What's the Pitch?

[toprecyler]

Yes, Charlevoix Yacht Club. I raced the Red Fox there one year on a beautiful J 109

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How long have you been sailing? My friend used to have a company that made sail boat parts. Spinnaker masks, I think. I used to make parts and help put them together. I think his company was Amco Marine, or something like that. It been a long time ago.


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[matthewsx]

I’ve sailed on and off since my early teens but recently active from 2014 till 2019 in Michigan.

Sorry, I’m not familiar with your friends company. There are many great small business around the field though. Probably some of the guys I sailed with would know.

John

 

[wachuko]

I miss island life… I was in the water every other weekend…



How I miss the water in the Caribbean…

 

[RJSakowski]

Having measured the pitch on my propeller inventory, I next went to making an impromptu balancer. A simple device, using a piece o 1/2" outboard drive shaft, the cones from the pitch gage, and two Nylon electrical cable feed throughs. The feed throughs were modified by drilling out to 1/2" and cleaning up the hole with a 1/2" reamer. My Tormach mill is leveled with my machinists' level and makes a great bed for the balancing. To build up clearance for the prop blades, I stacked three 1/2/3 blocks on either side. The assembly will roll on the block until the heavy side is facing down and is sensitive to better than 1 gram.



I had mentioned earlier about making a pitch block to form repaired blades. I thought that I would have a go at modeling one up in SolidWorks. I started by making a series of 12 pitch helices ranging from 4" to 10" in diameter through a 120º angle. Along each of these curves, I extruded a .1" tall by .001" rectangular solid. Next I created a lofted extrusion between each helix, resulting in a reasonable facsimile of a helical propeller blade. I can then import this model into SprutCAM to generate a file for cutting the helix with my Tormach CNC.


This was so much fun that I decided to try my hand at modeling a propeller. I created a splined curve to fit the outline of the propeller blade and cut away everything but the blade. The I used the circular pattern feature to create the remaining two blades. Lastly, I modeled the hub and added it to the part. An actual propeller is thicker at the root of the helix so I would have to modify my rectangular solid for each helix to reflect that. I still would have to model the internals of the hub, including the 13 tooth spline but that is relatively trivial. The result is a reasonable facsimile of a working propeller.