Possible solution for lower unit gears / other parts

[David_L6]

Check out this video.

http://widgets.nbc.com/o/47f1317f105...a4377d3bfd6c81

[ZUL8TR]

That is amazing

Check out this video.

http://widgets.nbc.com/o/47f1317f105...a4377d3bfd6c81

One way to get those prop blades matched and to find out what the pitch is all over the blade.

The really neat part is how the plastic model can be made with all the moveable parts recognized without scanning each individual

The probable downer is the cost, no problem for Leno

[sam]

Yeah, the cost of the fab machine might be prohibitive to many, but so is a new mill or good big lathe or anything CNC driven. More likely something for guys like Bass or Selewach.

The scanner was only 3 grand. I'd really like to see scans of props DeWald tried to make the same but turned out differently ... like a prop an F-1 guy keeps as his best and one he wants to send back as a dud.

Learning what makes 2 very similar props behave differently would be worth 3 grand to any prop maker.

I have long suspected the differences are not on the blade faces that lay against the pitch blocks (the back side of the prop when mounted and in use), but in differences in thickness at critical points of the other side of the prop (front). To learn where these critical places are would be a dramatic leap forward in prop technology.

[David_L6]

Yeah, the cost of the fab machine might be prohibitive to many, but so is a new mill or good big lathe.

The scanner was only 3 grand. I'd really like to see scans of props DeWald tried to make the same but turned out differently ... like a prop an F-1 guy keeps as his best and one he wants to send back as a dud.

Learning what makes 2 very similar props behave differently would be worth 3 grand to any prop maker.

I have long suspected the differences are not on the blade faces that lay against the pitch blocks (the back side of the prop when mounted and in use), but in differences in thickness at critical points of the other side of the prop (front). To learn where these critical places are would be a dramatic leap forward in prop technology.

How about the way / to what degree each blade flexes? I suspect that has a lot to do with why two "identical" props don't always perform the same.

[sam]

If that fabrication machine could directly deposit casting wax (instead of plastic), practically everything could be made very cheaply.

I wonder if the deposited plastic can be used as casting wax? I think they said it was polyethylene or some thing. It looked like weedeater string and the machine basically works like a laser jet printer. When the patents run out these things will be everywhere.

[sam]

How about the way / to what degree each blade flexes? I suspect that has a lot to do with why two "identical" props don't always perform the same.

Flexing could be it. It could be related to the grain in the metal and not actually dependent on the shape of either side of the blade.

If flex is the problem, it might be possible to test individual blade flex on raw castings before they have more work done to them and save a lot of labor.

The scans could help prove this. If the shapes actually are identical, uneven flex would be the only explanation I can image.

[B Walker]

Talking to some metal specialists I have becone convinced metal grain and other inconsistencies in a casting is the biggest factor in 2 props that are measured to be identical have completely different performance characteristics.

BW

[ZUL8TR]

Props are perhaps like Stradivarious violins, to this day they are still a mystery and nobody can build one that matches the sound even after taking many sophisticated wood thickness and sound measurements thru the full range of the instrument. Many theories exist like the woods used and grain and the way they vibrate, glue used, varnish recipe used, etc. but the secrets died with the Italian master.

Perhaps we will never really know what makes different props work better than identical others, so testing and luck will be the way.