72" wrench

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I've got to build a prototype wrench 72" long. The wrench end has to handle 800FT/LBS. From what I was told at 72" it will take about 125lbs of force to turn the other end. I was looking at using 1.25" OD .120 wall 4130 chromoly tubing. What I need to know is if the tubing will handle that much force without bending too much or breaking. Open to any ideas for the handle also (dif. types of tubing, gussets) The whole tool has to be under 15lbs so the handle is a big part of it. Thanks for any help. Airco Ac/Dc 300 HeliwelderMillerMatic 200 (stolen)Miller Maxstar 150STLMiller AEAD200LE (welding and generating power) Hobart MIG
Reply:800 ftlbs at 6 ft:800/6 = 133.33333333 lbs DUN dun DUN dun DUN dun DUN dun....You're going to need a bigger wrench!I would be looking at using a length of rectangular tubing.  See if this helps:http://www.steeltubeinstitute.org/pd..._table_bro.pdf- MondoMember, AWSLincoln ProMIG 140Lincoln AC TombstoneCraftsman Lathe 12 x 24 c1935Atlas MFC Horizontal MillCraftsman Commercial Lathe 12 x 36 c1970- - - I'll just keep on keepin' on.
Reply:Why when you can use a torque multiplier, and a human sized wrench?Disclaimer; "I am just an a$$hole welder, don't take it personally ."
Reply:Mondo, I was thinking the same thing. 84" would be better. Would square tube be any better for strength/weight?  Tozzi, you can't reach the nut with a normal sized wrench.Airco Ac/Dc 300 HeliwelderMillerMatic 200 (stolen)Miller Maxstar 150STLMiller AEAD200LE (welding and generating power) Hobart MIG
Reply:I'm sorry to hear you can't get a normal sized wench to reach your nuts... Sorry I couldn't resist. Someone had to say it.... .No government ever voluntarily reduces itself in size. Government programs, once launched, never disappear. Actually, a government bureau is the nearest thing to eternal life we'll ever see on this earth! Ronald Reagan
Reply:What you really need to know is how much deflection you can tolerate. Then go onto one of the beam calculator pages and start entering in data for for tubing sizes to find one that is tolerable. use the data table for cantalevered beams. Remember that rigidity is more a function of diameter than of wall thickness.  The other more simplerer way to do it is to go to the steel yard, pull out 8' of a 20' stick of tubing and put your weight on it and see how much it deflects, do this until you have found the right size.
Reply:Walker, that is what I will prob do. I have never had to use chromoly before so I don't know how much stiffer it is than mild steel. It is ok for the tube to bend a little, just don't want it to spring back if someone slips using the tool and get hit by it.Airco Ac/Dc 300 HeliwelderMillerMatic 200 (stolen)Miller Maxstar 150STLMiller AEAD200LE (welding and generating power) Hobart MIG
Reply:Originally Posted by SquirmyPugWalker, that is what I will prob do. I have never had to use chromoly before so I don't know how much stiffer it is than mild steel. It is ok for the tube to bend a little, just don't want it to spring back if someone slips using the tool and get hit by it.
Reply:Chromoly isn't any "stiffer" than regular mild steel.  It may resist permanent deflection a bit better, especially if it is heat treated.Definitely use square or rectangular tube, not round. Pound-for-pound, in a roughly equivalent section, square will be twice as "stiff" and over 50% stronger when loaded in the flat direction (not corner to corner)."USMCPOP" First-born son: KIA  Iraq 1/26/05Syncrowave 250 w/ Coolmate 3Dialarc 250, Idealarc 250SP-175 +Firepower TIG 160S (gave the TA 161 STL to the son)Lincwelder AC180C (1952)Victor & Smith O/A torchesMiller spot welder
Reply:Thanks guys. Fegenbush I'm just a welder, you need to dumb it down a bit for me  Oldendum, that helps alot. For this type of load is there any real advantage to using chromoly? After we get a prototype made it will be tested to see if the company thinks it is worth having it made. If they like it we will have an engineer design one for retail.Airco Ac/Dc 300 HeliwelderMillerMatic 200 (stolen)Miller Maxstar 150STLMiller AEAD200LE (welding and generating power) Hobart MIG
Reply:Under 15 lbs?  Hell, the head alone will chew up a 1/3 to 1/2 of that.  Just a guess, but I'd cut the head out of 1" plate and the handle out of maybe 1" x 3" 14 ga. tubing.My name's not Jim....
Reply:Yep the head won't be light, thats why I'm trying to find the lightest/strongest way to make a handle. The head has to work with 4" and 2" or 6" nuts, don't remember which. Has to be open end wrench because of chains holding the nuts. The company was thinking about using titanium, but we want to try steel/aluminum to see if we can make it work. We are ordering alot of solid fiberglass handles for another tool soon, going to see if we can get one at 6' to test that also.Airco Ac/Dc 300 HeliwelderMillerMatic 200 (stolen)Miller Maxstar 150STLMiller AEAD200LE (welding and generating power) Hobart MIG
Reply:I work on a lot of big equipment, and when it comes to tough ones like this, if possible I put a 3ft aluminum pipe wrench with a pipe extension, and I use a hi lo for premium torque I hate being bi-polar it's awsomeMy Heroes Have Always Been Cowboys
Reply:Mike I think they have been using big pipe wrenches with cheater bars. They want something lighter and simpler to use because they have to go under the part to put it on the nut and hold it in place. Company is big on safety.Airco Ac/Dc 300 HeliwelderMillerMatic 200 (stolen)Miller Maxstar 150STLMiller AEAD200LE (welding and generating power) Hobart MIG
Reply:Titanium is pretty light....$$$$$$$$$$$
Reply:Originally Posted by SquirmyPugThe whole tool has to be under 15lbs
Reply:Originally Posted by MikeGyverWhy...?you gunna get fired if it's 17?
Reply:Gosh, how I love the internet.. I'm a geeky engineer type.  I was trying to figure out a way to predict the amount of force required to bend 4130 round tube. This wrench problem as stated got me to thinking.. Its sorta the same problem.. how much force required to bend tube is sort of the same as how much strength required to prevent bending.   Anyway, I've built a super spreadsheet to do the calculations for me.  As the 4130 round tubing data (including weight and cost / foot) is readily available online from aircraftspruce.com, I went ahead and did the calculations for ALL of their material offerings.  They are reasonably priced, although you gotta add shipping prices to the mix...Most of the stuff fails... I used the criteria, at 800 ft-lbs of torque, 72" tube, and safety margin of 2:1 for yield strength.  Lightest material = 2.5" OD tubing, with 0.095" material thickness.  total cost for 6' of tube = $88.80 plus shipping, weight = 11.6 lbs.    I did NOT yet analyze the loads at hex bolt end of this thing.  Thats pretty thin material, and I suspect there could be problems attaching a cutout open wrench end.  At least you know this is the minimum, that in theory has the strength.  Displacement = 1.07" (remember your old Sears Craftsman bent beam torque wrench?)     Ouch. Still too heavy. Other things to look at: Titanium tube, Aluminum hollow rectangular extrusions, Carbon Fiber composites (don't ask me to calculate loads on that!)  Wood. Ever really reefed hard on a shovel with a long handle?  Yup, wood. If you want to go thicker, to better enable attaching your wrench cutout shape, then 2.5" OD, 1/8" nominal thickness, price = $71.82 (cheaper!) 6' tube weight = 18.3lbs, displacement = 0.88" Max stress = 18,841psiI haven't done the calculations (yet) for box sections.  Anybody know of a web site with easy to copy #'s?  (I can start with AircraftSpruce's offerings, but they don't have much..)And thanks for the opportunity to see my own problem (manual tube bending) from a different direction.  Squirmy Pug.. if you are serious about this one, I can do a complete analysis including CNC cutout for an open end wrench panel, send me a private message (PM).  I'm a registered Prof Engineer (as if that matters boo to anybody..)--zipUpdate for rectangular tubing.  None of the 4130 stuff aircraftspruce provides enough strength.  If you go to commonly available Hot rolled tubing, depending on material composition its a little different ball game.  1 x 2 x 0.12 will work in A513 (13.5 lbs), if you go to A36 or 1018 low carbon hot rolled, you would have to jump up to 1 x 3 x 0.12 to maintain that 2:1 safety margin for yield strength. ( 18.5 lbs)  It does get heavy this way..   I do think the rectangular tube is MUCH easier to manufacture into a viable wrench.  You'd do a wrench cutout that fits just right to the inside of the tube, drill a couple of holes for retaining bolts and move on.Last edited by zipzit; 11-17-2012 at 11:39 PM.
Reply:Originally Posted by FegenbushSince an actual, rational thought was presented here, I think I can assist.  All carbon steel has the same "stiffness" or modulus of elasticity (29,000 ksi).  Deflection will be controlled by this and the section properties of the beam.  If deflection is the controlling criteria and the material of construction is fixed, your design criteria is based on the section properties.
Reply:Other materials to help reduce the weight:  --Titanium (expensive, and seems to be only readily available with very thin material thicknesses)--Carbon fiber composites.  Definitely would work, but don't ask me to do the calculations.  Not easy to do.--Aluminum hollow tubing in rectangular extrusions.  --Wood.  Ever pry hard on a long handled shovel, or hey, pull hard on a wooden boat oar?  Yup, wood.  You could even make the handle hollow, use a clear grain matrix glue up with thickened epoxy.  ( Look up how they make a hollow wooden mast for a sailboat.  Its kinda cool.)If I can find the Modulus and yield strengths for this stuff (less the carbon fiber) I'll put it into the spreadsheet.
Reply:Wow I wasn't expecting a response with that much detail zipzit. We just want to get a working prototype before putting too much into it. After that I may send you a pm and we can have something better made. We need to check on the strength of the fiberglass before spending alot on other materials (fiberglass we use is 1.25" solid made by pultrusion usually 3'. Going to try to get a few 6').  Mike, we were told 15lbs so that is the goal. Also your last response helped alot. So chromoly will bend about the same amount but won't fail (permanent deformation/breaking) at the same pressure that mild steel will.Can't thank you guys enough. I've got welding down but still learning about everything else Airco Ac/Dc 300 HeliwelderMillerMatic 200 (stolen)Miller Maxstar 150STLMiller AEAD200LE (welding and generating power) Hobart MIG
Reply:It would be nice to really understand the requirements better....--When using this wrench is the operator forced to stand in an ackward position? Does the operator use one hand or two on this wrench in its critical operation? (i.e.  does tool balance matter,  should it be heavier at the wrench opening end?)--How really important is the weight of the wrench?  --How durable does the wrench have to be?  How often is it expected to be used?I used a HUGE safety margin for my initial analysis. Actually safety is the wrong word.. think of this as a tool durability margin.   (for my first shot I used stress calculated = 1/2 of yield strength)  If weight is really the driving factor,  we definitely could lighten up on the % durability margin.--But.. while we are there.. if the tool fails in mid use, is there a danger to people or property?  If we go light, the likely failure would be a bent tube handle (if working in metal...   or a loud snap/break if working in wood or composite.)   If this is the tool used as an emergency shut off for the sky is falling valve that wouldn't be a good thing.   --How much room to spin the wrench is available (in degrees of arc?  in distance the operators hand can travel at the end of a six foot wrench.?  Some materials bend easier than others.. They don't fail, they don't yield, they just bend easily.  Can the geography you are working in take that?  (I'm thinking an operator standing on tippy toe, with 6' wrench extended in one hand while jammed between wall and furnace with only 8" of movement possible...)  That's going to be hard with a fiberglass handle.. doggone things bend a lot before transfering energy.Two suggestions pop... --rectangular aluminum tube for handle, progressively drilled from handle end to wrench end to  minimize weight, but provide strength where required.  --Carbon fiber / fiberglass over a round / shaped foam tube.. (go find a custom surfboard builder for this...)I'll try to recalculate with a less generous durability factor, add a few more material data points then display results here.  give me a day or so.. (gotta help wifey with Turkey day shopping!  Its at our house this year.)  I really want to add in some wood calculations but I had no idea there were so many different types of wood (You can't just get the numbers for hickory.. you have to know which of the six types of hickory you have and you need to know the wood's humidity, etc...  eight types of red oak? huh? and Southern white pine is NOT a choice... you get seven different types of pine that I never heard of...) aaah.. but this is a welding forum and i digress.let's talk, zip.
Reply:Hang one of those geek engineers by his ankles while he holds a regular wrench, maybe he will flex on your 15 LB limit.  Maybe this needs to start over....Why do you need such a long wrench?  What are you trying to accomplish?
Reply:Zip, theres not alot of working room for the wrench (turning it) but it only needs to break the nut free. After that it is removed by hand. From the nut there it a pipe about elbow height and 60" away. l  o  l  is about what it would look like ( l=pipe, o=nut)Same on both sides of it. I don't think wood would be good for it because I'm sure it will be dropped/chipped. My dads idea is to use 1/2" aluminum 4" wide at the nut end and 2" at the handle end with another piece welded to it about like a T joint to keep it from bending the other way. Not sure if this almuinum would go the full 6' or if we would weld on a socket to use our 3' fiberglass handles. There are alot of options, just not sure what will work yet. Also don't feel like you have to do all this work, it would help alot but you have helped alot already Blackbart we need a long wrench because it needs to be able to aply alot of torque. Also, I don't think I can find an engineer that is under 15lbs and if I do..I'm sure he would break before getting the whole 800FtLbs out of him Airco Ac/Dc 300 HeliwelderMillerMatic 200 (stolen)Miller Maxstar 150STLMiller AEAD200LE (welding and generating power) Hobart MIG
Reply:make a tapered handle with a center web, wider at the head (like a I beam) working up to a round handle for the grip area,Originally Posted by Farmerboymake a tapered handle with a center web, wider at the head (like a I beam) working up to a round handle for the grip area,
Reply:Originally Posted by Farmerboymake a tapered handle with a center web, wider at the head (like a I beam) working up to a round handle for the grip area,
Reply:Originally Posted by weldermike I think we have a winner!
Reply:Originally Posted by WeandiviazibeGood afternoon. I sat for a long time after having a baby at home. Now, when my daughter grew up and I can go back to work, I realized that did not want to bring back to their old work - I am an economist. Thought long and realized that I wanted to become a hairdresser - I want to make people beautiful. Especially because I've always enjoyed doing hair and her friends at school and university, and now my daughter dress like that. A friend advises to go study in the International Training Centre "MAY". Says it's ideal: they teach special technique Pivot Point and just a year of training I can get a new profession. Also, as promised Center, in addition to the state diploma, I also get an international diploma, which is recognized in almost all countries of the world. Never do not know how to turn life - what if in a few years my family and I'm going out of the country. Personally, I am embarrassed by the relatively high cost of training, even though I am aware that the good can not be cheap. So I ask your opinion about the other centers - if anyone where he studied and to share personal experiences.
Reply:Originally Posted by SquirmyPug  Tozzi, you can't reach the nut with a normal sized wrench.
Reply:You can reach it but you can't be under the part when breaking the nut free. The wench sticks out  1' past a piece of pipe. It only needs to break the nut loose, after that the nut is removed by hand.Airco Ac/Dc 300 HeliwelderMillerMatic 200 (stolen)Miller Maxstar 150STLMiller AEAD200LE (welding and generating power) Hobart MIG
Reply:When we grab a cookie and the gallon of milk to take a break while contemplating this wrench build... let's remember that the completed 15lb wrench must weigh less than two gallons of milk. I think that's asking a lot of an inexpensive shop-built wrench that has to take 800 ft lbs of torque and be 6' long.It's gonna be tough to complete the magic triangle of: cheap enough; strong enough; light enough.With all the concern for wrench weight and hoping to have any schoolgirl able to loosen the nut, I wonder if this shouldn't be loosened and tightened with a "slugger wrench," or else a wrench that's pushed by a Port-A-Power. A plus for the hydraulic pusher is that it would allow for precision gauged tightening. A geared actuator would be better still. To me, it seems like the man/woman/crew who can't easily "manhandle" a 50lb (give or take) wrench set-up probably has no business dealing with 800 ft lb manually turned hardware.But it's not my nuclear reactor that needs the water valve opened  cheap and easy, so I'll just shut up. Good LuckLast edited by denrep; 11-19-2012 at 01:18 PM.
Reply:Denrep it doesn't have to be cheap. But for the prototype we want something that will work and not cost too much because they may decide to go with something else. They don't want guys to have to crawl under the part and lift and hold 50lbs to break the nut free. The nut will be torqued back on after the part has been moved to another location.Airco Ac/Dc 300 HeliwelderMillerMatic 200 (stolen)Miller Maxstar 150STLMiller AEAD200LE (welding and generating power) Hobart MIG
Reply:Make it 2 piece. The head can be fitted onto the nut and the handle placed on the head.Tim Beeker.
Reply:Originally Posted by SquirmyPug. . .But for the prototype we want something that will work and not cost too much because they may decide to go with something else. They don't want guys to have to crawl under the part and lift and hold 50lbs to break the nut free. The nut will be torqued back on after the part has been moved to another location.
Reply:Why does the wrench have to be so long? Make it so a pipe slips over it for more leverage.Welding/Fab Pics: www.UtahWeld.com
Reply:double
Reply:I've used 1 1/4 inch pipe of similar length as a reaction bar with a torque multiplier at 1800 ftlbs.  It handled it fine though it does take a nice bow to it when you load it up.  I also have a 60 inch Ridgid pipe wrench with the handle bused off of it, not really sure how that happened.
Reply:The only wrench less than 15lbs that can do 800+ftlbs:Trouble is, the hammer may weigh more than 15lbs.