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The argument is over "How A Torque Wrench Functions." |
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The disscusion
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Safety first. |
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Good Guys
Hey Allan you will always be one of the Good Guys in my book!
Keep developing items like this, dont let this little side show stop you coming up with good engineering solutions. I think your nose job is great and I might be in a position to order one next month, hopefully Peter will have got his through the UK system by then. |
x .8 ?? debate
The debate here is the accuracy of using the x .80 conversion for getting the desired fastener torque when using a 3 inch torque extension regardless of the torque wrench effective handle length.
Any debate on where to grip the torque wrench or adding extensions to the handle has little merit. The wrenches are calibrated with the handle pulled at a particular spot and videos show that final torque can be effected by hand position. Using a different technique would require verification to show accuracy. Just because it clicks or indicates a value does not mean that the indicated value is the same as the fastener actual torque value without verification. The industry standard is to use the formula in FAA AC 43.13-1B (chapter 7), instructions that come with the torque wrench or the formula posted in this thread. They are all the same. The result of the formula is different for different torque wrench effective handle lengths. When using a 3 inch extension the .8 formula only works with a 12 inch effective handle length. I have a digital Snap-On 1/2 drive torque wrench with an effective handle length of 22.18 inches (total handle length, center of square to handle end, is 25.375 inches). Using the 43.13 formula when torquing a Harzell prop to 65ft/lb the S-O wrench would require a 57.25 ft/lb indicated setting/reading when using a 3 inch torque extension. If the .8 formula was used with the S-O wrench, the indicated wrench setting/reading would be 52 ft/lb (65 x .8). When taking the 43.13 formula and converting the indicated 52 ft/lb (from the .8 formula) back to the actual torque at the fastener the result is 59.03 ft/lbs. If the widely accepted formula is correct, the fastener would be under torqued by almost 10%. Using a 60 ft/lb desired torque (the minimum Hartzell torque value) one would only get a fastener torque of 54.49 ft/lb using the S-O wrench, 3 inch extension, .8 multiple for the desired torque and running the numbers backwards with the industry used formula. 5.51 ft/lb below the recommended minimum torque. There is actually more going on here than simply adding a longer arm to get leverage. The torque wrench is only measuring the twisting force centered on the drive hole in the torque extention. The second force is the pressure neccessary to move the torque extension in an arc centered on the torque extension pivot point. (post #296) The 43.13 formula takes this all in to consideration. I like Allan's tool and may purchase one. I am still waiting for his video and would hope there are torque wrenches much longer than 12 inches used in the comparison. George RV8 |
Coming video!!!!!!!
I set up and shot some video tonight and need to do a little editing (to long). Should post in a day or so. Regards all, Allan:rolleyes:
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Those exclamation marks from Allan look awfully enthusiastic...
Erich |
Gifts!
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if you can find it, snap-on form SS428A-3A called "Bolts, Tension and Torque"
16 pages of answers. or form SB565A titled "Torque Problems" or SS1276 called "threaded fasteners & torque" if you can get them. The formula that we used for extensions and adaptors. Lever length of the wrench is extended reading correction required! Calculation is requiredto find new reading (NR) NR = L X T / L + E where T is torque value required L = length of torque wr from hand position to center of sq drive E= extension length from center of sq to center of hex. NR= dial numeral representing torque value required formula are tough in a post but I hope you get the idea. |
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Thanks, Bob K. |
I answered this question from Mike Starkey in another thread on this debate:
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The nut will see absolutely no torque at all.Think about it or try it out to prove to yourself that it's true. I think this proves the correction multipler cannot be a constant. Hope that helps. -- Stephen |
90 degrees
For the love of mary, put the thing on 90 degrees and be done with it! Or calibrate your elbow... seriously. Does anybody really torque spark plugs, an 3 bolts, brake backing plates or mag attach nuts?
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I torque spark plugs every time. One stripped thread in the cylinder isn't worth it to me. Without a torque wrench, I tend to over-torque stuff, especially AN-3 stuff.
I really have to watch it!........ :o |
Sorry to do this, but . . .
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So . . . Mike's pure torque of 100 will result be resisted by an equal torque at the nut. There are no force couples involved. the distance is not relevant since there is no force couple involved. OK, all ready to pull your hair out now? Think about it . . . if you applied a pure torque to that wrench and it was not attached, what would happen - it would spin, right? So the reaction at the nut can NOT be zero and the real answer is it is equal to that applied. For the extension - use the FAA and torque wrench book formula. Why? Lets say the FAA is correct - the factor is not fixed at 0.8 . But I use the 0.8 anyway. The prop torque needs 60-70 ft-lb of torque. I usually use the middle number since i don't know which way my tool may be inaccurate. So let's use 65 ft-lb. If I use a 16.5 inch wrench ( my real number) and using the .8 factor, I will be actually 6.7% low, according to the FAA formula. What if my click wrench is 4% low? Then I am 10.7% low now, or only 58 ft-lb of real torque on the nut. That is 2 ft-lb below the low end of the range. Is that enough to worry? I don't know, so I will be using what my engineering training, experience, and the FAA formula tells me. |
It is after midnight...
I just had to see what all the huboob was about and clicked on this thread. I read every post to page 11. I said to my aching brain...let's skip to the last page and there I will find out if the length really does matter. Okay, I can sleep tonight since I have been flying behind my prop that was torqued with a 90 deg adapter. We used the same formula that is in AC43.13 in the military. I would hate to have to go back and recheck torques from 23 years ago. I am going to bed, my calibrated elbow is hurting too.
Now I figured out why Mike Starkey was recommending to a new builder "torque wrench how-to lessons" before starting his -10 emp. I was wondering what kind of crazy recommendation was that.:D |
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Found a nice online calculator
It even (correctly) takes into account the angle-off of the adapter.
http://www.cncexpo.com/TorqueAdapter.aspx Try putting an angle of 180 degrees in, see what happens. You can change the length to see the results as well. |
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-- Stephen |
Both could be right! Advanced Statics....
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In case 1, you do your best to hold the impact driver still. In doing so, you provide a reaction force that counters the wrench interaction on the nut. You get a force couple that cancels the moment, with no torque on the nut. In case 2, you do not resist the motion of the impact wrench, only its rotation. The wrench will try to orbit the nut, and in doing so, transmit the pure torque to it with no force couple. This assumes it does not orbit so fast that centrifugal force throws it off the nut though! :rolleyes: |
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But when attached to the nut, it would apply ONLY a 90-degree side-load on the nut, and ZERO turning force. No torque would be applied to the nut. In order to twist the nut with torque, the square-drive end of the adapter has to move sideways through an arc, which the electric motor with a slip-clutch can not provide. EDIT: This was posted before I saw Steve Smith's post. I am NOT an aero engineer!!! YMMV. Do your own testing. My .02, etc. :rolleyes: |
Large order
Wrench Order
-------------------------------------------------------------------------------- ...When I came in today I received a purchase order from one of the largest propeller manufacturers in the world for 250 of our tools. They requested that we stamp into the tool the multiplier < TRQ X .8 > So their customers will use it correctly and avoid any confusion. ...The purchasing agent that I spoke to said they are having quite the laughing session throughout their facility over this. He informed me that they actually have one of the on line calculators posted for people to use. He said in their instructions is that popular diagram that keeps popping up, they never dreamed anyone would be so misinformed as to not understand that the L dimension is always 12" with all ft lb tools. I'm Happy Today! Allan __________________ Allan Nimmo AntiSplatAero.com Innovative Aircraft Products Info@AntiSplatAero.com Southern California (KREI) RV-9A / Extra-300 Great! Which Prop manufacturer? |
Allan said:"The purchasing agent that I spoke to said they are having quite the laughing session throughout their facility over this. He informed me that they actually have one of the on line calculators posted for people to use. He said in their instructions is that popular diagram that keeps popping up, they never dreamed anyone would be so misinformed as to not understand that the L dimension is always 12" with all ft lb tools."
I have quite the opposite impression when I look at all the manuals, the AC and online calculators. Laugh all you want, but I don't know how anyone could possibly think anything other than to use the actual length of their particular torque wench. The meaning of L is explicitly shown in the diagrams. I haven't seen ANY documentation for the use of torque wrenches that says that L is always 12 with ft lb torque wrenches. Either Allan and his friendly purchasing agent are very wrong, or all the existing documentation is badly misleading. I await efforts by others to present video demonstrations. Erich |
Handle length does matter
Allan,
While I have great appreciation for the products you are bringing to the RV community and have already purchased the Nose Job and have your prop wrench on order, I humbly submit that I believe you are incorrect in your statement that a .8 multiplier can be applied regardless of the handle length of the torque wrench. I have taken some time to demonstrate the mathematics in this analysis of the forces and moments involved. I welcome critical review of this analysis and hope it results in improved safety for all...a sentiment you expressed concern for towards the end of your video. As an aside, I recently viewed your video and while I would agree that this is a first-year engineering student math, it's not 5th grade math. ;) All the best, |
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So...............is the SnapOn gauge incorrect? Are the torque wrenches incorrect? Is your mathematics incorrect? Is the time honored mathematics incorrect... |
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After reading your question about which math is right, I looked up what AC43.13-1B has to say about this. I had intentionally not looked it up until after doing the math myself from scratch. Turns out they have the exact same formula (using different variable names) as I do. Their formula: T*L/(L+E)=Y Where: T is actual torque on the bolt Y is apparent (indicated) torque (i.e. what you set the torque wrench to) L is effective length lever E is effective length extension Rearranging their formula to show the same ratio as my analysis gives: T/Y = (L+E)/L ==> T/Y = 1+E/L Which is identical to what I came up with. Hrm...maybe all those of years of schoolin' paid off after all? ;) |
PLEASE LOOK AT THIS POST!!!!!!!!
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-Jim |
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Allan, your credibility just went up 10 fold. It sucks when you're wrong but it takes a big man to admit it. |
Allan must be crazy... like a fox!
The objective of guerilla marketing is to get noticed so you can sell more product. I can unequivocally state that Allan is the biggest guerilla on VAF! Well done! |
Thanks for the cross reference
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P.S. It might be a good idea to remove those two videos from your website. :) |
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1. The retraction linked above is a post to a thread in Classified; so the whole thread is scheduled to disappear in 30 days. That being the case, we have here a situation like many on the Internet where dangerous misinformation outlasts its debunking. Hello. I have been asked by the owner of the VAF site (Doug Reeves) to help enforce the forum posting rules. I deleted your recent VAF post about _____Questioning Member's Credentials_____ for the following reason(s): _X_ Civility / Tone __ Not RV-related __ Commercial promotion by non-advertiser __ Mod/Policy bashing __ Politics / Government __ Illegal video clip __ eBay / Barnstormers / etc. The posting rules are explained in greater detail at: www.vansairforce.net/rules.htm If you feel the need, please direct comments regarding this to the owner of the site (Doug Reeves). His contact info can be found at: www.DeltaRomeo.com Thank you. Thanks, Bob K. |
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You seem to be suggesting that Allan Nimmo deliberately provided misleading and unsafe information about his product, knowingly tarnished his credentials, produced a deliberately falsified video of his product being tested, and willingly subjugated himself to a very public humiliation.....all to gain some exposure in order to sell a few low cost prop spanners. :confused: As far as conspiracy theories goes this is right up there with the Apollo moon landings being faked in a studio on earth. :cool: No doubt the truth of the matter is far, far simpler. |
The original video is still up
The original video that introduced the wrench and made the original statement about the 80% that started the whole discussion is still up on the antisplataero web site.
Allan, wondering if you might edit that? |
Done!
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PIREP
I got to use one of Allan's prop wrench's yesterday to take the Hartzell off my engine and I give it a big thumb's up. It cut the time to remove the prop at least in half and I am now looking forward to using it to re-install the prop in a couple weeks. Thanks for the great products you have developed and made available to us at such a reasonable cost Allan!
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