What's new
What's new

Propellor pattern

CalG

Active member
Why are "screws" as used in water not given "air foil" shapes!

It works for air!

Inquiring minds....
CalG
 

isfltd

New member
Well they are foiled, except they call them hydro-foil.

We also make struts which hold the prop in place, basically a barrel, that the shaft goes through, with one or two "legs" that attach to the hull with a mounting plate called a "foot"....I think I made that sound more complicated than it is:D

The legs of the strut definitely have a hydrofoil shape looking at the cross section.

Hopefully this link works now....

http://industrialshapeandform.com/blog/blogs/?s=propeller&submit=Go
 

isfltd

New member
It's not information that's easy to find. It's even hard to find print manuals for doing it anymore.
 

dgfoster

Active member
Dense?

Ok, not to be too dense, but how exactly is the one blade mold used to make a 5-bladed or 3-bladed prop? I can dream up some unlikely scenarios but what I can imagine does not seem to make sense. It has to be trick ot get them all registered correctly and bedded into a foundary mold. Pray tell how it is done.

Denis, who seems to have bronze where his brains should be....
 

isfltd

New member
There is a hole in the top of the pattern.

They use that to line the prop up on an index plate.

The index plate has designations in degrees, different angles make 3,5, or any number of blades on a prop. 120 degrees makes 3 blades for example.

They use a starting position, mold one blade, on its drag face, move it according to the index plate and repeat until you are back to where you started in a circle.

The same starting position is used on the cope face and the whole thing is repeated using the index plate.

The two halves are closed together, metal is poured in and you have a prop.

Well then the machinists get a hold of it...then its a prop ;)
 

dgfoster

Active member
Thanks,
The indexing of the mold is easy enough to see--now that you have explained it. But isn't there a somewhat complex surface on the drag that has to match the cope at the leading and trailing edge of each blade? What I am saying is that surface has to vary in height as you sweep through 120 degrees for a 3-blade prop. So how do you get the two surfaces that need to fit tightly together to actually do so? Is the "seam" of the casting at the leading and trailing edge fo the blades? I guess another photo or two of say a rough casting and or a drag might clearly answer the question I am *trying* to be clear about.
Denis--only 50 miles south of you in Bellingham.
 








 
Top