Using stamps for numbers and lettering.

[drmico60]

It is not easy to achieve a good spacing of numbers and letters when using stamps to mark metal.
A little trick that I have used several times is to first print out the text onto a paper label using a similar font and character size to the stamps.
The metal to be stamped is set up on a solid surface with a vertical straight edge to guide the stamps in a straight line. Stick the label onto the metal just in front of the straight edge and use the text to guide the position of stamp. The stamp can be pressed firmly into the label with hand pressure and this leave an indent in the label but not the metal so you can check the position. Once satisfied with the positioning then the stamp is repositioned in the label indent and hit firmly with a hammer to indent tne metal.

[rgsparber]

This method works great. I found that Arial Unicode MS 14 is a close match to my Harbor Freight stamp set. I print out the text on my DYMO LabelWriter 450. Since all of the text to be stamped is visible, I can use a given stamp at every position that needs it. That way I don't have to pick up the same stamp twice. Does speed up the process a bit.

Now, if I could just be more consistent with my imprint depth...

Thanks drmico60,

Rick

[tonyfoale]

Now, if I could just be more consistent with my imprint depth...
Rick

It would not be too difficult to make some form of stamp holder with a vertical extension to hold some form of weighty block at an appropriate height, on a slide. Add a trigger (for example) release and hey presto - even indents every time. A little experimentation prior to building would soon get the mass and height of the block determined.

Of course this will only work on surfaces that you can arrange to be horizontal. Although a bell crank could turn the force.
For non horizontal surfaces you could replace gravity with a solenoid or maybe a pneumatic cylinder into which you could rapidly dump a set volume of air at an appropriate starting pressure.

[CanBeDone]

It would not be too difficult to make some form of stamp holder with a vertical extension to hold some form of weighty block at an appropriate height, on a slide. Add a trigger (for example) release and hey presto - even indents every time. A little experimentation prior to building would soon get the mass and height of the block determined.

I have tried that years ago - it produces multiple imprints because punch and hammer rebound. And I have also learned that I cannot suppress rebound even if I build the hammer as deadblow: my stamp, the item to be stamped, and the support upon which the item rests are all elastic, and will cause rebound. Once you look at the physics, you'll see why: dropping a hammer plus stamp of mass m a distance h stores energy
E=m.g.h
in it (g=9.81m/s is the acceleration of earth). When the stamp then penetrates a distance x, leaving its imprint behind, the (dynamic) force F it exerts is
F=Edx²/dt²
And in this formula all the problems with non-repeatable penetration depth are represented but not visible, since much of what goes into it is hidden: how the item deforms as the stamp starts to penetrate is a function of x, how much it is accelerated downwards due to the force applied to it, the mass and elastic properties of the support it rests on, you name it, all contribute to x, and as a result it muddies up the penetration depth x to make it as good as unpredictable. Since the stamp's downward moving velocity v is
v=dx/dt
it follows that, for repeatable penetration depth, the first derivative of x, the velocity with which the stamp moves downward must be close to zero, and thus the force, dependent upon the second derivative of x with respect to time t, exerted by the stamp on the item must be static in nature, not dynamic. And static forces require a press, not a hammer blow.
How potent a press? I have progressed so far that I can say for a 4mm number stamp I need a force in the vicinity of 5 ton for a decent impression in mild steel, i.e. an arbor press is ruled out as not powerful enough. The next question I need to decide is whether I want to measure and control the force acting on the stamp, using a strain gauge, or do I want to measure and control its travel into the item using a DTI? On that I am currently undecided, what is more robust? and what is more repeatable, to a measuring error of, say, 20 micrometer? After all, my eyes are quite capable of perceiving such a step, and that is the measure I need to apply.

[tonyfoale]

This method works great. I found that Arial Unicode MS 14 is a close match to my Harbor Freight stamp set. I print out the text on my DYMO LabelWriter 450. Since all of the text to be stamped is visible, I can use a given stamp at every position that needs it. That way I don't have to pick up the same stamp twice. Does speed up the process a bit.

Now, if I could just be more consistent with my imprint depth...

Thanks drmico60,

Rick

Rick,

I was just idly browsing through a tools listing, not looking for anything in particular when this popped up
https://www.ebay.es/itm/38pc-AUTOMAT...sAAOSwzJ5XUrxZ
Something like that could be the answer to your even imprint problems, I guess that it works just like an automatic centre punch.

[bruce.desertrat]

I have one of those sets, it's not exceedingly powerful, and did not make decent impressions in steel; Also the letters are quite tiny. Yes, it's essentially a center punch with a stamp holder instead of pointy bit.

Maybe something like this Spring Center Punches & Nail Sets - Lee Valley Tools with a holder for the stamp instead of a punch on the business end.

[drmico60]

The problem with stamping uniformly is not solved by having a consistent pressure/impact. This is because each letter/number has a different total line length and therefore requires a different pressure. For example the length of the lines making up the letter H is nearly three times the length of the lines making up the letter I so to stamp an H needs nearly three times the pressure to get the same indent depth as stamping a letter I. Each letter is different so there require different pressure on the stamp.
Mike

[tonyfoale]

The problem with stamping uniformly is not solved by having a consistent pressure/impact. This is because each letter/number has a different total line length and therefore requires a different pressure. For example the length of the lines making up the letter H is nearly three times the length of the lines making up the letter I so to stamp an H needs nearly three times the pressure to get the same indent depth as stamping a letter I. Each letter is different so there require different pressure on the stamp.
Mike

How come the flipping obvious is so often hidden in plain sight?

[bruce.desertrat]

Duh! brilliant and simple idea! I've been meaning to remake our dogs's name&phone ID tags, since their existing ones are kinda beat up, and I always seem to make them look more like a ransom note than anything else :-)

[blkadder]

I can't believe that I missed this when it was first posted. I have not had great luck with my stamping projects (usually home built firearms), and this would pretty much solve the issues that I was having. It would also be useful to make templates for etching information into metal. Thanks for posting this.