Black Blades

[ChrisOlson]

I built a turbine that's going to Canada to power an off-grid home there, and the owner wanted black blades.  Black is one of the hardest colors to work with because it shows every defect or sand scratch.  I got the blades done and they are absolutely beautiful.  You can use these blades for a mirror to shave in the morning if you want.  These blades are going to flash in the sunlight and probably be visible for miles.

They're done with PPG Delstar with DXR80 urethane hardener.  This paint is flexible so it won't chip or crack and it's incredibly tough and easier to spray than DuPont Imron.

First set of black blades I've ever done.



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Chris

[Watt]

Yes, these are sweat.  How long have you been using this type paint and what has your experience been with maintenance intervals.  Awesome.     

I built a turbine that's going to Canada to power an off-grid home there, and the owner wanted black blades.  Black is one of the hardest colors to work with because it shows every defect or sand scratch.  I got the blades done and they are absolutely beautiful.  You can use these blades for a mirror to shave in the morning if you want.  These blades are going to flash in the sunlight and probably be visible for miles.

They're done with PPG Delstar with DXR80 urethane hardener.  This paint is flexible so it won't chip or crack and it's incredibly tough and easier to spray than DuPont Imron.

First set of black blades I've ever done.

(Attachment Link)

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Chris

[ChrisOlson]

Yes, these are sweat.  How long have you been using this type paint and what has your experience been with maintenance intervals.  Awesome. 

This is the first time I've used Delstar.  I've used DuPont Imron before and that stuff is very hard to work with, to say the least.  Imron is an acrylic-based polyurethane while Delstar is an acrylic-based enamel with urethane hardener.  The mechanical properties of the two paints are very similar, and both were developed for the aviation industry and later adapted to automotive and industrial.

They are both very tough - you can strike fully cured Imron or Delstar with a hammer and it will not chip.  You can, of course, scratch it or gouge it.  But I expect to get every bit the service life out of Delstar that I've gotten out of Imron.  The only maintenance required with Imron has been to clean and wax the blades once a year.  I've run machines in hail storms and never had any damaged paint before.  But that was on fiberglass blades.  With these wood blades I suspect running them in hail storms would leave dents in the leading edges of the blades.
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Chris

[97fishmt]

  In the snow zone I think black should help shed snow and ice and with a smooth finish it will be a perfect match for the climate.  I have gone this route also,  darker colors  get lost in the sky in dim light and in bright light don't flash as much as reflective surfaces. Although if you have a mirror finish?  I can see why those blades have so much torque siting there on your bench.

   I don't know how I could go about carving a set like that, maybe a router setup I guess.  I'll sleep on that tonight.  I have seen a very large set before on a 4 blade wind charger.  It was turning in the slightest breeze at a organic farm energy fair here in Washington.  I remember it was a geared machine but, the blades overcame the friction of the gears and could crank out the power and operate in low winds.  I'm still trying to copy that machine.  It must have been about a 20 footer and I'll never forget it.  It was way cool!  I think I could add a gear box to my servo motors and get way more power out of them.  I did gears years ago with brushed motors and it wasn't such a good outcome.  No low wind performance.  Maybe its all in the blades.

  Take care
  Mike

[ChrisOlson]

  In the snow zone I think black should help shed snow and ice and with a smooth finish it will be a perfect match for the climate.  I have gone this route also,  darker colors  get lost in the sky in dim light and in bright light don't flash as much as reflective surfaces. Although if you have a mirror finish?  I can see why those blades have so much torque siting there on your bench.

   I don't know how I could go about carving a set like that, maybe a router setup I guess.  I'll sleep on that tonight.

That's exactly why he wanted them black.  He lives in an area, 125 miles from the nearest power lines, where severe icing is common and the black blades will thaw off and shed their ice while white ones will run for days with 2" of ice built up on the leading edges, even after the sun comes out.

As far as torque, I've never been able to completely stall these blades.  Even with the rotor turning so slow that you can count the blades going around the tips are still running fast enough to make lift.  And the tips got the most mechanical advantage on the shaft thru the long lever of the blade.  These blades are pure animals.  The harder you load 'em, the harder they pull.  That's why I've stepped up the gear ratio in my latest geared turbines - to steepen the power curve of the generator and maintain better control of the rotor at higher wind speeds.

I got those blades from Royal Wind & Solar and they'd be really, really hard to carve by hand and get them right.  I think Dave Moller does them on a CNC router.
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Chris

[wiredup]

Hi Chris what angle of attack are those blades set on???

[ChrisOlson]

Hi Chris what angle of attack are those blades set on???

Hi - I assume you mean pitch angle, which is 10 degrees.
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Chris

[tanner0441]

Hi Chris

What was the curing time on the urethane paint? I had to use some on a boat and the curing was 5 days, and not recommended for stoving and the hardener amount was tight.

Brian.

[ChrisOlson]

What was the curing time on the urethane paint? I had to use some on a boat and the curing was 5 days, and not recommended for stoving and the hardener amount was tight.

I went 30 minutes between coats, the paint was dry to the touch in about 2 hours and full cure time is 5 days.  I left the paint cure for a week before I rubbed them out to remove any minor overspray and imperfections, and waxed them.  They're so slippery right now that you have to make sure you're hanging right on to them or they'll slip out of your grip when you try to pick one up.
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Chris

[vawtwindy]

great work, chris, can we have more closer look at these blades, immediately i tried your picasa links, but got disappointed bit..

[ChrisOlson]

great work, chris, can we have more closer look at these blades, immediately i tried your picasa links, but got disappointed bit..

Yeah, sorry I haven't sync'd my Picasa Web Albums lately - I have to finish captioning a lot of these photos and get that done.

Here's some more photos:

These are the raw blades as they came out of the crate - these are ash blades:



Here I am building the hub for them:



And here I'm balancing the rotor with the rotor dangelizer (is that even a word?  LOL!)



This is one blade with the raw paint not rubbed out yet:



And here's the full set after they got painted and letting the paint cure:



Hopefully I got all those attachments in the right order there.

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Chris

[jarrod9155]

I've been running these blades from royal wind for 6 months now with just 3 coats of urethane auto clear coat to keep the natural look of the wood and craftsmanship . Has worked awesome just to add some options out there . If I could figure out how to post photos on the I pad I would add some photos !!

[vawtwindy]

beautiful work chris,