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Smithing Biomechanics

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Hello all.  First, I wanted to say I had a good weekend at the NWBA conference, and enjoyed talking to everyone.  I’m still amazed at the opportunity these conferences give us to learn from and rub elbows with the likes of Darryl Nelson.  How fortunate we are.


We had the pleasure of observing a ‘young’ smith at work, and it was fun watching Alec move metal.  It was also fun hearing all the differing opinions about forging with those heavy hammers.  Which is the main reason for this post which is a request.


Now, I don’t want to get into a discussion on the merits of one individual technique/belief/myth over another, I’m merely looking for information.


I’m interested in researching the biomechanically correct postures for forging.     

Through some conversations, it was suggested that as a physical therapist, (physiotherapist for the rest of the Globe), I weigh in with my knowledge/opinion.  With many years of treating musculoskeletal injuries through postural corrections and teaching patients to exercise specific muscles, I’m confident that if any of you were to come to me with pains, I could guide you to recovery of pain-free function.  I’m not 100% confident I could weigh in on the “correct” biomechanics of forging yet, not due to lack of knowledge of the body, but lack of information on what musculoskeletal injuries are common.  At this point, I could only give basic general postural guidelines, not specific suggestions, because you can’t fix what you don’t know is broken, and ‘if it ain’t broke, don’t fix it.’   (Ok, so maybe I did weigh in with my belief/myth…) ;) 


If anyone could point me to articles/research on common blacksmithing injuries (I doubt there are any) or if y’all would be willing to share your experiences, that’d be great.  And for clarity, no offense to the hobbyists out there like me, but info from full time smiths (SOBs as Grant used to say) would be more useful for studying repetitive use injuries due to smithing.


If you want to send info by e-mail feel free (patient privacy and all….) :rolleyes:



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Let's get it out in the open.


I shod horses full and part time from 1964 to 1971. I began to take on ornamental jobs in 1968. In the mid-1970's, I got a pain in my left wrist so that I could not handle the tongs. It was diagnosed as a necrotic lunate bone, one of the 8 little bones in the wrist. Necrotic translates as "dying." The bone becomes "spongy" and less sclerotic. I couldn't work because of the pain. I'm right handed.  I went to the "orthopods" and they wanted to replace the bone with a plasticene one. I didn't go for that. They then prescribed a thick leather prosthetic cuff. That did not work and it eventurlly began to stink. I went for Swedish massage. No help. Then I went to a Japanese acupuncturist who put me on a pseudo macrobiotic diet and limited my alcoholic consumption to 1/2 glass of beer per day with one meal. After 10 treatments of needles, moxibustion, and deep massage (he walked on my legs, butt and back...ouch), he announced that my body was in alignment and to "Come no more!" I said, "But Doc, it still hurts." He repeated loudly, "Body in alignment; come no more!" Two weeks later, the pain disappeared and I went back to work. In hindsight, I think the bone problem may have been caused by constant tong holding tension. But those were my alcoholic consumption days too. I've given that up; it's been over 30 years now.


Currently I'm 77, and I have some range of motion troubles with my arms seeming to originate in the shoulder/bicep area. I suspect the right shoulder problem is due to repetitive stress. Several months ago, I fell on my left side, knee, hips, and shoulder. I had some chiropractic, but the left shoulder/bicep area is still bothersome. It makes it difficult to sleep on one's side at times.


I recall the dean of American blacksmiths, Francis Whitaker, saying that in his dotage, his right shoulder (hammer arm) bothered him somewhat.


Some smiths get tennis elbow, but I haven't encountered that personally.


I began a regimen of tai chi form in the 1980's which I believe has helped me in the shop. In tai chi, the idea is to "unlock all joints" and to relax (not collapse). The opening arm-raising motion in Yang tai chi is akin to the hammer raising and lowering motion.


Reference hammer weight, I've heard of no studies. As a farrier, I used a 2.5 # rounding hammer. When I began smithing, I used a 3 # cross peen hammer for years. I now use a 2.5 # cross peen for much of my work. However, I have a whole arsenal of hammers. I made a 4.5 # hand hammer which I use on heavy ironwork. My two handed sledge hammers are 8 and 10 pounds.


I'm doing fairly well, considering. I'll be demoing May 3-4-5 for the Northeast Blacksmiths in New York.

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A couple of years after I started blacksmithing I tore the tendon on my right elbow, treated conservatively and wore a forearm strap for years. Do not wear it anymore and it seems to have disappeared but does occasionally cause me grief. Developed golfers elbow in my left elbow ( pain and swelling on the inside elbow ) that settled down and flairs up occasionally too.

Now, for the last year I developed dequervains in my left thumb/wrist and soon after, the same in my right wrist too. That really slowed down my forge working abilities especially the pain and loss of function. So, I have just had surgery, dequerveins release to both wrists. The results 2 weeks on are amazing....instant pain relief and full movement back again, although a bit wasted, so am madly doing exercises to strengthen them. I reckon I will be back in the forge soon. I am seriously pursuing buying a power hammer to lesson the stress to my hands because I am certainly not ready to give up yet. Been blacksmithing full time initially but part time at the moment for the last 20 + years.

Hope this is useful to you. Feel free to ask more info if interested billyO


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Thanks for all the replies, and please keep them coming!  I'll probably have my thoughts compiled/organized in a couple of months, after I get more info. and do more research. 


Frank - Thanks for jumping in and leading us off.  I'm glad you didn't go for the ortho replacement.  That would have been a nightmare recovery process.  Re: the Tai Chi, I would recommend this, yoga, or any other gentle, controlled end-range stretching program for all smiths.  The key to keeping physically able is to maintain a balance of joint flexibility/stability, flexor/extensor strength and work the body equally, in all directions.


Denise/Nobody/Frank - My guess would have been elbow/shoulder/wrist/thumb as most likely candidates for overuse injuries and possibly/probably from faulty mechanics for the particular body of the smith.


rockstar - Yes, too simple an answer.  But she was probably right for 1/2 the population.  I have contradictory thoughts on this one, maybe I'll figure this one out. 


Thanks again.     

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Long VS short handles....  There is definitely a divide in opinions among everyone on this.  A short handle (actually choked up) and held loosely works best for me (to avoid stress). 


I do, however, have friends that are professional smiths that go the other way and feel strongly about it.

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My elbow was complaining years ago, the power hammer did more good than anything else. That said I used about 2# hammers the most then, now I am moving into heavier hammers, I think they bounce back less than the light ones and therefore you do not need to catch them. I think that is what causes the tennous elbow thing. I think good hammer control has more to do with not injuring yourself than a particular hammer size, square blows do not bounce off at odd angles and strain things getting the hammer back under control. Maybe a choked up grip helps to keep things under control and then you can do more with a choked grip if the hammer is larger. With a light hammer you use that longer handle to get vellocity. All that said right now I use a real mix depending on the job, if I really need to move metal I use the power hammer. Looks like my answer is really not helping for your question.

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there are no studies at this time from what I have researched. The problems I have seen in other smiths are nerve damage, tennis elbow, neck and shoulder pain. it all starts where the hammer hits the metal. Vibrations, proper grip, posture, and swing. You should be throwing the hammer and just guiding it towards you target. whether you use a short handle or a full handle. I like a 16" handle with some practice you can change handle position even when using a heavy hammer with little effort. With length and speed you gain velocity. more velocity more metal moves. I like to stretch and I use Tia chi in all I do. At 54 I have to take care of my body recovery time takes longer I have noticed in the last year. I have no problem forging a 8 to 10 hour day with a 5# hammer.  

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Again, thanks for the replies and keep em coming!


Looks like my answer is really not helping for your question.


Actually, quite helpful, thank you.  I agree with most of what you said.  Tennis elbow is, more specifically, Lateral Epicondylitis. (Golfer's elbow is Medial Epicondylitis.)   Anytime you see a word ending in -itis, or -osis, that means inflammation.  So, tennis elbow is inflammation around the Lateral Epicondyle, which is the bony attatchment on the promimal radius near the elbow where the Common Extensor Tendon attatches.  There are a few muscles that make up the common extensor group, but all of them extend and radial deviate the wrist/hand.   (Which, to visualize, imagine holding your R arm by your side with your elbow bent to 90 degrees and your palm facing the left.  Radial deviation ismoving your hand so the thumb goes straight up, and extension is moving the hand so the palm faces forward.  If you use your left hand to gently grab the muscles around your right elbow, you'll feel the muscles contract.) 

It's called Tennis Elbow because it was common in tennis players in the early 20th century, when it was considered "un-manly" to employ 2 hands during a backhand, and the repetitive shock on the extensor muscle group during said backhand will tear up that musculoskeletal attatchment.  Basically, the inflammation/irritation comes from overuse, the tricky part can be finding the ultimate cause of the overuse.  Could be overgripping, not letting the hammer rebound, too heavy a hammer and/or forging when fatigued, improper postures, poor hits causing the hammer to shift and the reflexive sudden tightening of the grip to regain control of the hammer, banging your elbow on the vice, or any combination of above.

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I've been blacksmithing for about 30 years (I'm 54) although I do not forge every day.  I've gone a week or more without picking up a hammer due to other commitments but I also have worked on production jobs that required 8-10 hour days at the anvil over the course of a few weeks - it just depends on the workload.  About 12 years ago, I had one bout with "tennis elbow" and was able to cure it over time by wearing an arm band (one with the velcro strap and a small gel knot imbedded in the belt to apply pressure).  I did not wear a band prior to the injury and do not wear one now; I believe I hurt myself by grabbing a heavy hammer and going to town one morning before warming up sufficiently - so now I try to stretch my wrists and arms before working.  Other than that, about the only serious injuries I've had are cuts and burns.  I do have some arthritis in the middle knuckles of my hammer hand but it is not incapaciting.  My doctor X-rayed it and commented that it might well have occurred anyway since arthritis runs in my family.  Knock on wood but I do not have any other chronic pain at this time.


I'm a firm believer in a healthy body so I lift weights, run, stretch regularly and watch my diet as a holistic approach to life (I was about 50 lbs heavier in my avatar pic than I am now).  I also believe that a relaxed grip helps with hammering so I aim not to use a death grip and if something hurts while working, I try to stop and figure out what the problem is - simply bulldozing ahead is what often leads to injury.  I use a 3 lb hammer for all general work and a 2 lb hammer for most forge welding.  I do not like using a heavier hammer but am not critical of those who do; I am just more comfortable swinging a lighter hammer at a faster pace to move material.

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Certainly an interesting and worthy discussion.


I have suffered from Carpal Tunnel, in my dominant hand, had the surgery a number of years ago which has sorted it. Currently suffer from stiffness in my hands, as there is arthritis in the family I've been working on a  physical approach- ie. just getting fit, I go to the gym for an hour and half 6 days a week, mostly cardio and some light weights, and will be starting yoga soon. I have found that I get "twinges' in my hand when I have been hammering all day, I then stop.


 I am hoping i have a few years left in me until I go back to working soft, supple silver!!  I get worried that a lot of these young ones are going to be doing their backs in early the way they forge!! I use a 3.5lb hammer for most work, and lighter ones for all the rest. Very rarely use something heavier than that. Am buying a power hammer in near future as well!! The industry could really use some bona fide research into techniques rather than relying on "he said she said"

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Around its circumference, where it is comfortable in use.

There is no fixed place, it depends on the hammer and what you are doing.

Generally near the head on the heavier hammers, and nearer the other end on the lighter ones,

In practice you will find on the "lighter" hammers, your hand moves along the shaft more than on the heavier ones.

What defines light and heavy is usually down to the user.

Its a bit like how long is a piece of string?

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I was thinking about this a bit and remembered reading somewhere about the differences in how stock moves under different hammers.


For example, lets say a fast swinging lighter hammer would deliver the same energy as a slower moving heavy hammer.  What I read indicated that upsetting stock with the faster hammer speed tended towards upsetting the struck end rather than deeper down into the stock. So riveting operations were better suited to lighter hammers and bumping up was better suited to heavier hammers.  Of course that assumes all other things are equal.


I'm nowhere near controlled enough with my hammers to make any scientific conclusions but lighter hammers feel better with lighter stock for me.

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Around its circumference, where it is comfortable in use.There is no fixed place, it depends on the hammer and what you are doing.Generally near the head on the heavier hammers, and nearer the other end on the lighter ones,In practice you will find on the "lighter" hammers, your hand moves along the shaft more than on the heavier ones.What defines light and heavy is usually down to the user.Its a bit like how long is a piece of string?

Cheers John. I did wonder that. I guess it depends greatly on the person doing the swinging too.

I'd like to try a 4-5lb hammer but part of me thinks that the extra weight is counteracted by holding it very close to or touching the head, this loosing a fair amount of the swing. Fulcrum, levers and all that.

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It also depends on the type of work that you are doing, and your technique.


Personally I have never had the desire to use a heavier than 2lbs hammer for longer periods than necessary, and only for a definite purpose. Looks too much like hard work.


It always feels like just heaving a large lump of metal at the work to beat it into submission, if I have to do this I used to resort to the Blacker or treadle hammer or a striker if available.

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I'm only a beginner smith but growing up a carpenter I believe I can contribute. As a carpenter you would generally use a 20oz claw hammer 16'' handle, a pretty light hammer, always held at the end of the handle. My father always had some embarrassing comment for me or a pop in the knuckles if more than an inch or two past the heal of my hand. The reason is that the most possible force to be transfered to the nail and holding the hammer at the end gives you the most leverage. As it related to smithing and using heavier hammers the added leverage becomes the issue and 5 pounds turns into 20. To illustrate this pick up a 5 pound weight, then put that weight on a stick of some sort and try to hold it out level. So there is a point where the weight of the hammer overtakes the leverage advantage, but that point depends on the person swinging the hammer and their balance better strength and endurance.


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The way I see it is this:


Force = Mass x Acceleration


Force is the amount of PSI we transfer to the steel with the hammer


Mass of the hammer


Acceleration of your swing


If I use a hammer with more Mass and swing with less Acceleration I can achieve the same amount of Force as if I swing a hammer with less Mass and more Acceleration.


So it comes down to personal preference, do you want to be tired because of swinging a big hammer slower? Or because of swinging a small hammer faster?


I personally use a 4.5lb Rounding Hammer I made with Brian Brazeal and Sam Falzone, I have used it for a year and am used to swinging a heavier hammer slower, so it is easy for me. Meanwhile, if i swing a 2lb hammer really fast, I can get worn out in no time, but someone who has swung only a 2lb hammer for a year may have issues switching over to my 4.5lb hammer.



It all depends on what you like and what you're used to.


My $0.02


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This is a very interesting discussion and I can attest to the fact that most blacksmith biomechanic injuries are in the elbow. I've been a full time smith since 1971 and many of the smiths I have known over the years have suffered the ailments mentioned above in this thread.


My personal experience happened many years ago when I pulled a bout of tennis elbow while forging a run of one piece hinge pintels. At that time I regularly forged with a 3lb. hammer and had the bad habit of gripping the handle tightly all the time.While forging the upset corners of these pintles in a block I was stricking down and using a pulling action at the same time, ( an improper forging procedure by an in experienced smith ) my arm was getting tired and I could feel it, but I only had 3 more to go to finish the 400 required.I pushed on to finish and felt a pop in my elbow. There was no pain and no loss of control but a definite loss of power, I was able to finish the remaining two. I went home with what felt like a tired arm and no pain but the "pop" I had felt had me worried. That evening all seemed fine but the next morning when I reached for the milk carton I could grasp i,t but not pick it up,my mind was saying to lift but my arm would not respond. It was to say the least a bit scary and worrisome.


I went to the Doctors and was diagnosed  with severe tennis elbow. Fortunately I was young and got most of my mobility back in about three weeks and was able to start forging again with the use of a strap on my forearm.It was a long recovery, forging was limited to light work and when my arm started feeling the least bit tired I stopped forging. I was advised by the Doctor to not become completely reliant on the strap or I might have to wear it indefinitely. As my arm healed I reached a point where I could forge with out it until the arm felt tired and then I'd wear the strap. Eventually I was able to work without the strap and haven't worn one for over thirty years. But the cure wasn't just from nursing the arm back. I obviously had been doing something wrong and had to change the way I was using the hammer.     


The answer to a healthy arm for me was to switch to a lighter hammer with a longer handle ( 1 5/8 lbs.16" ) and learn to throw the hammer. The longer handle afforded me the power I wanted for the style of forging I do with less effort. But I feel that the most important thing regardless of handle length is teaching yourself to release your grip! When teaching I advise students to try and imagine having a piece of string between the top of the handle and your hand.Then try to imagine pulling on that string while your hammer is in motion.The string would be able to be pulled out from between handle and hand at any point except for the split second of impact/rebound on the bottom of the stroke and again at the opposing instant at the top of the stroke when your arm resists the inertia of the impact to force the hammer down again. This is throwing the hammer! Often it can help to modify the handle by shaving it smaller making it easier to release your grip and leaving an enlarged end on the handle to help keep it from flying out of your hand. I firmly beleave that it's the death grip on the handle that gives most smiths all of their biomechanical problems.

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