Some nice moulding going on here.

Using wooden gaggers as well.

 

Looks like a museum, how they crafted in the late 19th / early 20th century.
Funny that the lathing appears not very precise. The guys do not use any PPE, I am curious how many injuries take place in this workshop. And they breathe sooty smoke from a dirty oil burning furnace... Not the way it works in the 21st century.
Modern propellers are cast and machined automatically.

 

Thanks for the video Chazza.
It it impressive from a size standpoint. I wondered too about the tool holder in the tailstock of the lathe moving while they were boring.
It was also interesting to see it on a boat at the end.

 

There are a lot of frightening moments in that video, one that really caught my eye was the guy hammering wedges into the pouring shank to secure the crucible, I wondered how often that breaks the crucible. Anyways, that's obvious a low rpm prop, with an as-cast painted finish, it would cavitate like crazy at high speed also, I can't imagine it's even close to being properly balanced.

 

Propellors are a black art at times, having a prop surface CNC'd to a fraction of a millimetre would make it quiet and fuel efficient. I'd heard stories of a local "Prop Doctor" who could heat and bend the blades to change screw pitch, that must be hard on the casting and risky too. Casting a large ship's propellor would be interesting to see if the old time photos of hand laid brickwork to make the mould is anything to go by.

 

It would be nice to see Titanic's props being moulded.

Yes; the imbalance of the lathe; the holes inside the bore; the spinning prop at high speed waiting for someone to walk into it are seriously piss-poor work, but the sand work was nice.

 

and people on facebook want to get on my case for the PPE I wear

 

Comments: I have never seen plastic used as “parting” previously. For this situation it seemed well-suited. Also I noted the use of dry sand as parting—-something I’ve been using for a year or so and have found to be excellent. I was a bit surprised by the incomplete drag surface that had to be interpolated by eye. It seems like better packing using a long thin (curved) tool might have pressed sand under the pattern prop nearer the hub.

The wood gaggers were amazing in their simplicity and number. And they, in cooperation with the grate, did a good job holding a difficult deep mold shape using minimal sand. That’s an image for me to tuck away.

Thanks, Chazza.

Denis