h a l f b a k e r yGo ahead. Stick a fork in it.
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This is a really simple idea. Equip hand power drills with a shock absorber. This would be a simple rod in tube style with a bypass valve to allow rapid extension and a restrictive passage to limit compression, possibly with a small knob to adjust the peak rate.
When you need to prevent the harmful
and dangerous action of "punch through" or simply need to drill a hole without a pilot the DSA is there. Mounting a ring on the end of the DSA that loops around the center line of the drill makes the action uniform for all angles of drilling.
For those unaware a frequent problem when drilling is what happens when the tip of the drill punctures the far side of the material and the surface shatters rather than sheers away with the cutting edge of the drill. This is primarily due to the application of down force by the driller and if the rate at which the drill tip could travel was limited the problem could be avoided.
The collapsible nature of the DSA also makes it a desirable accessory for those who frequently need to drill precision holes on flat surfaces as it would act as a natural arbor for vertical or (with additional adjust ability) angled drilling.
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so it has nothing to do with "shock absorbing" then; what you describe is a governor. Could also be used to help line up a hole which is where I usually screw up [+] |
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I'm imagining a small diameter mono tube style setup,mounted directly to the top of the drill. it could be kept in a collapsed state unless needed with the ring guide flipped out of the way. In use it would be released and extended, the ring guide flipped forward and thus centered around the point of the drill. And yes, given a rubber no-slip surface it would act as an anti-wander device. It could also help when making holes in hard metal where overheating the drill tip is a major problem. |
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I'm pretty sure this is baked - I remember reading about this exact problem in relation to drills used for brain surgery. |
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I'm not sure whether a a // small diameter mono tube // would be able to take the bending force that results. |
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I like the idea. It rests on the supposition that materials that exposit exit-shattering beahviour would not do so with sufficiently low forward velocity of the drill, though, and i think this might be wrong : For a material to be drilled, the drill has to be pressed against the material with a certain force. At the end of the drilling, the remaing thickness of the material is not able to support that force, and breaks outward taking adjacent material with it because of shearing action.
For materials where the actually needed force (and therefore the thickness of material still ripping) is small (wood), your device would bring relief, but for materials where this force is high (stone) it might not work. |
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actually quite to the contrary, in wood the speed restrictive nature of a speed limited piston would be the primary source of resistance, you would "push" against the fluid and waste energy to turbulent friction. the piston would be "rate limiting" whereas with stone or metal the material would keep the feed rate below the "over speed" restriction in the piston and it would be as if the piston was not there at all, until you reached the far side and drilled that last 1% at which point the sudden increase in speed would prevent a violent "punch through". Obviously some adjustability is going to be needed. I'm sure if a monotube was to weak we could utilize another design. |
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I actually always hope that somebody else has come up with the same idea at some point in the past, I would feel somewhat lonely if that wasn't true. |
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[WcW]: my point was that i suspect the pressure, and not the velocity to be the factor in the breaking of the material, so rate limitation would not be sufficient. - The machines for testing breaking strenght of materials often "punch" through by only a fration of a millimetre after the material gives way, as the pressure is built via hydraulics, in that case the material still breaks, simply because the pressure exceeded it's rating. |
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As i said, in wood it would probably work, but for drilling stone et al, it is advisable to put the material onto something else, so the load is pure compressive, and not shearing/otherwise. |
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//Cures a common problem in hand drilling.// I would have thought that the sight of the drill emerging through the other side of the hand itself might be enough to deter all future ventures into this sort of activity. |
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Would a good name for hand drilling be: Trepalming? |
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I suppose I should have included a heat guidance system and custard somehow. I'm not in love with the idea, just curious about how it would work. Punch through is really only a problem in materials where sheeting or fibers are present, in metals when you punch through the drill tends to stall or "screw" on the burs left in the hole dragging the drill down without sheering a clean hole. A problem that currently lacks a solution.
In woodworking the problem of splintering has inspired a host of solutions, from magic drill bits to special tape. Some of them work, sorta. |
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If you were squishing, say, a foam sleeve or a spring resting against the front of the drilled surface with the drill body while you drill, the pressure applied to the bottom of the drill hole would decrease gradually as the sleeve compresses. |
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