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Posted: 4/11/2009 3:26:53 AM EDT
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Im using a DPMS 1.10 gas block and want to drill and tap it so I can use a limiting screw on the gas system. Due to the curve in the block in the exact location that the hole needs to be, its gonna be tough to do with a standard drill bit.
I used 3/16" SS stock to make the gas tube, its fairly thick walled. Can I just drill and tap the gas tube itself, or do I need to use an end mill on the block to cut a flat surface and drill from there? |
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Im no machinist by any stretch of the imagination, so someone who is more knowledgable than me will be along shortly to give you the real information, but whenever i need to drill a hole on a curved surface i always put it in the vice and start lightly tapping the spot with a punch. Once i have a small dimple, I hit it a little harder to enlarge the dimple. Depending on the size hole, sometimes I start with a little drill whose tip fits inside the dimple (to prevent walking) and then move up sizes until i get when i need to be.
Im sure theres a proper way to do it that I just dont know about, but this has always worked for me. |
| I think your best bet is to use a small endmill and make a flat spot where you need it. The gas tube seems too thin to really get some good threads in that will be durable. I dont even know that a low profile gas block will have enough material if thats what your using. Take a look at the PRI offering if your using a low profile model. It may be a easier route or give you a better design to work from. I guess you could always tap a hole in from the front too though. |
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I often make my own gas blocks, I make them adjustable. I'm not sure exactly what gas block you have, but you'll need to spot it with a end mill, you might be able to get away with a center drill though.
What are you using to machine this? If its a drill press, you'll likely have issues with it. Are you making a custom length gas system with that tube? You'll need to turn it down so it fits in the carrier key and the gas block unless you open up the gas block hole with a reamer(best tool for it, need a tight fit). I recently did this on a tok build and its a pain in the ass to get that gas tube to line up with the carrier key. The screw hole for the adjustment screw is .5" off center of the bore and .295-.310(depending on where the port is) from the shoulder it sits on. Tap it 6-32, put the gas tube in then tap it again to insure a good fit with the screw. Jon |
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