasks are tack-glued to the upper face of the tool so I can pour in more rubber. That tall rubber sprue channel gives me enough pressure-head to insure a quick and complete fill of the propeller cavities once the molten metal is introduced.













David

[He Who Shall Not Be Named]

In the picture of the sail moulds you're sanding the laminate in the tool with the Dremel tool. I take it the rubber is flexible enough to give way as you get near the line?

Good eye, Andy. And you surmise right: the rubber jumps out of the way, the rigid GRP does not. A guided hand, and the properties of glass and rubber get the job done with little damage to the tool.

Can't do this to a hard-shell tool without the risk of damage at the flange line.

David