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91

Gunsmithing/Kit builds / Re: Gatling gun build

« Last post by JonesL on June 30, 2021, 11:29:30 AM »

You're right. Once the etching makes it past the mask, it will continue sideways in addition to down. Most of my electro-etching is lettering down into the background and there you can get a pretty deep etch.
For raised lettering, you have to watch the process closer and my guide is when I start to see the mask start to lift on the finer detail, I stop.
>>With any metal working or etching process; practice on some scrap first to get a feel for the job.<<

For extra fine detail I use this outfit http://www.img-electromark.com/ I send them my artwork and they convert it to a stencil, basically a very fine mesh silk screen. I tape the stencil down and when my electrical current is applied the electron flow is only through the open mesh. For this fine line etching, I set my battery charger on 2 amp trickle and have even used a Q-tip alligator clamped to the negative lead and the tip dipped into the electrolyte. Pictures are of that process and the results.
Last two are of chemical etching.

https://ibb.co/XjPJxcv
https://ibb.co/j5d7Yzv
https://ibb.co/gdnpnnH
https://ibb.co/3fMRfRm
https://ibb.co/nQbWV5g
https://ibb.co/LPX5jwm

Another process, this time chemical etching on brass, is to use ferric chloride (used to make printed circuit boards). Read up on ferric chloride before you start as it has some odd properties; "Ferric chloride is not an acid but acts like one in the presence of water" which means that the diluted solution is more active than the concentrate.
Be very careful of spills because even if you wipe it up immediately, it'll leave a mark on any brass it touches. Get a drop or two on your skin and you'll end up with a yellowish stain that's as permanent as a USDA beef tattoo.

A silk screen shop screen prints my artwork on brass sheet (make sure any lacquer or wax coating is completely removed down to bare brass first) and the ferric chloride goes after the copper in the brass alloy. This is a very slow process but gives super fine detail. Coat the back of the sheet with a mask of your choice or the plate will be thinner than when you started.
Again, when I start to see the mask lifting, I stop and rinse off the surface with a baking soda and water mix and a scrub brush to neutralize the solution. Dip in acetone to remove the screen print and you're done. Ferric chloride can be used over and over so i just pour off the solution into a container for the next job. Hazmat rules apply with ferric chloride.
With the electro-etching process, you're only dealing with salt water electrolyte and that can be poured down the drain or on weeds you want to get rid of.

92

Gunsmithing/Kit builds / Re: Gatling gun build

« Last post by Sparky_NY on June 30, 2021, 08:02:38 AM »

Thanks for all the great info !        I think I understand the basics,  probably will do some experimenting to really get a grasp of the process.

One question I have:    When etching, the area not etched is masked off but as the etching proceeds the side walls of the characters will not have any resist,   won't the etching cut into those side walls of the raised characters?     I am guessing that the depth of the etching is limited to quite shallow because of this.

I seen a etched brass medallion for a .22 gatling (small, about 1-1/2" dia) that a local fellow did.    He used a process of printing the design on a laser printer and transferring the toner from the paper to the metal as a etch resist.    The end product came out pretty nice.     On the surface it seems like a relatively easy process for a novice.

93

Gunsmithing/Kit builds / Gatling related accessories

« Last post by JonesL on June 29, 2021, 07:44:02 PM »

Here are a few trinkets I made up. I figured if the artillery guys had crossed cannon ornaments, guys in Gatling Detachments ought to have crossed Gatlings pins.
Stamped sheet brass one is more historically accurate. Pin on card is solid cast copper.
Cast iron plates are from a carriage restoration we did.

A detail regarding Gatling builder's plates (spotting copies). There are quite a few brass builder's plates out on the market and most of them are fakes. Quick way to tell is the raised blob just in front of the "9" in one of the patent dates. That's from a little bit of sand dislodged by a "vent pick', a long slender rod the mold makers used to shove into the sand to vent gases as the molten metal was being poured in. When the original plate was copied to make duplicates, whoever made the pattern copied the blob left in the sand too. You gotta wonder how even an experienced mold maker could hit that exact same spot with his vent pick time after time after time.
Not every builders plate back then was made of brass and kept polished. Cast iron was another material of choice.

https://ibb.co/sJzzr6B
https://ibb.co/b1jqkHr
https://ibb.co/0FFzb5b

94

Gunsmithing/Kit builds / Re: Gatling gun build

« Last post by JonesL on June 29, 2021, 07:08:41 PM »

My electrolyte is plain ol' salt water for better conductivity. My set-up is a clean five-gallon bucket, a home car battery charger and knowing a couple of tricks;

I use Contact self-adhesive shelf paper and cut out my design with an Xacto knife.
For anyone with access to an outfit that makes embossing dies to do high end stationary or wine labels; You can get a magnesium made that has all kinds of depth. All you need is camera ready vector artwork and tell the etching shop you want your job to be done "right reading" (the die reads correctly and not backwards like a rubber stamp), and "black up" (means the lettering and border is raised above the background).

For electro-etching;
Fill bucket enough to completely submerge the part. Connect positive to the work piece and negative to a metailic plate of the same material you're etching. Etching aluminum = aluminum plate, steel = steel plate.
Insert common sense disclaimers here>> Wear rubber gloves!! Remember, we are playing with electricity here.<<
>> Do any etching jobs outdoors!! And I don't mean out in the garage with the door open. As the etching process is working, gases you shouldn't be breathing are being released.<<
>>If you want to check on your progress, turn off the battery charger, don't just unclip your leads. (Refer to Common Sense disclaimer 1.)<<

Here's Trick #1 The plate should cover the area to be etched and be positioned an equal distance from the work piece using an insulating spacer; nylon, wood blocks, anything that won't create a dead short. If you give yourself enough space between the two, you can even peek in and see how deep your etch is.
A small scrub brush or old toothbrush is handy to get the sludge that collects out of the etch.
If you were to use a bolt for your negative electrode instead of a plate that overshadows the area to be etched, the etch closest to the bolt will deeper 'cause electricity follows the path of least resistance. The farther away form the negative electrode, the shallower the etch.
I also mask off the back side of the plat I'm etching with gloss spray paint or self adhesive shelf paper because any bare metal will also be affected (etched).

Here are some pictures of my set-up for some motorcycle parts I did.

https://ibb.co/C2m0302
https://ibb.co/D9K4FDC
https://ibb.co/LxfGCcc

95

Gunsmithing/Kit builds / Re: Gatling gun build

« Last post by Sparky_NY on June 29, 2021, 07:44:31 AM »

Those brake plates look fantastic, never suspect they were not original.     What do you use for electrolyte when etching?     Never seen etching done on aluminum, only brass/copper and that was non electrical.      Someday, I want to make about a 3-4" medallion for my .357 gatling, etching would be a possibility but I have zero experience.

96

Gunsmithing/Kit builds / Re: Gatling gun build

« Last post by JonesL on June 27, 2021, 01:34:35 PM »

Very true, Sparky.

But I must admit that sometimes I do cheat a little. I've machined parts out of billet then textured them with a needle scaler (used to chip mill scale and rust from steel). I also have taken a part out of the mill then put it back in by just eyeballing it. The misalignment can end up looking like parting lines from the mould halves.
Sometimes weathering can add to the illusion too. To get an original part look, just giving it a good rub down with a scotch brite pad does a good job of knocking off the sharp edges.

Here are a couple of pictures of a set of brake backing plates I made for my 1921 Harley board track racer.
Started with a couple of pieces of 6061T6 "tool plate", machined them and then threw in my electro-etching set-up, primarily to etch the lettering.
The "mask" I used is spray can primer and it's slightly porous which lets the electrolyte penetrate it to a small degree. Gloss if I don't want the solution leaching through.
The result; my hours old backing plates now look as "original" as the rest of the bike.

https://ibb.co/2s6gkbB
https://ibb.co/9GqZRYf

97

Gunsmithing/Kit builds / Re: Gatling gun build

« Last post by Sparky_NY on June 26, 2021, 04:47:55 PM »

That is some beautiful work !     Casting really adds authenticity to a gatling.   

98

Gunsmithing/Kit builds / Re: Gatling gun build

« Last post by JonesL on June 25, 2021, 09:48:08 PM »

Yep. I talked to Paul when I first started building in 2003. Met him and his son in person at one of the Denver gun shows a couple of years later. He let me lend a hand in making the foundry patterns for a miniature badge plate for his guns. Always a great guy and happy to share information and Gatling stories.
He'll be missed.

99

Gunsmithing/Kit builds / Re: Gatling gun build

« Last post by Dave on June 25, 2021, 08:57:27 PM »

Thats cool stuff!

Arent you one of Paul Moores friends?

100

Gunsmithing/Kit builds / Re: Gatling gun build

« Last post by JonesL on June 25, 2021, 08:00:11 PM »

Thanks for the kind words, Frank.
Access to bigger machinery helps too. Here's the breech casing set up on a Bullard (Vertical Turret Lathe) to do the internal boring.

https://ibb.co/ss1zVKg
https://ibb.co/SBRmbWD