Walker Trailing Logs bits?

[Simes]

The post further down about the WASP trailing log impellers made me think.

Given that there is a finite number of Impellers out there. Given that this number is reducing year on year (I have lost three due to unforeseen circumstance).

Does any one have any good ideas on how to create (build, turn, manufacture . . .) new ones.
I asked a small machine shop if they could copy one for me, yep, no problem £150.00 each if I order 10+ and pay up front.

I am wondering if a short length of copper pipe with 4 small vanes soldered to the outside.

Must be a better way.

Simes

 

[sarabande]

thinking about modelling chess pieces.

You can buy silicon rubber to make a mould, then pour in a resin-reinforced mixture, allow to set then peel away mould. If you are clever, mould is re-useable. If you are even cleverer, you make lots of them and flog em on ebay.


http://www.tiranti.co.uk/product.as...echnical+Booklets+-+Books+&+Videos&Product=53

Size and shape of impeller is critical to accuracy.

 

[Poignard]

thinking about modelling chess pieces.

You can buy silicon rubber to make a mould, then pour in a resin-reinforced mixture, allow to set then peel away mould. If you are clever, mould is re-useable. If you are even cleverer, you make lots of them and flog em on ebay.


http://www.tiranti.co.uk/product.as...echnical+Booklets+-+Books+&+Videos&Product=53

Size and shape of impeller is critical to accuracy.

Or cast it using a mixture of epoxy and powdered lead.

 

[Simes]

Cast in Epoxy . . . .

I had thought of this, the wings (vanes?) are really quite thin, I need to try and cast anything that thin.

Sarabande (what is a Sarabande?) you say that the size and shape are critical to accuracy?
How critical and why? I can see that the size and angle of attack of the wings is critical but what about the rest of the body?

Many thanks for the thoughts,

Simes

 

[sarabande]

(Sarabande = slow stately baroque dance with complicated rhythms)

Shape of the body needs to displace water in sufficient volume to make the wings rotate at a pre-determined rate. Also to hold the knot of the logline

There could be many variable shapes of the body, but target is to get a shape which rotates in a predictable relationship with the odometer and water speed.

Criticality is minimum, as provided you know the variation from norm, you can allow for under- or over-reading log by taking a run over a measured mile.

 

[Simes]

I see . . .

So as long as I am very close to the original in dimensions (Diameter, Length and Weight) then all should be well.
As you say there is no problem when allowing for error.

Many thanks Sarabande,

Simes