First AR Build/Future SBR

[jafierst]

I bought a stripped lower last weekend for my first AR. I am planning on starting with a 16" 5.56 upper and eventually getting a 300BLK SBR barrel to suppress. I spent a few hours this weekend making a fixture and doing the engraving myself.



I think it turned out pretty well. Now I can fill out my Form 1 knowing that the lower isn't going to be ruined during engraving. It was nerve wracking when I pressed the cycle start button... I used the same program that I had done my practice engraving with, but I forgot that the practice program also drilled the trigger pin holes so I could lay it on top of the receiver. Luckily I was able to hit the E-Stop before the cutter hit my clamp.

Now begins the long wait for my stamp... Hopefully the wait will be less than a year...

[cds_arms]

The engraving job looks great!

That's really nice that you have easy access to a good setup. Need to sell your services lol.

I'd say you should hope to get the stamp in 4-6 months. I've seen F1's take 3 months recetly, but you also hear the horror stories of 6+.

Good luck!

[EandGWZ]

Looks great, best of luck in getting a timely stamp

[TTR]

Looks awesome. PM on the way..

[AlpacaFarmer]

You should definately sell your services! I got my Form 1 back last week...took 5 months. Good luck!

[cds_arms]

You should definately sell your services! I got my Form 1 back last week...took 5 months. Good luck!

Could.. But it would require a FFL, insurance, PA sales tax license, etc. Could do a couple here and there for friends so long as the firearm owner stood there and maintained custody of the firearm.

What kind of CNC mill setup is that?

[jafierst]

The mill is a Sherline 2010. It was retrofitted with stepper motors to make it computer controlled. As you can see from the picture below it is really a table top mill. I also have the 4th axis for it, but have only used that once to jewel the bolt on my Dad's Ruger Mark III. I have also jeweled the bolt of my 10/22 and one of my knives...







The main thing I have used it so far is making lithophane Christmas ornaments for the family. Here are pics of the first one I made (my new niece):

As machined:

Backlit:

And some video of the machine in action: http://youtu.be/lk99JRkQ91o
And of another finished lithophane: http://youtu.be/UT0Ac0Tv0i8

[cds_arms]

Cool setup.

What kind of software does it use? Is it a custom CNC stepper setup, or is it one of the Sherlinde 'CNC' kits they sell on the website? http://www.sherline.com/packages.htm

What is your experience and skill level to use the setup? Do you need to do a lot of manual work? I do professional IT work full-time, so the computer side isn't a problem, but the machining/CNC/setup is as I have little to no experience there. I've seen people do wild homebrew CNC setups, but I'm not looking for that lol.

I'm in need of an engraving machine, and if that works well enough for small stuff, I may just grab one of the mini mills.

I've been looking at small CNC mills, but I don't know enough about them to buy.

[jafierst]

I mainly use 3 programs (luckily I have access to all of them due to my day job) to create the designs and machine code.

SolidWorks - to create 3d models
AutoCAD LT - to create 2d drawings
MasterCAM - to create g-code from my drawing or model

And the program that actually takes the g-code and runs the mill is MACH 3 http://www.machsupport.com/

I have also tried BobCAD for creating the g-code but it seems backwards. It it like no other cad or cam software I have ever used.

There seems to be a few free engraving programs out on the web that may work, but haven't tried any of them yet.

I actually purchased my machine off of craigslist a few years ago, it was a deal that I couldn't pass up. I had taken a machine technologies class at CCAC (one of the community education classes) and had some experience with manual machines in college. I was looking for a small machine that I could use to learn g-code and to do small projects. The original owner was a very talented young man that was going into the armed forces and didn't want to put all of his things in storage, so he was selling everything on craigslist. He actually converted the machine over from a manual machine. He added the stepper motors (which seem bigger than the ones that Sherline supplies). He also designed and built the controller box.

I've been able to dumb my way through everything so far... Luckily the parts on the machine I have broken have all been relatively cheap and easy to replace (usually the most expensive part is shipping and handling). I have learned enough about MasterCAM to get by and any problems I run into I look up on the net or ask the expert at work the next day.

For engraving I think the machine works fine. My friend at work swears that the best engraving cutter is a centerdrill and it does seem to work pretty well. I have also ordered some special cutters from http://www.2linc.com/. One of the upgrades that the original owner had installed was the high speed spindle kit. This is just a different ratio pulley set that raises the max speed to 10,000 rpm. This is nice when using very small cutters.

The main issues I have had with the machine are due to the stepper motor drives and the potential to lose position. This is compounded by the fact that the Sherline mill uses regular threaded lead screws and not ballscrews. If the lead screw binds up or the carriage sticks for a pulse or two the position is now off. There is no feedback with the steppers.

The hardest part for me is the setups... I spent an hour trying to get the receiver to indicate flat in my fixture. Since I was shooting for .003 deep letters having the part be out .005 over the length of the engraving wasn't going to work. I would indicate, then unclamp and shim, and then indicate again. I'm sure with more experience I will get better at it, but it is still frustrating.