Author Topic: Budget gear testing?  (Read 1254 times)

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Offline Garbonzo

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Budget gear testing?
« on: October 20, 2006, 03:21:10 pm »
I'm making more and more soft goods for myself.  Stuff like redoing the straps on my daisies (Fish's replacements have way too big of a girth hitch loop), home made russian aiders, harness for a chest roller, and so forth.

I'd like to venture into more stuff, but the more "life supporting" it gets, the more I want to at least proof test things at say up to ~10-15 kN.

While a full hydraulic rig with a calibrated load cell of some sort would be nice, it is way outside my budget.

I'm envisioning some sort of rig with a big lever arm attachment of a known mechanical advantance of say 20-30:1 with a steel pin to pull with, and stationary steel pin (moveable to multiple holes) to pull against.   Using known dead weight you could readily put pretty accurate forces onto gear.

Anyone else do such a rig?

Should I just sew the crap out of it and hope for the best?  For example I put about 300-400 stitches of #69 thread into my replacement diasy strap.  With an expected break strength of >10 lbs/stitch, I'm looking at >3000 lb break strength of the seam, which is well above where the ancra buckle cuts the webbing.  Sounds good, but it would be nice to really know.

Other ideas?

Offline euroford

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Re: Budget gear testing?
« Reply #1 on: October 21, 2006, 08:50:19 am »
you'll need a load cell of some sort.  and instead of the hydro you can just get a come-along.  i've ratchated those things up to like 5000lbs testing anchors.

Offline noshoesnoshirt

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Re: Budget gear testing?
« Reply #2 on: October 21, 2006, 09:12:01 am »
Have you thought about making your own load cell with strain gages?  They're cheap and accurate (but a real bitch to glue and solder), and you'll need an amplifier for the signal.  Smack a Wheatstone bridge on a load bearing member of your pull rig that will deform elastically in your desired range of force, and calibrate it with known loads.

Online deuce4

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Re: Budget gear testing?
« Reply #3 on: October 21, 2006, 10:24:09 am »
Here's some old notes of a hydraulic puller I made some years ago.   THe ky was getting a pressure guage with a maximum needle (that sticks to the high point of the main needle).  I think McMaster Carr has everything you need, or try the discount freight places.

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Offline caribouman

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Re: Budget gear testing?
« Reply #4 on: October 21, 2006, 09:22:58 pm »
For pull-strength, why not use the dynamometer at the closest community college engineering lab/ mechanical shop?  Professors love that stuff, 'cause it's real world application & small enough that you can fit it in their machines. I tore apart bucket loads of gear in the lab at my college...
when the going gets weird, the weird turn pro.