[Gubi]

C'mon, Don. You're not under any obligation to try convince me, I'm just telling you it would take actual data. I'm also trying to help people not buy the world's most annoying-to-use type of torque wrench.

You know you don't work for me, right? I mean, I don't actually have any power around here: if I did demand something you would in fact be allowed to ignore it

In many (not all) cases, the problem is not the tool, it is the methodology. The higher-tension fasteners require a different methodology than simple click-types can provide.

My issue is that you've never given any technical references for the methodology you posted. I've never seen nor heard of it in my career or hobby, nor has my satellite-manufacturing spouse, nor is that methodology documented anywhere I've ever been able to find. Maybe that's how your company did it years ago, but as far as I can tell it is by no means well documented or proven. You're free to try to prove me wrong, or you're free to ignore me.

Anyway, I'm confident that for low-tension fasteners any type of torque wrench is fine. For torque-to-yield fasteners the common methodology is torque+angle, and any torque wrench is fine for that too.

Safe travels on your trip.

 

[PSk]

Because I'm bored ... I've never used a beam type torque wrench. In this case I mean the one with a needle that you line up with a scale. I would find that concept very difficult to practically use because you would need somebody else to read the dial and say "stop" when you have reached the right torque.

BUT the torque wrench I use for conrod caps, crankshaft caps and head nuts/bolts is a beam type that has a clicker thing on it. This was my fathers torque wrench (probably should get it calibrated). You adjust the position of this click thing and when the beam bends it pushes on this clicker and that indicates you have reached the right torque.

Otherwise I use a cheap and nasty ratchet clicker one I bought, i.e. torquing wheel nuts on alloy wheels. It is possible that this one is more accurate than my father's one but "we" trust my fathers one
Pete

 

[ossodiseppia]

O-M frickin' GAWD!

 

[PSk]

It's no different to some like blondes and others red heads, or Chevys or Fords, or Michelins or Pirellis, or zinc in their oil

Pete

 

[goats]

Don, thanks for your contributions on this topic as well as all others over the years. I've learned a LOT from you!
Have a safe and fun flight! How do you like living down there after -- what is is-- about 6-9 months so far? Is it everything that you had hoped for , (hopefully even better!)
bob

 

[DPeterson3]

I tripped over a thread from 2011 (easy enough to find with a simple search). Among other things, it shows how often people read half of a post, then try to counter the author's point. The result being a tangent, rather than a contribution.

Myth Busted: You DONT get more "clamping&quot...

Have always wanted to validate the difference in the "clamping" force acheived when you use a oiled thread Vs a clean dry thread. As I had the equipment from work that I use for testing bolts in concrete sitting in the back of my car I thought hey why not do it. Sure if you want to get...

www.alfabb.com

The overall challenge is:

What is the best way to counter the geometric onset of friction and stoppages due to fastener defects when setting a critical pre-load?

If you can work through that dominant problem, you'll begin to understand why the best solutions are not click wrenches.

In the last fifteen years I've presented three show winners, and done numerous other engine overhauls, and Alfa semi-restorations. I used only a 1/4", 3/8", and 1/2" beam wrench. Was able to happily reach everything that needed it, and to read the resulting numbers.

 

[Gubi]

Well, I was trying to have a technical discussion here, not tick anyone off. But Don has apparently blocked me (after PM-ing me to "**** off" and saying I had a mental disorder. At least we agree on the latter 😆)

Anyway if you want to follow Don's procedure (oil, torque, hold for creep) there's absolutely no need to use a beam wrench. You can do the exact same thing much more easily with a digital wrench. They're not that expensive, and unlike a beam they ratchet and can be used without looking at the scale, so they're actually usable when working on, you know, a car.

I agree 100% with Don that torque is an imperfect measurement of clamping force due to varying frictional effects. I just disagree when it matters and how to deal with it. I can find zero documentation of the methodology he's proposing from any technical resource, he has not referenced any, and there are no restrictions I can find on click wrenches in aviation or any other industry from any source. That's why I'm dubious about taking his advice.

Used fasteners can actually have lower friction than fresh ones because the threads and head tend to self-polish when installed. Torque specs (unless otherwise noted) typically assume dry threads, so oiling every fastener isn't a great idea unless the manual tells you to. Industry experience also seems to show that (barring careful controls) most bolts are overtorqued rather than undertorqued, and I suspect that in many cases Don is overtorquing things on a car using his methodology.

Anyway, my advice is use whatever wrench you're comfortable with and just follow the specs in the manual, as they're designed to account for variation in friction and tool accuracy. Depends on what I'm installing, but if there's a range I'll usually use the higher end when installing a dry fastener with a calibrated too, and that should certainly provide appropriate clamping force.

If you're dealing with something like a head gasket, gasket relaxation is the bigger factor rather than the precise initial torque. So very important to follow the proper retorque procedures in the manual.

 

[ossodiseppia]

Good grief, DEWD!

 

[Gubi]

Good grief, DEWD!

Indeed!

 

[Jim G]

I’ve used the new digital torque wrenches. The ones I used are snap on brand. They are neat and they are basically a modern version of the beam torque wrench. Because as you come up to the torque setting it will light up that your getting close so you need to slow down. As all of a sudden it will turn green. If you go past the setting it goes red. But it does take practice as its easy to go past your stopping point.

But there real strong suit is torque angles which manufacturers started going to in the 90’s. You tell it what angle you need to do and it will keep up with it even if you have to stop and swing the ratchet backwards because you ran out of room.

I still use clickers. But on head torquing I run a rethreading tap and die on the studs and nuts. Then lube everything with the ARP thread lube. I found that it works better then just oil. Especially when doing the retorque in 500 miles.

 

[Gubi]

Because as you come up to the torque setting it will light up that your getting close so you need to slow down. As all of a sudden it will turn green. If you go past the setting it goes red. But it does take practice as its easy to go past your stopping point.

Yeah, when I switched to the digitals I found the same thing: after being used to the clickers it was easy to go over at first. But once you figure it out it's fine. Just gotta be careful with those first few fasteners.

I can't afford Snap-On, but the GearWrench ones I got both beep and vibrate as you hit the limit, which is nice. They're adjustable so that you can set the warning to start (repeated beeping) at x% before the target value, where it then switches to a solid tone.

I also like that they show you the max torque you hit after the pull, so you can verify you did it right.

 

[DPeterson3]

Jim F,

You’re on the right track.

A dominant misunderstanding is that the precision of the wrench is one of the smaller variables in achieving the desired preload. We found this myopic view to create large problems in many realms of industrial measurement and control. People do love a rigidly defined procedure, and complicated-looking equipment.

I’m convinced that click wrenches started out as a good idea, but rapidly found a profitable market where they are misused.

There are several, distinct realms in which fasteners are intended to be assembled.

New assembly
Repair
Maintenance
High preload
Low/moderate preload.

Parallel we have the design engineering and production engineering.

In new assembly, we have all new components in a controlled environment. A high value is placed on production speed, and repeatability. The design engineer defines (for example) an XXX preload for the head bolts. The production engineer does a bunch of experiments and says (in the past) “we get what we want by using Y lubricant, with a defined tightening pattern, in a defined series of torque steps, using a calibrated click type torque wrench.” He/she will have determined that the resulting preloads fit the design engineer’s standards a very high percentage of the time.

In this scenario, the wrench is a “torque limiting” device. The “torque setting” is the entire process, including all-new components, specific lube, etc.

None of us are working within this entire process, nor does using one component out of the total achieve the desired result.

This entire subject is huge, and wide ranging. I am not interested in arguments. I am happy to help, but there is no point in butting heads. I note Gubi continues to post, but I have him set on “ignore”, the better to enjoy my day, and when time allows, add an additional piece to this puzzle.

The above, brief description of “new assembly” is a tiny part in understanding the process of setting preloads.

Brief anecdote…

Years ago I made a presentation to a large German chemical plant. At the end, the chief chemist came to the front, shook her finger at me, and said (in a fit-for-movie-accent), “I see that you are correct, but I still disagree!”

To one of our German collaborative instrument manufacturers, I teased by noting “German operations make measurements. American operations make money”

Do not be distracted by precision or process. Focus on what actually works.

What “actually works” is not proven by “none of my work has failed yet”. Way too small of a data set. For me, one failure in 100 would be an unacceptable result.

 

[ossodiseppia]

Thanks for this, Don. Not intending to throw a wrench into this topic, but.....what are your thoughts on the Cam-over wrenches?

 

[Gubi]

He can’t see me, lol, but he won’t like them. The Cam Over wrenches are basically a clicker, except you can’t apply force beyond the click: the wrench just pops to a new position via an internal clutch.

The advantage is that an operator can’t push past the click to apply more torque than the setting. It’s useful in manufacturing where you may not trust the guy using the wrench to use it correctly. Not really an advantage vs a clicker for a skilled user.

Don won’t like this one: he insists that a torque wrench needs to be held at torque for a while, and any wrench that can’t do this is useless. It’s something he was taught at some point, apparently, but it’s not correct.

 

[ossodiseppia]

Good grief, Tom. You just won't stop. This sort of behavior is childish and petty.

Please review my previous post. I asked Don for his opinion as that is who's opinion I am seeking.

Thank you.

 

[PSk]

Maybe Alfa Romeo did not use them, but I've watched a few engine assembly YouTube videos and there is a NOT a torque wrench used by a human any where. They lower a machine that torques all cylinder head or crankshaft bearing bolts/nuts at the same time. Same process for conrod caps but maybe 2 at a time ... have to watch another one.

So I wonder what the machine uses?. I assume some sort of digital sensor ...

Pete

 

[DPeterson3]

Osso,

I’m not familiar with the “Cam Over” design. Enlighten me.

I mentioned a case in the above thread from 2011 regarding a French aircraft engine. The official, factory wrench for securing the head nuts was maybe 7” long, and had beveled edges. Using the wrench literally inflicted pain as one neared the intended degree of preload.

The “intended preload” was never published by Renault. However, the extremely similar design by Dehavilland published a number, that we decided must be similar.

Comparing my torque wrench results to the “stop the pain” result show much the same outcome.

These were low-compression, slow-revving engines, so not a lot of preload was required. Friction was not the dominant variable at this load.

My much newer design 916 GT used super-long head bolts. The “torquing sequence” involved a few progressive steps up to (IIRC) 25 ftlbs. After that, three sequential rotations of 99 degrees. Scary high preload.

This process was Alfa/Fiat’s way of saying “we don’t trust torque wrenches above XXX preload”. Friction becomes such a dominating factor that trying to measure the “torque law” is like trying to understand a whisper during a wind storm.

 

[DPeterson3]

Maybe Alfa Romeo did not use them, but I've watched a few engine assembly YouTube videos and there is a NOT a torque wrench used by a human any where. They lower a machine that torques all cylinder head or crankshaft bearing bolts/nuts at the same time. Same process for conrod caps but maybe 2 at a time ... have to watch another one.

So I wonder what the machine uses?. I assume some sort of digital sensor ...

Pete

Pete,

My bet, on the new robo-assembled engines, is as I described for “new assembly” combined with the process for my 916 below.

I’d place good money that the auto tightening system have a sensor that detects when pre-load resistance is first felt. Then, X number of degrees. With new components, themselves highly standardized, the engineer can define X rotations from contact and deliver good results.

Alternatively, tighten-to-stretch. The best method.

Humans are expensive, and argumentative. Machines just bang things out, no complaints.

 

[ossodiseppia]

Osso,

I’m not familiar with the “Cam Over” design. Enlighten me.

I found a video:

After watching it, I wondered if this type of tool might be better option for some folks. As you know, you can over-torque using a beam-type or click-type torque wrench. But, with the cam over type, there is no risk of over torque. It's pretty neat!

 

[goats]

I find that cam-over style interesting but not practical at all for my use.
IN my shop, on the stuff I work on - non mission critical things like head gaskets, brake caliper attachments, suspension fasteners, when I read this whole thread I am reminded of one of my Dad's sayings

Measure it with a micrometer, mark it with a piece of chalk, and cut it with an axe. File to fit and paint to finish!