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Challenge: Can You Beat This Scary Turbine PumpkinCutter Halloween Project ? Answered

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This Halloween project is so scary that the inventor (myself) felt shock and awe at it. I was genuinely scared at the running of this machine...and rightly so! So I figured I would spread the scariness to all who see this machine, to set the mood for a DIY Halloween... The machine in question is what I have named the Tesla CD Turbine. The CD Turbine is magnetically-coupled to a Skilsaw blade. (What I teasingly call the PumpkinCutter Attachment). The Tesla CD Turbine uses recycled CD's and neodymium magnets for rotating parts...nothing else. It can rev up to thousands of rpm. It has no bearings or seals and is magnetically coupled to implements. It runs on either compressed air or water pressure. But hey, put on a magnetically-coupled Skilsaw blade, run it at thousands of rpm, and you have a very dangerous PumpkinCutter! (Instructable is ready...if you dare!) Beat that for a wild, scary, hi-tech, cheap and recycled Halloween project!!

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mrfixitrick (author)2007-11-06
The Pumpkin Cuttin' Ceremony using the new Steampunk Edition of the Tesla CD Turbine with PumpkinCutter Attachment was an outstanding success!


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mrfixitrick (author)2007-11-05

New Video out today; Tesla CD Turbine PumpkinCuttin' Ceremony" . Live action of the new Steampunk version CD Turbine doing pumpkin carving. See a pumpkin cry.

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mrfixitrick (author)2007-10-31
Here's a high-speed run with a non-magnet CD Disc Pack,
in my "New Test Facilities". I love the sound!

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mrfixitrick (author)2007-10-31
Here is my
latest video of the Magnetic Coupler that seems so mysterious to many. It enables the CD Turbine to do useful work. The Magnetic Coupler is what holds on and rotates the Skilsaw blade for example, or runs other implements such as the brand-new MeatGrinder Attachment. It also puts Scary Unknown Alien Technology back into Halloween.
We will see how well it performs in tonight's (Oct31st) "Pumpkin Cuttin' Ceremony" !
Hopefully, I will be able to post the video...

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NachoMahma (author)mrfixitrick2007-10-31

. ROFLMAO!!! "Whoops." Good vid, the whoops only makes it better.

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Brennn10 (author)NachoMahma2007-10-31

Haha yea, that Whoops was pretty funny. Nice videos mrfixits!

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mrfixitrick (author)Brennn102007-10-31

Hey, a big thanks to both NachoMahma and Brennn10 for your input. I do have a heck of a lot of fun doing these videos. They are not rehearsed and I don't do re-takes to fix glitches. It captures more of the wildness and mystery that way. (Even I don't know, what the ending is going to be!)

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mrfixitrick (author)2007-10-31

Here's a good web site with info on exploding CD'. Apparently, about 25,000 rpm is the limit before explosion. I have done 14,500 rpm so far with basic Cd Turbine on 1/2 throttle air, 10,000rpm with the Magnetic Coupler.

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chooseausername (author)2007-10-21

Manipulating a valve so close to the blade is not safe at all ............. If something went wrong, you would have lost your fingers ................

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Also. I have repositioned the shut-off valve further away from the business end.

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mrfixitrick (author)mrfixitrick2007-10-22

See recent pics for improvements.

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This version looks slightly safer ! ;-)

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yeah, I don't run away quite as fast...

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That's why I ran! This is not yet a safe machine!

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NachoMahma (author)2007-10-21

. Most circular saw blades are not meant to run at (or even near) 10,000RPM. See this PDF I found for more info.

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Goodhart (author)NachoMahma2007-10-21

Yeah, I once saw a video of a few young fellows (engineers) blowing air from a compressor into an old bearing race, and wound it's spinning speed up until the race gave way and the bearings flew out. At the speed they were going, it would have nearly been like being shot had anyone been hit by them...As it was, 2 bearings are still (missing).

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mrfixitrick (author)Goodhart2007-10-21

So, if the CD Turbine came apart at 15,000 rpm for example, yes it would be like being shot... by an old BB gun. According to the chart supplied by NachoMahma above, at 15,000 rpm, the speed of the 5" discs would be about 90 m/s (or 270 feet/second) or exactly the muzzle velocity of a very weak pump-action BB gun (not a good ol' Daisy with 450 fps).

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Goodhart (author)mrfixitrick2007-10-21

This seems to have become my most oft quoted seasonal quote this year: "you'll put your eye out kid." LOL

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mrfixitrick (author)Goodhart2007-10-21

Yes, I was going to use this line in my last post...it probably came from the common misuse of airguns in the old days. Anybody know?

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Goodhart (author)Goodhart2007-10-21

Ooops, the movie is "A Christmas Story" and yes, it was about a B-B gun

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mrfixitrick (author)Goodhart2007-10-21

Oh yes I remember something about that...A Daisy BB gun, I think. The roots of the phrase was in prehistoric times, originally uttered for the first time when a kid picked up a sharp stick. haha

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mrfixitrick (author)mrfixitrick2007-10-21

Yep, Daisy Model 1938 Red Ryder... Back then, maximum nozzle velocity was 350 fps with a good lever-action pump. The new reproduction ones are only 280 fps (too many eyes poked out??) That would be roughly equivalent to 90 m/s, and when we consult the chart supplied by NachoMahma, above, we see for a 5 inch CD disc would be 14,000 rpm. I will post a new video where I take the CD Turbine up to 14,500 rpm, but without magnets between CD's.

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Goodhart (author)mrfixitrick2007-10-21

The B-B gun was a "Red Ryder" :-)

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NachoMahma (author)mrfixitrick2007-10-21

. But it won't be BBs flying at you, it will be shards of plastic (hard to find on X-rays) or, in this case, a circular saw blade.

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mrfixitrick (author)NachoMahma2007-10-21

Absolutely... this is real world scary, not a phony-balony costume party. I plan to do the pumpkin cuttin' ceremony from around a corner with a long stick...

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Kiteman (author)mrfixitrick2007-10-21

If you were to give each of the saw's teeth a slight upward twist, you could be looking at a 15krpm helicopter ricocheting around the place.

> evil grin <

Another thought - rather than cut the pumpkin, mount it on a toothless disc and run it up to full speed - imagine the scene when centripetal forces get the better of the pumpkin... =D

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mrfixitrick (author)Kiteman2007-10-21

Thanks...both excellent suggestions! I've considered the first...don't want to go there except I will make something that revs up and flies. As for the second, hahaha, I will try it later and post the results!!

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mrfixitrick (author)NachoMahma2007-10-21

Hey Nach, thanks for this chart...it is EXACTLY what I was looking for! Obviously the rpms must be kept down for both safe experimentation or for any any reasonable use. I would not advise anyone to actually use the Skilsaw attachment...

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