Who Knew Cutting Circles was So Easy

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Blog entry by BassHunter posted 10-25-2012 04:13 PM 1325 reads 0 times favorited 5 comments Add to Favorites Watch

I am helping my 8th grade son build a wind turbine for his Science Fair Project. He is testing the impacts of different blade designs on energy production efficiency. As part of the project, we have to build a hub to attach the blades to the generator unit.

So I thought about different ways to cut a circle – not sure yet how big we need, but probably a half foot to foot in diameter will be needed. The options were – router, drill press (most likely not enough capacity), table saw or bandsaw. As I want my son to build most of this project as possible, I decided on the Bandsaw. About 5 minutes worth of putting together a jig and that was it. Once we know how big a hub we need, I will help him cut out the three circles he will need.

I was amazed at how well it worked. Started playing around with it and made multiple test circles for fun…Remember, I am new to this hobby.

Will post pictures of the Wind Turbine when it is complete…

As an aside, his theory is if he builds a blade with an airfoil design known to provide a lot of lift (vs traditional air foil designs) that it will improve the efficiency of the turbine. He will be testing a flat blade, a traditional symmetrical airfoil and a KF-3 (Kline-Fogelman) airfoil design…It will be interesting to see the results.

Stay tuned for more info…


-- If you choose not to decide, you still have made a choice...

5 comments so far

View VinnieP's profile


141 posts in 3376 days

#1 posted 10-25-2012 05:06 PM

Wow, that’s quite the project. I’m interested in the results too. Really curious how the high lift airfoil theory works out.

View patron's profile


13611 posts in 3396 days

#2 posted 10-25-2012 05:13 PM

me too
also like to see
your take on a circle jig

welcome to LJ’s

-- david - only thru kindness can this world be whole . If we don't succeed we run the risk of failure. Dan Quayle

View BassHunter's profile


24 posts in 2100 days

#3 posted 10-25-2012 09:15 PM

I will keep you posted as we progress and show a few pictures of the turbine (even though not exactly fine woodworking….

I have attached a few pics of the jig. I just used a scrap piece of plywood and a short runner for the miter slot on the saw. I just finished making runners for a small cross-cutting sled so I had no work to do as I had a few extra pieces to use for the runner…

Here is the jig:

I used a spring clamp as a stop to keep the jig in the right position on the saw:

I drew a line on the jig at the end of the kerf and drilled holes at 1” increments. I clipped the head off of a small nail to use as rotation point for the work piece. Here is a circle with a 1” radius:

As you can see, it is a very quick and dirty effort, but will do what we need for now.

-- If you choose not to decide, you still have made a choice...

View Gregn's profile


1642 posts in 3038 days

#4 posted 10-26-2012 12:08 AM

Welcome to LJ’s,
It’s amazing how simple things can be trying new things.
I look forward to seeing your son’s project as it progresses.
Sounds like something I would like to play with myself.

-- I don't make mistakes, I have great learning lessons, Greg

View gfadvm's profile


14940 posts in 2745 days

#5 posted 10-26-2012 01:38 AM

Good job on the circle cutter. I built one that looks just like yours but mine cuts spirals! I did something wrong obviously but couldn’t figure out what so back to freehanding and sanding.

-- " I'll try to be nicer, if you'll try to be smarter" gfadvm

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