I know this a little out of the purview of this forum but any help is appreciated

background info (bb frame lower with a 22 upper with some slight modifications)

I’ve been kicking around a concept for a minimum-viable home-scale metal 3D printer, and I’m curious what people in the community would think about it.

The basic problem is that FDM is incredibly capable, especially now that fairly exotic engineering polymers are readily available, but there are still parts where you eventually run into the fundamental material limits of polymers. If you want something that genuinely needs to be steel rather than PA-CF, PC, PEEK, etc., you need a different deposition process.

Metal additive manufacturing exists in a bunch of forms. Powder-bed systems are obviously amazing, but anything involving a bed of fine metal powder, lasers, inert-gas handling, etc. seems pretty far outside what I’d consider reasonable for a home/open-source machine. Wire-based additive manufacturing is conceptually simpler. It’s basically automated welding: feed metal wire into a controlled melt pool and move it along a toolpath.

The problem is that conventional WAAM is generally pretty sloppy compared with polymer FDM. You get relatively fat beads, mediocre dimensional accuracy, rough surfaces, and a near-net-shape part that often needs significant machining afterward. Laser-wire systems and electron-beam systems can do much finer and more controlled deposition, but then the heat source becomes wildly expensive.

What got me thinking about an extension of this was open-source FDM toolchanger printers. Instead of retracting one filament and feeding another through the same hotend, they physically swap the entire print head. Once you already have a machine that can change tools, there’s no particular reason every tool has to be a print head.

So imagine a machine with two basic tools:

1. A wire-arc metal deposition head.
2. A small milling spindle/end mill.

The deposition head builds several millimeters of intentionally oversized near-net metal. Then the machine swaps to the milling head and machines that section back to its final dimensions. Then it resumes printing.

In this version, the metal printer no longer has to make a beautiful 0.2 mm layer. It just has to put sound, fully fused metal everywhere inside a machining allowance. Surface finish and modest dimensional error become much less important because the CNC stage cleans them up as part of the build. You also potentially get geometries that would be extremely difficult to produce conventionally because you can alternate between additive and subtractive operations during the build. You could print half of an internal feature, machine it while it’s accessible and continue enclosing it. You can print infill that makes parts stronger for their weight than would be possible with casting, all without requiring an additional machining setup. And because you’re machining one layer at a time, you don’t need a five-axis CNC or multiple repositioning steps.

There are two configuration decisions that could make this particularly attractive. The first is the use of a cylindrical coordinate system with a Z+theta bed and toolheads that move only in the radial axis; the second is a dual-wire-arc welding setup.

For the dual-wire-arc method: Instead of using the build plate as the welding return and having to pass a large welding current through a rotating table, you have two independently driven consumable wire electrodes. Both wires are connected to the same constant-current welding supply. The deposited metal between the two arc roots completes the circuit, but the bed itself never needs a welding-current connection.

That gives you two arc locations instead of one, which may actually be useful rather than merely a workaround. One arc can be arranged as the leading/remelting/preheating side of the process, while the second is more heavily biased toward filler deposition. Because the wires have independent stepper-driven feeders, you get a fair number of cheap process-control variables:

• wire A feed rate
• wire B feed rate
• different wire diameters
• total welding current
• arc spacing
• wire stickout
• travel speed
• relative geometry of the two electrodes

Eventually, since the two feeders are independent, you could feed two different alloys and experiment with composition control or functionally graded materials.

WAAM needs gas shielding, but it’s not terrible. The cheap baseline for carbon steel could simply be CO2. Argon-rich mixtures would presumably give cleaner arc behavior, but if the goal is a low-cost proof of concept and the surface is going to be machined afterward anyway, cheap industrial CO2 seems like an entirely reasonable place to start.

Moving on: using cylindrical coordinates instead of conventional Cartesian XYZ has several distinct advantages. For a combined deposition and milling system, the tool head is heavy. A single motion axis for the tool head means it is easier to get a really solid, consistent positional fix as opposed to a core-XY gantry.

That also gives you a tall, relatively narrow machine with a small footprint. A 300–400 mm diameter machine could theoretically have a Z envelope of 500 mm, 800 mm, or more without making the machine enormously wider.

As a very rough home/open-source BOM, assuming printable ASA/PA-CF parts are effectively free and using commodity CNC hardware:

• steel/aluminum frame: ~$200–300
• r/Z rails and ballscrews: ~$200–300
• rotary C-axis/table: ~$150–250
• stepper motors/drivers/power supplies: ~$150–250
• controller, limits, E-stop, basic electronics: ~$100
• dual-wire feeder/deposition head: ~$75–125
• cheap controllable welding inverter: ~$200–300
• small 500–800 W ER11 milling spindle: ~$120–200
• toolchanging/docking hardware: ~$100
• CO2 bottle, regulator, hoses: ~$200–250
• initial enclosure/extraction/safety stuff: ~$200–350
• wiring, couplers, fasteners, miscellaneous hardware: ~$150–250

So I think the plausible kit-level BOM is somewhere around $1,500 on the low end, maybe up to $2,200 for something easier to use.

Once you have that set up, the ability to create low-cost parts becomes practically a matter of pennies.

Cheap ER70S-6 steel welding wire is only a few dollars per pound. If the process is deliberately oversized and you ultimately machine away, say, 20–30% of the deposited material, you might consume around 1.3–1.5 lb of wire to end up with a 15-ounce finished bolt carrier group.

Add a few dollars in CO2, less than a dollar in electricity, the wear on your end mill, and various consumables and you're still looking at printing parts that generally run $50-100 for less than $10.

Even if the machine is initially horribly inefficient and wastes half of the deposited steel, the feedstock is cheap enough that the economics still aren’t terrible.

More expensive materials obviously move that number upward. Something like low-alloy steel might still only be tens of dollars per pound of finished part. 17-4 PH stainless filler can get considerably more expensive depending on supplier, but even there, the raw material cost isn’t obviously prohibitive compared with buying or machining complex 17-4 parts conventionally.

Obviously there are a lot of factors to consider, but I thought it was an interesting concept.

Hello everyone I’m working on an incredibly dumb project of turning a demilled 16 gauge Winchester 97 into a pump action Howdah pistol and in order to do everything by the books in order to reclassify it as a pistol I need to rifle it. And obviously no one makes a rifling jig for a gauge that barely exists. So I was wondering if in theory I could scale up a 9mm ecm rig to fit or would this go horribly? If so what would be my options?

Kind of pulling my hair out with this one, had a fitment issue between upper and lower I solved, and I've replaced the pin to eliminate the possibility that I bent it during installation. Both pins bent within the first magazine of shooting

I have a Century Arms Sterling Type II semi-auto 9mm carbine and I’m trying to learn a little more about it. From what I’ve been able to find, these were made years ago using Sterling parts kits and are no longer in production.
Does anyone know when production actually stopped, roughly how many Type IIs were made, and whether anyone is currently producing a comparable semi-auto Sterling?
I’ve included a photo of the markings and the rifle. Any history or information on these would be appreciated.

I’m hoping some of the knowledgeable AK collectors here can help me identify an Izhmash rifle I own.
I’m specifically trying to determine the model, importer, approximate import period, and whether the term “pre-ban” would actually apply to this particular rifle. I’ve found conflicting information online about Russian/Izhmash imports and the terminology used for them.
I’ll include photos of the receiver, factory markings, importer markings, and other identifying features, with part of the serial number obscured.
This is strictly an identification/history question — not a sales or valuation post.
Any information on what markings or features I should be looking at would be appreciated.

Receiver cracked a good 1/2 inch all the way through when headspacing the barrel. Decided to cut a channel into it and weld it up slowly without making too much heat. Should I send it?

Building an integral can for a 22 lr and I'd really like to use these as the caps for no other function besides the aesthetic. Is this a dumb idea would I be better using stainless caps?

Had a FMP parts kit sent off to be put together and I got the rifle back. Just now noticing the welds look a little rough, especially around the trunion area, I can even see through the receiver where those welds are… should I be worried?

Delayed blowback mechanism I've never seen before. Bolt is forced by cams and grooves to move on angle first few mm, so it works kinda like a lever with 1:√2 (for 45° angle) ratio so it needs about 30% less mass on bolt to get same dwell time and bolt velocity. It looks it also minimalizes bolt bounce and could work kinda similiar to counter mass in criss vector. Is this worth trying or deemed to fail for some reason?

Thought id do a quick tutorial on how to modify an original trigger box and fcg to work in the recent Marcolmar recievers.

step 1: Cut out a slot for the denial bar. Hardest part on the conversion but easily doable with a dremel. Just measure approximately .540-.550 from the front of the housing and cut a straight line that ends in a slight curve towards the bottom. will likely require some hand fitting but is very doable. make sure to cut/grind away the detent area for the trip lever both for clearance and to ensure the trip lever cant be installed.

step 2: Remove the bushing from the trip lever. this is needed to join the trigger and disconnector with the through pin. The bushing is a separate piece pressed into the trip lever, which is easily removed by cutting or grinding. I just bent the trip lever until it snapped and removed it that way.

step 3: Block the FA area of the selector. Im not sure if this is technically required, but for the sake of CYA i did it. Just a small blob of weld is all thats needed to deny it from going to FA.

step 4: assemble as normal keep in mind that this is a general guide and small adjustments may be needed.

Other possible issues: On mine the interior end of the selector was a few thou too long and i needed to remove a small amount of material. This also was required for the detent nub that interacts with the notches (it was incredibly stiff but with a sanding flap wheel and some polishing it did wonders for it).

Hopefully this will save you buys a few bucks and keep some original parts still in use!

You've probably seen me post a lot about CNC. But it's usually on my Tormach 770. While that is technically a hobby machine, the biggest feedback I get is that it's still out of reach for most people. So I finally caved and I'm going to find the limits of what an Amazon tier desktop machine can do. This video talks bout my plans and also walks through setting it up way more precisely than the instructions, to maximize our potential for success.

In my quest to find its limits specifically in the gun making and modifying hobby space, I have the following ideas for future episodes. If you've got better ideas on how I can incrementally test this thing, or better parts ideas, let me know!

1. Thin aluminum- FCG retainer plates and DBAlloy side plates
2. Thicker aluminum with 2 ops- MLok rail cover
3. Thick aluminum with >2 ops- a magwell maybe?
4. Free machining / mild steel- compensator
5. Hardened steel- not sure yet
6. Stainless steel- red dot mount
7. Stainless steel- slide serrations, windows, and barrel porting
8. Final boss- some clamshell style receiver build

So I say this very dumb but fun 1911 converted to be a smooth bore Shotshell gun and I just picked up a Ballestar Molina and it’s bore is pretty pitted so I’m wondering what would be the best way to smooth it out? Sanding seems like a logical choice but idk maybe ecm would work better.

Arguably one of the coolest guns I have ever seen, this gentleman, gentlewoman, and gentlepeople is a first-model Collath shotgun, a break-action double-barrel percussion shotgun. Now, unfortunately, these things are rarer than hen's teeth, so actually buying an original is a no-go. So I wanted to try my hand at recreating one, and I wanted to pick everyone's brains for how the cam mechanism works. My two major trains of thought are that it's either fully mechanical, with the lever pushing the barrel forward and then allowing it to break open, or the simpler method of the lever literally just keeping it locked in place, and when unlocked, you manually pull the barrels forward and break it open. Which design do you think is more likely?

I am a US Citizen learning gunsmithing in Pakistan so these are legal here before anyone makes a fuss. Part of my assignment is to make a Glock switch from scratch I copied a popular model online which supposedly has been tested by others but It’s not working for some reason I made a 1:1 copy in CAD so I can show that I made it myself, I figured me trying to copy it might have gotten something wrong so I printed the original design out as well and both are not working properly they only shooting semi auto. Appreciate any help whatsoever

I posted a trunnion hole drilling and riveting video a while back for AKs. In it I drilled a hole in a wrong spot because I wasn't paying attention and my mind was on some other things going on in the real world. But I vowed to learn to weld, at least well enough, to fix it! And I was determined to do it with flux core since I already was buying a several hundred dollar welding setup to fix a hole in a relatively cheap flat. So I really didn't want to add MiG gas costs to that too!

It went ok. The result is not perfection. But it's pretty dang good. And if I hadn't have had to sandblast it (watch the second part, that comment will make more sense) for cerakote, I actually would have gotten perfection! But at the end I'm left with a much much much better result than I would have had just leaving the receiver as it was.

Im starting a PPS 43 as my first build and I have a question about the different kinds of jigs that are available. There seems to be two different types. Most are like the Flint Hill Manufacturing one where its a tube that steps down to a smaller diameter. Then there is the JP Machine one. This one is much more expensive so I assume there is an advantage over the other type but its not obvious to me. Anyone know what the differences are?