Aluminium propeller blade

[tahustvedt]

I'm bored. It's snowing, dark and cold out, so I can't fly. I decided to play with my router a little and milled a little propeller blade from aluminium. I have made large blades from oak and flown them but I never made one from aluminium. that is, I tried yesterday but ruined it when I forgot to check something. Doh.

I really wish Aspire would ramp on the 3D milling operations and would let me decide not to avoid conventional milling in raster, but it works.

I milled the bottom surface first. I hogged out the majority of the material with a 1/4" roughing ball end mill first. then I used a 1/8" Ball end mill and pocketed out the material on each side of the blade to relieve the bit when I finish. Then I did an offset finishing pass and finally a very tight raster finishing pass across the blade.

I drilled one hole on each end of the blade to align the piece as I flipped it around.

The other side was started by roughing a oval pocket on the top surface to relieve the finishing offset pass when it plunges in. Finally a raster finishing pass across the blade. That's what you see in the video.

I just uploaded it so it may not be available just yet:

EDIT:
I also attached a picture of the oak propeller. It has a diameter of 530 mm.

[Thkoutsidthebox]

That is so very cool!!!!

[tahustvedt]

Today I decided to try milling a rotor head for a scale helicopter I'm building. It's supposed to be a starflex rotor hub, for those that know eurocopter. Not 100% scale, but it will look scale when it's finished. I might try making another one after I make some changes to the drawings, and I'll use a slightly different technique then to eliminate the offset pattern on the surface and achieve a nicer surface finish on the arms. It's not bad now though. I used 0,1 mm stepover with a 6 mm end mill, but on shiny aluminium anything is visible.

[moto633]

WOW!

Was that real time on the video? If so what Feed/speed are you milling? That thing is flying!!

Thanks,
Nick

[tahustvedt]

Yeah that is real time. It was running 70 mm/second there. I do profile and pocketing at up to 100 mm/s on aluminium and very shallow pass depths, speed and depth depends on the tool size of course. Works great.

[John H]

What were your pass depths in the video?

[tahustvedt]

Very little. It was a second finishing pass across the blade to improve the finish. Normally I run 0,13 mm depth with that too size and 49 mm/s feed rate. With 4 mm 4-flute endmills I run 20000 rpm, 99 mm/s feed and 0,17 mm pass depth. Eats through aluminium in no time with no problems.