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Torque wrench calibration
- Thread starter ichthos
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Check with a local airplane maintenance company. They have to have their wrenches calibrated regularly. Many shops have a calibrated wrench tester in house for quick checks before critical work. They should at least tell you about local calibration shops.
I just did a quick search for 'calibration' in my local online yellow pages and got 3 hits.
No idea about the cost. Never had to pay for it myself
I just did a quick search for 'calibration' in my local online yellow pages and got 3 hits.
No idea about the cost. Never had to pay for it myself
D
Deleted member 3577
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I have a 1/2" & a 3/8" Snappy and send them back to Snap On every other year for recalibration.
Not cheap...Something like $75.00
Makes me feel much better when I'm installing critical fasteners.
Not cheap...Something like $75.00
Makes me feel much better when I'm installing critical fasteners.
dklawson
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There should be local businesses who can do this for you if there are any manufacturing or assembly firms in your area. For ISO standards most assembly and test equipment has to be calibrated regularly and there are companies that do nothing but equipment/tool calibration.
That said, you can get an idea how close your (click type) wrench is at home. You need a relatively accurate set of bathroom (spring type) scales and a mounted bench vise. Take the bath scales to the workbench and weigh yourself. Write your weight down. Set the torque wrench for the range you're concerned about. Wrap a piece of tape around the torque wrench handle at a place 2 feet from the center of the drive end of the wrench. Clamp the drive end of the wrench in the vise such that you can pull up on the wrench handle. Step on the scale, grab the handle at the tape mark, pull upwards slowly while watching the scale. Note the reading where the click happens. Write that down. Now do the math. Take the scale reading, subtract your weight, multiply by 2 (for the 2-foot tape mark) and that's the actual torque (lb-ft) your wrench "clicked" at. Repeat this several times to get and average you can trust.
This DIY home method will only be as accurate as your bath scales and is obviously subject to errors, but it will tell you if your wrench is close enough to be trusted... or what amount of offset you need to dial in. It's better than using a totally uncalibrated wrench. I use a nice old Craftsman unit that is very accurate. I also inherited a Harbor Freight special and it is NOT accurate nor is it linear. I only keep that one for sentimental reasons.
That said, you can get an idea how close your (click type) wrench is at home. You need a relatively accurate set of bathroom (spring type) scales and a mounted bench vise. Take the bath scales to the workbench and weigh yourself. Write your weight down. Set the torque wrench for the range you're concerned about. Wrap a piece of tape around the torque wrench handle at a place 2 feet from the center of the drive end of the wrench. Clamp the drive end of the wrench in the vise such that you can pull up on the wrench handle. Step on the scale, grab the handle at the tape mark, pull upwards slowly while watching the scale. Note the reading where the click happens. Write that down. Now do the math. Take the scale reading, subtract your weight, multiply by 2 (for the 2-foot tape mark) and that's the actual torque (lb-ft) your wrench "clicked" at. Repeat this several times to get and average you can trust.
This DIY home method will only be as accurate as your bath scales and is obviously subject to errors, but it will tell you if your wrench is close enough to be trusted... or what amount of offset you need to dial in. It's better than using a totally uncalibrated wrench. I use a nice old Craftsman unit that is very accurate. I also inherited a Harbor Freight special and it is NOT accurate nor is it linear. I only keep that one for sentimental reasons.
T
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I,m almost positive there is a National Institute of Standards and Technologies certification lab within driving distance.
I'll bet they would test, calibrate and certify an auto mechanic torque wrench for maybe in the $400 to $500 range.
Look them up in the yellow pages and let us know what they say.
PS: That letter of certification and sticker they give you, will allow you to to tighten fasteners at any FDA facility in your state for one year. Might be a decent paying side job.
check it out!!
d
I'll bet they would test, calibrate and certify an auto mechanic torque wrench for maybe in the $400 to $500 range.
Look them up in the yellow pages and let us know what they say.
PS: That letter of certification and sticker they give you, will allow you to to tighten fasteners at any FDA facility in your state for one year. Might be a decent paying side job.
check it out!!
d
D
DougF
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Your local Sears may have a service.
T
Tinster
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DougF said:
Highly doubtful Sears is "The National Institute of Standards & Technology" certified calibration lab.
d
martx-5
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Thanks for all the information. Sorry, but I need more help. I figure I can get a used Snap On torque wrench and pay to get it calibrated (Thanks Art) for the price of (or sligthly more) a new Craftsman wrench of equal range. Which would most of you choose to do?
Kevin
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I'll have to remember to ask next time I go to our Sears. On the other hand, I have the fondest recollection of when their tool section used to be loaded with almost every tool they sold, AND it was staffed with people that could actually understand and USE some of those tools. AND they would repair broken ratchet handles on the spot or replace cracked sockets on the spot, free (as part of the lifetime warranty). But my local Sears isn't like that nowadays. :frown:DougF said:
TR3driver
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What I did was pick up a used Craftsman, and check the calibration with a digital (fish) scale. Still cheaper than a new wrench, and the scale is useful for other things.ichthos said:
Of course that assumes the scale is accurate, but it seems pretty good.
Scott_Hower
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Tinster said:
For $500, it should sing and dance and, well, you get the picture.
T
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Doug-
as an expert fisherman- I know from experience the fish weigh
scales automatically add 30% for bragging rights!!
Here's a 140 pound tuna Mara caught last week.
dale
as an expert fisherman- I know from experience the fish weigh
scales automatically add 30% for bragging rights!!
Here's a 140 pound tuna Mara caught last week.
dale
TR3driver
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My tests seem to indicate that it is considerably more accurate than my bathroom scale, but of course YMMV. For starters, the fish scale is repeatable down to an ounce or two; while the bathroom scale isn't even repeatable to better than 5 pounds!dklawson said:
Try weighing first an empty gallon jug, and then putting exactly one gallon of water in it. If the difference is 8 lbs 5 oz; you've got a winner.
D
DougF
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Our local Sears wanted $25 several years ago, when the wrench only cost $56.