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Posted: 3/19/2010 12:59:29 PM EDT
I am tired or putting together kits from other peoples lowers and parts. I would like to have one I have built. Could you guys help me with some links to lower slugs? Also does anyone have a copy of the gcode to cnc a lower receiver or a link to the plans. I am planning to CNC one from a slug. thanks guys I have contemplated this for some time now and I am ready to take the plunge. thanks in advance guys for your assistance 
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Spike's has a good price on raw forgings, http://www.spikestactical.com/z/index.php?main_page=product_info&cPath=104_65&products_id=226
Can't help you with G code, I use C++ code. |
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G code programs are a text file that are specific to the brand and type of CNC machine being used to perform the job. No one is going to be able to give you a G code program unless they are a very specialized consulting company.
Even then they would need to be intimately familiar with your machine and how you intend to fixture and locate your parts. The fact you ask this question tells me you are probably not qualified to try to do this project yourself. I don't mean that in a mean way, so please don't take offense. |
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Yeah, shouldn't forget our very own arfcom library. Scroll to the bottom of this page, there are blueprints and some CAD drawings. http://www.ar15.com/content/index.html
After reading PFC's comment, I thought surely there would be some open source AR15 G code files online somewhere, but I took a look around, and I sure don't see any. Good luck. |
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Quoted:
Yeah, shouldn't forget our very own arfcom library. Scroll to the bottom of this page, there are blueprints and some CAD drawings. http://www.ar15.com/content/index.html After reading PFC's comment, I thought surely there would be some open source AR15 G code files online somewhere, but I took a look around, and I sure don't see any. Good luck. G Codes are MACHINE-SPECIFIC. Even if someone was crazy enough to post programs on the internet for cutting receivers they would be useless unless you knew what machine they were written for, which tools were being use, and how the parts were being fixtured. I am a machinist with several years' experience programming and operating CNC machines. I'm pretty sure I'm correct on this one. 
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Snag, I understand that, I think I'm just looking at it from the point of view of some guy that wants to make one or two lowers in his home shop. He will be willing to put more time and effort into it as a hobby project than would make sense in a production environment.
If you were to start with the Ray-Vin manual and write several procedures, maybe one per chapter or one per setup, starting from 0,0 wherever the RV manual says, AND your goal is write code as generic as possible for the benefit of the home builder, isn't that really a pretty plausible scenario? That's what I'm surprised *not* to see out there, some small time machine control that has the AR home builder in mind, and as long as he can learn or get help with some minor G code editing, the machine will do most of the work for him; probably not broach the mag well or thread the buffer tang, but most of the simple mill and drill operations. |
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There are machines such as the Bridgeport EZ track out there that are essentially CNC machines with user friendly controls, but they are still not hobby priced.
Your best bet is to buy fixtures like the ones made by tactical machining and use them with a hobby milling machine to finish your 80% lowers. If you DO find hobby grade/priced computer controlled milling machines let me know! I thought you were wanting .nc or .txt program files that you could just load on a CNC machine and run and that's not really feasible. ETA: various machines really DO vary a LOT in what codes they need. The biggest thing are the more arcane codes that set up various machine parameters or cancel them at the conclusion of the program. Even assuming you had a "generic" .nc program that would work, you would still need to know how the programmer established his work zero in relation to the lower. You would need to know if there are clearances issues in regards to how you wish to clamp down the workpiece. You would also need to know what each tool represented by the "T" codes is. Is it a drill? Is it a milling cutter? You may have the luxury of using D offsets to compensate for the actual diameter of the tools, but lengths can be important too. A case in point is the trigger hole in the bottom of the lower. That takes a long skinny milling cutter. ETA II: If you have a machine available to you now, you could probably research things a bit and figure out how to write your own code, but be prepared for trial and error. There are some budget CAM software titles available too, but they can be of questionable value. |
| Hell...a Bridgeport with DRO will do a beautiful job on a 0% blank forging......the secret is making a nice pair of setup blocks to simplify clapming and positioning the lower. Do a little research and find the E book by Ray-Vin on completeing a 0% lower....it's well written ......and spoon feeds the process where even a novice has an exceptional probability of successfully completing a blank forging. |
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Hell...a Bridgeport with DRO will do a beautiful job on a 0% blank forging......the secret is making a nice pair of setup blocks to simplify clapming and positioning the lower. Do a little research and find the E book by Ray-Vin on completeing a 0% lower....it's well written ......and spoon feeds the process where even a novice has an exceptional probability of successfully completing a blank forging. You mean like these?
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No doubt manual machining has its fascinations, but lets think about this.
Given a person has access to a CNC machine center. Given a person could anodize in house if needed. What could such a person do with a program to cut receivers? With states lining up to tell the FedGov to mind it’s own business one could imagine several things. |
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No doubt manual machining has its fascinations, but lets think about this. Given a person has access to a CNC machine center. Given a person could anodize in house if needed. What could such a person do with a program to cut receivers? With states lining up to tell the FedGov to mind it’s own business one could imagine several things. CNC has its place if you are making billet receivers or many forgings. But the amount of time it would take to make the fixtures, write the program, set up the mill, run the first part, make adjustments to the presets or program to correct errors, and run the second part that hopefully will be within tollerence; you could have the receiver done on a manual mill. |
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Here's some generic G and M Codes.
There are special lines of code to make sure the machine is ready to run the program (This is one place the reason for not being able to just give out the program can be seen), canned cycles for drilling, tapping and reaming and too many more to list here. It's a headache mainly. G0 rapid positioning G1 linear interpolation G2 circular/helical interpolation (clockwise) G3 circular/helical interpolation (c-clockwise) G4 dwell G10 coordinate system origin setting G17 xy plane selection G18 xz plane selection G19 yz plane selection G20 inch system selection G21 millimeter system selection G40 cancel cutter diameter compensation G41 start cutter diameter compensation left G42 start cutter diameter compensation right G43 tool length offset (plus) G49 cancel tool length offset G53 motion in machine coordinate system G54 use preset work coordinate system 1 G55 use preset work coordinate system 2 G56 use preset work coordinate system 3 G57 use preset work coordinate system 4 G58 use preset work coordinate system 5 G59 use preset work coordinate system 6 G59.1 use preset work coordinate system 7 G59.2 use preset work coordinate system 8 G59.3 use preset work coordinate system 9 G80 cancel motion mode (includes canned) G81 drilling canned cycle G82 drilling with dwell canned cycle G83 chip-breaking drilling canned cycle G84 right hand tapping canned cycle G85 boring, no dwell, feed out canned cycle G86 boring, spindle stop, rapid out canned G87 back boring canned cycle G88 boring, spindle stop, manual out canned G89 boring, dwell, feed out canned cycle G90 absolute distance mode G91 incremental distance mode G92 offset coordinate systems G92.2 cancel offset coordinate systems G93 inverse time feed mode G94 feed per minute mode G98 initial level return in canned cycles M0 program stop M1 optional program stop M2 program end M3 turn spindle clockwise M4 turn spindle counterclockwise M5 stop spindle turning M6 tool change M7 mist coolant on M8 flood coolant on M9 mist and flood coolant off M26 enable automatic b-axis clamping M27 disable automatic b-axis clamping M30 program end, pallet shuttle, and reset M48 enable speed and feed overrides M49 disable speed and feed overrides M60 pallet shuttle and program stop |
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CNC has its place if you are making billet receivers or many forgings. But the amount of time it would take to make the fixtures, write the program, set up the mill, run the first part, make adjustments to the presets or program to correct errors, and run the second part that hopefully will be within tollerence; you could have the receiver done on a manual mill. I would imagine a good machinist could do several forgings in the time it would take. However that’s not really the point. People don’t do stuff like this because it is quicker or easier or whatever. Typically CNC does not screw up, receiver number 10 will be the same as number 1. Yes, crap happens and you get the occasional reject and yes getting the first good part can be an adventure. No this is not for everyone, but I would bet there are a number of people on the board who can see the potential and would jump on this in a second if they had the resources to do it. Also don’t discount the commercial aspects of pulling this off. |
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My buddy and I just finished up machining the mag wells today on 4 lowers. Took me an hour just to program, 15 minutes to set all the tools, and about 35 minutes to single step the first part. The next 3 were cake....we just hung out and watched the machine all morning. We have a manual mill but I prefer the cnc. I have thought about machining a lower from a block but to be honest it would be cheaper just to buy 1. Even the 0% forgings end up costing me more than if I just went out and bought 1 but I still wanted to make my own
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Quoted:
My buddy and I just finished up machining the mag wells today on 4 lowers. Took me an hour just to program, 15 minutes to set all the tools, and about 35 minutes to single step the first part. The next 3 were cake....we just hung out and watched the machine all morning. We have a manual mill but I prefer the cnc. I have thought about machining a lower from a block but to be honest it would be cheaper just to buy 1. Even the 0% forgings end up costing me more than if I just went out and bought 1 but I still wanted to make my own I would not do 0% lowers unless I had access to a full stocked machine shop. Some of the tooling is too oddball and/or expensive for most small shops to have or afford. The receiver extension tap would be a good example. 80%'ers still allow you to "make it your own" without the huge investment in tooling. |
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