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Posted: 3/17/2015 10:16:35 PM EDT
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So, last week I decided to see how much weight I could shave off the nose of a 16" M4gery by simply cutting the barrel to a .600" pencil profile. Pulled the barrel, stuck in in the lathe, and about a half hour later, it was 3.3 ounces lighter. Still unsatisfied and never particularly liking the look of an A2 birdcage anyway, I ordered up a length of 3/4" 6Al-4V ELI titanium to play with.
My piece showed up today, and I immediately went to the lathe with it. Now, this is my first go with Ti, so I wasn't sure what to expect. Turns out the stuff really machines pretty easily, but thread tapping is a bitch, as the highly elastic metal tries to close up on the tap. Nonetheless, after several trips in and out of the hole with high sulpher gear oil to help, it was threaded. Once the profile was cut, it was into the indexer for the mill work. I decided to keep it short, so it is only a two chamber, six port design. Weight reduction of the Ti comp over the birdcage is another 1.1 ounces, so the net savings between the barrel turning and comp is 4.4 ounces-a little over a quarter pound where it counts the most, on the nose of the rifle. 
I may revisit the steel comp I built for my .308 AR now, as that thing could stand to diet a little 
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I have built a bunch of titanium comps for myself and a few others. Yours looks lighter than mine but I am happy with the way mine work. I also made 20 titanium lug nuts for my last custom car all by hand on a small lath and you're right the hardest part is the drilling and tapping. I did find a trick to tapping use a tap with at least three flutes preferably four and cut the back of the teeth down. Hard to describe and I don't have any pictures but like you said the metal seems elastic. So you want to eliminate as much metal contact between the tap and the inside threads. You leave the taps cutting edge alone but from just behind the cutting edge grind the teeth down to the root. You'll be shocked how much easier the tap cuts with so much less friction.
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Quoted:
I have built a bunch of titanium comps for myself and a few others. Yours looks lighter than mine but I am happy with the way mine work. I also made 20 titanium lug nuts for my last custom car all by hand on a small lath and you're right the hardest part is the drilling and tapping. I did find a trick to tapping use a tap with at least three flutes preferably four and cut the back of the teeth down. Hard to describe and I don't have any pictures but like you said the metal seems elastic. So you want to eliminate as much metal contact between the tap and the inside threads. You leave the taps cutting edge alone but from just behind the cutting edge grind the teeth down to the root. You'll be shocked how much easier the tap cuts with so much less friction. <a href="http://s146.photobucket.com/user/908ssp/media/machinework/comp_zps3b829ad7.jpg.html" target="_blank">http://i146.photobucket.com/albums/r245/908ssp/machinework/comp_zps3b829ad7.jpg</a> Why didn't you at least time it so the weld is at the 6 o clock? |
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Quoted:
So, last week I decided to see how much weight I could shave off the nose of a 16" M4gery by simply cutting the barrel to a .600" pencil profile. Pulled the barrel, stuck in in the lathe, and about a half hour later, it was 3.3 ounces lighter. Still unsatisfied and never particularly liking the look of an A2 birdcage anyway, I ordered up a length of 3/4" 6Al-4V ELI titanium to play with. My piece showed up today, and I immediately went to the lathe with it. Now, this is my first go with Ti, so I wasn't sure what to expect. Turns out the stuff really machines pretty easily, but thread tapping is a bitch, as the highly elastic metal tries to close up on the tap. Nonetheless, after several trips in and out of the hole with high sulpher gear oil to help, it was threaded. Once the profile was cut, it was into the indexer for the mill work. I decided to keep it short, so it is only a two chamber, six port design. Weight reduction of the Ti comp over the birdcage is another 1.1 ounces, so the net savings between the barrel turning and comp is 4.4 ounces-a little over a quarter pound where it counts the most, on the nose of the rifle. http://i110.photobucket.com/albums/n117/Hunter2506/Mobile%20Uploads/IMG_20150317_195023987_zpsuoxi9x3f.jpg I may revisit the steel comp I built for my .308 AR now, as that thing could stand to diet a little That comp looks nice. |
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