G'Day

**canado** · 15th December 2009, 05:27 AM

G'day everyone

I'm from Vancouver Canada

I work as a pattern-maker, we actually have a couple of respected Aussie pattern-makers in our local industry.

I was trained by my dad, and now my brother and I run the shop.

We are one of the few shops that still concentrate on handwork we have CNC and computers, but that's usually only used for multiples or production volume.

We have a lot of experience with marine pattern work (props and struts)....if I may (Admin let me know if I'm braking rules) we have a really cool explanation of how a prop pattern is made, everyone who sees it thinks it's neat.

How a Marine Propeller Pattern Is Made

Its a process that needs alot of hand work, not only the prop, but the struts need to be custom fit to the hull.

any way, we kind of pride ourselves, on being a shop that can do anything.

I have some experience in carving, cabinet making and furniture making.

I'd love some questions.

**munruben** · 15th December 2009, 08:05 AM

Hi my friend and welcome to the forum. You may not get much response to your thread here because a lot of members don't visit this part of the forum.
There is a CNC section HERE and we have no less than 5 forums relating to boat repairs and building etc. You will find those under the heading "Wooden Boat Forum" on the main index page if you scroll down. I am sure you will get plenty of guys/gals very interested in your work.

**artme** · 15th December 2009, 10:12 PM

G'day Canado and welcome to the show.

A few Canadians here,so you won't feel lonely.

Glad you joined, I've learnt something new. Did not have any idea of how propellers were made until now

**joe greiner** · 15th December 2009, 10:48 PM

G'day Canado. And a hearty welcome aboard.

Thank you for the fascinating exposition.

Perhaps you could expand on how the pattern is used to make a multi-blade mold. A question remains: Does the foundry mold all the copes, and then all the drags? (Which seems awkward, I think) Or separate copes and drags, to be joined afterwards for casting?

Cheers,
Joe

**masoth** · 15th December 2009, 11:39 PM

G'day and welcome. I'm sure your link will draw plenty of inspection, and not from the boat builders only. Fascinating stuff.

soth

**canado** · 16th December 2009, 05:24 PM

Basically the molders setup the prop with an index plate that sits on top of the hub, that plate designates the number of blades for the prop.

They point the blade in direction" X", mold the drag side of the blade, move the whole thing "Y" degrees using designations on the index plate and mold the drag side again. They continue untill all the points on the plate, equal all the blades molded.

They use the same starting position for the cope and use the same process as above. The cope and drag come together after some gating is spooned into the sand and the metal is poured in.

If you've never watched a pour its really something to see.

Thanks for the warm welcome!

**Christos** · 16th December 2009, 08:32 PM

Welcome to the forum.

**joe greiner** · 17th December 2009, 03:02 AM

Thanks again, canado.

I can never remember which is the cope and which is the drag.

The process you describe makes a lot more sense now. I guess I had a brain fart about the first option. And about the second option too. By molding the drag and cope separately, only one flip of pattern and sandbox is needed.

I highly recommend a visit to a foundry. I visited one in Ohio about 40 years ago, making large AL fan blades for Aerovent, and also AL components for Airstream trailers; both the foundry and Aerovent now gone AFAIK. More recently, Florida State Uni has a Master Craftsman program with occasional cast iron pours, open to the public.

When/if I'm in Vancouver again, I'll be sure to call on you.

Cheers,
Joe

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