So long as it’s repeatable and the +- weight is close I’ll be happy spending the $29. I don’t measure torque values on stock screws and shoot for groups and then try a different value and do it again and again and again so I’m sure it will be good for my needs.
I agree, not the best out there, but for a hunting rifle, it should get the job done.
As I have mentioned before on these pages, over a period of about 10 years, my employer allowed me to spend a quarter of a million dollars on friction coefficient testing of various thread lubes. During that testing we reinvented the wheel with regard to some aspects of knowledge with regard to establishing a preload using a torque wrench and added to the overall body of knowledge with other findings. One thing that cannot be over emphasized is that your torque wrench, as long as it is consistent, is a minor player in the overall equation. The big player, the one that means that on the best day of your life, carefully applying a specific torque using an established tightening procedure, you will get variation of 33% from the highest preload to the lowest preload in a representative sample ( 5 fasteners is ok, 10 is more to our liking), is variation in the surface finish of the fasteners, even if all are from the same manufacturer's lot. 40 to 60% variation in preload in a sample is not uncommon at all.
Basic tightening procedure is simple; from snug, tighten the fasteners in sequence in 3 or 4 approximately equal increments, with a brief pause between each pass (resetting the wrench for the next pass gives you a nice increment for that). Wait a couple of minutes minimum after the last pass, then apply a check pass with the wrench still at the final torque. Do the check pass clockwise or counter clockwise around the bolt pattern (mechanic's choice), not in the pattern dictated by the actual bolt pattern, snuggling any that move back to the final torque. Our tests, and those conducted by others, have confirmed that using more than 3 or 4 incremental steps doesn't make any improvement with regard to reducing preload variation.
None of the above is meant to disparage your comment, just an opportunity to pass along a small amount of what we learned with all that big bucks testing so that the readers of these forums know a bit more about what's going on than less informed wrench twisters.
As I have mentioned before on these pages, over a period of about 10 years, my employer allowed me to spend a quarter of a million dollars on friction coefficient testing of various thread lubes. During that testing we reinvented the wheel with regard to some aspects of knowledge with regard to establishing a preload using a torque wrench and added to the overall body of knowledge with other findings. One thing that cannot be over emphasized is that your torque wrench, as long as it is consistent, is a minor player in the overall equation. The big player, the one that means that on the best day of your life, carefully applying a specific torque using an established tightening procedure, you will get variation of 33% from the highest preload to the lowest preload in a representative sample ( 5 fasteners is ok, 10 is more to our liking), is variation in the surface finish of the fasteners, even if all are from the same manufacturer's lot. 40 to 60% variation in preload in a sample is not uncommon at all.
Basic tightening procedure is simple; from snug, tighten the fasteners in sequence in 3 or 4 approximately equal increments, with a brief pause between each pass (resetting the wrench for the next pass gives you a nice increment for that). Wait a couple of minutes minimum after the last pass, then apply a check pass with the wrench still at the final torque. Do the check pass clockwise or counter clockwise around the bolt pattern (mechanic's choice), not in the pattern dictated by the actual bolt pattern, snuggling any that move back to the final torque. Our tests, and those conducted by others, have confirmed that using more than 3 or 4 incremental steps doesn't make any improvement with regard to reducing preload variation.
None of the above is meant to disparage your comment, just an opportunity to pass along a small amount of what we learned with all that big bucks testing so that the readers of these forums know a bit more about what's going on than less informed wrench twisters.
No problem at all. We learn from people that have more knowledge about a product/process than ourselves. Thanks for sharing that information!
As I have mentioned before on these pages, over a period of about 10 years, my employer allowed me to spend a quarter of a million dollars on friction coefficient testing of various thread lubes. During that testing we reinvented the wheel with regard to some aspects of knowledge with regard to establishing a preload using a torque wrench and added to the overall body of knowledge with other findings. One thing that cannot be over emphasized is that your torque wrench, as long as it is consistent, is a minor player in the overall equation. The big player, the one that means that on the best day of your life, carefully applying a specific torque using an established tightening procedure, you will get variation of 33% from the highest preload to the lowest preload in a representative sample ( 5 fasteners is ok, 10 is more to our liking), is variation in the surface finish of the fasteners, even if all are from the same manufacturer's lot. 40 to 60% variation in preload in a sample is not uncommon at all.
Basic tightening procedure is simple; from snug, tighten the fasteners in sequence in 3 or 4 approximately equal increments, with a brief pause between each pass (resetting the wrench for the next pass gives you a nice increment for that). Wait a couple of minutes minimum after the last pass, then apply a check pass with the wrench still at the final torque. Do the check pass clockwise or counter clockwise around the bolt pattern (mechanic's choice), not in the pattern dictated by the actual bolt pattern, snuggling any that move back to the final torque. Our tests, and those conducted by others, have confirmed that using more than 3 or 4 incremental steps doesn't make any improvement with regard to reducing preload variation.
None of the above is meant to disparage your comment, just an opportunity to pass along a small amount of what we learned with all that big bucks testing so that the readers of these forums know a bit more about what's going on than less informed wrench twisters.
Great info, and though I haven't spent $ on testing, I've seen compelling evidence of this over my years of wrenching on engines and other equipment. The finish of the various friction surfaces always appeared to me to be a huge factor.
Are you able to share anything about what you found with different lubes -- did some of them perform dramatically different from others?
Good question, and the answer is yes, there are very significant differences. We needed a specific friction range for each lube tested in order to establish a mean friction coefficient for calculating the torque to be used in assembling a specific joint, plus knowing the range helped us select a value above or below the mean if there was a reason to weight the calculation either way from what the mean would yield.
General rules of thumb for use with dry assembly values if the torque value or table you have dosn't apply to a specific lube:
1. For use of motor oil or automotive grease, do not reduce the dry torque value (these do not have the types of pressure additives that make a good thread lube - that area falls to anti seize compounds).
2. For graphite based anti seize compounds like Never Seize, reduce the dry assembly torque by any value between 35 and 40%.
3. For molybdenum disulfide based lubes reduce, the dry assembly torque by 48 to 54%.
The key to thread lube performance is the presence of ground up micro fine pressure additives, commonly either graphite or molybdenum disulfide, and some micro fine metallic additive, commonly zinc, aluminum or copper, as are found in anti seize compounds along with an oil or light grease carrier.
Very interesting. I'm surprised that the oil and grease doesn't reduce friction enough to even consider, but given the amount of pressure in that type of situation I suppose it does make some sense when you think about it...
I agree, not the best out there, but for a hunting rifle, it should get the job done.
As I have mentioned before on these pages, over a period of about 10 years, my employer allowed me to spend a quarter of a million dollars on friction coefficient testing of various thread lubes. During that testing we reinvented the wheel with regard to some aspects of knowledge with regard to establishing a preload using a torque wrench and added to the overall body of knowledge with other findings. One thing that cannot be over emphasized is that your torque wrench, as long as it is consistent, is a minor player in the overall equation. The big player, the one that means that on the best day of your life, carefully applying a specific torque using an established tightening procedure, you will get variation of 33% from the highest preload to the lowest preload in a representative sample ( 5 fasteners is ok, 10 is more to our liking), is variation in the surface finish of the fasteners, even if all are from the same manufacturer's lot. 40 to 60% variation in preload in a sample is not uncommon at all.
Basic tightening procedure is simple; from snug, tighten the fasteners in sequence in 3 or 4 approximately equal increments, with a brief pause between each pass (resetting the wrench for the next pass gives you a nice increment for that). Wait a couple of minutes minimum after the last pass, then apply a check pass with the wrench still at the final torque. Do the check pass clockwise or counter clockwise around the bolt pattern (mechanic's choice), not in the pattern dictated by the actual bolt pattern, snuggling any that move back to the final torque. Our tests, and those conducted by others, have confirmed that using more than 3 or 4 incremental steps doesn't make any improvement with regard to reducing preload variation.
None of the above is meant to disparage your comment, just an opportunity to pass along a small amount of what we learned with all that big bucks testing so that the readers of these forums know a bit more about what's going on than less informed wrench twisters. <img src="https://www.rimfirecentral.com/forums/images/smilies/smile.gif" border="0" alt="" title="Smilie" class="inlineimg" />
As a guy who works in precision maintenance. I appreciate the bit of knowledge. Had never given much thought to the variances from MFG to MFG of actual fasteners, but it makes sense.
thanks, been looking to pick one up.
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