Large, Long Holes in Wood...

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Terminal velocity for a billiard ball oughta be a *lot* higher than that -- 120 mph is (approx) TV for a clothed human, and a billiard ball is denser and smoother by a long stretch.
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Agreed... Useless info but... a 400 lb. Rubber band ball dropped from an airplane reached over 500 MPH and the free-fall skydivers could not keep up with it. I'm guessing that a much more dense item like the bilalrs ball with a smooth surface would best that number by quite a bit... Which makes *my* story look even more like I made it up.
Got me scratching my head here wondering how we did it...
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Joe Agro, Jr.
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Joe AutoDrill wrote:

Hmm - ever consider that the guy you almost hit returned fire with your own billiard ball? :-)
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Morris Dovey
DeSoto Solar
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Morris Dovey wrote:

Gives new life to the old saying:
"Cave ne ante ullas catapultas ambules."
What are the odds I'd ever use that? :-D
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Morris Dovey
DeSoto Solar
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About the same as me knowing what it means withoit a Google search. :)
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Joe Agro, Jr.
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denser
up
makes
http://www.grc.nasa.gov/WWW/K-12/airplane/termv.html
Plug in the numbers, and you'll get the answer.
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wrote:

Terminal velocity for a billiard ball should be about 43.5 m/s, or 97.4 mph. The drag coefficient for a smooth sphere is C = 0.5.
Some info on terminal velocity with examples:
http://hyperphysics.phy-astr.gsu.edu/Hbase/airfri2.html
A page with a calculation app. that you can see the results of a vertical shot for a spherical object like a billiard ball:
http://hyperphysics.phy-astr.gsu.edu/Hbase/mechanics/quadrag.html#c1
The radius of a standard billiard ball is about 2.857 cm, density about 1637 kg/m^3 (1.637 gm/cm^2). Mass about 160 grams.
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charlie wrote:

Good thinking - just as with routing and milling, depth of cut per pass, adequate airflow, and a suitable feed speed are important factors for controlling heat build-up. In the case of laser cutters, I think additional control can be exercised by controlling pulse frequency and/or duration.
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Morris Dovey
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Joe AutoDrill wrote:

It's because I'm so lazy and such a cheapskate. I's a fatal combination.
If the approach could be made to work (depends heavily on collimation of the laser beam), it'd only be necessary to drop the log on the cradles with a fork lift, locate the height of the center of the log, specify the diameter, and stand back. There'd be a minimum of mechanical stuff to maintain, and no expensive bits to sharpen or replace (or stock in different sizes). I'm guessing that power consumption would at least not be worse than a traditional boring machine.

Probably, smoke should be considered a solved problem - and shouldn't be more complex than ventilating a spray booth. Setting up guards, interlocks, and shields for safety should be straightforward.
I don't know what kind of beam collimation is current state of the art, but I'd guess that seven or eight feet should be workable.
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Joe AutoDrill wrote:
...

...
...
I didn't see this until Morris had already made the suggestion, but that was my first reaction as well.
As for the safety issues, those could be pretty easily taken care of w/ appropriate fixtures I would think. If they're doing this extensively, a little extra for the fixture shouldn't be any drawback.
At former employer in a previous life :) we begin using laser penetration/welding in pressurizing nuclear fuel rods w/ inert gas during the manufacturing process "way back" in the late-70s. Laser focussed to make a pinhole in fuel rod end cap, evacuated and then filled w/ argon; laser defocussed and welded shut the hole. Same thing; a fixture and interlocks prevented any way of getting the laser activated w/o the required shielding in place.
I would thing there could be a heat removal issue in such a thick enclosed piece, but where there's a will there's a way.
The description of a current tool that reaches (apparently) the full length and leaves the core is leaving me w/ the desire to see that puppy... :)
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Joe, have him look at Vermeer's moles. He won't need anything that serious, but the parts and drives are there. Horizontal boring is one of their specialties. They bored a hole from the church parking lot on my street, past my house and down the street a total of 1300 feet, going through deep roots, rocks, all kinds of stuff and ended up exactly where they wanted. I can't imagine they wouldn't be able to help him.
r
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Joe AutoDrill wrote:

Sounds like a job for Technidrill http://www.technidrillsystems.com/ or one of their competitors.
Google "gun drill" and you should be able to come up with more hits. A call to the appropriate division of BAE Systems might also yield the name of their tooling supplier (or might not depending on how close to the vest they like to keep their manufacturing).
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"Joe AutoDrill" wrote:

National carbon used a "gun lathe" to machine 6" dia thru holes in 20 ft long graphite logs for the nuclear industry.
They found both the lathe and a milling machine at an old armory auction as I remember it. (This was 1960 era).
Lew
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Joe AutoDrill wrote:

.. snip

No leads,but it seems like having the cylinder left behind would be a benefit -- the remaining cylinder could either be drilled to a smaller diameter, or used in some other way. Seems like a drill that operated in the typical manner would generate a lot of waste needlessly.
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Depends on how many they need to do, how much they are willing to spend and how hard they are willing to work, doesn't it?
Two hundred years ago, this was done by hand. Logs were bored out and used underground in municipal water systems. I recall reading a few years ago that there were some still in use, but that may not be so. If you look for "pump auger" or "pipe log auger" you may find some of the antiques that were used. According to Mercer, it took two men about a day to bore 16 foot white oak logs in 1926.
Could you drive it by power instead? Certainly - perhaps a post hole auger or a pipe threader. Check rec.crafts.metalworking and you'll see that oldjag just successfully used a pipe machine to bore through 20 feet of earth with a 2 inch pipe.
For a machine made for doing exactly this kind of work, albeit in metal, look for a horizontal boring mill. Lots of them available at auction, and an old clapped-out machine would still be much more accurate and powerful than they would need. They could probably find one for little more than scrap price, although you're probably looking at 10 tons at the least.
Coring the log sounds nice, but I wouldn't insist on it. Coring doesn't leave much room for chips, and there will be a lot of them. Also, the core will contain the pith of the log, so it won't be much use as is. The guys doing it by hand bored a small (2 inch ?) hole which they then enlarged with reamers, which seems like a good method.
John Martin
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LOL. Yes.
CLIP

I was following that one closely. However, it looks like his hole was 2" diameter and he used one heck of a contraption based on a magentic base drill...

Good point...

Would love to see a time lapse film of that... If only they had good film back then. Must have been an interesting job and LOTS of work to pipe a street, etc.
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Joe Agro, Jr.
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On Tue, 5 Aug 2008 09:39:24 -0400, "Joe AutoDrill"

<snip>
I don't know what the application is but wouldn't it be easier to rip it on a bandsaw mill, core box bit the insides and glue it back together?
Regards, Tom.
Thos. J. Watson - Cabinetmaker http://home.comcast.net/~tjwatson1 / tjwatson1ATcomcastDOTnet
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That is what we said... But I guess they need it in one piece for some reason. All I could picture was high end sail masts for sailboats with an aluminum mast hidden inside... And customers who were too picky to accept a "split down the middle" wood look...
...But God only knows what they will actually be using the wood "tubes" for after they are done...
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Joe Agro, Jr.
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"Joe AutoDrill" wrote:

These days, high end sailboat masts are strictly carbon fiber.
If you have to ask, you can't afford.
Lew
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Maybe as cannons on mythbusters?
scott
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