john.r.davies Posted May 28, 2022 Report Share Posted May 28, 2022 I love to browse online auctions, and one came up with some small-force torque wrenches. I bid, and won! It was 'only' £12, although P&P was another £10 (!) and when I got it, I realised, this is a VERY small-force torque wrench, up to 35 pound-force INCHES, 4Nm or 3 lbs-ft. The whole device is 10" long. Any watchmakers like to buy it? But it's a nice piece of kit; unless someone else really wants it, it's a keeper. Tested on the bench it slightly overreads, like 2 lbf-ins. There's a large screw, right through the body, visible above at 11 o'clock from the dial. is that the screw that compresses the spring that applies the torque? Would adjusting that recalibrate it? John Quote Link to post Share on other sites
Ransomes256 Posted May 28, 2022 Report Share Posted May 28, 2022 John, This type of torque meter is really meant as a quality control tool and is designed for over checking installed torques. The tell tail pointer should be set to zero and the torque slowly applied to the fastener. When the fastener moves and the torque drops the tell tail gives the maximum reached. They can be used as torque wrench but at higher torques are very difficult to read and control. Yes they can be calibrated against a master gauge against various values. Neil Quote Link to post Share on other sites
BlueTR3A-5EKT Posted May 28, 2022 Report Share Posted May 28, 2022 Agreed with Neil it is best suited to checking torques rather that applying them. Useful to know rotating resistance of an assembled engine etc. I have the big brother of that which reads in Ft lbs. Quote Link to post Share on other sites
john.r.davies Posted May 28, 2022 Author Report Share Posted May 28, 2022 Thank you, Neil, and Blue! But I don't understand how this may be used to check applied torque, when that is much, much greater than the rating of the tool. How could it be used to check a fastener at, say, 30Lbs-ft? Please explain further! It's not obvious from my photo, but the drive bar is 1/4" square, so it's not designed for large torques. John Quote Link to post Share on other sites
Lebro Posted May 28, 2022 Report Share Posted May 28, 2022 Quite right, it is not designed for car use at all ! We used to have small torque wrenches to tighten electrical RF connectors (SMA etc), as too much torque would damage them, & too little could allow then to come undone. Your device could be used to test the torque applied, or to apply the torque. Bob Quote Link to post Share on other sites
Ransomes256 Posted May 28, 2022 Report Share Posted May 28, 2022 John, You have to select the correct wrench with the torque range of the fastener being checked. Neil Quote Link to post Share on other sites
john.r.davies Posted May 28, 2022 Author Report Share Posted May 28, 2022 But could be used on the car, Bob, if there were bolts that were so lightly tightened? I have to admit, I thought a TW to do up the lighter bolts, like sump bolts, would be nice, and misread the auction blurb! As you say, Neil, the right range of TW is needed, and I read the description as up to 35lbs-ft, which would be about the right range. Doh! John Quote Link to post Share on other sites
BlueTR3A-5EKT Posted May 28, 2022 Report Share Posted May 28, 2022 Agreed with Neil it is best suited to checking torques rather that applying them. Useful to know rotating resistance of an assembled engine etc. I have the big brother of that which reads in Ft lbs. In a previous life I worked rebuilding aeroplane engines. The Rolls Royce turbine engine casings of one type of engine were held together by dozens of 1/4” bsf fasteners. They were all tightened to 75 inch lbs using preset torque wrenches. All those torque wrenches were checked and calibrated every 7 days by the standards department Quote Link to post Share on other sites
michaelfinnis Posted May 30, 2022 Report Share Posted May 30, 2022 On 5/28/2022 at 7:27 PM, Ransomes256 said: John, You have to select the correct wrench with the torque range of the fastener being checked. Neil Exactly. We use torque wrenches just like this in the aircraft industry for things like electrical terminal stud connections. It used for applying torque the same as any other torque wrench. Not much use on cars though. Mike Quote Link to post Share on other sites
john.r.davies Posted May 30, 2022 Author Report Share Posted May 30, 2022 On 5/28/2022 at 8:10 PM, BlueTR3A-5EKT said: In a previous life I worked rebuilding aeroplane engines. The Rolls Royce turbine engine casings of one type of engine were held together by dozens of 1/4” bsf fasteners. They were all tightened to 75 inch lbs using preset torque wrenches. All those torque wrenches were checked and calibrated every 7 days by the standards department Do you know how they are adjusted, Peter? Be nice to have it accurate, even if too low in range for anything I'd use it for. As I originally asked, there is a large screw that looks as though it might do so, but it has a special nut on it, slotted, so that the shank divides the slot into to. I'd have to make a special tool to grip it. John Quote Link to post Share on other sites
Lebro Posted May 30, 2022 Report Share Posted May 30, 2022 You used a separate gauge to indicate the torque being applied. Bob Quote Link to post Share on other sites
Charlie D Posted May 30, 2022 Report Share Posted May 30, 2022 1 hour ago, Lebro said: You used a separate gauge to indicate the torque being applied. But how was that gauge calibrated? Charlie Quote Link to post Share on other sites
BlueTR3A-5EKT Posted May 30, 2022 Report Share Posted May 30, 2022 8 minutes ago, Charlie D said: But how was that gauge calibrated? Charlie Known weights on a known length of bar Quote Link to post Share on other sites
Charlie D Posted May 30, 2022 Report Share Posted May 30, 2022 Excellent answer to a silly question. Quote Link to post Share on other sites
john.r.davies Posted May 30, 2022 Author Report Share Posted May 30, 2022 This is all getting a bit chicken and egg! Yes, suspending a known weight, a measured distance from the axis, is a very accurate way of checking a TW. That's how I checked the above tool. I've described before doing the same for an ordinary TW, and was told that I should allow for the weight of the handle. In that case the handle weight was trivial, but here it was significant! So I allowed for it. If anyone wants to get silly about 'how do you know the weight of the test mass', I suggest bags of sugar/flour etc that are sold by weight. They MUST be a certain weight by statute. Can no one tell me how to adjust the tool? John Quote Link to post Share on other sites
BlueTR3A-5EKT Posted May 30, 2022 Report Share Posted May 30, 2022 (edited) 1 hour ago, john.r.davies said: This is all getting a bit chicken and egg! Yes, suspending a known weight, a measured distance from the axis, is a very accurate way of checking a TW. That's how I checked the above tool. I've described before doing the same for an ordinary TW, and was told that I should allow for the weight of the handle. In that case the handle weight was trivial, but here it was significant! So I allowed for it. If anyone wants to get silly about 'how do you know the weight of the test mass', I suggest bags of sugar/flour etc that are sold by weight. They MUST be a certain weight by statute. Can no one tell me how to adjust the tool? John Drift time…… Thankfully our leader has decreed lbs an ozs, feet and inches will be back any time soon. So your torque wrench purchase will be bang up to date Shrewd purchase I’d say. Is that insider trading? You have to wonder if they have warned the standards office. Edited May 30, 2022 by BlueTR3A-5EKT Quote Link to post Share on other sites
Ian Vincent Posted May 31, 2022 Report Share Posted May 31, 2022 14 hours ago, BlueTR3A-5EKT said: Drift time…… Thankfully our leader has decreed lbs an ozs, feet and inches will be back any time soon. So your torque wrench purchase will be bang up to date Shrewd purchase I’d say. Is that insider trading? You have to wonder if they have warned the standards office. Total piece of nostalgic nonsense by our leader. It’s only old fogies like us who understand Imperial measurements. My kids (both in their forties) wouldn’t know a lb if it fell on them. They’ve been brought up in a metric society. Rgds Ian Quote Link to post Share on other sites
john.r.davies Posted May 31, 2022 Author Report Share Posted May 31, 2022 Grabbing the steering wheel and wrenching us back onto the road.... Obviously, there are people here who used these microTWs in real life. Can no one tell me if that big screw is an adjuster? John Quote Link to post Share on other sites
Ian Vincent Posted May 31, 2022 Report Share Posted May 31, 2022 47 minutes ago, john.r.davies said: Grabbing the steering wheel and wrenching us back onto the road.... Nothing wrong with a bit of thread drift. Quote Link to post Share on other sites
John Bracher Posted May 31, 2022 Report Share Posted May 31, 2022 Hi John I have asked our workshop manager if the people we use to calibrate our measuring instruments can calibrate such a wrench? If they can, I will try to find out how. Quote Link to post Share on other sites
Charlie D Posted May 31, 2022 Report Share Posted May 31, 2022 John, Why not just twiddle the screw and see what happens. What could go wrong? Looking at the pictures, it would seem that the dial is on the wrong side. Surely it means that you could only use it for side pointing nuts or downward pointing nuts Even then if the thing you were working on was big it may well obscure the dial. Charlie Quote Link to post Share on other sites
john.r.davies Posted May 31, 2022 Author Report Share Posted May 31, 2022 Indeed, Charlie! But I'll need to make up/adapt a tool to turn it. There are drive bars on both sides. John Quote Link to post Share on other sites
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