Adjustable wrench use and design musings

Reading Joe Michaels' post about spud wrenches etc., spurs me to share and solicit thoughts about two adjustable wrench issues.

I was taught by my father to use an adjustable wrench (Crescent-style were what he had) so that, if you were pulling the wrench handle toward yourself, the adjustable jaw would also be on your side of a line through handle and bolt axis. This was supposed to take best advantage of the strength of the tool.

In later years, I came to disagree with this advice, although I think it is standard.

If you visualize how the jaws of the wrench bear on the nut or bolt-head corners, it will be seen that if you use the wrench as my father advised, the load is imposed near the tip of the movable jaw, and near the root of the fixed jaw. It seems obvious that the fixed jaw on a crescent style adj wrench is stronger than the movable one, so I now, whenever it is not hopelessly inconvenient, pull on an adjustable wrench from the side OPPOSITE the adjustable jaw.

I will offer my speculation as to why a technique IMHO incorrect is taught as standard. If I examine the construction of the old monkey-wrench on which the movable jaw is a sleeve around the shank at whose end the fixed jaw is formed, it appears to me that the movable jaw is the stronger, and this supposition is borne out by the large number of monkey wrenches I have seen (most of them!), whose jaws are no longer parallel because the shank has bent.

So, I believe the "standard advice" about how to use an adjustable wrench, was formulated and is correct for a monkey wrench, and has merely been transferred to the newer style wrench without being reevaluated and corrected.


Another tid-bit. My favorite Crescent-style adjustable wrenches are those made by JH Williams, Blackhawk...and I think one more mfr whose name escapes me at the moment. This is because the track for the rack on the movable jaw, and the rack itself, are D-shaped rather than cylindrical. This would seem a more expensive way to make them, because the track would have to be broached rather than only drilled. (I don't know, perhaps they are all broached to enlarge a milled slot) But the flat tracks normal to the stress tending to peel the movable jaw out of the handle, would not exert any force tending to wedge the cheeks of the handle apart, as the same pull on a cylindrical rack would. I think I have seen adjustable wrenches loose due to such wedging, 'though not near as many as sprung monkey wrenches.

Would your analysis of the monkey wrench situation, only, be different if you considered square nuts rather than hex nuts?

Monkey, more properly "Coe's" wrenches are optimized for square headed bolts and square nuts, which were standard in those long-ago days. (1840's: see http://datamp.org/patents/advance.php?pn=2054&id=13678&set=4 )

I will say that this is a thought-provoking thread. The next time I see a "sprung" monkey wrench, I'm going to measure which jaw is out-of-square. I have a hunch they will be found to be "normal" to the bend bar, with just the bend in the bar being the cause of the lack of parallelism.

Definite agreement that sprung wrenches of both Crescent and Monkey (Coe's) type are very commonly encountered.

JRR

FWI among my "monkey wrench " stash is a massive one marked L& N RR ...handle abt 20 inches long ......best thing around for straightening 42 in lawn tractor blades after strikin stones. /iron rods etc ( common around the farm)..........just put the blade in the vise tighten the wrench on it & SHOVE /TWIST down ....( easier when i weighed 220 than now at 180 )...... & a big old "aligator wrench " ( fixed jaws like an open alligator mouth ) hanging on the wall does wonders for loosening up square nuts on farm implements ....if you can access it .it will either remove the nut or shear the bolt ...
best wishes
doc

Thanks for the term, "Coe's" wrench, SB34. Is that the name of an original patentee. mfr, or?

Hex and square nuts displace load proximally or distally in the same sense as hex , but the loads are applied closer to the support, ie the cantilever is shorter for hex nut than for square. That would seem to make a hex nut easier on wrench than square, but it does not, because to exert the same torque at a shorter radius the force has to be correspondingly greater, so thus far it is a wash. But only on square splines is there essentially no wedging action to add bursting stress to a hub or springing stress to a wrench.

The bearing surface of the corner of a square nut lies not normal, but at around 45 deg to the direction of the tangential applied force, the bearing surface of a hex nut at around 30 deg. Clearance lessens those angles,and any deformation of the corner lessens them more, so a large radial or bursting component arises to open the wrench and crush the corner. The more the corner is crushed, the greater the force, until the nut is round. The hex nut is harder on the wrench.

In addition to being easier on the wrench, square nuts are more rugged and take more torque, for the same metal properties and same nominal size, because 1) radius of action is larger, therefore tangential force to achieve same torque is smaller, and, 2) force is more nearly normal to the surface, so there is less wedging action to crush the corners of a square nut.

So why are square heads obsolete? Saving of material, Not only is the hex nut lighter, but more importantly bolting flanges can be narrower and so they can be thinner as well since their cantilever is shorter. Hex or 12 pt sockets are smaller in OD than 4 or 8-pt, as well, for the same nominal size.

12 pt heads, or even Allen socket cap screws, anyone? Does anyone else miss the Bristol key?

Doc, despite its undoubted usefulness in your skilled hands, I think I would class your alligator wrench along with EZ-outs and Harbor Freight MIG welders, as great moneymakers for the machine shops guys have to bring their parts to after they have thoroughly buggered them at home.

On crescent type wrench, all the force, if used in the way you propose, is trying to shear the threads off of the adjuster screw. If you use it like a monkey wrench, the movable jaw will tend to bind in the track I think so that less load is transferred to the adjuster.

It probably, realistically, makes little or no difference. The correct answer is to simply get the correct size wrench for higher torque fasteners...and use the adjustable for lower torque stuff in the name of convenience.

magneticanomaly said:

Thanks for the term, "Coe's" wrench, SB34. Is that the name of an original patentee. mfr, or?

Click to expand...

Yes- Loring Coes of Worcester, MA, patented and manufactured the first version of what we think of as a "modern" monkey wrench in 1841.

Andy

magneticanomaly said:

I was taught by my father to use an adjustable wrench (Crescent-style were what he had) so that, if you were pulling the wrench handle toward yourself, the adjustable jaw would also be on your side of a line through handle and bolt axis. This was supposed to take best advantage of the strength of the tool.

In later years, I came to disagree with this advice, although I think it is standard.

If you visualize how the jaws of the wrench bear on the nut or bolt-head corners, it will be seen that if you use the wrench as my father advised, the load is imposed near the tip of the movable jaw, and near the root of the fixed jaw. It seems obvious that the fixed jaw on a crescent style adj wrench is stronger than the movable one, so I now, whenever it is not hopelessly inconvenient, pull on an adjustable wrench from the side OPPOSITE the adjustable jaw.

Click to expand...

It looks like you actually have that backwards....

Looking at the "line of action" or "force vector", it seems to me that the way most suggest using the wrench, the movable jaw is being pushed back into the handle, which is its strongest direction.... and avoids the wedging action you mentioned. Line of force is angled from nut toward your hand, with a good portion of it pushing the jaw against the handle. That takes advantage of the strongest parts of the jaw

The way you propose, it appears the movable jaw is being pulled outwards, and the line of force is outwards away from the wrench handle and through a point out toward the tip of the movable jaw. The force is placed on the weakest parts of the moving jaw, with a larger leverage.

??????

Doc,

I'd like you to take a good look at that Alligator wrench you mentioned:

"a big old "aligator wrench " ( fixed jaws like an open alligator mouth ) hanging on the wall does wonders for loosening up square nuts on farm implements ....if you can access it .it will either remove the nut or shear the bolt ..."

Look carefully to see if it was made by Roebling. This is THE Roebling steelworks of Brooklyn Bridge fame. It was just south of Trenton, NJ.

Yes, I must agree that an Alligator wrench can mangle a nut, but it's not a sure thing that the nut will get mangled.

FWIW, I always thought the reason square nuts/sq. hd. bolts were used on agriculture machinery was a) because they are still grip-able after considerable rust and b) they are more compatible with adjustable wrenches.

John Ruth

This is an interesting topic.

My comments will relate solely to the type known in the US as a Crescent wrench, and over here as a shifter.

Decades ago I was working with a gnarled old Australian engineer who said he fired anyone he caught using a shifter the wrong way. I didn’t know there was a wrong way. He didn’t know I didn’t know, either.

I figured out that the right way must be such that the corner of the nut bears on the sliding jaw as low as possible, so as to minimise the bending moment on the sliding jaw.

Subsequently I never bothered which way I used it, or gave it much thought.

Until about 2 weeks ago, when I found this:-



It’s a ‘Clyburn’ type adjustable with a ratchet. Made by Palmer & Sons of Birmingham, probably in the 1860s. I can’t see much value in having a ratchet, but it does turn my theory upside down, in that you can only use it such that the sliding jaw contacts the ‘outer’ corner or the nut.

Then I looked at some old 'Fastfit' self-adjustable wrenches. These have a pivoted handle which tightens the sliding jaw onto the nut. They only work one way, and that way is as per the ratchet type above.

It struck me that it probably doesn’t matter very much with hexagonal nuts, as the distance between the ‘inner’ and outer corner isn’t that great. It might be more important with square nuts, though.

Intuitively it seems that a wrench with an angled head might slip off the nut easier if it's used one way rather than the other way, but I can't see that being the case.

Incidentally, the Clyburn spanner was introduced by Richard Clyburn in 1842. A number of companies continued making them until very recently. I have a modern small copper alloy one. It was a good, strong design, with the sliding jaw being well supported for all jaw openings. Typically, though, the range of opening was relatively small, and they were relatively expensive, being accurately made. Accurate guidance of the sliding jaw reduced the chance of rounding the nut’s corners off.

Having said that they’re strong, the sliding jaw of my old Palmer is cracked! Probably a combination of abuse and brittle material.

Thanks, JST.for your interesting suggestion. So much for engineering being an exact science! Like so much else, all depends on your assumptions.

Your model depends on there being a lot of friction between the nut corner and the wrench jaw surface. If so, then, yes, the movable jaw is driven into the wrench body. Whether then there would be enough friction between movable jaw and its track to unload the rack....I dunno.

Shall we write a grant for a series of experiments on wrenches of different degrees of dirtiness, rustiness, and lubricatedness, used both ways?

Worth noting that the D-shaped tracks of the Williams and Blackhawk versions seem to suppose that the wrench is used "my" way, and pullout of the movable jaw has to be resisted.

Asquith's wrench is obviously made so that you have no choice but to load the tip of the movable jaw, JST's way.

I have a very stout old Crescent style adjustable (I'll try to remember to photograph it tomorrow), on which the fixed jaw, not the movable, cracked and was brazed back together

Perhaps "the right way" not only originate with, but only applies to Coe style.

When I found this adjustable, it was a solid ball of rust, soaked it in Kroil and this was under all the corrosion.

No debate about which way to turn it, one way tighten, flip it over to loosen.

Thanks to SB34 for the info that the inventor's name was "Coes", not "Coe" ! I like to get it "right".

I have a couple of the old monkey wrenches, not sure who made them, in indifferent condition with wood handles over a tapered tang, with a conical nut on the end, and also a couple of all-steel ones, one of a more modern pattern with a rack cut on the beam and a worm to adjust, one with the more traditional separate elevating screw. All get used occasionally.

This was to be a PM reply to SB34's PM, but his box is full.

The self-tightening geared wrenches resurface periodically. Their success relies on ASSUMPTIONS about the actual wedging taking place in service, to ensure that then mechanical advantage of the gearing can overcome it.

Since the effective wedging can approach infinity, if the wrench is not gently preadjusted to the fastener head or if the fastener is nearly round, I do not like them. They are an example of "destructive feedback", where applied force causes deflections which alter the geometry to increase the force, which increases the deflection, and so, on to destruction.

I had always thought the "alligator" wrenches were solely for pipe or round stock. Roebling was in the business of building suspensions bridges and making steel castings and wire rope for them. My guess would be the alligator wrenches made by Roebling were for use in turning or holding back on tie rods used on certain types of bridge or timber frame/truss construction as might be used on a bridge deck.

The great debate over square nuts and bolt heads vs hex has also got me to thinking. If we consider the evolution of the nut and bolt, we have to think in several areas:
-what materials were available
-what means of producing nuts and bolts existed

At the time nuts and bolts were first being produced, chances are they were made of wrought iron and hand forged by blacksmiths. Wrought iron is a great material with certain limitations, one being a low tensile strength and correspondingly low shear strength.

A smith could easily hand forge a square cross section or forge it in a trip hammert with open dies- without needing a set of hexagonal swages. The comparatively low tensile and shear strengths, and correspondingly low crushing strength of the wrought iron meant larger bearing areas on the nuts and bolt heads. It all added up to a handy fit of square heads with the manufacturing technology of the day and the available material.

If we take a further look at applications in that same time period (say about the time James Watt perfected the first rotative steam engines to about 1850), things were fairly simply and loadings on fasteners were fairly low. Square nuts and bolt heads worked fine.

I am not sure when hex heads came on the seen, but I think it must have been some time prior to the Civil War. However, materials for bolts, nuts and stud bolts probably was not something that was really well defined or consistent. Steelmaking was in its infancy and "Bessemer" steel was about all that was out there for anything except specialized fasteners. Those might be made from a crucible steel with higher carbon content.

I am not sure when "graded" bolting of known strengths and the more compact heads came on the scene. Once the better grades of steel with predictable and consistent strengths were common, I think bolting moved to the system of compact heads and grading.

The old Monkey Wrenches worked fine on square nuts and bolt heads. On the old "high head" heavy hex nuts and bolt heads of larger diameter bolts, a monkey wrench will work pretty well. If you look at tool kits for automobiles and trucks in the 'teens into the 'twenties, an "auto wrench" was often included. This was a lighter pattern monkey wrench with the handle being part of the body forging. Once the present standards for hex heads and hex nuts took over, the monkey wrench stood a better chance of chewing the corners off them than not.

Today's adjustable wrenches are OK, but a lot of "real" mechanics will not use them, claiming they tend to round the corners on nuts and bolt heads. There is a story of some novice motorcycle rider who wanted to buy a used BMW "Airhead" motorcycle. He asked his brother in law, who was an experienced rider and sometime mechanic to check the bike out for him. The brother in law took a quick look, and said: "But this bike- the owner or whomever maintained it were real mechanics, no corners chewed on any of the nuts or bolt heads".

I have an assortment of adjustable wrenches up to 15", and will admit freely to using them more than I should, either for want of a larger wrench than I have in my sockets or combination end wrenches or out of sheer laziness. I also have monkey wrenches up to about 24", the larger ones being made by Coes. These come in handy for making up or loosening pipe unions more than anything else.

I do have a "Bahco" ( sp ?) Swedish made adjustable wrench in my shop. It is a bit of a PITA to use as it opens opposite hand to a US made adjustable wrench. You have to turn the jaw screw in the opposite direction to any other adjustable wrench. Other than that, it is a well made wrench. I think it might have come from a 144 Volvo tool kit from the 1960's, back when car makers provided real tool kits. There is an old joke, probably long forgotten, about sending apprentice kids to the tool crib to get the "left handed monkey wrench". While not a monkey wrench, the Bahco wrench is the proverbial "left handed" wrench and can drive a person a little crazy when using it.

Incidentally, Richard McKenna, the author of "The Sand Pebbles" wrote a number of short stories about engine room sailors on the river gunboats in China in the 1920's. One such story is "The Left Handed Monkey Wrench". Supposedly, an engine room sailor (machinists mate) had time on his hands when off watch. He took steel and made a left handed monkey wrench in the ship's engine room. He did have access to a lathe, vise, drill press and files. I recall McKenna mentioning that the machinists mate used rubber from worn out shoe heels as a medium for casehardening the steel of the jaws, and heated them in the furnace of a coal fired Scotch marine boiler. He cut the thread on the jaw screw opposite hand to a "normal" monkey wrench. The machinist mate left this "Left Handed Monkey Wrench" lying around the engine room and watched the Chief machinist mate go nuts when the wrench did the opposite of what he expected.

Joe Michaels

Joe Michaels said:

At the time nuts and bolts were first being produced, chances are they were made of wrought iron and hand forged by blacksmiths.

Joe Michaels

Click to expand...

Those 'chances are' is most certainly true.

And, consider the larger tolerance for a wrench fit with a square nut.

What else would be practical in a blacksmith-oriented world?

testing

I was tightening a square nut on a conduit hanger many years ago with a 10" adjustable.The hanger jumped off the steel beam,and fell to the floor just as one of our managers came around the corner.He had observed that I was using the wrench in the "non standard" way and said something to me about it,and I showed him that I needed to turn the wrench over because of the tight quarters.This was many years before internet and 800 numbers,so he wrote a letter to crescent.They replied that they hadnt tested the wrenches in that mode,and didnt know which was stronger.That was probably 1973.

here is a patent from 1835 : US Patent: X8,153 - Wrench

Anyone earlier?

Best regards
Søren

SouthBendModel34 said:

I will say that this is a thought-provoking thread. The next time I see a "sprung" monkey wrench, I'm going to measure which jaw is out-of-square. I have a hunch they will be found to be "normal" to the bend bar, with just the bend in the bar being the cause of the lack of parallelism.

JRR

Click to expand...

I am in agreement with magneticanomaly's thoughts regarding the "correct" way to use a crescent wrench.

Interesting thing about the monkey wrenches, though. Every one that I have seen sprung has had the handle bent BACK, so as to open up the jaws. Definitely not the way they would be bent had they been used properly (which to me, if the monkey wrench is viewed as the letter F, is to pull the handle to the right). On the other hand, if you use the monkey wrench properly, any bending of the handle bar would be resisted by the tightening of the jaws on the nut. Since you can't crush the nut, the bar shouldn't bend. Use it backwards, and the bar should bend in the direction that will open up the jaws.

Curious.

John Martin

magneticanomaly --

The first commercial "D-hole" adjustable wrenches were made by J H Williams, of Buffalo, New York. I don't know when the D-hole was introduced, but Williams claimed it made for a stronger wrench (and I wouldn't be surprised if it also made for a simpler, less expensive, forge die for the adjustable jaws).

By the late 1960s, Williams was one of a half-dozen companies manufacturing Crescent-type adjustable wrenches in the US -- Crescent, Diamond, Proto, Utica, Western Forge, and Williams -- and they all manufactured adjustable wrenches to be sold under other-tool-company names.

In the late 1970s (IIRC), J H Williams' corporate owner, TRW, sold the company in what I believe was a "leveraged buyout", and with the economic slowdown in the early 1980s Williams found itself in serious financial straits. The Buffalo plant was shuttered, Williams' physical assets sold in bankrupcy, and that was all she wrote for the Williams-made adjustable wrench line.

I have handled Williams D-hole adjustable wrenches stamped with a number of different brands, including Armstrong, Blackhawk, Boker, Channellock, Craftsman, Husky, New Britain, Penncraft (J C Penney house brand), Sparta, TRW, and, of course, Williams. I consider these Williams-made adjustables to be the all-time belles of the US-made adjustable wrench ball.

The final generation of Utica-made adjustable wrenches also were D-holed -- I suspect a patent ran out -- and were also sold under a variety of different labels, including Bonney, Herbrand, Utica, Powr-Kraft (Montgomery Ward's house brand), and a few others I don't recall.

Distinguishing a Williams-made D-hole adjustable wrench from a Utica-made D-hole adjustable is pretty straightforward. The Williams has a wedged transition from the bears-on-fastener-head surface of the fixed / handle jaw to the adjustable-jaw-guide surface of the handle and a relatively small-diameter knurl, while the Utica-made wrenches have a short-radius transition between the fastener and sliding-jaw surfaces of the handle and a relatively large-diameter knurl.

John

John Martin:

Yes indeed, if the Coes' [Monkey] wrench is used in the correct direction, you cannot crush the nut but you can certainly break out the top strap holding the jaw to the bar! If the bar flexes, perhaps even short of its elastic limit, that strap is a goner.

This has been like a revelation to me. In years of browsing through Flea Markets, I've seen many Coes' with broken top straps. I always thought this was due to over-striking when using the back of the top jaw as a hammer. Now I have a better hypothesis for this common damage.

Old Coes' ads reproduced in one of Ken Cope's wrench books state that Coes case-hardened their Monkey wrenches.

I smiled at Joe Michaels' mention of his Bahco from a Volvo tool kit. My bicycle tool kit contains the Bahco 8" adjustable that came in the tool kit of my father's 1966 Volvo 122S, the car I learned to drive on. Instead of a round hang-up hole, or 12-pt box-wrench, the tail of this Bahco is- - - -an alligator wrench!

Many thanks to John Garner for illuminating the history of the D-track wrench. Apparently all I have ever seen with this construction were in fact made by Williams. I think most of the wrenches I have seen with the radiused-square opening were Diamond, including a pair of pliers I have with an adjustable wrench at the end of one leg and a screwdriver at the end of the other.

Back to Joe Michaels' post, I had not related square fastener heads to the hand-hammer and open-die forging days, but it makes perfect sense. in fact, 'most all stock was square in those days, so a bolt would likely have been made by swaging a round shank from square stock, then cleaning up the bearing face by driving the bolt through a pritchel hole, and then cleaning up the square with two blows on adjacent flats. I have read of making bolts by wrapping and forge-welding a strip of iron around the end of a rod, then forging the head square or hex, but I guess this would have come along after round rolled stock became common.

As far as the date of appearance of the modern standardized SAE and ASTM grades of fasteners, I suppose it would not be too hard to look up, although it might cost money to get access to the actual dated standards, but my own experience taking things apart suggests that such standard fasteners were not widely used until the late 1950's