[drcrash] sent in this thorough how-to on converting a cheap bike pump to pull a vacuum. Apparently it’s just the thing for small vacuum bagging projects. I’m thinking that this could be combined with a low rpm motor and a pivot. Just picture an old steam locomotive wheel drive, and you should get my idea. (A windshield wiper motor would probably be perfect.)
Is it less of a hack to make one from scratch?
http://sci-toys.com/scitoys/scitoys/aero/vacuum/
(One caveat for this page: Do NOT heat the PVC over an open flame! It releases VERY toxic compounds! Either use a smaller PVC cap that fits inside your pipe, heat the plastic in sand heated over the stove, or find some other way to plug the pipe.)
Posted at 1:01 am on Jul 2nd, 2007 by Amos
My air compressor is a refrigerant compressor driven by an electric motor/fanbelt. It is nearly silent, and compresses a lot of air fast, it has been in service since it was repurposed for 50 years or so. ..Anyways, I once wanted to get a big Jeep tire off the rim and switched the intake and exhaust to suck all of the air out of the tire and hopefully pop the seal but instead the tire turned into a rubber square on a rim. I’ve never tried converting an auto air conditioner compressor (magnetic 12v clutch, infinite horsepower) – I don’t know if they would be reversible either, I think modern ones need lubricant in the compression chamber anyways.
Mine is a two piston double reed valve type, that’s why it blows and sucks equally well. I’m sure there are other decent compressors out there though.
Posted at 7:59 am on Jul 2nd, 2007 by mike
I’ve built an automated bike pump similar to what you mentioned. It consisted of a large PVC disk motorized by a fairly meaty 12V electric motor. The disk was reasonably heavy to smooth out the varying resistance in a pump action. A small bike pump was attached to the circumference and the outlet was mounted to a frame.
I had underestimated the torque required for such a device (This was an attempt as a homemade air compressor) and simply overloaded the motor. It’s definitely something worth revising – I was thinking an RC motor with gearing but your windshield wiper idea sounds like a much cheaper and easier solution.
Great write up. I had an old bike pump in the closet and built my own while reading his write up. My pump is a bit fancier one but worked great.
Posted at 10:10 am on Jul 2nd, 2007 by Brandon
*Off Topic*
Anyone know what happend to inventgeek? they seem real quiet lately. they used to have a artical every month. but its been 3-4 months. any info would be sweet as they seem noncom.
Tom.
Posted at 11:35 am on Jul 2nd, 2007 by tom needer
I actualy heard that jared (The head dude at inventgeek) is battleing cancer. the lack of update on his condition is worrysome.
Posted at 1:57 pm on Jul 2nd, 2007 by Andrew
Wolf says “Too bad he couldn’t reverse the check valve as well…”
Actually I could have, if I’d wanted to use that check valve. (I think it would work fine; I just wanted a little less resistance.)
You could do it by gluing the check valve back in place with J.B. Weld or some other epoxy, and epoxying a hose barb on top of it. Then you wouldn’t need to buy a new check valve, and the whole thing would cost about $12 if you have epoxy lying around. (Hot glue would probably work if you duct tape the hose to the cylinder so that you don’t stress the joint.) You might need a spacer (maybe a big nut) so that the hose barb doesn’t poke all the way into the threaded hole; I’m not sure.
One reason I didn’t do that was just that I didn’t feel like carefully cleaning things at the gluing point, or waiting for the epoxy to set.
(I also like the “neat” look of the way it turned out, but that’s probably a bourgeois affectation I should get over if I’m going to hack $10 bike pumps.)
Good hack, but motorizing it just isn’t worth it. I use a compressor from an old fridge or freezer as a vacuum pump, & they work just fine, as long as you don’t allow any liquids or corrosive vapors into it. They will pull enough vacuum for a discharge tube, but not enougn for neon work. For neon, one has to add a cheasp diffusion pump to the setup.
Automotive AC compressors make excellent air compressor setups, I built one close to 30 years ago, & it is still working, & has never had lubricant added. Comp is a Ford unit from the early 70s, with 3/4hp electric motor & tank. I used the mag clutch to eliminate any check valve or unloading. You simply hook the coil of a relay across the start switch, & use that to activate a small power supply that runs the clutch. That way, the load is off of the motor until it is up to speed. Match the relay’s coil voltage to that of your motor.
Posted at 4:01 pm on Jul 5th, 2007 by Tekwiz
Funny amos should post that link (with the marshmallow demo) just as I was about to post this one, with a video demo using Peeps:
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too bad he couldn’t reverse the check valve as well…
good hack none the less
Posted at 12:46 am on Jul 2nd, 2007 by Wolf