I built a "Clothesline Racer"...

starhawk

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Oct 4, 2004
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Info on Clothesline Racers --> http://www.richardvannoy.info/clothesline-racers.php

I found out about it from Make: Mag. Very cool stuff... a lot more potential for fun times in a good way, IMO, than you'll ever get from eg NASCAR. Besides, you get to build the racers here, rather than just passively watch them wreck...

Here's mine... built in my usual horribly thrown-together way...





*shrug* Hey, it works... here's the gory details...

The frame is a drive cage (either floppy or one hard drive; I suspect the first) from a discarded computer. Built up on top of that using Popsicle sticks (!), some cut-to-length PCI slot brackets, and about a full tube of super glue gel (half Loctite brand from Mal*Mart, half The Original Super Glue brand from Dollar Tree) is a frame around a pair of toggle switches. One switch is an on-off SPST, the other is center off DPDT. Another pair of PCI slot brackets is used to form the hangers for the "clothesline". I need to find some inexpensive low-friction tape to wrap around them, those notches will give me hell otherwise...

The DPDT switch has a "circuit" (some flat metal shapes with insulating stuff in between) that forms an H-bridge. Super stupidly simple bang-bang speed control -- but it's all that's needed here ;) The "circuit" came out of a B&D PivotDriver electric screwdriver that used those infernal "VersaPak" NiCad batteries. Ugh. We used the thing maybe a dozen times over the course of two batteries and at least as many presidential terms ;) It's a real POS.

*ahem*

Both switches are my own -- the PivotDriver used a momentary rocker where I needed a latching toggle. Both were center-off, but the momentary rocker was not looking terribly helpful... so off it came (I took it apart to see if I could modify it and make it work for my purposes -- and was rewarded with some totally useless switch guts that I threw out) and I rebuilt the "circuit" onto a switch I'd ordered from Mouser that was the wrong one for the project in question. That project is on hiatus right now due to lack of interest, so I pulled the replacement switch (from Radio Crap) from it and used that here as well -- it's the SPST switch I mentioned above.

The actuator brackets going to the switches (so that when it gets to one end or the other, it trips the relevant switch) are also cut-and-drilled PCI slot brackets. There's a cushion on each one: a bit of self adhesive furniture pad (the foam grippy kind) wrapped in electrical tape. Don't want my handiwork to go flying apart from the impact... ;)

The motor involved is from an "O2COOL" brand 2xD battery fan courtesy of Mal*Mart. (Don't kid yourself, it's not cool at all. Another total POS.) I'm running it at 4.8v from a quartet of NiMH AA's. Works great! The motor is a knockoff clone of the Mabuchi RF-500TB. The real deal from Mabuchi can go all the way up to 9v but I didn't feel like pushing my luck ;) especially considering I'm not actually dealing with a Mabuchi...

The motor is attached to the frame with screws left over from taking apart an old laptop a couple years ago. (I keep those screws, they're handy.) Two similar screws hold on the battery box. Two more, similar but different, hold the spare lid onto the bottom of the pill bottle above it. The last pair of screws (identical to the second-to-last pair) holds the fan rotor (blades removed with an Xacto) to the pill bottle and spare lid. (The pill bottle is wrapped in 3M "Transpore" gauze tape, for grippiness. I've no idea how we ended up with that stuff, but it was there when I went looking, so there you go.) The rotor press-fits onto the motor shaft. It's a little loose, so I have to futz with it or it wobbles like hell. It's weird -- half the time, it'll wobble around and damn near fall apart (or rip up the motor) and then all of a sudden it straightens out and is totally fine. The other half the time it just wobbles until I shut it off and futz. I've no explanation for that behavior...

To make it fly ;) put the batteries in with both switches pointing towards the front (right side of the photo where you can see the switch bats and the Popsicle sticks). Pull the rear (left side of the photo) actuator bracket out, and it'll start off. When it reaches the end, it'll bop against the stop and that /should/ trip the DPDT switch with its H-bridge "circuit". It then travels back until it hits the other stop, tripping the SPST switch and shutting it off. Done.


Let me know what you folks think...
 

Mohonri

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Jul 29, 2005
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I like it! You should post this in the ghetto mods thread... :D
 

starhawk

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Thanks!

*sigh* you're probably right about the Ghetto Mods thread. I'll probably wait till I build another Paper Tiger to post anything there, though... ;)
 

starhawk

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Not likely. I don't have any airplane cable. Even if I did, my house is 80ft long -- the regulation length of cable is 100'. My front yard is that wide, but I definitely don't have stakes that sturdy.

There's also the matter of not having the money to get 100' of cable or the stakes... and that my camcorder is pure shit. Sound is good, video looks like I shot it with a disposable toothbrush ;)
 
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