"Ghost Gun" Table Top CNC machine

Could be....

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Originally Posted by crays

The "anti-slop screw" hole, maybe?

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Originally Posted by Great-Kazoo

We still talking AR lowers?

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Originally Posted by crays

Could be....

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Sounds like the kind of discussion that belongs over in my "I did it" thread......

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Yeah but the video is great.

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Originally Posted by Danimal

TL;DR That machine is dumb, use a drill press with a milling vise.

This kind of thing actually makes me a little mad. I have constructed CNC machines out of the exact same materials and simply put, there is nothing about that machine that will make it any easier to make an 80% lower. It runs off of a GRBLshield with and Arduino uno as a controller. This platform literally has 32kb of flash memory. Yes I said kilobytes so most complex functionality is omitted to allow for basic 3 axis control.

This alone could still produce a lower, but the complexities with alignment make a "plug and play" scenario a little far fetched. You would need to be able to place the piece vertically with .005 accuracy to stay within the mill spec depth requirements of the receiver. This is from the installed tool tip depth, so it would change every time you installed an end mill, and touch off capability is still not a part of the package for GRBLshield as far as I know. People have done it, but not easily.

Now we are to the hard part. The milling. You can hear that when it is running, it is spooling at high RPM. This pretty much means that it uses a cheap router spinning at 30,00 rpm which taking feed speeds into account based off of end mill chip load pretty much limits the machine to a single flute 1/8 diameter cutter. Now you need a 1/8" end mill capable of cutting a slot that is 1.25 inches deep. Talk about tool deflection. So now to avoid the problems with tool deflection, not to mention general machine rigidity and backlash, you will need to make the depth of cut very shallow in order to prevent deflecting, overloading and snapping your end mill. Probably about .01 or less. That means that the CAM program will need to perform at least 125 passes at about 30 - 40 IPM. That would take all night for one receiver.

To make a short story long, that is an over dramatized machine that would make it 1000 times harder to mill out an 80% lower.

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Originally Posted by Danimal

I just hate seeing someone say "it is like pressing print" when the truth is that it is harder than hell to do that. Maybe Little Machine Shop should make a video like that about their micro mill, or their mini mill. And it is cheaper.

Bam! Just saved you hundreds or dollars and it can mill anything, including 1911's.

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You guys aren't wrong, but you are missing the point. The magic milling box is marketed to guys who have no machining training/experience and don't want to, or don't have the time, to learn. The idea that you can mount a 80%, hit go and it is finished off without brain damage is highly sought by the masses who don't know how to work with their hands (or think with their brains).

As an aside, no diy 80% is ever going to be finished to mil specs. .005? with a drill press in an average garage? I would be surprised if the table is aligned with more than a square or a bubble level to the bit. But it doesn't need to be to work, and home built ghost guns don't need to be perfect, just work.

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Originally Posted by clodhopper

You guys aren't wrong, but you are missing the point. The magic milling box is marketed to guys who have no machining training/experience and don't want to, or don't have the time, to learn. The idea that you can mount a 80%, hit go and it is finished off without brain damage is highly sought by the masses who don't know how to work with their hands (or think with their brains).

As an aside, no diy 80% is ever going to be finished to mil specs. .005? with a drill press in an average garage? I would be surprised if the table is aligned with more than a square or a bubble level to the bit. But it doesn't need to be to work, and home built ghost guns don't need to be perfect, just work.

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Sounds like an AK flat bending jig. Clamp, press, align, heat treat.

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Originally Posted by Great-Kazoo

Sounds like an AK flat bending jig. Clamp, press, align, heat treat.

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Never folded up an AK receiver. Doubt I would have a hard time with it, but, yeah, there is nothing about a kit assembled AK that is to any spec, other than the "does it work?" standard.

I do appreciate home machinists that have skill and the patience to do things right. Most people have absolutely no concept of how long it takes to machine a single part correctly.

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