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I can only wonder at what makes you think that the accuracy of electronic measuring instruments is limitless. The accuracy of the cheapest one I saw on Amazon is quoted as 2%, which is not bad if it can be relied upon, but the accuracy of my 1970s Norbar torque wrench was between 2% and 6% when I checked it in 2011. What accuracy to you want, and why?
Extremely useful information Brucey - especially resolving the question about what happens after overloads. Fascinating! I guess the safest solution is simply to not overload it and if you do, just buy another.Brucey wrote: ↑19 Sep 2024, 8:53pm IME gadgets with batteries are great if you use them every day but are of diminished utility if you don't. Also they tend not to work well if it is cold or damp, which is OK for stuff you keep indoors, but a lot less good for stuff you keep in a garage or shed.
Strain gauge technology is great but it is not infallible. In addition it is worth looking at the 'what ifs' and seeing how they might affect calibration. First the good news; torsional overloads tend not to cause dramatic changes in section at first; also torsional strain is proportional to radius which means that if the strain gauge is attached to a bar that is largely free of residual stresses, yield starts at the surface and then progresses inwards. This generally results in a weak surface residual stress field of opposite sense, ie. a CW overload will create a weak surface CCW residual stress field. This means that the thing will still work the same way CW (once re-zeroed), but CCW loading will result in premature yield. As long as strains are low (including plastic strains), and the strain gauge is still well-attached, the device will still work well in either direction. However any excursion that does not return the gauge to zero immediately has probably permanently altered the residual stress field. This means that a good check is to take the gauge to the maximum each way and be sure that it returns to zero each time. Provided it passes this simple test, it will probably be OK at lower torque values too.
Personally I think you only need to buy one low-ish rated torque wrench, provided you have the right extensions. I suppose I instinctively prefer a mechanical solution to what is, after all, a mechanical problem. Because of this, I have designed a set of torque-indicating extensions, each having a low modulus centre section and a simple adjustable pointer system. This would give much the same functionality as the electric gizmo, but having no ****ing batteries it'd be a lot more reliable and immune to the same problems.
Instead of a calibration certificate the Lidls one came with a warning label saying "NOT CALIBRATED". I initially returned it because of this, but then I read up on the tech and now I don't really mind. I don't think it needs to be calibrated in the same way as a spring-powered yuk device doescycle tramp wrote: ↑19 Sep 2024, 3:00pm ..that's nice, which engineering firm calibrated it for you?
As I understand it, 2% accuracy is fine for a torque wrench. 6% accuracy is fine. Even 50% accuracy is (usually) fine. Loads of people have tested these digital torque adaptors on youtube. I briefly watched one video where two adaptors of this type (costing £12 and £50, respectively) were tested and they remained extremely accurate (much better than 6%) at both ends of the range even after 1,000 cycles. That's much better than I need so I was happy. See here: https://www.youtube.com/watch?v=jsC4fzXNfxMaxel_knutt wrote: ↑19 Sep 2024, 3:40pmI can only wonder at what makes you think that the accuracy of electronic measuring instruments is limitless. The accuracy of the cheapest one I saw on Amazon is quoted as 2%, which is not bad if it can be relied upon, but the accuracy of my 1970s Norbar torque wrench was between 2% and 6% when I checked it in 2011. What accuracy to you want, and why?
I just realised I am guilty of using the term 'extension' ambiguously. In the first instance it means a relatively bulky (but perhaps no bulkier than anything else that drives sockets) length extensions for a low torque value wrench, turning it into a higher torque value wrench. However the 'extension set' I refer to later means 1/4", 3/8", 1/2" square drive extension bars, about 6" long. These could be rated at 0-10, 0-50, and 0-100 ft.lbs respectively. They will store flat, just like any other extension bars. If folding pointers are used, a small box ~1"x 6" x 4" might do for storage.
I have one of those, and I tested it by hanging weights. I'm an instrumentation professional.SprokenBroke wrote: ↑20 Sep 2024, 12:46am I don't know if this is any good but it's a neat looking thing. You could take it on tour.
https://www.amazon.co.uk/Venzo-2-10NM-B ... B00V4CQEGW
I bought one. Couldn't resist it. I read a bunch of reviews and some people had tested it. Most claimed that it's accurate. The pointer on mine is not quite at zero, looks like about 0.2Nm. Not a problem I don't think. It's so small you could definitely take it on tour if you were so inclined.Andy Stow wrote: ↑24 Sep 2024, 8:24pmI have one of those, and I tested it by hanging weights. I'm an instrumentation professional.SprokenBroke wrote: ↑20 Sep 2024, 12:46am I don't know if this is any good but it's a neat looking thing. You could take it on tour.
https://www.amazon.co.uk/Venzo-2-10NM-B ... B00V4CQEGW
It was accurate within its readability (better than ±1 N·m.)
My OCD would object to a 0.2Nm non-centering. Can you ask the seller to send you another one?SprokenBroke wrote: ↑24 Sep 2024, 8:52pmI bought one. Couldn't resist it. I read a bunch of reviews and some people had tested it. Most claimed that it's accurate. The pointer on mine is not quite at zero, looks like about 0.2Nm. Not a problem I don't think. It's so small you could definitely take it on tour if you were so inclined.Andy Stow wrote: ↑24 Sep 2024, 8:24pmI have one of those, and I tested it by hanging weights. I'm an instrumentation professional.SprokenBroke wrote: ↑20 Sep 2024, 12:46am I don't know if this is any good but it's a neat looking thing. You could take it on tour.
https://www.amazon.co.uk/Venzo-2-10NM-B ... B00V4CQEGW
It was accurate within its readability (better than ±1 N·m.)