Forum

[jefrs]

Clement, the differences between Pete Snidal and the Workshop Manuals can be resolved from first principals by using engineering rules or simply looking up standard engineering tables (google "torque on 3/16 screw" e.g. https://www.engineersedge.com/torque_table_sae.htm) for the screw thread diameter and the materials being fixed. And it is mainly the diameter not the thread pattern, certainly not the length, a screw holds on no more than four turns of thread whatever its length. Some screws have a torque mark on the head, most don't. Obviously when fixing dissimilar materials, go by the weakest one.

[PeteF]

"One could use weights but the vise jaws are horizontal"
So hold it in the side of the vice?

[jefrs]

Gosh Dennis, do you really think I have something like an Instron machine lying around the house? If I was still working and really wanted my torque wrench calibrated I'd hand it to my mates in the mechanical cal lab; the principle would be the same - stick weight on it until it goes click and note the wrench settings down at several points, adjust if necessary.

The cost of recalibrating some cheap tools out-weighed their purchase, we'd throw them away or re-home them and buy a new calibrated one as required.

[jefrs]

PeteF - could do, why not. I tried that but the wrench tips over, doesn't pull straight on axis. I've got two permanent vises, small and a huge smithy's stirrup-leg vise, plus I've got spring balances not a set of weights. If I ever gave 6 lab techs or craftsmen the same job, they'd always find at least 9 ways of doing it, all good.

[Barry N]

I have a cheap bendy-bar type (Draper) which I am happy with. I only use it on the cylinder head studs, which I torque to 19ft/lbs (with an alloy barrel) and have had no issues. I read an engineering review of wrenches once which was very praiseworthy about the accuracy of these devices. What is the opinion of those who have used them?

[jefrs]

I have a bendy bar. The reproduction of the spring bar is very reliable and long lasting. The accuracy is limited by how well one can read the gauge. The distance between the pointer and the scale is large, you have to be directly above it and that can lead to very inaccurate readings to either side. Personally I would not use it on a cylinder head but might buy a new little click wrench for the job. The bendy bar type is very good at at it does and will last forever but it is far from accurate in use, I wouldn't use it where even pressure from several fasteners is important.

[nickbarber]

If you don't have "the feel" for torques, then yes buy one if you must. I have a ratcheting snap-on torque wrench that I bought when I was an apprentice aircraft engineer (best you can buy, but quite expensive) but once you get a feel for torques, your knuckles become a mighty fine (almost calibrated) torque wrench.

[Dennis C]

It certainly does Nick, you apparently have the magic touch.

[nickbarber]

As do you with your computer keyboard, Dennis.