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| drilling/boring a very long hole? |
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| SPiN Racing:
Morning gang, I have an idea/project I have, and Im trying to understand/crack how to accomplish it, and or ask for the proper thing when I go have this done. I have a bolt, that is appx 2 feet long. It is a strong bolt, that is under some measure of tension, and will encounter a bit of vibration. The bolt is strong enough, and there is no real threat of it breaking as it is. I do not believe its hardened, it is a normal bolt.. even though its about 1/2 inch in diameter. You can drag a file across the shaft of it, and it will make a mark. This being said... How does someone drill a hole through it? This is NOT a firearm.. but I was thinking something like a smoothbore barrel.. someone has to drill those out I would assume. That being said... what would I ask for if I was gonna go someplace and ask them to do it? And or.. do they even drill them? Or are they forged that way? The project needs a hole 1/8 inch or slightly larger through it. The inner bore is not critical. :scratch: Thanks for any insight! (Yes I have a bridgeport, and a 11x36 lathe.. but dont think I have anything like the tooling to do it.) |
| BillTodd:
For a 2 foot x 1/8"hole you will need a gun drill (e.g. http://www.sterlinggundrills.com/) These are far too expensive and troublesome for a one off, so you'll probably want to find an engineering shop willling to under take the task - oh and take a well filled wallet with you ;) [edit] You might just be able to find hollow bar stock about that size , if the hole dims are not critical |
| dickda1:
You might drop a note to Guy Lautard over in Canada. He built a refiling machine and has written quite a bit about how to build and use gun drills. http://lautard.com/rmv.htm -Dick |
| Lew_Merrick_PE:
Spin -- ø.125 X 24.00 deep is nothing trivial. A gun drill would be the best way to drill it, but figure you will be paying for a full hour of shop time to get it done ($50-$125 depending). However, a set of (12 + a skosh long) bell hanger's drill bits might work for you. I would definitely set my nominal diameter as large as possible (ø.188 would be a major improvement). Start with a ø.125 long drill and drill just short of half-way through from each end. Move in very carefully. Withdraw the bit to clear out the chips and relubricate everything about twice as often as you think necessary (or even four times as often). Redrill to (say) ø.156 (5/32) going past the half-way mark from each end (being exceptionally careful at breakthrough. Finish off by drilling out to (say) ø.188. Keep all your lucky charms within reach. Stroke them regularly. Clear chips & lubricate (repeat, repeat, repeat) -- and you might be able to pull it off. (I had to drill 200 gas-reaction latches ø.094 X 8.00 deep some years back. It took me approximately 275 pieces of bar and probably somewhere close to 60 drill bits to finish the job.) Good luck! |
| AdeV:
You MIGHT be able to get a custom-made twist drill in that sort of size, but expect to pay $$$$ for it. The one I used here: http://madmodder.net/index.php?topic=2726.msg30078#msg30078 cost me £180... but that's 5/8" x 600mm flutes; you want 1/8" which I imagine would be a tall order... |
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