Beginner's question on guns and knives

technogypsy · Nov 5, 2009

I was wondering about how one handles engraving on a stress bearing part of a firearm or a knife blade. Do you need to heat treat after or is it possible to engrave on hardened metal? If the latter, do you have to stress relieve after?

If you can't and you have to anneal the metal first, how do you protect the engraving in the thermal cycle? Especially with inlays and enamel work?

Confused
Kevin

John B. · Nov 5, 2009

Kevin.
You normally do not engrave hardened knife blades with cutting tools.
Most that are decorated are done with acid etching.
They can be cut before hardening and then carefully polished.
That can result in stress problems in some cases.
In most cases it is best to avoid annealing gun parts for engraving and most parts do not require it.
Where a part such as a hammer with attached built-in sear surfaces requires to be annealed and rehardened it is advisable to consult an expert for this service.
Just my thinking....others may disagree.

technogypsy · Nov 6, 2009

John,

Thanks. That makes sense. I couldn't see how it would work but I am mostly clueless about it.

How does one protect them from scale in hardening? An oxygen free furnace or something?

Kevin

John B. · Nov 6, 2009

Kevin,
Yes, an oxygen free furnace is probably the best way.
But some use a stainless steel foil wrap with a small piece of paper enclosed to quickly burn off the oxygen.
Neither of these methods is perfect and some heat color will need careful polishing.
One must allow for this at the time of engraving as super fine detailed work or bulino could be damaged by the polishing.
Take a look at the postings of our artist friend Montejano on this forum.
He is an expert at the decoration of knife blades and other hard metals using etching.
He has done many tutorials showing his wonderful technique.

monk · Nov 7, 2009

i have engraved on annealed blades. even some of those were super buggers. i'd never consider doing one that was hard. engraving on hardened gun parts that take pressure stresses during firing can certainly be done. the fact that you're inquiring, however, leads me to think you are somewhat lacking in experience. one should never anneal or heat treat gun parts without an absolute knowledge of what they are doing. this can prove disastrous.

technogypsy · Nov 7, 2009

Ah, somewhat? Monk, I am about as raw in this as you can get. Let's be kind and say close to an idiot on this topic. I do know a little about heat treatment and metals from my day job, but if it isn't polymeric, I'm not expert.

I did know about the carbon trapping trick for knives. The etching makes more sense...

I was actually curious as I do occasionally forge a knife or re-harden a chisel and couldn't see how one could do that engraving on something that hard (even when tempered). As to the guns, I just wondered as there are so many examples here. I've seen a stress rise cause a pressure vessel to shatter and wondered. I guess the cuts aren't deep enough to create one. If I ever get out of the "sucks" stage, I may try on a repro kit...

Thanks again. I suspect there will be lots of dumb questions in the next few years.

Kevin

Hot Knobs · Nov 7, 2009

Engraved blade

Keven, here is a picture of a knife I had engraved before it was heat treated, it was finished to 400 grit, heat treated in foil then finished with 600 grit on a block, blade is 440 C stainless, handle is mammoth ivory, bronze between blade and ivory, nickel silver sheath.

John B. · Nov 7, 2009

Thanks for the pics Hotknobs.
Will you be at the Reno show this year? Hope to see you there.

Kevin, you will notice that Hotknobs avoided having super delicate engraving put on this knife because of the need for post finishing.
You also asked about inlays and most precious metal inlays are OK with the heat required to heat treat most steels.
I can't speak about enamel inlays as I have not used them and am not sure of their firing temps.

Hot Knobs · Nov 7, 2009

Reno Show

John, I will be at the Reno show if at all possible, have a table next weekend with a friend at the Big Reno Show if my new knee will let me walk that far.

John B. · Nov 8, 2009

Hotknobs,
Look forward to seeing you in January
Take care of that knee, Hotknobs and hope it serves you well.
Just the thought of that kind of surgery has a certain pucker factor, for sure.

McAhron · Nov 8, 2009

For firescale free parts you have 3 choices.#1 use a inert atmosphere furnace#2 heat treat foil and #3 for non-stainless steel use anti-scale compound from Brownells, you apply it at 500f and it coats the steel and protects it to 1850f,it washes off with hot water.

Beginner's question on guns and knives

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