Touchmark diameter?

[falsevacuum]

Hi!

I've decided I'm going to take advantage of the fact that I have free access to a machine shop and machine myself a touchmark. I've settled on making two designs, a large and a small (attached). However, I'm trying to figure out an appropriate diameter.

My original thought was to make one 1/2" and one 1", but after thinking about it some more, a lot of work (e.g. hooks) often doesn't have anywhere on it that's a 1/2" across. Also, 1" is huge. On the other hand It doesn't seem to me that steel under 1/2" diameter will hold up under a hammer.

My current best plan is doing larger one as 1/2" and shaping the smaller down to 1/4" at the design end with a 1/2" shaft and striking end.

What are your recommendations? If it's relevant, the steel I'm planning to use is S7.

Thanks!

[Alan Evans]

Only you know what size of pieces you make...and therefore what diameter will be most appropriate. You seem to be reasoning it out yourself quite effectively!

The longer the shaft the heavier cross section you require to make sure the energy does not dissipate in whip.

The taper down to the face needs to be fairly shallow so you can see where the mark will come on your workpiece easily. 

Good idea to build in an alignment flat into the shaft so you can clamp a bit of bar across the workpiece and ensure that the mark is then punched in line. Looks awful if it is drunken on an orthographic / symmetrical / formal piece.

Looking at your proposed designs I would be wary of too much detail and too many ends. Enclosing geometric frames can help with establishing focus onto the logo and making the punch itself inheritantly stronger. 

Of course if you are intending to make a punch by cutting those black shapes into the surface of the square borders you show, be aware that you will need a very heavy blow to push all that material down and leave the black part upstanding...the black areas tend to get dragged down and the image is fairly indistinct until you have hit it quite far into the surface, even if you are able to maintain perfect registration. Which has obvious implications for distortion of the workpiece.

Alan

[falsevacuum]

[falsevacuum]

[VaughnT]

I wouldn't use an 8" shaft on the touch mark.  That's mighty long and most companies I've seen are only offering a 5" punch for hand-held use.  Also, the more massive the punch, the more energy will be needed to break it loose.  A body at rest tends to stay at rest, after all, and getting a pound of steel to move is far more difficult than getting a quarter-pound of steel to move.

As for size of the actual mark, think about the types of things you do.  While you want your mark to be visible, you don't want it to stand out like a squished bug.  A small mark can be used on items big and small, but a big mark only looks good if the piece it's on is proportionate in size.

Also, pay attention to line thickness and the open spaces between and inside the characters.  If you're putting a mark on cruddy steel, covered in scale and hammer marks like so many customers prefer, you'll lose a lot of the detail in your mark.  Heavy, thick lines, as has been mentioned, require a ton of force to sink into the metal.  The more there are, the more force it takes.  The cartouche surrounding your initials can afford to be thin because it's only there to draw the eye to the initials.  If it's too thick, you're adding to the work needed to drive the stamp into the metal.

Of course, a lot depends on how you plan on stamping the metal.  A lot of pros recommend using a press whenever possible because it allows you to get precise placement and depth.  If you go that route, you don't have to worry too much about the rest.

[falsevacuum]

Hmm... I've already sent in the design and specs to the machine shop, and they really hate changes. (I've already been chasing them in circles for weeks just to get an OK on the project) Do you think I'll probably be OK with the above designs? I can definitely cut the touchmark down to 5 inches pretty easily afterwards, though!

 

Edited July 20, 2015 by falsevacuum

[neg]

My touchmark is probably 4" long. I really wish it were longer, I just end up burning yourself trying to hot stamp things with it. You'd think you could just hold it with tongs and it wouldn't be a problem, but when you mess up or don't stamp deep enough and have to realign the stamp on the steel, it can take some time and it's hot.

[VaughnT]

False, the smaller one you last showed, with the cartouche, will probably work.  If that's the actual size, I think you're pushing the limits of what you can do with a hand-held punch and get consistent strikes.  The larger one... way too much mass to move around.  Those thick black likes and all the letters will require you to use a press of some kind, or a ten-pound sledge.  I could be wrong, but I don't think you'd get a good impression even if the metal was good 'n hot.  

If the shop is already set to do the work, let them do their thing and consider it a learning experience.  An 8" stamp might be good for you, and you can always cut it shorter if you feel the need.  Personally, I generally mark metal while it's cold so I can get precise alignment without worrying about losing the heat or getting burned.  If you find yourself doing a lot of hot stamping, that long shaft would be really nice to have!

[kayakersteve]

In regards to 'Neg's" comment, if your stamp is appropriately heat treated, you can cold stamp with it.  That's what I do with mine from CMT tool

[falsevacuum]

Thanks for the advice!

Neg & Kayakersteve: I do plan on using it as a hot stamp most of the time, and I plan on heat treating it as such. S7 for hot work, from what I've read, should be quenched at orange in still air, then, once cool, should be twice reheated to 900F, which is just barely visibly radiating in the dark, and cooled. Is that correct?

Vaughn: Hmm... I do have access 10lb sledge but I would never subject my 150# anvil to that. Moreover, I don't have access to someone to swing that hammer for me If it fails, it will be a learning experience. If it succeeds, I'll come back and post it here! I'll definitely keep them both at 8" unless I feel they need to be shorter.

 

Honestly, I'm not that concerned about it being the most beautiful stamp in the world since I'm just getting started with forging. It's all learning experiences.

 

Also, a separate question: should I heat treat the striking end? Since I'm buying annealed steel, it seems like that would be wise to ensure my hammer doesn't mushroom the striking end. I don't really want to buy a separate hammer just for striking if I can avoid it.

[VaughnT]

The struck end of any tool needs to be dead soft.  Mushrooming is a cost of doing business and far far cheaper than the medical bills resulting from catching a flying shard of steel as it takes off like a speeding bullet.

Your 150# anvil can easily handle a 10# sledge, especially for one or two strikes needed to put a mark on something.  

[SpankySmith]

Just as a total aside:  I originally ordered a 1/2" from CMT, got it and decided it was too big for MOST of what I work on, so I ordered another at 1/4".  But that larger one has come in handy to mark books!   I purchased a book that had a leather cover and wanted some way to distinguish it as mine because I sometimes lend out books that end up getting irretrievably "mixed in" with someone else's collection.   A quick stamp in the bottom right corner of the cover looks REALLY nice and there's no mistaking it as mine now.   I'm sure there are infinite other such uses for touchmarks besides iron.