Numb arm

I was doing a little blacksmithing this weekend and I was beating on a bar uncoiled from an old car spring. Afterward, I noticed numbness in
the hand I was using to hold the bar. I was wearing leather gloves, but that didn't help. What other precautions should I take to avoid RSI or whatever?
Thanks for your help, Rob
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Hi Rob,
I have experienced the first twinges of RSI, but this was in my student years doing computing, not beating the crap out of a piece of hot metal.
I don't get any pain at all from impact, so can forge until the muscles bunch up and become too swollen to move. The reason my arms are like this is due to a side effect from some strength and coordination exercises I do.
The exercises can be done by yourself, however a partner will give a better workout.
The equipment :- a sledge hammer handle and something to hit, either a solid wooden post in the backyard, or a partner similarly equipped with a sledge hammer handle. It is advisable to get a cricket glove for your hammer hand if you have a workout partner.
Basically the sledge when striking a solid object will transfer some of the vibration and impact into your forearm. The first few times your forearms feel like they're going to explode, however your muscles adapt and you learn to hit without getting damaged. This means that you can hit with solid force and be fine.
Sounds like crap, but it worked for me. I could video the exercises if anyone wanted them.
Regards Charles
Rob wrote:

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Note that the symptoms are in my workholding arm, not my striking arm. I also wasn't working that long, perhaps 1/2 hour.
Thanks, Rob
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(snip)

One of the things my silversmithing instructor recommended was leather bicycling gloves with gel-packed palms. It helps absorb the vibrations. You can get fingerless ones and wear them under regular leather gloves as well.
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I've found soreness in the holding arm more common than in the hammer arm. Lots of beginners hold the work with a death grip. Since that arm isn't moving as much, it gets sore then numb. Even the subconscious apprehension of a flying piece of red hot steel makes them grip harder.
Later, as they develop both hammer and tong control and maybe do some exercises to work harden the arms and hands, the problem solves itself. They develop a better feel for how tight a grip is adequate to the task.
Sooner or later, everyone is going to have something slip and fly. It does take a while to learn just to let a workpiece fly and pick it up after it lands. Above all, don't try to catch it, even with good gloves on. :)
A trick some of the folks on theforge have mentioned is to drill a couple of holes a few inches apart in the hammer handle near the head and jigsaw a cut between them. I haven't tried that, but it would give the handle more flex and absorb more shock. I just hold my hammers lightly but firmly and ease my grip just as the hammer hits the steel.
I guide the hammer more than grab it.
HTH
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It would help that arm too ;-) Charles
Rob wrote:

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I'd guess that you were working the steel too cold and a lot of vibration was being transferred to you hand. Personally, if I feel any of that bone-numbing vibration, I stop doing what I am doing and figure out a different way to hold the work. I'll bet you had some rather long pieces. That just makes things worse. You also may have been holding things at odd angles while doing the work and that will just make things worse. As you probably already know, you shouldn't work spring steel as cold as one sometimes works mild steel (or as hot---- nowhere near a welding heat.
Hope I'm close on one or two counts, Pete Stanaitis ----------------------
Rob wrote:

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I may have been working it a little cold. I was worried about burning it up. I thought it was plenty hot (kind of a medium orange), but it was pretty hard to work, even with a 2# hammer.
Thanks, Rob
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Rob wrote:

Get a bigger hammer. A two pounder is kinda light for spring steel. I use a four pounder for rough shaping and a three pounder for fine work. Medium orange is about the right temp, roughly 2200 F. When it goes back to red, back into the fire. I've beat a LOT of 5160 in my time. It works just like mild steel, just use a bigger hammer.
Charly
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wrote:

I can't swing a 4 pounder very long before I start to lose control. One of these days I'll make a JYH :)
Thanks, Rob
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Rob wrote:

I don't 'swing' the four pounder, I let gravity do the work and I just steer it on the way down. If your arm wears out quickly, then you're working too hard. Here's an idea to build endurance... take a one gallon milk jug and fill it halfway with water and curl it while you're watching TV. Do this every night until the arm starts to tingle. Don't count reps. In a week or so, it'll become automatic and you'll be able to do it for hours on end. It won't give you bulgy arms like Popeye, but it will condition the muscles to the repeated strain. I used this when I was tourney fighting in the SCA to build up my shield arm, worked like a champ. That ten pound shield weighed less and less the more I did it. Now, no one wants to fight me; they all say I hit too hard. I really can't figure this out, just because I can pick up a cylinderhead with my fingertips is no reason to wuss out on a little fighter practice.
Charly
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Charly the Bastard wrote:

Sometimes when I'm pissed off with the world my arms get tired faster and the 4 lb hammer takes its toll ;-)
I use HA shields myself, they don't need to be as thick as SCA shields, as we use metal in combat not rattan cane. A club will do more impact damage than a sword.
I thought the point of SCA combat was to hit as hard as possible, well that was the reason an SCA friend gave me for the non-HA armour i.e. 12 gauge sheet and lots of padding. So your friends shouldn't complain.
You need to find more friends that are a little tougher... getting hit with a sledge hammer handle (my training sword) without armour toughens you up a little.
Regards Charles P.S. Although you go down like a sack of potatoes when hit in the janglies :-(
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When Chilla put fingers to keys it was 2/6/07 4:28 PM...

The object is to hit the other guy just hard enough to get him to take it. _Usually_ that's not "as hard as possible". I've never hit anyone as hard as I could. No need.
I've only intentionally hit a few guys harder than I think is reasonable. Once it was after I had killed all his squires with reasonable shots and hit him with several reasonable shots then some shots that were reasonable+. I did finally give him a good clobber, I hope his kidney armor was good. Even that shot was _slightly_ moderated.
Most of the time the fighting and calibration is quite reasonable. I'm proud to say that my armor is not all that thick and it has very few dents, because I don't _make_ the other guy hit me that hard.
-- Carl aka Meister Frydherik Eysenkopf, OL, OTC, etc...
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Carl wrote:

I don't hit as hard as I can either. Usually 'planish' is more than enough. I have four force levels; planish, bend, forge, and weld. I have only had to go to forge once, and that opponent had to be helped from the field. But... he was a notorious rhino. Do you remember the guy with the bowling ball on a post that went around the Knowne Worlde in the mid eighties? I ran across him at a Pennsix and managed to move the ball a little over seven feet with my 'too hard' shot. When he published in TI, I ran the math on the shot and the answer came up a little over 3000 ft/lb/secs. Damn, that's almost five horsepower! I really try not to hurt anyone, this is supposed to be just a game, after all. My tank suit is made from roadsign aluminum. It protects me from the Bruise Brigade, but I can feel the lightest tap, as I don't wear padding under it. Only fourteen pounds, nose to toes. Yeah, it's not a period metal, but it's infinitely better than ABS. I call 'em pretty light, bruises and contusions interfere with the 'evening activities'.
Charly, the Last Dworf in Ansteorra
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Chilla wrote:

I've only been hit in the 'janglies' once. It picked me up and tossed me back about ten feet. Good thing I had a steel cup on that day. 12 ga sheet? Must have been from the East Kingdom. Tourney fighting in the SCA is more of a martial sport than a historical recreation, so there is considerable lattitude given in the equipment end. Long ago, we used to use freon cans for helms, and carpet for body armor. Thankfully, those days are long gone with the increase in good metalworkers that a maturing organization brings. Down here in Ansteorra, (Texas and Oklahoma) we still have a lot of leather armor, due to the heat/himudity of summer in the area. It's tough to hang out in 98/98 in the ohtoobright sun in steel plate and still be able to go four rounds or more of elimination on the field. There have been times that the field was the winner, Gulf Warz I springs to mind. The event has since been moved to mid-March. South Mississippi in June is a real killer.
Charly
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You might consider a treadle hammer. It's in between a hand hammer and a powered hammer. The muscles in your legs do the work. And each blow can do a lot more work. The treadle hammer also allows both hands free to hold work and tools. Depending on the design, one can be built for as little as $250 or so, depending on your ability to scrounge.
Pete Stanaitis --------------------
Rob wrote:

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Rob wrote:

A friend of mine tied his sledge to the rafters with bungee cords. He says it works great (at least compared to no spring).
Steve
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When Rob put fingers to keys it was 2/5/07 9:26 AM...

Too much shock is being transmitted to your hand, find ways to cut that down. Things that might make a difference:
Ease up on your work grip. Use fingers instead of the palm.
Find ways to hit the work that don't make it buck (as much) in your hand.
Don't hold the work by the end.
Slip some thin closed-cell foam into the glove, if you can do palm, fingers, and thumb, that'd be great. I have a glove for armoring that has foam in the thumb and forefinger, it's a big win.
As has been mentioned, work hotter. (The bigger hammer will make the work go better (if you can work it) but the shock-to-the-hand is a separate issue, and could be made worse by the bigger hammer, depending on what is causing your problem.)
Use tongs. Real tongs, not a vise-grip. You want the slightly sloppy connection, so that the shock is not well-transmitted.
- Carl
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I read a book about automotive spring steels and they only named off and discussed the most common and that was about a dozen of them. ;)
60 types was mentioned as a total number of different alloys used, and this was a late 80's book.
No kidding they can swap steels and sometimes not even have to modify the process times or temperatures from what they were using for the steel they happened to be using before.
I go along with calling all that-steel-5160 as much as anyone, but want you to know that's only a good(?) guess. Even my spark testing wouldn't necessarily tell me either, a blacksmith could prob'ly tell me quicker "how it feels under the hammer" that two automotive spring steels are different.
5160 vs 6150 vs 9260 for example.
Alvin in AZ
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