Technology dooming gun control?

[HTRN]

Two things about that - If you already have an object in hand, you can easily make a rubber mold, split it with an exacto knife, and then use a wax injector to fill it.

If you're making a one off, that will promptly be dipped in investment, you can CNC mill a wax pattern. This tends to have better finishes(especially with machines that can accurately do small stepovers) and then promptly dip in investment. If you're gonna do alot of something, you can machine an aluminum wax mold, polish it, and then use a wax injector.

[MarkD]

The thing that excites me about this is the application to another of my hobbies, model trains. Big companies make popular cars, locos, etc from styrene via injection molding, and injection molding equipment is expensive so they have to sell lots of them to make a buck. Less common items are usually cast in resin (basically epoxy), they start with a hand-made styrene master, make a rubber mold from it, and cast the parts. This technology could either be used to make the master instead of doing it by hand, or it could be used to make the actual parts from plastic.

[McClarkus]

A little side note question regarding machining brass. The 10th Spl Forces want me to make another carving for them but this time with a real Colt dagger instead of the carved wooden dagger and with brass inlays where the maroon gear ring is. They also want real hex bolt heads blackened with the torch glued in for decoration. I can get .025" brass sheet on line. I was thinking about using spray rubber adhesive on both sides and sandwich it in between two sheets of 1/8" baltic birch. Then screw the sandwich to the CNC spoilboard where the cutter will not hit screws. I want to use an 1/8" carbide upcut endmill to machine it. I have only cut wood with this machine thus far and this will be the first time I've machined brass. I thought I remembered someone talking about some formula to calculate spindle speed (can go up to 18K) and feed rate (can only go 300IPM). I was going to take a guess and start at about 12K and 10 IPM. I don't want to mangle the brass 'cause they ain't exactly givin it away. Am I nuts? comments - suggestion?

[bubblewhip]

Now, about "replicators" destroying gun control..

Don't bet on it.

Rapid Prototyping(the proper name for the technology, not "3D printing") has been around awhile - I remember my school just getting an Stereolythography machine just as a I was about to graduate. It cost them about a quarter million dollars. Nowadays, extruder based additive fabricators intended for hobbiest like RepRap and Makerbot have made the tech accessible to anybody with a decent job - Makerbot for instance, can be bought full assembled for 2500 bucks.

But here's the problem - everybody focuses on the first word of the name "Rapid" and forgets the second "Prototype". They don't make anything useful. They never have.

Well the new Makerbot Replicater is much more elaborate and makes stuff that is resembling more like commercial plastic products. It can make stuff that is useful that's more than just basic shapes, such as the new replicator can make much more elaborate things such as a parametric container. You also have much less finishing that you have to do than in the past with the current replicator.

I wouldn't doubt that 3D printers are the future for household prototyping. Simply because CNC machines at the moment are impractical and hazardous to put in a regular household the size of a Makerbot. You would need a Garage that would be able to take up the space and safety of a proper CNC mill, or water jet.

while 3D printing is in a primitive state atm, they are rapidly getting better year over year.

[HTRN]

I would doubt it. There's been no big push for innovation in SLA machines in industry, who's $$ amounts makes the hobbiest look like pocket change. The Only big "innovation" that's come along is cheap affordable motion control, and that's less to do with new technology(in fact, the common stepper is 1960s tech - most of the what "real" cnc machines use is AC Vector drives and servo motors.) then with the Chinese seeing a niche and exploiting it.

The only real big innovation that I can think of since I got my Man. Tech. degree is the Selective Laser Sintering machines, which have a jawdropping price. Frankly, The next logical step in hobby grade rapid prototypers is probably the traditional SLA machine, but the laser is going to add serious bucks to the price, not to mention what the consumables cost - last i heard, the resin started around 400 bucks a gallon).

Alot of the demand pushing development of this tech evaporated in the late 90s when new exotic cutters and high speed machining centers hit the market(case in point, Haas offers a 30K rpm option on their smaller VMCs, for 24 grand), at prices that were far lower than the typical SLA machine. The fact that they could be used to produce actual parts is just icing on the cake.

One of the things everybody overlooks is cultural, what makes everybody assume that they're going to even want to make it themselves? There's a bunch of tools out there RIGHT NOW that can be bought for modest prices, that can make/repair a huge variety of objeects, but how many people actually own a mill and a lathe? or even just a cheap buzzbox?

To put it bluntly, unless there is some jawdropping innovation sometime in the decade, I really don't see it happening. Even then, it would have to be cheap enough to justify spending thousands on a machine that is going to take up space, and require some learning(this is, quite frankly, a bigger obstacle than the cost in my experience) to use.

In the meantime, I'm back to digging though the couch cushions in the vain hope of financing a VMC - anybody want to lend me 25 grand or so, I heard about a possible deal on a VF-4..

[Highspeed]

Rapid prototyping certainly has been around for a long time. I remember having an acquaintance in the early 90's who worked for a company which did just that. He explained it to me, but I think I fell asleep half way through.

I like lathes, milling machines, files, hacksaws, scrapers and a charcoal forge. I'm a dinosaur

[mekender]

How long before we can afford a printer that will print an AR lower well enough for a parts kit to fit?

For one that can fire once? Right now.

For one that has a service life approaching that of a conventional lower? Not for the forseeable future, and going by past trends, not anytime soon.

Comparable to the service of a metal lower, not right now... But the ones I have seen done on various websites would likely survive a few mags at least and I suspect they will survive several cases of ammo.

The lower of an AR really does not have all that much stress on it so it does not need to be as durable as you think. Hell, I have seen pics on ARFCOM of AR lowers made out of wood and made out of lexan type plastics and screwed together. AK pattern rifles only use 1mm to 1.6mm steel flats for their receivers.

Hell, if I can get a good job here soon, I may go ahead and buy a printer and make one just to find out exactly how durable it is.

[randy]

How long before we can afford a printer that will print an AR lower well enough for a parts kit to fit?

For one that can fire once? Right now.

IOW one good enough to produce a Liberator model AR?

[HTRN]

Rapid prototyping certainly has been around for a long time.

SLA(Stereolythography - IE, using a laser to polymerize a liquid) was patented in 1986. The first SLA machine was, IIRC, introduced in 1989.

[Rod]

Yahoo put THIS up just to get reactions. Comments are more interesting than the article.