General Category >> Technical Documents/Reference >> Cheap Torque wrench

Message started by vtail on 07/05/07 at 17:00:33

Title: Cheap Torque wrench
Post by vtail on 07/05/07 at 17:00:33

Yes ,yes I have 2 torque wrenches, On in ft/lbs and one in inch/lbs. But many times they do not fit in the limited space available. Solution;  At any good hardware store get a old fashioned hook scale. Put boxwrench (preferred) on the nut (bolt) and hook the scale onto the other end of the boxwrench. Just pull at 90 degree angle to boxwrench for proper torque. Example; Nut needs to be torqued till 25 ft/lbs= 300 inch/lbs (25x12). If box wrench is 8 inches long from center to center, devide 300 thru 8 = 37.5 lbs of pull at 90 degree angle to wrench for proper Torque. Great,inexpensive and works in tight spots like oil drain plug, cylinder head cover nuts etc :o

Title: Re: Cheap Torque wrench
Post by Paladin on 07/05/07 at 18:55:20

If not the hardware store try sporting/fishing goods -- the scale used to check the weight of a fish should be under $15.  Many here will already have one.

Title: Re: Cheap Torque wrench
Post by Todd Perry on 06/21/08 at 10:22:46

Good idea, and I've used it myself. However, keep in mind that you need to stay reasonably close to the 90 degree angle as you can through the arc if the wrench turns (i.e. don't pull in a straight line, pull keeping the scale perpendicular to the wrench.) As you deviate from a straight line, the effective torque drops off (with the sine of the angle, in case you're a geek like me.) So, at 90 degrees, you get full torque, and it's not bad until about 65 degrees (90%), but drops off pretty quickly (45 degrees = 70% and so on) This is usually a problem at lower (i.e. inch-pound) strength torques as many times the tolerances are tighter and you may not get enough torque. At serious foot-pound settings, you usually can't make much of a difference  :D

Title: Re: Cheap Torque wrench
Post by northshore_paul on 06/22/08 at 16:42:13

I have purchased the harbor freight 1/2" drive wrench for less than $20 on sale...I know you ask how accurate is it...well now that you ask it is within 5% from 10lbs to 100 ft lbs. When the calibration van came to work I asked them to do a check and I was pleasantly surprised. Also had them check my Harbor freight voltmeter and it was spot on!

Title: Re: Cheap Torque wrench
Post by Digger on 06/25/08 at 21:31:07

Here's another way to torque fasteners that are impossible to access with a plain torque wrench:

I've got lots of impromptu torque adapters I use while working on my bikes.  For instance, here are two that I've rigged up to torque the two 6mm nuts that are on the starboard side of the bottom of the cylinder assy.

This one uses a standard 10mm combination wrench.  The open end of the wrench fits perfectly on the drive square of my 3/8" torque wrench:

This one uses a 10mm crow's foot popped onto the drive square of my 3/8" drive torque wrench:

Just get an accurate measurment of the new perpendicular moment arm and do the math.  The offset angle of the 10mm wrench is small enough such that it can be neglected, by my calculations.

I keep the conversion factors in a book in my garage.  I currently have nine different torque adapters listed in that book. » Powered by YaBB 2.2!
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