round or flat hammer face to hit punches?

[Ethan the blacksmith]

I have thought for a long time that you should hit a punch with your flat die of your hammer, but recently, I have seen some people turn to their round die for punching. Is their a reason or recommendation for this?(only applies if you have a rounding hammer...)

[arftist]

Ideally one wouldn't use a forging hammer to strike sets or punches, though I know some who do. Even more ideally, a young fellow such as yourself should learn the proper names for tools and their parts. A rounding hammer may have a round face or a flat face. Hammers do not have dies. 

[arkie]

Technicus Joe recently addressed the hammering technique of using the flat versus rounded face of a hammer.  Do a search of his videos for details.  According to Joe, hitting with the flat face sometimes results in either off-center hits or hits not perpendicular to the tool.  Using the rounded face reduces off-center or mis-strikes.  One doesn't have to use his/her forging hammer to strike, but can use other dressed hammers dedicated to striking tools.

Edited May 1, 2015 by arkie

[Jim Coke]

Greetings Ethen,

The best way to get escorted out of my shop is use a forging hammer for chisels or drifts. Just My 2c

Forge on and make beautiful things

Jim

[Ethan the blacksmith]

Question: why not use a forging hammer for punching hot iron?

[Steve Sells]

because the tool is not hot and can marr the face. or small pieces break off and end up in the eye, face etc.

[Michael Cochran]

Because you don't wanna mess up the pretty and smooth dressing. You could mark up the hammer face and then either leave marks in your forgings or have to redress it again before you use it. 

[Charles R. Stevens]

It is generaly beter to use a soft face hammer (such as a drillers hammer) on a tool that may be hardend. A proper smiths hammer has a hardend face, just like an anvil. Despite what you have seen on Mith Busters (new store bought hammers have softer faces now due to liability issues) striking hardend faces together is bad juju (shrapnel) and by the time you have spent properly heat treating and dressing a hammer i dont want to risk palding the face, even if i dont have to have the ER doc remove it from my belly. Belive me (9 staples in my arm) properly heattreatd and dressed smithing tools (in this case a cold chisel) are not the tools you buy at Loes'

[SJS]

After learning the hard way I make it a habit to use a brass or copper mallet, or an annealed steel hammer to strike tooling. I have a large stock of S7 and H13 tool steel drops.  So most all of the struck tools that I make are made of fancy air hardening tool steel.  Which means they are HARD all the way through, and when they spall they have a LOT of energy.  Most of my forging hammers are softer than my tooling, and if I hit the tools with my hammers they lose, and I have to redress the faces.  Using 4140 and coil spring for your stock for making your struck tools, and using them as forged and just normalized like I remember Brian teaching.  Your hammer should be harder than the struck end of the tool???  But salvaged steel is notoriously unreliable in how it behaves, some times it normalizes like you expect it to, and sometimes it air hardens unexpectedly. Not to mention that even when a tool is normalized, if you beat on it long enough many steels will work harden, and can still spall.  When a tool spalls the word shrapnel  is really descriptive of what comes off, because it is hot, is moving fast, and can tear you up. It can hurt you, someone you love, or someone in the crowd watching you...  It is a liability you don't want to mess with.  Always keep the struck ends dressed back to prevent mushrooming, and it is still safer to use a softer mallet.  With a copper mallet you don't deform the tool, and the mushrooming of the mallet isn't really of much of concern, because the chunks that come off the soft mallet don't seem to have the energy of (work) hardened steel.  Best practice is to use a softer hammer on struck tools.  Lots of people try to "engineer" their tools so they can just use their forging hammer for everything...  But what happens when you get a fancy chisel or slitter made out of some hardened tool steel, or when the tool mushrooms and work hardens.  Think about risk management, everything we do is dangerous, how do we minimize those risks.  It only takes one accident to change your life forever, and you only have to protect anything you would like to keep... Which would include your family farm and your business, a personal injury attorney with a liability law suits play for keeps!  A little due diligence with a belt grinder, or right angle grinder helps keep your tools in properly dressed, and safer.

[Ethan the blacksmith]

I make all my punches out of mild or annealed spring, because I follow brains teachings. and I do try to keep the ends of my punches dressed and ground. so I m good right?

[Matt_K]

Hit a round with a flat, and a flat with a round. If the hammer's chipping, or marking up, get a different (cheaper) hammer.

[VaughnT]

I use the flat face of the hammer regardless of how the impact end of the chisel/punch is shaped.  The idea that you might get a mis-strike isn't entirely accurate because you can also get a goof by using a rounded face.  If your hammer is rounded, that really narrows down the sweet spot and anything even a little off-center will throw your hammer to the side.  With a flat face, you can get a solid contact even if the hit is a bit off-center.  It will twist the hammer in your hand, obviously, but it won't be nearly as glancing a blow as if you used a round-faced hammer.

Does that make sense?

Definitely want to use a soft hammer so you don't end up marring your good hammers.  Even if you anneal the end of the punch, it's still a pretty hard surface.

[Quarry Dog]

  Has anyone ever heard of a slightly concave faced hammer made of mild steel?  I have a stonecarver for a buddy that uses one, and only that one, on his carbide tipped tools, as advised and sold by the manufacturer.  He says as long as he doesn't completely miss, it is basically impossible to strike a glancing blow.

  I honestly want to try something like it myself.

[Alan Evans]

I have heard old boys refer to a concaved  faced hammer as "having a hole in it". The only one I have is one of my chasing hammers, I inherited it from my grandmother who used it for punching designs into her leatherwork. The other ones I have are traditional chasing hammers; all relatively large diameter and flat faced.

A round faced hammer for driving punches is all wrong as far as my experience goes. With glancing blows almost a given. What you want to do is transmit energy into the tool not focus it in one place and cause the struck part to upset or mushroom quicker.

Having said that I invariably put a subtle crown on the end of all my struck tools so that the energy is directed towards the centre of the tool.

Alan

[arftist]

To recap for clarity; 

a forging hammer is usually polished, at least somewhat. Striking hot metal will not harm such a finish, striking cold steel will or at least could. 

Then there is the shrapnel issue. Hard metal against hard metal = bad. 

finally we come to crown. Most hammers (even nail hammers properly called roman claw hammers) have at least a slightly crowned face, so no, you really don't want to use a "flat" face on a struck tool. As mentioned by others, a slightly crowned hammer face helps with slightly offcenter blows. Frosty can probably explain the physics of it better than I can, he seems gifted that way. 

To make life simple in the shop I use ball pein hammers to strike tools. I don't use them for general forging other than riveting or I am using the ball end,  and so don't have to worry about the face too much. 

And yes, if you want to see me snarling, grab a polished hammer out of my rack without asking and start whacking a center punch or cold chisel. 

As to the ultimate safety issue; in my career of a little over 35 years I know of two deaths from shrapnel, Yes, deaths. One hit in the neck and one in the groin, both bled out. 

Some of this stuff is not to be taken lightly. 

[SJS]

I make all my punches out of mild or annealed spring, because I follow brains teachings. and I do try to keep the ends of my punches dressed and ground. so I m good right?

​Yes, Ethan mostly, with milder tools with a normalized heat treat, and well dressed struck ends you should be safe enough.  Spalling doesn't happen very often even when you do everything wrong, its just it can be disastrous when it does.  You just don't want to be one in a million that way. What a lot of us believe is you should establish safe working habits that work across a wide range of situations.  If you only work with your own tools, then that practice is probably safe enough.  But what about if you are at a conference, or if someone gives you a set of fancy Brent Bailey tools for Christmas, its the exceptions, and the odd situations where habit takes over that get you in trouble.  If you were to come to my shop and work with me, and struck  a tool with your forging hammer, it could end badly (your hammer face gets all garfed up, the end of the cutter spalls, I freak out;-)  The principle is to protect yourself from an equivocal situation, where you think its safe, but it actually isn't.  We are all training ourselves, consciously or unconsciously.  With my tools and technique it is rare for me to need to redress either end of a tool, other than my thin round punches.  I have a hot cutter that I have used for 10+ years, and have probably never resharpened.  It is convenient and faster to use the normalized tools and just use your favorite forging hammer.  As long as you are conscious of the issue, when you are in a strange situation, you will hopefully remember...

My copper and bronze mallets take a concave face after a bit of service.  A note about hammers with a DEEP concavity, your struck tool ends need to be long enough that the hammer doesn't hit your hand with and inch or two of the tool sticking up past your hand...  My old favorite bronze mallet took on a VERY concave form, I started to cave in the eye, and had to rehandle it several times before finally retiring it.  I am tempted to recast it into a new hammer head... In my copious free time...

[Ethan the blacksmith]

thanks all for the suggestions am currently trying out what works best for me.

[SmoothBore]

I use the flat face of the hammer regardless of how the impact end of the chisel/punch is shaped.  The idea that you might get a mis-strike isn't entirely accurate because you can also get a goof by using a rounded face.  If your hammer is rounded, that really narrows down the sweet spot and anything even a little off-center will throw your hammer to the side.  With a flat face, you can get a solid contact even if the hit is a bit off-center.  It will twist the hammer in your hand, obviously, but it won't be nearly as glancing a blow as if you used a round-faced hammer.

Does that make sense?

​Well, ... not exactly.

The "Human" factor, ... introduces a lot of "variables".

Unlike a Machine, ... when a Human swings a Hammer, it travels in an arc.

Therefore, ... geometrically, ... there is only 1 point in that arc, where the Hammer face, and the end of the Punch are actually parallel.

The rest of the time, ... the 2 surfaces are meeting at a shallow angle.

So in reality, ... a rounded hammer face, is more likely to direct it's energy into the center axis of the struck tool.

 

Understand, ... we're talking about a gently "rounded" Hammer face, ... NOT a Ball Pein Hammer.

 

.

 

[Alan Evans]

​Well, ... not exactly.

The "Human" factor, ... introduces a lot of "variables".

Unlike a Machine, ... when a Human swings a Hammer, it travels in an arc.

Therefore, ... geometrically, ... there is only 1 point in that arc, where the Hammer face, and the end of the Punch are actually parallel.

The rest of the time, ... the 2 surfaces are meeting at a shallow angle.

So in reality, ... a rounded hammer face, is more likely to direct it's energy into the center axis of the struck tool.

 

Understand, ... we're talking about a gently "rounded" Hammer face, ... NOT a Ball Pein Hammer.

Well, ... not exactly.

It would be the crown face of the punch rather than the hammer which would direct the energy into the centre axis of the tool. The crown face on the hammer may help prevent the hammer from pitching and rolling...

When I am grinding the crown on the tool I envisage a sphere with the centre point on the cutting edge of the chisel or the other end of the punch. The length of the tool is the radius. So a strike anywhere on that surface is directed to the working point.

Alan

[Charles R. Stevens]

Concave faces may be good for stone carving tools (many have a hardend hollow striking end that bites the hammer face) but for a little wile one carpenters hammer manufacture tried it, and it sucked for driving nailes. As to flat faces, I know that common farriers rounding hammers have very flat faces, and untill redressed the slightest off center blow causes the hammer to jump in your hand. As the rounded face on on a rounding hammer realy isnt round, its prety flat torf the center, and Brian is aiming for effecency, he desighns his tools to be struck by the same hammer he uses for everything else. This saves him heat. Be aware if the risks and prepair safety proticals for your shop, your tools. But be aware that other proticals exist for other tools and other shops. I my self have struck my tools with my forging hammers, but i found that H13 handled tools were to hard on the struck end and had to change my working proticals to acomidate that. 

As to the curved swing, proper technique takes most of the curve out of the swing, alowing inersa and gravity to to most of the work after initial exeleration and before "rist snap" alowes you to pull your elbow back as your forarm aproches horizontal. We are not machines but we are very versital and mucle memory can be used to develop good as well as bad habits.

[Quarry Dog]

I could definitely see concave hammers and nails not mixing well.

"Hmm,  I can't sink my nails all the way without marking up my wood?"

I've never used his carving tools.  Heck he won't even let his wife touch 'em.  I would imagine that maybe the hammer would try to twist a little if you don't hit pretty close to center.  I  would imagine a little tweak to the wrist would hurt less than nailing my thumb with a 4 pound crosspein.

I guess I'll have to make one some day.  Maybe as practice for making one that I'd actually use for forging.  It would be a perfect opportunity to acquaint myself with punching and drifting an eye.

[basher]

I,m with Alan on this one I always crown my punches and chistles. and happily use any of my workshop hammers with a nice wide face.

 I make chisels with normalised striking ends and dress them regularly and sub critically anneal them on a regular basis as well to insure they are soft and kind to the hammers and me.

 struck tools are consumable in practice.

 

Edited May 2, 2015 by basher

[Francis Trez Cole]

you should always keep you punches dressed it reduces the risk of pieces breaking off. I keep my hammers oh the harder side so the use has little to no effect on the face. I do not keep my forging hammer with the face mirror polished. I do buff my sheet metal hammers polished. But I would not hit a punch  with them.

 

[SmoothBore]

It would be the crown face of the punch rather than the hammer which would direct the energy into the centre axis of the tool.

​Perhaps, ... but a fellow Countryman of yours had a somewhat different opinion .....

"The relationship between an object's mass m, its acceleration a, and the applied force F is F = ma. Acceleration and force are vectors (as indicated by their symbols being displayed in slant bold font); ... in this law the direction of the force vector is the same as the direction of the acceleration vector.

Therefore, ... my understanding of Newton's 2nd Law of Motion, leads me to believe the Hammer and Punch have an equal influence in directing the force of the blow.

 

Since the original post was a question about the shape of the Hammer Face, ... the response deals primarily with that issue.

 

.

[Alan Evans]

​Perhaps, ... but a fellow Countryman of yours had a somewhat different opinion .....

"The relationship between an object's mass m, its acceleration a, and the applied force F is F = ma. Acceleration and force are vectors (as indicated by their symbols being displayed in slant bold font); ... in this law the direction of the force vector is the same as the direction of the acceleration vector.

Therefore, ... my understanding of Newton's 2nd Law of Motion, leads me to believe the Hammer and Punch have an equal influence in directing the force of the blow.

 

Since the original post was a question about the shape of the Hammer Face, ... the response deals primarily with that issue.

 

.

​

Well I admit my conclusions are based on empirical observation rather than theory, but I think they conform to Sir Isaac's law. 

 

My understanding of the law you quote is that it refers to the direction of movement of the hammer head itself, and not a line perpendicular to the hammer face crown, which is what you appear to be saying. 

 

The crown of the punch or chisel head as a section of sphere centred on the working end as far as I can understand is what is directing the energy there. The shape of the hammer face has little beneficial influence on this, and in my experience is better flat than rounded from the point of view of glancing blows.

 

Given that the angle of incidence we are talking about between a hammer and a long and thin hand held punch or chisel is pretty negligible the effects either way are also fairly slight.

 

However slight, the principal of my crowned head system was arrived at initially from using flat and wide faced chasing hammers with crowned topped commercially made punches via the use of "dee" shaped fullers which conform to tapers under the power hammer pallets and a not particularly misspent youth which involved an occasional game of snooker, as Illustrated below.

 

Alan