Borka torque wrench: 62 and 68 inch-lbs. settings

[kortik]

I was asked several times in the past if Borka multi torque driver can be used to generate 62 and 68 inch-lbs. of torque, recommended for certain firearms fasteners. While officially MG driver does not have these particular settings, here is a simple trick, which allows to apply both 62 and 68 inch-lbs. of torque. Strictly speaking, by calculation it would be 61.2 and 67.8 inch-lbs., which is real close to 62 and 68 for any practical purposes.

Please look at the pictures below:

For SH members familiar with operation of Borka tool, these two pictures should be sufficient to figure out what to do. But in brief, in order to get 62 inch-lbs., set up the driver to 65 inch-lbs. and apply tightening force not to the middle of the handle finger groove, as typically required to generate 65 inch-lbs., but to the edge of the finger groove, as shown.

For 68 inch-lbs., just set up the driver to 72 inch-lbs., and do the same thing.

Please be advised that this approximate 6% reduction is only applicable to 65 and 72 inch-lbs. marked hex holes. Reduction of the torque output will not be of the same percentage for other hex holes, which are closer to the driver handle, due to relatively complex relationsip between the change in handle "break force" and the change in "active lever" distance.

Just wanted to share this trick with Borka torque driver owners, who may find it useful...

Boris

 

[Platypus]

Re: Borka torque wrench: 62 and 68 inch-lbs. settings

Boris,

Thank you for the heads up. Posting this up and doing the math to share with the shooters is just another reason why the Borka Torque Driver is in my kit.

Danel

 

[Redmanss]

Re: Borka torque wrench: 62 and 68 inch-lbs. settings

Tagging this one. Thanks Boris.

 

[NOMAD]

Re: Borka torque wrench: 62 and 68 inch-lbs. settings

You are the man Boris!!

Anyone that doesnt have this tool in their gear, you are missing out!!

Highly recommended piece of gear.

 

[spiralseal]

Re: Borka torque wrench: 62 and 68 inch-lbs. settings

Tagging this also for my SCAR

 

[vman]

Re: Borka torque wrench: 62 and 68 inch-lbs. settings

Very nifty

 

[hrt4me]

Re: Borka torque wrench: 62 and 68 inch-lbs. settings

Thanks for the tip!

 

[Tburkes]

Re: Borka torque wrench: 62 and 68 inch-lbs. settings

Okay, I've got to ask this question. Is three or four inch pounds really going to make a difference in the grand scheme of things? Aren't what we really needing is consistency which this tool provides with the current layout.

Everyone always says 65 inch pounds on the action screws when what you really need is a way of reassembling the rifle consistently. I've always used 55 inch pounds and have never had a problem with anything. Now with this tool I'll just go to 57 inch pounds and be done with it.

Am I missing something?

 

[kortik]

Re: Borka torque wrench: 62 and 68 inch-lbs. settings

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Tburkes</div><div class="ubbcode-body">Okay, I've got to ask this question. Is three or four inch pounds really going to make a difference in the grand scheme of things? Aren't what we really needing is consistency which this tool provides with the current layout.

Everyone always says 65 inch pounds on the action screws when what you really need is a way of reassembling the rifle consistently. I've always used 55 inch pounds and have never had a problem with anything. Now with this tool I'll just go to 57 inch pounds and be done with it.

Am I missing something? </div></div>

Tony, you're certainly correct and my own thinking is in line with yours. Consistency is the key. You're not missing anything.

David from Brock@Norris (the only Borka Tools authorised dealer in U.K.), AKA Ratwhiskers on SH, told me that he assembled scoped rifle with use of MG driver, zeroed it, then disassembled it, assembled it back with use of the MG driver, and it stayed zeroed. He seemed to be pretty much satisfied how it all worked out. That is what MG driver is about, on top of actually letting the operator to have all fasteners tightened in sufficiently accurate manner and in line with recommendations. Of course, the other thing about MG driver is that it is easy to carry around...

I would suggest the same thing as you did - just apply consistent, close to recommended, torque settings, and everything will be fine. I personally consider it acceptable, from my general engineering knowledge, to tighten firearms fasteners with consistent and repeatable torque in the range of +10% to -15% relative to the recommended torque value. Your example of using 57 inch-lbs. setting for doing recommended 55 inch-lbs. is a good one, 2 inch-lbs. above 55 is just +4% deviation from the nominal, and will cause no harm to the threads or change the function/accuracy of the whole setup.

On the other hand, I do not feel comfortable telling people just to ignore manufacturer's torque recommendation and go with something else. It is also a liability issue - just imagine, I tell somebody to use 65 instead of 62, something, even unrelated, will break or whatever, and although common knowledge supports the use of 65 instead of 62, I may end up looking guilty.

In addition, it is important to remember that torque by itself is not something very special, it is just a way to try to control CLAMPING force, generated by the fastener. Torque can be measured or pre-set by a simple tool, while measurement of clamping force requires some serious lab hardware, so torque is being used as a primary parameter, while in reality, it is a secondary one.

I bet most of the time the actual clamping force may be quite different from "theoretical" clamping force, which is intended by the manufacturer to be used for a certain fastener, even if applied torque is the recommended one. This happens because lack or presence of lubrication on the surface of the threads greatly affects the amount of clamping force produced by the applied torque. In fact, well lubricated fastener may deliver nearly twice the clamping force in comparison with the dry fastener, with use of the same torque value. There is a lot more potential variation in a system because of this lubrication factor than because of using +10%/-20% deviation from the recommended torque value. People should remember that and try to keep critical threads either consistently dry or consistently lubricated, depending on specific recommendations. Also, while loctite, sometimes used for scope rings fasteners, is not a lubricant, it can also change coefficient of friction in threads, with end result being that scope clamping force may be somewhat affected one way or the other - but cap screws will certainly stay in place, can't dispute that...

 

[Quickdraw40]

Re: Borka torque wrench: 62 and 68 inch-lbs. settings

tag

 

[Sean the Nailer]

Re: Borka torque wrench: 62 and 68 inch-lbs. settings

Exemplary, Boris.

As Nomad stated above, for consistency, reliability, and stability, EVERYONE should have this in their kit. (I may have embellished on it just a little)

These three points ARE keys to marksmanship, no?

 

[LoneWolfUSMC]

Re: Borka torque wrench: 62 and 68 inch-lbs. settings

Very Nice.

 

[kortik]

Re: Borka torque wrench: 62 and 68 inch-lbs. settings

Plan to try to design simple adapter to elongate driver arm a bit, and get 90 inch-lbs. torque out of existing MG driver.