Cutting down a prop

When one cuts down the diameter of a prop, what's the best way to measure the blades to ensure their length is EXACTLY the same as one another?

Regards,

Jim Lee in KS makes and sells a tool for marking props. It is a piece of machined brass that fits the prop hole and has a sharpened music wire pointer for marking the tips. Works great, Jim isn't on line but he should be in the PAMPA directory.

Jim's stuff is first class!

The place to start balancing a prop is to make both (all) blades equal length.

See Ya

Roger, What they said!! Jim's stuff WORKS!
Bill <><

I take the low tech method. I took a chunk of chipboard. Drilled a hole in the center and stuck in a dowel. Put a scale on the board. Slide the prop on the dowel and mark the spot of the prop where I want to cut. Cut one blade, put it back on the dowel. Mark on the board the cut and swing the prop around and mark the props other blade and cut. Once done, recheck.

>I take the low tech method. I took a chunk of chipboard.
>Drilled a hole in the center and stuck in a dowel. Put a
>scale on the board. Slide the prop on the dowel and mark the
>spot of the prop where I want to cut. Cut one blade, put it
>back on the dowel. Mark on the board the cut and swing the
>prop around and mark the props other blade and cut. Once
>done, recheck.
>
>

Randy Powell

Mine is even lower tech (Or, maybe higher). I have a similar fixture that I made with a bolt sticking up of the appropriate size for the prop to just fit over. I clamp this fixture to the table of my band saw the appropriate distance away from the blade and then cut the first blade, rotate the prop, and cut the second blade. Works on 3-blade and 4-blade props, too, You cut the same length, same shape on each blade. It gives just a slight rounding to the end. If all you are doing is trimming a little, you can accomplish the same thing by clamping it to the table of the disk sander. Just bring it slowly into the disk and it will trim and sand at the same time.

LAST EDITED ON Feb-09-04 AT 11:25 PM (CDT)
 
Heh heh heh...

My approach to cutting down props involves a prop balancer and a set of big nailclippers..

I have a fixture that is indexed and clamped to my disk sander. It consists of a flat plywood base and a steel dowel pin. The dowel pin is located located a distance from the sanding disk equal to the desired radius of the prop. Put the prop over the dowel pin and rotate it through the sanding disk- first one blade and then the other. Perfectly equal length is guaranteed.
To ensure accuracy, be sure the dowel pin is a tight fit in the prop hole and a press fit in the fixture base; hold the hub of the prop firmly against the fixture base while sanding.
Speed fliers often use more elaborate versions of this same concept.
Derek Moran