milsurpcollector Posted March 13, 2007 Report Share Posted March 13, 2007 Im building a 98k Long side rail sniper rifle and I need to drill 3 holes in the side of the reciever. My question is, How do you accurately locate these holes. A punch is too big and the mount tends to shift when I hit the punch. Drilling the holes is no problem but accurately locating them is another matter Thanks in advance Link to comment Share on other sites More sharing options...
hodgie Posted March 14, 2007 Report Share Posted March 14, 2007 not that i have done this, but with my scope drilling fixture i made. i could flip it sideways in a vice to drill the holes. i guess you dont have a milling machine, right? but i would drill the hole spacing i need in a plate. then make some drill bushings,then mount the plate to my base. presto! i dont know what you may have for a scope jig, but it would work on most any type i've seen. in theory it sounds simple. thats how i would do it. Link to comment Share on other sites More sharing options...
Limpid Lizard Posted March 15, 2007 Report Share Posted March 15, 2007 First locate a sharp drill bit that just fits into the holes in the mount. Second, locate and superglue the mount in place. Use the bit that just fits the holes to start a hole in the receiver. Swap the bit out for the correct one for the tap you are using, and it will center itself in the dimple you made with the larger bit. LL Link to comment Share on other sites More sharing options...
hodgie Posted March 15, 2007 Report Share Posted March 15, 2007 i did my very best to make this to the tightest tolerances possible. there is zero slpo, but still goes together easily. to drill the holes like you asked, i would make another plate that bolted to side of the jig, measure out the hole spacing, drill and ream for drill bushings. when i was assured all is square and located to my satisfaction, i would drill away. i wish i knew how to make these smaller!!! Link to comment Share on other sites More sharing options...
Doble Troble Posted March 17, 2007 Report Share Posted March 17, 2007 Making a template (and checking it twice) is a great idea. My Bubba approach would be to try the superglue approach and use a transfer punch to locate the first hole. I use transfer punches all the time and don't know how I lived without them before I found them cheap at Harbor Freight. After drilling and tapping the first hole I'd attach the mount with the first screw and use the mount itself as the template for the remaining screws. Drilling the holes is only the first step. Getting them tapped square is also a problem. Using the mount as a template will help insure that any tapping wobble (which should be avoided at all costs, but without a rock solid set-up is inevitable) won't likely result in problems torquing down the mount. Link to comment Share on other sites More sharing options...
Limpid Lizard Posted March 17, 2007 Report Share Posted March 17, 2007 After drilling one hole, swap the bit for a tap in the chuck. Turn the spindle by hand. This will insure the hole is tapped straight. You are using a drill press. aren't you? LL Link to comment Share on other sites More sharing options...
milsurpcollector Posted March 17, 2007 Author Report Share Posted March 17, 2007 Thanks to all who replied. I found my own way to do this. I bought a Phase II X-Y table for my drill press. Then I mounted the receiver to the receiver holding fixture that I secured to the table using holdown clamps. This is a very rigid setup. I used a center drill #1 that I eyeballed to the center of the mount hole. The receiver DOT 1943 was soft enough that the center drill worked easily in all but the hole closest to the receiver I the drilled and tapped using a trutapper I bought from brownells. The results are almost perfect. The X-Y table was $60 on sale and its a typical cheap chinese product, but it is precise and rigid where it counts Link to comment Share on other sites More sharing options...
Limpid Lizard Posted March 18, 2007 Report Share Posted March 18, 2007 As far as not using a jig being the Bubba approach, one must remember that there are manufacturing tolerance in everything. If you use a jig to locate the holes, the fit to the base will not likely be as accurate as the method I detailed. A base mounted on top may be afixed with machinist clamps rather than superglue, but I have seen some instances where glue was the only alternative. If one locates the hole in the base accurately, drills accurately and taps accurately, the base to receiver alignment should be more accurate than using a jig and then finding out the base was produced at the maximum tolerance for hole location. Congratulations on a successful mounting. Each one after this becomes easier. LL Link to comment Share on other sites More sharing options...
hodgie Posted March 18, 2007 Report Share Posted March 18, 2007 you know the saying, opinions are like #%!#^. im sure if 10 people gave ideas, you'd prob have nine different. all that matters is that you were succ. congrats! Link to comment Share on other sites More sharing options...
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