Harbor Freight 1" pneumatic gun

[JackConrad]

My torque stick is stamped 475 FT. LB. +/- 5% When I received it (purchased new in the package) there was nothing mentioned about caliibrating it.  I had never heard of this.  If I get a chance to be somewhere that I can have a brief access to a big torque wrench, I will check my torque stick.  Jack

[kyle4501]

The torque stick set I had (was for cars) came with instructions for calibrating the impact wrench. I don't know if this applies to the one Jack has.

The short version ;
Tighten a nut (with a known good torque wrench) to the value of the torque stick.
starting with low air pressure on the impact wrench, start tightening nut as you increase air pressure.
When the nut turns, back off the pressure slightly.
Install another nut with the torque stick.
Verify the torque with a known good torque wrench.
You have calibrated your impact wrench & it will use the same air setting for all sticks in the set.

Torque sticks are a torsion spring and you can exceed the rating if you drive them hard enough.

My local tire store uses torque sticks. I watched & verified the one used on my car was 80 ft-lbs. When I got home, I tried to remove a wheel to change brake pads. It took about 300 foot-lbs (my 200# standing on a 18" breaker bar & I bent the bar). I went back to the tire store & found no regulators & a 175 psi air compressor.

I take my own torque wrench now, it is so much easier than replacing wheel studs, nuts & etc. & then trying to collect restitution.

The plastic & duct tape are great ideas!

[NJT5047]

Thanks for the "calibration" explanation.  The automobile scenario appears to be an unexact science.   How do the torque sticks set the torque?  They are pre-calibrated somehow.   Do they slip or flex??  Sorry to run thiis thread into the ground, but looked at the website that was posted, and the concept looks good, but apparently won't work with my torque multiplier...but it could be used with the impact when at home.  I've never changed a tire on the road....yet.
Best, JR   

[Grease Pit]

I have the 1" impact from Harbor Freight and it works great. I have an extra air tank from a bus and use it as a relay tank. I have a 3/8" air hose fronm the compressor going into the tank and a 8'x3/4" hose from the tank to the gun. The tank is not heavy and with relay tank the gun will kick butt. The relay tank refills quickly so it's ready by the time you get the next lugnut ready. The only comment about the gun is you just need to make sure everything stays tight. I had a couple if set screws loosen up but a little Lock-tite fixed that.