Hi Carter
If I send you my TW could you do the 3D graph with deflection compensation
etc. What was that? you'd like me to leave in short jerky movements?
Graham
----- Original Message -----
From: Carter Shore <clshore@yahoo.com>
To: Oliver, Chris MAJ <oliverc@monroe.army.mil>;
<spitfires-digest@autox.team.net>
Sent: Monday, February 07, 2000 3:01 PM
Subject: Re: Torque wrench tester
>
> Try this:
> 1) On your Torque Wrench, measure and record exact
> distance from center of socket adaptor to handle
> pivot, or center of handle if no pivot.
> 2) Clamp a large bolt horizontally into a bench vise.
> 3) Use socket on TW to fit bolt head.
> 4) Adjust bolt position in vise so that arm of TW is
> horizontal. Use a level if you are AR.
> 5) Attach coat hanger wire to TW handle, use duct tape
> as required. Attach in exact center of handle if no
> pivot.
> 6) Using known weights (should be easier to find a
> precision scale than a precision torque meter), attach
> weights to coat hangar, record TW readings. If you are
> AR, also weigh the coat hangar and duct tape and TW
> itself, plus calculate the centroid of TW.
>
> Calculate the applied torque on the wrench by taking
> the product of the distance from step 1, and values of
> the weight(s) from step 6. (convert from in-lb to
> ft-lb as required)
>
> If you are AR, put the values into a spreadsheet, then
> print a color graph of the calibration curve, and post
> it on the wall of your garage.
>
> If you are *truly* AR, perform the trials above at
> different temperatures, then you can print a 3-D graph
> that is temperature compensated. Can also measure any
> deflection in TW arm, then do vector math to
> campensate.
>
> FYI, unless you are torqueing brand new threads or
> aerospace fastener$ under absolutely ideal conditions,
> any values must be considered very approximate, (i.e.
> +- 20%), as the variations in friction from the
> threads, and mating surface under the bolt/nut are the
> dominant influence on the TW readings obtained,
> whereas the actual desired result is the clamping
> force that is generated. That's why some fasteners are
> spec'ed by measuring the stretch in length rather than
> applied torque.
>
> So a 5% variance in TW is probably worth ignoring.
> ( 5% of 85 ft-lb = 4.25 ft-lb)
> YMMV
>
> Carter Shore
>
> --- "Oliver, Chris MAJ" <oliverc@monroe.army.mil>
> wrote:
> >
> > I have been kicking this around off line, and though
> > maybe some one out
> > there might have a good solution. How does the home
> > mechanic test his
> > torque wrench to ensure it is with in standard? I
> > know that if you use it
> > alot, and do a lot of mechanical work you develop a
> > feel for torque. But
> > what about if you don't have that "feel"? It was
> > suggested that the local
> > Technical College might be of help, and if your
> > company has a facility and
> > lets you use it you are good to go. I was looking
> > for the home shop
> > solution. Maybe it does not exist, but I would like
> > to hear your ideas.
> > thanks Chris
> >
> >
> >
> Do You Yahoo!?
>
|