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File 148903837769.jpg - (25.74KB , 660x430 , ECMrifling-660x430.jpg )
103021 No. 103021 ID: cad48c

Looks like a much more DIY-friendly idea for rifling barrels has cropped up. Might merit some experimentation / refinement by some of the locals, and certainly on my extended to-do list.

Makes me miss the STEM board.

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>> No. 103024 ID: 19518e
>Makes me miss the STEM board.
Honestly, I think most of what was posted in /stem/ would have been fine in /k/ material. I mean what's more /k/ than finding extremely obfuscated ways of weaponizing stuff, especially science things?

It's one thing to cook up science matter so it goes boom, it's another to use 3D printing to make electrochemical system that rifles a barrel so you can then do the practically-stone-age-weapon-thing-of-throwing-bits-of-metal-fast-good.

Whenever I see solid carbide coolant-through twist drills at work, I can't help but scream internally as my desire to have a gun barrel made with tungsten carbide intensifies. I bet it wouldn't wear out as fast even with barrel-burner calibers, and could be made into a thin liner and pushed into a regular steel sleeve (so you wouldn't need a new solid carbide barrel if you dropped your gun on the floor). It could work, or it could shatter like glass on the first round. I think it would work with the right blend of carbide and sleeve. Either way just trying it out would be rad as hell.
>> No. 103025 ID: d4c8ee
  Not exactly a new process. S&W has been using ECM since the early 90s as I recall.
>> No. 103027 ID: bdfe28

Yup. Still pretty cool, sometimes all we have to do is take older proven ideas and find ways to implement them with new technologies. Now instead of needing hundreds of thousands in capital, a few 3D printers and some creativity can go a long way.


I bet a lot could be done with printing layers of metal on a flat, and then rolling/hammer forging around a mandrel ala Steyr... might be one way to get your carbides in there selectively. Or lots of other ways probably.

tfw when you realize most people walk around with things that used to be classified guidance systems, and have no clue
>> No. 103028 ID: 19518e
File solid_carbide.webm - (1.34MB )
Webm shows a pretty extreme example of a solid carbide tool not snapping. This is also what you get when management overloads your shop's programmer. Then management subsequently has to subcontract out a program the subcontractor thinks slotting with a 1/8th endmill 2" long in 0.025" DOC steps is a good idea. The part is also stupid because why would you need spigots like that, but that's another rant entirely.

When doing something like this, the correct way would be plunge roughing in % of tool radius step-overs (% would have to be whatever step-over is easiest on the tool, anywhere from 25% to 75%); once the material is out of the way, you clean up the scallops using the side of the endmill without much problem. You can easily machine with an endmill that long if you're taking 0.010" or so on the tool's flutes from the sides, and very little if any on the bottom of the flutes, even if your depth of cut is large. Slotting with an endmill that long is how you push carbide "brittleness" to it's maximum. It's just a terrible idea in general.

That could probably happen, but from my experience with carbide tools, they're brittle, but not as brittle as some would imagine. They're even less brittle when "supported" by steel somehow.

When dropping a solid carbide tool, it's much more likely to chip locally at the impact point than break completely like dropping a glass bottle. Yes, carbide is more brittle than steel, but "more brittle" is relative. All carbides are not the same, and all carbides (even from the same company) can have their blends of 11 herbs and spices for whatever purpose they need, with a bajillion coating types and blends on top of it all.

I'd use regular carbide tool methods, the wheel is already invented and making a good carbide thing is not really hobbyist friendly. Manufacturers can make a 0.015" diameter solid carbide twist drill with coolant holes twisting down inside the flutes (I'll get a picture, we have some at work, and microscopes to be able to see the coolant holes too), they can probably make a rifle barrel. They'd probably need the mandrel like hammer-forged barrels, but beyond that it would be their usual carbide production space magic.
>> No. 103032 ID: e7e851
I love /stem/ but it was so dead. Good stem threads in /k/ will be preserved there though.
>> No. 103041 ID: 19518e
File 148913124955.jpg - (1.85MB , 3263x2619 , gfgfgfdgafds.jpg )
Here we go, took pics of some nifty drills.
>> No. 103042 ID: 19518e
File 148913139759.jpg - (229.49KB , 1381x941 , fdsfsdaf.jpg )
These coolant holes don't go down the center of the drill, they actually follow the twist of the flutes. From how I understand it, they use wire that they twist in the same rate as the flutes and pack the carbide around it, then remove the wire to form the holes.

I tell ya. Space magic.
>> No. 103043 ID: 19518e
File 148913179434.jpg - (440.94KB , 2171x1675 , saffffag.jpg )
Head to head, we can see that it must have been mighty fine wire to make holes that small. The microscope wasn't really good enough to be able to tell what grind or form that the 0.0079" had as for cutting tip angle. From what I can see, it's probably 135 degree with a pretty standard chisel tip. The chip relief grind/form on the spiral is generous, I assume this is intentional to allow easier chip evacuation as there is no coolant-through to help.

Small peck depth is probably the way to go with a drill that small, and fuck you're screwed if it has any runout. Better get a shrink fit tool holder for this one...
>> No. 103045 ID: 8c968b
Man. and I thought I was doing pretty good doing these M2 threaded holes in 309 SS. That's almost 10x the diameter of that little drill.
>> No. 103046 ID: 19518e
File 148919356143.jpg - (838.58KB , 2012x2924 , smallp.jpg )
Smallest I've personally had to deal with was this. M1x0.25, we only had one spare tap so I had to set it up so they wouldn't fuck up. Since the tapped hole went though a pocket and had to resume past the pocket, I had to program in a tool change after drilling halfway to call up a 1/32" ballnose. It went down the hole and spotted the pocket, then the drill came back out and drilled through the rest of the part.

It's Invar. Ended up pecking 0.010" at 100RPM and I parked an operator to blow off and Rocol the tap every couple of pecks. Worked like a charm.
>> No. 103049 ID: 1b9ff7
File 148925181384.jpg - (557.09KB , 3456x2592 , IMG_0871.jpg )
>micro machining thread?
>micro machining thread!

crappy pic, but a screw i had to cut for a hairspring stud holder

it's the silver thing between Abe's nose and chin
>> No. 103055 ID: 19518e
Damn that's small, you got any better pics?
>> No. 103056 ID: 7c3c05
I can't even imagine how you do that. Did you build a really tiny Bridgeport mill as the first step? Seriously, that's impressive.
>> No. 103057 ID: 1b9ff7
File 148937313237.jpg - (0.96MB , 3456x2592 , IMG_0835.jpg )
it's not that hard. Behold my workhorse, and old WW2 pattern lathe of dubious origins!
Threading his done with a die held in the hand and the slot in the head is made with a special file, called a slotting file.
>> No. 103058 ID: 19518e
What thread is it? It looks quite a bit smaller than a 0-80...
>> No. 103060 ID: 1b9ff7
good question. The die set is packed away god knows where now, but it does not use metric or US standards for thread pitch. It's probably close to a metric 0.5x0.125
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