Hammer Technique question

[Buzzkill]

I'm sure my question will make it obvious that I am a novice, but here it is anyway:

 

Is there a good or specific hammer technique that will result in growing the width of steel faster than the length?

 

I have access to a fair amount of round coiled half inch spring steel used in the brake chambers on semi-tractors and trailers.  After straightening and pounding a length flat I ended up with about 0.9"  width at about 0.15" thickness.  I had really hoped I would be able to achieve a little over 1 inch width at that same thickness.  For short pieces I'm guessing I could upset the steel to some degree before pounding it flat, but hopefully one of you veterans has some tricks of the trade that can help me get more width from those springs without folding the flat pieces back on themselves and forge welding.  Please let me know if you can shed some light on this for me.

[patrick]

You can determine the theoretical width you'd get assuming no material loss to scale and no elongation by caculating the cross sectional area of the starting stock and the thickness you want to reach. If that width is not as wide as you want you will have to upset. If the math shows you can get to the desired width, then you need to spread the metal using a fuller or cross peen type hammer. A flat faced hammer will move the metal in all directions, resulting in significant elongation. A narrow peen or fuller can be used like a rolling pin to direct the metal where you want it to go.

[Buzzkill]

Please forgive my ignorance, but I could use a little more explanation.

If I understood what you are saying then a 0.5 inch diameter rod could theoretically produce flat stock a little over 1.3" wide at 0.15" thickness.  Obviously that would be impossible to produce, but that's the limit according to the math.

I did use a flat faced hammer for this. If I were to switch to a cross (or straight) peen hammer then I think what you are saying is strike so that the peen is parallel to steel on contact and work side to side to get greater width than length expansion.  Did I understand that correctly?

[Glenn]

You are changing shape NOT volume. The volume remains the same unless you upset, or fold and weld.

For instance 1 inch square can be 1/2 x 2 inches, 1/4 x 4 inches etc and the volume is still the same. You can not make 1 inch square to a final size of 2 inches square without adding material by upsetting or fold and weld.

Edited July 8, 2015 by Glenn

[Buzzkill]

Right, but I'm trying to maximize width expansion while minimizing length expansion.  The volume remains constant, but I'm trying to find out how to move the metal into the shape I want in the most effective way.  I believe what I have already done reshapes the steel in a way that produces roughly the same amount of length expansion as it does width expansion.  I think patrick understood what I was asking and was steering me in the right direction.  I just wanted to be sure that I was clear about his advice.

[BIGGUNDOCTOR]

Patrick is right. Some type of straight peen will need to be used. By running the peen edge parallel with the rod it will spread more sideways, than lengthwise. 

 

 

[Glenn]

Calculate the volume of both and compare notes.

To move metal East West and not North South you will need to pinch or fuller the material. This can be done with two round surfaces squeezing the metal between them, or a round and flat surface, or any combination you can dream up to do the job. You will need to continue to upset the end, driving it back into the metal to prevent the North South dimensional growth, or let it grow and cut off any excess.

Try this with modeling clay first so you can understand what is happening.

Edited July 8, 2015 by Glenn

[Buzzkill]

I think I have the idea now.  Thanks for the speedy replies.  Hopefully I'll be able to give it another shot this weekend and get the desired results.

[Glenn]

Use the modeling clay first. It will give you real time answers to your technique.

Try the horn of the anvil and a cross peen hammer for spreading metal fast. Be sure to make the expansion shallow enough so you can them flatten them without forming folds etc in the metal. Think of it as small rolling hills rather than mountain ranges. You want to then drive the hills down and fill the valleys to make things smooth.

If you have time, or are going to make very many pieces of the new size, consider building a spring fuller with large diameter rods.

 

Edited July 8, 2015 by Glenn

[ThomasPowers]

Please be aware that many modern cross/straight peen hammers are *much* too sharp.  The old one I have the peen looks like a 1" rod was welded on the end for the contact portion making a great spreading shape.  I often use it on top with the horn of my anvil underneath to get double fullering.  Flipping the piece so the other side is up the next time helps keep the hammering even as the horn and hammer are not the same curve. and yes with a straight peen the peen should be parallel to the long axis where you are trying to widen the short axis.

[Charles R. Stevens]

Several posts on dressing hammers on here. Usualy I would go into a long explination but the forum has a bug that dosnt like us doing that right now.

so your looking for a 1-1/2 to 2# cross pein or "blacksmiths" hammer. As TP pointed out it needs a faily blunt pein (i use a chopsaw then grind and sand) and a slightly crowned and well dressed flat face. 

So after going one pass down your heated stock to make a nice flat, flip the hammer over and aply the pein longways down the flat (1/2" is small so lift it off the anvil between blows) now target the hup on each side of the vally. Continue "pulling" the steel sideways. If you have hammers with bigger radie peins, it is good to swich to a lager pein as your stock gets thinner and wider, as it leaves shalower dings. 

I like Brake pot springs for punches, pricels, chisels etc as well. And as they see a relitivly low cycleing in their service life (we no longer rediaphram them) the springs are usualy not fatiged.

Edited July 8, 2015 by Charles R. Stevens

[matei campan]

what I do when I want maximum width from round stock I do that: first just hammer a bit the round stock to have some small flatness upside on and under the bar, just enough to "stabilise" it. then, I take a quiet "sharp" (~10mm diameter) cross pein and hammer it with it parallel to the length (obvious), alternating the faces. when the bar achieves some width comes some closer to the desired thickness, I take a less aggressive cross pein (~30mm dia) which helps removing the marks of the previous hammer and widens the material more. just when I'm close to the final thickness I take a flat hammer and finish the surface.

[Buzzkill]

Thanks for all the info.  I really appreciate it.

 

Charles R. Stevens - quick question. What do you do to get the springs out safely?  I was thinking about placing them on the forge to heat the pot and springs up to red hot to relieve the tension.  The spring was broken in the one I took apart so far, but I'd really rather not injure myself getting at the rest of those springs.  

[SmoothBore]

I have several short lengths of 1'' to 2" diameter round bar, welded into a "T" shape, ... using a bit of square stock that will fit into the Hardy Hole, as the "leg" of the "T".

 

By using the round stock as the "fuller", ... I can use a "flat" faced hammer.

I find this easier than trying to strike precisely on center, with a cross pein.

 

.

Edited July 8, 2015 by SmoothBore

[Pat Roy]

I don't know what you are making with this material but it sounds like a lot of work to get the size you want. If you are making a lot of pieces, I would consider buying stock of the right size (or nearly the right size) and going ahead from there. 

[Charles R. Stevens]

Use a press, heating the brake pot will melt the aluminum and burn the ruber diaphram. If you pace it in a press, you can then cut the steel band holding the two halves (they used use a clamp that unbolted but one tomany fool tried unbolting them with out copressing the spring) now you can relise the press and it will open up safley. 

Pat, this is the same descusian that always goes back and forth, but if your not a proffecinal, then "upcycling" has a certain apeal to some of us. Even some of our customers like to brag about what this hear tool used to be.

Edited July 8, 2015 by Charles R. Stevens

[Buzzkill]

I'm going to be melting the aluminum down for other projects anyway, but the press does sound like a much safer way to go as long as I can keep it from bending in the middle while decompressing the springs.

SmoothBore, great idea.  I think I'll fab one of those up and give it a try.  That should be a little bit easier to use than the horn of the anvil.

Pat, right now this is a weekend hobby for me and the family budget doesn't tolerate much additional expense for it.  I can get these springs for free and in general I like to use what I already have or can get for free rather than buy new stuff.  But you're right of course.  It's a lot less work to purchase what you need or close to it.  On the other hand we could also purchase a lot of the things we make, but where's the fun in that?

[Charles R. Stevens]

A elcheapo 12 tonn press from harborfreight works just fine, you dont have to squish the thing to death, just depress the acuator rod to compress the spring. A guy could weld up a frame and use a threaded rod with a cut to trap the rod if he would rather, but you beed to use 3/4" allthread to be safe

S a side note I have seen theis little nasties used as clamps by a guy who builds gates and stock pannels, aply air and they relise, vent the air and the apply, might make a heck of a vice...

Edited July 9, 2015 by Charles R. Stevens

[Frosty]

A elcheapo 12 tonn press from harborfreight works just fine, you dont have to squish the thing to death, just depress the acuator rod to compress the spring. A guy could weld up a frame and use a threaded rod with a cut to trap the rod if he would rather, but you beed to use 3/4" allthread to be safe

S a side note I have seen theis little nasties used as clamps by a guy who builds gates and stock pannels, aply air and they relise, vent the air and the apply, might make a heck of a vice...

Ayup, I have a brake can vise and single shot air hammer drawings somewhere. The guys in the heavy duty shop screwed a bolt in one side to lock the spring down. Once they opened it up they could release the spring without it getting away. I never watched them do it nor have I opened one so that's all I know.

Oh, there's one other thing I know, don't mess with them unless you know what you're doing, they'll kill you faster than fast.

Frosty The Lucky.

[DSW]

Search "caging air brake springs"

 

 

I saved this "tutorial" on caging air brake springs that another guy did on line so I'd have a reference so I'd know how for later.

 

 

Quote:

 

I had to change a service diaphragm in a chamber today so I thought I'd take a couple pics for you on how to cage the chambers.

First picture is what we're starting with. Side view, notice the bolt above the two air lines? We will be using this bolt. If you don't have a bolt on the chamber you can get one at most places that sell heavy truck parts.

 

 

 

 

Removing the bolt from the chamber. This bolt is called a caging bolt and it get's utilized as a tool. It is a 3/4 wrench size. Don't lose the nut or washer, sometimes the threads are a special square cut.

 

 

 

 

This is what the bolt will look like when you get it out. You will need to clean the threads with a wire brush, they get lots of crap on them from being in those holes, put some oil on the threads too  to make it easier on yourself. Take note of the "T" end of the bolt.

 

 

 

Looking down the end of the chamber in the hole, you should see an aluminum piece with a stamp out that will be shaped like the "T" on the bolt. Insert it into the hole and turn it clockwise until it stops (90 degrees) and then try to pull it out to make sure it is engaged right. If it pulls out, try again. Sometimes you have to hit them in with a hammer a bit and use pliers to get them to turn into the slot.

 

 

Tighten the nut down until it stops. The end result will look like this. There will be some tension to overcome when tightening this bolt. Keep in mind your compressing a spring that has coils like large automotive strut springs, they're tough to compress. With both sides like this, the brakes should be released. If the shoes don't back away from the drums, beat on the drums and shoe frames with a big hammer, they should pop free. Hope this helps, if you need a pair of caging bolts let me know.  Zombie

 

 

 

 

 

Thanks again to Zombie over on weldingweb for his write up that I quoted above.

[rockstar.esq]

Smoothbore's advice reminds me of a Woodwrights shop episode with Peter Ross.  Roy Underhill referred to the anvil as "the hammer that never misses".  It seems obvious but as a novice I find myself trying for incredible levels of hammer precision rather than putting the smaller target area of the work on the anvil (or anvil tooling).  Plus it's much easier to hit harder with less precision so if the "precision work" is on the anvil side, you'll get more work done in fewer heats.

This seems like a good application for a smithing magician, or a clapper die set that's fastened to the anvil. I could also see a crowned wheel in a rolling mill working pretty well for the fullering.

[SReynolds]

Post up a video or some pics of removing the spring from the brake chamber. And include  any remarks like "this next step is where people die" so as to warn us.

[Charles R. Stevens]

That works fine on the truck, as the cans are probbably dismounted, put the can in the press accuater rod up and press down on it. 

[ThomasPowers]

After explaining how the "hammered look" is more a function of the Arts and Crafts movement and not traditional smithing and how I try to have smooth even hammering I tell my students that the anvil is a much superior hammerer than either of us is.  Octagonalizing the taper on an S hook shows this well---especially on their first one.

[Buzzkill]

DSW, the caging bolts that come with air brake chambers are too short to relieve the tension in the springs if you cut the pot loose from the aluminum piece in the middle.  Someone could get seriously hurt if they tried to cage the spring, cut the pot loose, then remove the nut from the caging bolt.  There will still be a LOT of spring pressure in the system when you run out of threads, which will create a dangerous projectile situation.