Wrench with non-parallel jaws
The jaws on this wrench are not parallel:
http://home.comcast.net/~bobengelhardt/wrench.jpg Specifically, the face of the movable jaw is perpendicular to the "ways", but the fixed face is not. But they aren't sprung or worn that way. It seems that it was made like that. But why? Just plain poor quality? But that's *really* bad. It's an old wrench, not Chiwandian. It says drop forged, if that helps. Bob |
Wrench with non-parallel jaws
The angle of the fixed jaw looks square to the rack slider. The
moveable jaw is definitly a few ° off, and it's not deformed that way from stress. The quality of machining and finish on the tool (discounting wear and tear) suggests poor factory work as the culprit. JR Dweller in the cellar On Tue, 10 Jun 2008 21:03:20 -0400, Bob Engelhardt wrote: The jaws on this wrench are not parallel: http://home.comcast.net/~bobengelhardt/wrench.jpg Specifically, the face of the movable jaw is perpendicular to the "ways", but the fixed face is not. But they aren't sprung or worn that way. It seems that it was made like that. But why? Just plain poor quality? But that's *really* bad. It's an old wrench, not Chiwandian. It says drop forged, if that helps. Bob -------------------------------------------------------------- Home Page: http://www.seanet.com/~jasonrnorth If you're not the lead dog, the view never changes Doubt yourself, and the real world will eat you alive The world doesn't revolve around you, it revolves around me No skeletons in the closet; just decomposing corpses -------------------------------------------------------------- Dependence is Vulnerability: -------------------------------------------------------------- "Open the Pod Bay Doors please, Hal" "I'm sorry, Dave, I'm afraid I can't do that.." |
Wrench with non-parallel jaws
Interesting wrench.
The width of the open jaws is very wide - I suspect the wrench is a jam on wrench. Does look odd. Martin Martin H. Eastburn @ home at Lions' Lair with our computer lionslair at consolidated dot net TSRA, Endowed; NRA LOH & Patron Member, Golden Eagle, Patriot's Medal. NRA Second Amendment Task Force Charter Founder IHMSA and NRA Metallic Silhouette maker & member. http://lufkinced.com/ Bob Engelhardt wrote: The jaws on this wrench are not parallel: http://home.comcast.net/~bobengelhardt/wrench.jpg Specifically, the face of the movable jaw is perpendicular to the "ways", but the fixed face is not. But they aren't sprung or worn that way. It seems that it was made like that. But why? Just plain poor quality? But that's *really* bad. It's an old wrench, not Chiwandian. It says drop forged, if that helps. Bob ----== Posted via Pronews.Com - Unlimited-Unrestricted-Secure Usenet News==---- http://www.pronews.com The #1 Newsgroup Service in the World! 100,000 Newsgroups ---= - Total Privacy via Encryption =--- |
Wrench with non-parallel jaws
Bob,
My guess is that it is a quality control escapee; either that or it has been abused at one time or another. I cannot imagine one like that being purpose-built. Are you SURE that that is the original jaw?? Flash "Bob Engelhardt" wrote in message ... The jaws on this wrench are not parallel: http://home.comcast.net/~bobengelhardt/wrench.jpg Specifically, the face of the movable jaw is perpendicular to the "ways", but the fixed face is not. But they aren't sprung or worn that way. It seems that it was made like that. But why? Just plain poor quality? But that's *really* bad. It's an old wrench, not Chiwandian. It says drop forged, if that helps. Bob |
Wrench with non-parallel jaws
"Bob Engelhardt" wrote in message ... The jaws on this wrench are not parallel: http://home.comcast.net/~bobengelhardt/wrench.jpg Specifically, the face of the movable jaw is perpendicular to the "ways", but the fixed face is not. But they aren't sprung or worn that way. It seems that it was made like that. But why? Just plain poor quality? But that's *really* bad. It's an old wrench, not Chiwandian. It says drop forged, if that helps. Bob I think it was just not a very precise wrench. I have seen this type of thing in very old tools. I imagine that when it was made its fit was plenty good enough to turn the big square nuts in use at the time and its strength might have made it a "quality" tool in spite of its imprecision. Don Young |
Wrench with non-parallel jaws
Bob Engelhardt writes:
The jaws on this wrench are not parallel: http://home.comcast.net/~bobengelhardt/wrench.jpg Specifically, the face of the movable jaw is perpendicular to the "ways", but the fixed face is not. But they aren't sprung or worn that way. It seems that it was made like that. But why? Just plain poor quality? But that's *really* bad. It's an old wrench, not Chiwandian. It says drop forged, if that helps. It surely looks like one of the lowest quality tools I've seen -- the imperfections on just about every surface border on bizarre. |
Wrench with non-parallel jaws
"Joe Pfeiffer" wrote in message ... Bob Engelhardt writes: The jaws on this wrench are not parallel: http://home.comcast.net/~bobengelhardt/wrench.jpg Specifically, the face of the movable jaw is perpendicular to the "ways", but the fixed face is not. But they aren't sprung or worn that way. It seems that it was made like that. But why? Just plain poor quality? But that's *really* bad. It's an old wrench, not Chiwandian. It says drop forged, if that helps. why do you assume that the jaws were NOT sprung by some gross overload? ** Posted from http://www.teranews.com ** |
Wrench with non-parallel jaws
"Bob Engelhardt" wrote in message ... The jaws on this wrench are not parallel: http://home.comcast.net/~bobengelhardt/wrench.jpg Specifically, the face of the movable jaw is perpendicular to the "ways", but the fixed face is not. But they aren't sprung or worn that way. It seems that it was made like that. But why? Just plain poor quality? But that's *really* bad. It's an old wrench, not Chiwandian. It says drop forged, if that helps. Bob The wrench looks so old that I would think it was made during a time when metal and craftsmanship were higher than what they are today. But that being said, they did make cheap crappy wrenches way back when, too. How long is the wrench? If it's long, there's more of a chance it's been overtorqued. Or it could have been bad from the get go, but that would not explain why it got used for that long a period of time. Puzzling. Steve |
Wrench with non-parallel jaws
"Bob Engelhardt" wrote in message ... The jaws on this wrench are not parallel: http://home.comcast.net/~bobengelhardt/wrench.jpg Specifically, the face of the movable jaw is perpendicular to the "ways", but the fixed face is not. But they aren't sprung or worn that way. It seems that it was made like that. But why? Just plain poor quality? But that's *really* bad. It's an old wrench, not Chiwandian. It says drop forged, if that helps. Bob Another thought ........ that slider is pretty long, indicating that it could be used for larger heads, hence more chance of tweaking. Steve |
Wrench with non-parallel jaws
On Tue, 10 Jun 2008 21:03:20 -0400, with neither quill nor qualm, Bob
Engelhardt quickly quoth: The jaws on this wrench are not parallel: http://home.comcast.net/~bobengelhardt/wrench.jpg Specifically, the face of the movable jaw is perpendicular to the "ways", but the fixed face is not. But they aren't sprung or worn that way. It seems that it was made like that. But why? Just plain poor quality? But that's *really* bad. It's an old wrench, not Chiwandian. It says drop forged, if that helps. Yeah, it's likely that they _are_ sprung, Bob. Look for pipe marks on the handle length. It was likely 4-6' long. ;) -- Besides the noble art of getting things done, there is a nobler art of leaving things undone. The wisdom of life consists in the elimination of nonessentials. -- Lin Yutang |
Wrench with non-parallel jaws
Don Young wrote: "Bob Engelhardt" wrote in message ... The jaws on this wrench are not parallel: http://home.comcast.net/~bobengelhardt/wrench.jpg Specifically, the face of the movable jaw is perpendicular to the "ways", but the fixed face is not. But they aren't sprung or worn that way. It seems that it was made like that. But why? Just plain poor quality? But that's *really* bad. It's an old wrench, not Chiwandian. It says drop forged, if that helps. Bob I think it was just not a very precise wrench. I have seen this type of thing in very old tools. I imagine that when it was made its fit was plenty good enough to turn the big square nuts in use at the time and its strength might have made it a "quality" tool in spite of its imprecision. Don Young Looks just like the wrenches you can buy today brand new from Horrible Fright... I refer to them as 'self adjusting slip wrenches' Carla One day, a man came home and was greeted by his wife dressed in a very sexy nightie. "Tie me up," she purred, "and you can do anything you want." So he tied her up and went golfing. |
Wrench with non-parallel jaws
"Bob Engelhardt" wrote: (clip) the face of the movable jaw is perpendicular to the "ways", but the fixed face is not.(clip) ^^^^^^^^^^^^^^^^^^^ Can you remove the movable jaw and measure the angle between the face and the "tang?" When you overlead this type of wrench, that's the most likely place for it to bend. I realize that is in conflict with your statement that the movable jaw is 90 degrees to the "ways," but it is still worth checking. I disagree with those who think it may have been made that way on purpose. That would be like building a car with a flat tire G. |
Wrench with non-parallel jaws
My suspicion is that this wrench has been abused in the past
and then had the jaws ground or filed freehand in an attempt to fix it. Look at the curve at the start of the fixed jaw and the sharp 90 degree corner of the movable jaw. If it had been manufactured that way, it would never have closed completely. I have a ten inch long or there abouts monkey wrench that I have used a three or four foot pipe on that looks very similar except for the fact that yours could never have closed tight. Also, this may have been manufactured as part of a line that is mostly hand made where each movable jaw is fitted to the individual wrench that it was sold with. If a person had two of them, it would be easy to assemble them with mismatched parts. Ron Bob Engelhardt wrote: The jaws on this wrench are not parallel: http://home.comcast.net/~bobengelhardt/wrench.jpg Specifically, the face of the movable jaw is perpendicular to the "ways", but the fixed face is not. But they aren't sprung or worn that way. It seems that it was made like that. But why? Just plain poor quality? But that's *really* bad. It's an old wrench, not Chiwandian. It says drop forged, if that helps. Bob |
Wrench with non-parallel jaws
Thanks for all the comments - some interesting and likely ideas. The
bottom line is that I shouldn't let myself get distracted with stuff like that. Toss it & forget it. Thanks again, Bob |
Wrench with non-parallel jaws
On Wed, 11 Jun 2008 20:51:26 -0400, Bob Engelhardt
wrote: Thanks for all the comments - some interesting and likely ideas. The bottom line is that I shouldn't let myself get distracted with stuff like that. Toss it & forget it. Make sure it isn't worth something before you toss it. http://www.wrenchingnews.com/ervin-a...8/catalog.html -- Ned Simmons |
Wrench with non-parallel jaws
Ned Simmons wrote:
Make sure it isn't worth something before you toss it. ... Here's one exactly like it, sold for $4: http://cgi.ebay.com/_W0QQitemZ330241...QQcmdZViewItem |
Wrench with non-parallel jaws
I bet Steve has the thought.
If a wrench is used 'backwards' - the weak side might break. So the jaw was taken from a larger wrench - the long thread bar hangs out... Maybe the larger wrench had a broken handle from a pipe assist! Martin Martin H. Eastburn @ home at Lions' Lair with our computer lionslair at consolidated dot net TSRA, Endowed; NRA LOH & Patron Member, Golden Eagle, Patriot's Medal. NRA Second Amendment Task Force Charter Founder IHMSA and NRA Metallic Silhouette maker & member. http://lufkinced.com/ SteveB wrote: "Bob Engelhardt" wrote in message ... The jaws on this wrench are not parallel: http://home.comcast.net/~bobengelhardt/wrench.jpg Specifically, the face of the movable jaw is perpendicular to the "ways", but the fixed face is not. But they aren't sprung or worn that way. It seems that it was made like that. But why? Just plain poor quality? But that's *really* bad. It's an old wrench, not Chiwandian. It says drop forged, if that helps. Bob Another thought ........ that slider is pretty long, indicating that it could be used for larger heads, hence more chance of tweaking. Steve ----== Posted via Pronews.Com - Unlimited-Unrestricted-Secure Usenet News==---- http://www.pronews.com The #1 Newsgroup Service in the World! 100,000 Newsgroups ---= - Total Privacy via Encryption =--- |
Wrench with non-parallel jaws
On Jun 11, 11:04*pm, "Martin H. Eastburn"
wrote: If a wrench is used 'backwards' - the weak side might break. So the jaw was taken from a larger wrench - the long thread bar hangs out.... Maybe the larger wrench had a broken handle from a pipe assist! Martin - Show quoted text - I'll bite, Martin. Which way do most people consider is backwards, and which correct? John Martin |
Wrench with non-parallel jaws
On Thu, 12 Jun 2008 07:34:05 -0700 (PDT), John Martin
wrote: On Jun 11, 11:04*pm, "Martin H. Eastburn" wrote: If a wrench is used 'backwards' - the weak side might break. So the jaw was taken from a larger wrench - the long thread bar hangs out... Maybe the larger wrench had a broken handle from a pipe assist! Martin - Show quoted text - I'll bite, Martin. Which way do most people consider is backwards, and which correct? Now you've done it, John. g (Just keep repeating to yourself, "The sum of the forces is is zero; the sum of the moments is zero; you can't push a string.") -- Ned Simmons |
Wrench with non-parallel jaws
On Thu, 12 Jun 2008 11:58:11 -0400, Ned Simmons
wrote: On Thu, 12 Jun 2008 07:34:05 -0700 (PDT), John Martin wrote: On Jun 11, 11:04*pm, "Martin H. Eastburn" wrote: If a wrench is used 'backwards' - the weak side might break. So the jaw was taken from a larger wrench - the long thread bar hangs out... Maybe the larger wrench had a broken handle from a pipe assist! Martin - Show quoted text - I'll bite, Martin. Which way do most people consider is backwards, and which correct? Now you've done it, John. g (Just keep repeating to yourself, "The sum of the forces is is zero; the sum of the moments is zero; you can't push a string.") But you CAN go **** up a rope! Gerry :-)} London, Canada |
Wrench with non-parallel jaws
"Ned Simmons" wrote in message On Thu, 12 Jun 2008 07:34:05 -0700 (PDT), John Martin wrote: On Jun 11, 11:04 pm, "Martin H. Eastburn" wrote: If a wrench is used 'backwards' - the weak side might break. So the jaw was taken from a larger wrench - the long thread bar hangs out... Maybe the larger wrench had a broken handle from a pipe assist! Martin - Show quoted text - I'll bite, Martin. Which way do most people consider is backwards, and which correct? Now you've done it, John. g (Just keep repeating to yourself, "The sum of the forces is is zero; the sum of the moments is zero; you can't push a string.") -- Ned Simmons Oh man oh man, I hope this thread doesn't deteriorate into a battle on whether or not 'centrifugal force' exists.......oh oh .......;) Phil Kangas, who climbed back up into the peanut gallery.... |
Wrench with non-parallel jaws
Take a wrench and hang it onto something.
One way you are putting the pressure on the top jaw, the other way puts it on the bottom jaw. You normally want it on the top one. The bottom jaw isn't as strong, being that of a sliding jaw that moves side to side and in and out. The latter can break if the main force is placed there. Martin Martin H. Eastburn @ home at Lions' Lair with our computer lionslair at consolidated dot net TSRA, Endowed; NRA LOH & Patron Member, Golden Eagle, Patriot's Medal. NRA Second Amendment Task Force Charter Founder IHMSA and NRA Metallic Silhouette maker & member. http://lufkinced.com/ John Martin wrote: On Jun 11, 11:04 pm, "Martin H. Eastburn" wrote: If a wrench is used 'backwards' - the weak side might break. So the jaw was taken from a larger wrench - the long thread bar hangs out... Maybe the larger wrench had a broken handle from a pipe assist! Martin - Show quoted text - I'll bite, Martin. Which way do most people consider is backwards, and which correct? John Martin ----== Posted via Pronews.Com - Unlimited-Unrestricted-Secure Usenet News==---- http://www.pronews.com The #1 Newsgroup Service in the World! 100,000 Newsgroups ---= - Total Privacy via Encryption =--- |
Wrench with non-parallel jaws
On Jun 12, 10:23*pm, "Martin H. Eastburn"
wrote: Take a wrench and hang it onto something. One way you are putting the pressure on the top jaw, the other way puts it on the bottom jaw. You normally want it on the top one. *The bottom jaw isn't as strong, being that of a sliding jaw that moves side to side and in and out. The latter can break if the main force is placed there. Martin Martin: I think you're way off the mark with your mention of the "main force". As I see it, if you're pulling on a wrench with 100 pounds of force on the end of the handle, then the far jaw should have on it 100 more pounds of force than the near jaw. It's pretty much meaningless, though, because it is dwarfed by comparison to the force on the jaws coming from the nut's trying to wedge them open. That force is equal on both jaws. I wasn't trying to set you up with a trick question, though. I do expect that most people will say as you did: if you are pulling a wrench, the adjustable jaw should be toward you. I'm not sure that's right - here's why. If you're pulling on a wrench with the solid jaw away from you, the force is at the base of the solid jaw and the tip of the sliding jaw. The force on the sliding jaw is also to push it against the wrench frame. If you're puling on a wrench with the solid jaw toward you, the force is against the base of the sliding jaw, and is also to pull it away from the wrench frame. I'd rather have the force against the base of the sliding jaw, even though doing it "backwards" like that does try to pull the jaw out of the frame. But I'd like to hear what some others think. John Martin |
Wrench with non-parallel jaws
I suppose you have to do the stress design on the entire part of the wrench.
This wasn't a obtw but from seasoned men I wish I had 1% of in me yelled to stop... Martin Martin H. Eastburn @ home at Lions' Lair with our computer lionslair at consolidated dot net TSRA, Endowed; NRA LOH & Patron Member, Golden Eagle, Patriot's Medal. NRA Second Amendment Task Force Charter Founder IHMSA and NRA Metallic Silhouette maker & member. http://lufkinced.com/ John Martin wrote: On Jun 12, 10:23 pm, "Martin H. Eastburn" wrote: Take a wrench and hang it onto something. One way you are putting the pressure on the top jaw, the other way puts it on the bottom jaw. You normally want it on the top one. The bottom jaw isn't as strong, being that of a sliding jaw that moves side to side and in and out. The latter can break if the main force is placed there. Martin Martin: I think you're way off the mark with your mention of the "main force". As I see it, if you're pulling on a wrench with 100 pounds of force on the end of the handle, then the far jaw should have on it 100 more pounds of force than the near jaw. It's pretty much meaningless, though, because it is dwarfed by comparison to the force on the jaws coming from the nut's trying to wedge them open. That force is equal on both jaws. I wasn't trying to set you up with a trick question, though. I do expect that most people will say as you did: if you are pulling a wrench, the adjustable jaw should be toward you. I'm not sure that's right - here's why. If you're pulling on a wrench with the solid jaw away from you, the force is at the base of the solid jaw and the tip of the sliding jaw. The force on the sliding jaw is also to push it against the wrench frame. If you're puling on a wrench with the solid jaw toward you, the force is against the base of the sliding jaw, and is also to pull it away from the wrench frame. I'd rather have the force against the base of the sliding jaw, even though doing it "backwards" like that does try to pull the jaw out of the frame. But I'd like to hear what some others think. John Martin ----== Posted via Pronews.Com - Unlimited-Unrestricted-Secure Usenet News==---- http://www.pronews.com The #1 Newsgroup Service in the World! 100,000 Newsgroups ---= - Total Privacy via Encryption =--- |
Wrench with non-parallel jaws
On Thu, 12 Jun 2008 22:20:06 -0400, "Phil Kangas"
wrote: Oh man oh man, I hope this thread doesn't deteriorate into a battle on whether or not 'centrifugal force' exists.......oh oh ......;) It could be worse, the thermodynamics of air pressure regulators hasn't come up recently. g -- Ned Simmons |
Wrench with non-parallel jaws
On Thu, 12 Jun 2008 22:11:56 -0700 (PDT), John Martin
wrote: On Jun 12, 10:23*pm, "Martin H. Eastburn" wrote: Take a wrench and hang it onto something. One way you are putting the pressure on the top jaw, the other way puts it on the bottom jaw. You normally want it on the top one. *The bottom jaw isn't as strong, being that of a sliding jaw that moves side to side and in and out. The latter can break if the main force is placed there. Martin Martin: I think you're way off the mark with your mention of the "main force". As I see it, if you're pulling on a wrench with 100 pounds of force on the end of the handle, then the far jaw should have on it 100 more pounds of force than the near jaw. It's pretty much meaningless, though, because it is dwarfed by comparison to the force on the jaws coming from the nut's trying to wedge them open. That force is equal on both jaws. I wasn't trying to set you up with a trick question, though. I do expect that most people will say as you did: if you are pulling a wrench, the adjustable jaw should be toward you. I'm not sure that's right - here's why. If you're pulling on a wrench with the solid jaw away from you, the force is at the base of the solid jaw and the tip of the sliding jaw. The force on the sliding jaw is also to push it against the wrench frame. If you're puling on a wrench with the solid jaw toward you, the force is against the base of the sliding jaw, and is also to pull it away from the wrench frame. I'd rather have the force against the base of the sliding jaw, even though doing it "backwards" like that does try to pull the jaw out of the frame. But I'd like to hear what some others think. I agree with your conclusion, and I think for the same reasons. But I don't agree that the "wrong" way applies the force on the moving jaw in a different direction, i.e., pulls the jaw away from rather than pushes it toward the frame. To apply a torque to the nut there are two equal and opposite forces (a couple, in statics jargon) applied to diagonally opposite corners of the nut. (As you said, we can safely ignore the relatively small force applied to the handle by your hand.) So depending on which way you apply the wrench, the force on the adjustable jaw can be acting either near the frame or near the tip of the jaw. In either case the force applied to each jaw face is the same magnitude and direction, and is resisted by the adjusting screw. What differs is the moment produced by that force, which is trying to pry the jaw out of the frame, and that moment increases as the point of application of the force moves away from the frame. Mark me down for pull with fixed jaw towards you. -- Ned Simmons |
Wrench with non-parallel jaws
On Jun 13, 11:26*pm, Ned Simmons wrote:
I agree with your conclusion, and I think for the same reasons. But I don't agree that the "wrong" way applies the force on the moving jaw in a different direction, i.e., pulls the jaw away from rather than pushes it toward the frame. To apply a torque to the nut there are two equal and opposite forces (a couple, in statics jargon) applied to diagonally opposite corners of the nut. (As you said, we can safely ignore the relatively small force applied to the handle by your hand.) So depending on which way you apply the wrench, the force on the adjustable jaw can be acting either near the frame or near the tip of the jaw. In either case the force applied to each jaw face is the same magnitude and direction, and is resisted by the adjusting screw. What differs is the moment produced by that force, which is trying to pry the jaw out of the frame, and that moment increases as the point of application of the force moves away from the frame. Mark me down for pull with fixed jaw towards you. -- Ned Simmons- Hide quoted text - - Show quoted text - Ned: I'm glad you agree that pulling with the fixed jaw towards you makes sense, because I now know that there are at least two of us doing it the way that almost all others, in my experience, believe is wrong. Since those forces are acting on diagonally opposite corners of the nut, can't you look at the forces on each corner as two vectors - one perpendicular to the face of the nut (and the face of the wrench), and one at right angles to it? It's that second one that I'm seeing as pushing the jaw towards or pulling it away from the frame of the wrench. It's been a long time since I took physics, though. Maybe I should ask my younger son Matt, who has just finished his second year in the physics PhD program at RPI. Here's a bet - if I do ask him and he asks some of his physics and engineering buddies - my bet is that there will be proponents in both camps. John |
Wrench with non-parallel jaws
"John Martin" wrote: (clip)Since those forces are acting on diagonally opposite corners of the nut, can't you look at the forces on each corner as two vectors - one perpendicular to the face of the nut (and the face of the wrench), and one at right angles to it? (clip) ^^^^^^^^^^^^^^^^^^^^ Yes, the forces can be resolved into two vectors, as you say, but if the wrench is properly adjusted, the forces are essentially at right angles to the jaw faces, so the second vector component is negligible. What makes the difference is that one of the forces is close to the base of the jaw, and the other is nearer the tip. Since the forces are equal, the one nearer the tip creates more bending moment. You want this to be in the stronger jaw. The movable jaw transmits its moment into the slot in the handle, which is likely to be weaker than the stationary jaw. So you want it to receive less moment. Therefore, turn the wrench so the force on the movable jaw is away from, the tip. |
Wrench with non-parallel jaws
On Sat, 14 Jun 2008 16:34:36 GMT, "Leo Lichtman"
wrote: The movable jaw transmits its moment into the slot in the handle, which is likely to be weaker than the stationary jaw. So you want it to receive less moment. Therefore, turn the wrench so the force on the movable jaw is away from, the tip. Count that five for those that understand moments. I could never understand how people could convince themselves that the other way was right. Mark Rand RTFM |
Wrench with non-parallel jaws
"Mark Rand" wrote in message On Sat, 14 Jun 2008 16:34:36 GMT, "Leo Lichtman" wrote: The movable jaw transmits its moment into the slot in the handle, which is likely to be weaker than the stationary jaw. So you want it to receive less moment. Therefore, turn the wrench so the force on the movable jaw is away from, the tip. Count that five for those that understand moments. I could never understand how people could convince themselves that the other way was right. Mark Rand RTFM Perhaps it is more a mental/physical preference in the handling of the adjusting screw more than a study of forces for most people. Seems to me that when the pressure is applied to the outer tip of the movable jaw the leading edge of that jaw is under tension. When the force applied is closer to the slideway the force applied is more in line with the adjusting screw axis. So how 'strong' are the adjusting threads when loaded like this? Phil Kangas |
Wrench with non-parallel jaws
"Mark Rand" wrote in message ... On Sat, 14 Jun 2008 16:34:36 GMT, "Leo Lichtman" wrote: The movable jaw transmits its moment into the slot in the handle, which is likely to be weaker than the stationary jaw. So you want it to receive less moment. Therefore, turn the wrench so the force on the movable jaw is away from, the tip. Count that five for those that understand moments. I could never understand how people could convince themselves that the other way was right. Mark Rand RTFM Is it possible that the "right way" was really established for the "monkey wrench" with the jaws at right angles to the handle? It would seem obvious that you would not want to pull them in a direction that might cause them to slip off. I also wonder if anyone has done any actual testing to establish which way the wrenches are stronger? Another thought is that if you put a very long "cheater" on the wrench the pulling force on the wrench handle can be very small. Maybe we need to use them the "right" way for short handles with lots of pull and then turn them over to the "wrong" way when we put a "cheater bar" on! What if you folded the wrench head over so the jaw opening faced the handle? Which way should you pull it then? This question really should be resolved so we can get on with other equally important matters. Don Young |
Wrench with non-parallel jaws
"Don Young" wrote:
"Bob Engelhardt" wrote in message ... The jaws on this wrench are not parallel: http://home.comcast.net/~bobengelhardt/wrench.jpg Specifically, the face of the movable jaw is perpendicular to the "ways", but the fixed face is not. But they aren't sprung or worn that way. It seems that it was made like that. But why? Just plain poor quality? But that's *really* bad. It's an old wrench, not Chiwandian. It says drop forged, if that helps. Bob I think it was just not a very precise wrench. I have seen this type of thing in very old tools. I imagine that when it was made its fit was plenty good enough to turn the big square nuts in use at the time and its strength might have made it a "quality" tool in spite of its imprecision. Don Young That's an interesting idea. Might a wrench with slightly open jaws like that actually be easier to use on square nuts? With square nuts, you certainly don't need as close a fit as you do with hex nuts to prevent damage and slipping. With the slightly open jaws, you could just push the wrench into the nut until it wedged on the nut and get a tight fit (at 3 points). A problem with adjustable wrenches is that when you adjust them to be snug, they tend not to come off, and or are hard to put on, so you have to either open them just slightly to use them, or tighten and loosen them for every turn. Might an open jaw design actually make it easier to get on and off and still allow a fairly tight fit and not risk much damage if you only used it on square nuts??? So maybe it was intentionally designed that way if the expected use was for square nuts? Bob - got any square nuts you can try it on (I just searched my shop and had a damn hard time finding a square nut - I found some holding one of my metal shelves together.... -- Curt Welch http://CurtWelch.Com/ http://NewsReader.Com/ |
Wrench with non-parallel jaws
Mark Rand wrote:
On Sat, 14 Jun 2008 16:34:36 GMT, "Leo Lichtman" wrote: The movable jaw transmits its moment into the slot in the handle, which is likely to be weaker than the stationary jaw. So you want it to receive less moment. Therefore, turn the wrench so the force on the movable jaw is away from, the tip. Count that five for those that understand moments. I could never understand how people could convince themselves that the other way was right. Mark Rand RTFM It's not so hard to understand. There are a couple of extra dynamics at work here you are not thinking about. The handle of adjustable wrenches are angled at about 30 deg (half of the hex nut 60 deg) to make it possible to flip the wrench over in tight places and continue to turn a hex bolt with minimal movement of handle (allowing it to be used in tighter locations than a wrench with a handle which was parallel to the jaws). This angle creates an issue however. If you push the handle perpendicular to the rotation of the nut (the normal way you work any wrench) the wrench will try to push off and slide off the nut if you turn it one way, and it will tend to slide onto the nut if you push it the other. Because the fixed head on standard adjustable wrenches is the one further way from the handle, you must turn the wrench in the "right" way, in order for the forces to cause the wrench to by pushed onto the nut, instead of being pulled off the nut. As the handle comes towards you when you are pulling, you start to apply a force which is not perpendicular to the handle. When using the wrench the wrong way, once the wrench gets to 30 deg away from pointing straight at you, if you keep pulling towards you, the force will be in perfect line for pulling the wrench off the nut. When using it the right way, it's sill applying a lot of torque to the nut at that same point helping to keep the wrench from slipping off. When using the right way, the forces are working to your advantage to keep the wrench snug against the nut. When using it the wrong way, the forces are working against you trying to pull the wrench off the nut. Adjustable wrenches are designed with jaws strong enough so they won't break or bend if they are used by a normal strength human without extending the length of the handle with a cheater bar. You don't need to worry about the jaw bending or breaking. What you need to worry about, is the wrench slipping off the nut and rounding it off in the process (and making your knuckles bloody). This is why there's a right way and a wrong way to use the wrench. But then there's the question of why don't they swap the location of fixed and adjustable jaw so it will both stay on the nut and reduce the force on the movable jaw. I think there's yet another dynamic at work here. When the pressure is applied further out on the adjustable jaw, more pressure gets applied to the ways, and less pressure gets applied to the adjusting screw. As a result, there's more friction on the ways, and less force on the screw working to make it slip open. So I strongly suspect that the two jaws are located how they are, instead of switched, because it actually works better to have the force applied further out on the movable jaw to keep it from slipping open. So again, if you use the wrench the wrong way, you create yet another risk. You increase the risk that the pressure will cause the adjusting screw to turn, allowing the wrench to open - again increasing the odds that you will strip the nut, and skin your knuckles as well as potentially marring both jaws as you try to torque down on a nut with the jaws open too far. So even though you are right that using it the other way will put less damaging force on the weaker movable jaw, I think that is not the risk you need to worry about. Keeping the wrench on the nut, and keeping the jaw from slipping open, is far more important than worry about damage to the movable jaw. The movable jaw is designed to take the pressure without damage. The only exception to this I would see, is if you were using a cheater pipe and trying to put far more pressure on the wrench than it was designed for, it might be wise to turn it the other way to minimize the odds of damaging the movable jaw because it will no doubt be the first part to bend when you try testing the wrench to destruction like that. But great care must be taken at the same time to not let the wrench slip off the nut, and to make sure the jaws aren't slipping open as you stand on that 10 ft pipe. :) -- Curt Welch http://CurtWelch.Com/ http://NewsReader.Com/ |
Wrench with non-parallel jaws
Curt Welch wrote:
That's an interesting idea. Might a wrench with slightly open jaws like that actually be easier to use on square nuts? With square nuts, you certainly don't need as close a fit as you do with hex nuts to prevent damage and slipping. With the slightly open jaws, you could just push the wrench into the nut until it wedged on the nut and get a tight fit (at 3 points). A problem with adjustable wrenches is that when you adjust them to be snug, they tend not to come off, and or are hard to put on, so you have to either open them just slightly to use them, or tighten and loosen them for every turn. Might an open jaw design actually make it easier to get on and off and still allow a fairly tight fit and not risk much damage if you only used it on square nuts??? Damn, you're good! That makes perfect sense. And since only the diagonally opposite points are actually in contact with the nut, it wouldn't matter if the jaws are parallel or not. So maybe it was intentionally designed that way if the expected use was for square nuts? If we wanted to be generous, we could say so. G Bob - got any square nuts you can try it on ... Ah, damn ... I took it back to the dump (Swap Shop) yesterday! Thanks, Bob |
Wrench with non-parallel jaws
"Curt Welch" wrote: (clip) The handle of adjustable wrenches are angled at about 30 deg (half of the hex nut 60 deg) to make it possible to flip the wrench over in tight places and continue to turn a hex bolt with minimal movement of handle (allowing it to be used in tighter locations than a wrench with a handle which was parallel to the jaws). (clip) Adjustable wrenches are designed with jaws strong enough so they won't break or bend if they are used by a normal strength human without extending the length of the handle with a cheater bar. You don't need to worry about the jaw bending or breaking. (clip) ^^^^^^^^^^^^^^^^^^^^^^^ These two statements, taken together, seem to make the entire discussion academic. When you maike use of the 30 degree offset in tight quarters, you are making half the pulls the "wrong" way. Since I believe Curt is right about the strength of the wrench, I now have decided that there IS NO wrong way. The "wrong way" to use an adjustable wrench is with a cheater. ;-) |
Wrench with non-parallel jaws
"Leo Lichtman" wrote in message ... "Curt Welch" wrote: (clip) The handle of adjustable wrenches are angled at about 30 deg (half of the hex nut 60 deg) to make it possible to flip the wrench over in tight places and continue to turn a hex bolt with minimal movement of handle (allowing it to be used in tighter locations than a wrench with a handle which was parallel to the jaws). (clip) Adjustable wrenches are designed with jaws strong enough so they won't break or bend if they are used by a normal strength human without extending the length of the handle with a cheater bar. You don't need to worry about the jaw bending or breaking. (clip) ^^^^^^^^^^^^^^^^^^^^^^^ These two statements, taken together, seem to make the entire discussion academic. When you maike use of the 30 degree offset in tight quarters, you are making half the pulls the "wrong" way. Since I believe Curt is right about the strength of the wrench, I now have decided that there IS NO wrong way. The "wrong way" to use an adjustable wrench is with a cheater. ;-) I'm relieved to know that (with common angled adjustables, anyway) there is no **WRONG** way. Dad, who became a mechanic when monkey wrenches were in fashion, always taught me to pull against the standing jaw. His other advice, equally sage, was always to pull on the wrench - never push. Disregarding his warnings, I have gathered a scar or two. Flash |
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