# first successfull cnc engraving



## gt40 (May 15, 2013)

I have been sidetracked from flashlights building a custom ar build. This was my first experience engraving with cnc and one of my first successful parts on my mill but it came out pretty good. Here is a video of it. I was unsure on the depth so I cut it several times and increased the depth by .001 in the video: 
 

Machining the lower itself:


I know it isn't flashlight related but cutting text with accuracy is really cool. 
Pics:


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## precisionworks (May 16, 2013)

That came out nicely 

You'll eventually want a high speed spindle for the engraving, somewhere around 50K rpm. I just happen to have one for sale if you're interested ...

ER collet extensions are super handy to get an end mill into areas that the full size collet nose cannot go. Mine are all made in the USA by Craftsman Industries & sold by ENCO. Most were on sale when purchased. 






Extension above is their ER16 "stubby" collet chuck with .750" straight shank. It's 3.75" OAL but over 1" of that goes up into the ER40 collet so the tool is extended about 2.5" lower. Their "regular" extension is 7.1" OAL so about 5.75" extension. http://www.craftsmanindustries.com/er.htm


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## wquiles (May 16, 2013)

precisionworks said:


> That came out nicely


+1

Very nice indeed!


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## gt40 (May 16, 2013)

precisionworks said:


> That came out nicely
> 
> You'll eventually want a high speed spindle for the engraving, somewhere around 50K rpm. I just happen to have one for sale if you're interested ...
> 
> ...


 You already got me on this one- have a stubby er20 extension for the lathe. Thanks again for the suggestion. I just ordered a second one to machine into a spring loaded engraving tool. Spring loading should allow for engraving on irregular surfaces. Here is a commercial one: http://www.2linc.com/spring_loaded_engraving_tool.htm


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## precisionworks (May 19, 2013)

Wow, they are proud of those spring loaded holders. Can you not program the head to follow contour?


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## 350xfire (May 19, 2013)

Very cool. Was that an 80% lower or did you machine the whole thing?


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## gt40 (May 20, 2013)

80 percent. I made my own cam file for finishing it. All the holes and fcp were cut via cnc


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## 350xfire (May 20, 2013)

Very cool man!


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## rmteo (May 20, 2013)

How long did it take for you to completely machine that lower receiver? Same question for the upper receiver (assuming you also made one).


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## gt40 (May 21, 2013)

rmteo said:


> How long did it take for you to completely machine that lower receiver? Same question for the upper receiver (assuming you also made one).



I machined the control pocket, engraving and the safety, trigger and hammer holes + cerakoted everything. The lower was partially completed and the upper is jd enterprises. It took about 5 minutes to cut the pocket and about a minute to drill the holes. What took a bit more time was the setup- making sure everything was aligned correct in the vice relative to where I set zero and making the cam files in mesh cam. That took about an hour.


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## PhotonFanatic (May 21, 2013)

Does that engraving read "caliber", or "calibar"?


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## gt40 (May 21, 2013)

PhotonFanatic said:


> Does that engraving read "caliber", or "calibar"?


 The "e" kinda does look like an "a" from that pic. It is a e. When I cut it extra deep, I started to cut away some of the detail in the closed part of the e. Head on, you can clearly still see it as an e. This has been mostly a learning experience for me on setup, setting zero precisely on parts in multiple dimensions and learning how to engrave. The fact that it works and gave me 1/2"-1" moa groups on sunday is a bonus...


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## PhotonFanatic (May 21, 2013)

Upon closer look, knowing that it is an "e", I can see it now. I would think that font selection makes a big difference in legibility when engraving.


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## rmteo (May 21, 2013)

Thanks for the timing info.


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## gadget_lover (May 21, 2013)

I have to wonder... 

You buy a 80% lower receiver to avoid the need to go through an arms dealer. It's not a firearm because it needs 'special skill and equipment' to make it into a usable firearm.

If one gets the lower and the appropriate cam files, will it still be considered 80% finished? 

Daniel


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## gt40 (May 22, 2013)

I love to make stuff and finishing a lower was a great learning exercise for me. I learned to indicate a part through multiple setups and have an ability to machine in multiple dimensions. This was the biggest set of skills I learned and, as the title of the thread says, learning how to do cnc engraving. I took a cad file reference design, used it to create a cam file from scratch using mesh cam and figured how to align it. It would have been much easier to just to go to a dealer and buy the part. That wouldn't have been the point though. Shades of buying a lathe and spending thousands of dollars on machine tools to make a light


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## precisionworks (May 23, 2013)

That's the nicest looking 80% that I've seen. Quite a few people buy them thinking they'll need nothing much besides a big hammer & a tube of JBWeld but then reality sets in. They should look first at the print & then decide.

http://www.firearmfiles.com/files/AR15/AR15 Lower Machine Drawing.pdf


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## bcannon87 (May 23, 2013)

gadget_lover said:


> I have to wonder...
> 
> You buy a 80% lower receiver to avoid the need to go through an arms dealer. It's not a firearm because it needs 'special skill and equipment' to make it into a usable firearm.
> 
> ...



You are allowed to manufacture 1 weapon for personal use per year. ATF doesn't really consider it anything.


"Life is hard, it's even harder when you're stupid."--John Wayne


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## precisionworks (May 24, 2013)

gadget_lover said:


> ... You buy a 80% lower receiver to avoid the need to go through an arms dealer.


Most of the ones I see are purchased by people who don't want to pay full price. At some point they realize that finishing out the lower is only a bit more challenging than the YouTube video that took nine minutes & ended with a fully machined part :nana:


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## gt40 (May 24, 2013)

It was a lot of work but now I get to use what I learned to make a lantern entirely in cad/cam.


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## cncwhiz (May 31, 2013)

Nice work. I have always used a center drill or other tool with a bevel angle and small web to do engraving. Good practice you did with stepping down in .001 increments to get it to the depth you wanted. I have a vise I made that I put my name in the top of a few months ago and went to deep. I have to mill out the pocket deeper and redo it. What software did you use to do this? I have used Mastercam and GibbsCam. I have an 80% lower as well that I need to do the writing in, just haven't had a chance. Saw a pic on facebook a few weeks ago where someone had written "no pew, pew, and pew pew pew" on a safety slector in pen on a military rifle. I thought that was pretty good, lol. I think I might do the pictograms on mine, like you see on a HK 416. I got my lower from Colfax Tactical. It is a very nicely done piece and they were great to deal with. I can easily finish the machining and all. The reason I bought mine is just to have another piece on my rifle that I made. I like having that satisfaction. I made the muzzle device on mine as well, and that was a challenge. It is fully pinned and welded. It's main purpose was to get the barrel out to 16+", as it is 14.5 without a muzzle device.


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