Best way to drill through cast iron???

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I'm stumped on a good way to add an outfeed table to my saw. Yet another "benefit" of the Jet Supersaw. Before I dimisss this idea entirely, I thought I'd ask the "Pro's".
If I wanted to attach some brackets to the table saw cast iron top, I think I'd be drilling some biggun holes into some purdy thick iron. Would I be an idiot to try this? Would it take forever? Would I go through 35 bits? Would I need some liquid coolant on the bore? Should I buy eight $15 Black and Decker cheapo drills and just burn them up?
Or - should I dimiss this approach and look for another way to attach the outfeed table?
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it isn't that tuff to drill. You are gonna drill about 1/2 or 7/16 holes? One bit should do the whole thing. We aren't talking grade 8 material here. Now that takes a cobalt drill bit, or better.
dave
tnfkajs wrote:

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--
In His Name, be Blessed,

Just drill with steady pressure and low speeds and I use power steering
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tnfkajs wrote:

I use rare earth magnets epoxy'd to the table that attach them selves and hold pretty well. You can find these in any old hard drive or do a web search for rare earth magnets.
Someone a long while back (it's been 8 months since I've been on the wreck) posted this message and had a web site showing it. Works great!
Mike
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Off memory (from when i drilled holes in my bandsaw table for an aftermarket fence), just use a standard high speed steel twist bit at about 1000rpm (I used a drill press). A little lube may help disipate the heat produced and protect the drill bit a little more but apply it only after you have drilled in a small way, so it doesn't slip while your trying to drill the first few mm's
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wrote:

No idea. Well behaved cast iron is easy to drill, "chilled" iron can be a nightmare. Give it a go, you'll probably find it drills very easily. Use a sharp twist drill and you don't need lubricants or cutting fluid. The swarf should come off as chips, not twirlies.
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Andy Dingley wrote:

Swarf. That's it. So after I just bragged about my perfect little twisty things, does that mean I did it wrong? Fed too fast?
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Andy Dingley wrote:

I'm offline at the moment, but I'll follow that directly.

Oh, right, cast iron. I was drilling a piece of railroad track. Whatever kind of steel that is.
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On Wed, 06 Aug 2003 20:41:43 -0400, Silvan

Steel isn't the same as iron. Not by a long way !
We no longer see much iron in use, just cast iron. And even that's getting rarer. Before the late 19th century and the Bessemer converter though, steel was a rare and expensive alloy used only for hard edges. Most things we'd now use mild steel for were made of wrought iron, of various grades. These days, decorative smiths can hardly buy wrought iron anywhere. There are only three (?) bloomeries left making it world-wide, and these are solely for the "arts and crafts" market.
Railway line is awkward stuff. Old rails tended to be fairly simple alloys, but modern ones are quite complex. They may even be a harder steel head welded to a less brittle rail, or a flame carburisation process where the alloy of the wear surface is changed. Some of these are damn near undrillable.
Around 1910, Newcastle Upon Tyne was noted for two things; the huge shipyards building armoured battleships, and the world's largest railway crossing at one end of Central station. Crossings and points are always awkward, as the "frog noses" (the pointy bit) wear rapidly. The solution to regular replacement and traffic disruption was to replace the frogs in this crossing by a specialised manganese steel, drawing on the shipyard's armour knowledge.
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On Thu, 07 Aug 2003 19:04:01 -0400, Silvan

I never said "good" or "bad", just that it's how CI behaves. Twisty swarf certainly isn't bad, it's just that you won;t get it, except for the most sophisticated grades of CI.
The other thing about CI is that it contains loose carbon between the iron crystal grains. This acts as a lubricant, so you don't need to add one yourself.

Doesn't really sound heavy enough !
My 8' beam car-portable treb <http://www.jarkman.co.uk/toys.htm began life with a 12 brick counterweight and was pathetic. With a 20 brick counterweight it got much more interesting. You need at least 20:1 weight ratio to make a treb start to behave.
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Andy Dingley wrote:

It isn't, but it's the most weight I could come up with without having to scrap the entire thing. Started life using part of an old weight set for weight. Came to 26 pounds. It was miserable.
The track weighs 62 pounds, so it does better. Track works because it's narrow enough to fit into the frame that I built to accommodate the original weights. Any wider, and I have to replace my nice hardened steel Nordic Trac axle with something else, and pretty much rebuild the entire thing from there.

I shoot a 5 oz baseball, so that's... Well, more math than I want to do after all this beer. Let's see... 16 ounces to a pound, so I have 5/16 of a pound... Looks like almost a 200:1 ratio unless I'm just demonstrating how bad Americans are at math.
No pictures. I haven't gotten around to taking any yet. It's a good bit smaller than yours, and much more heavily built. Maybe I over-built it, but it sure has lasted well. I have it strapped to a hand truck so I can roll it across to the big parking lot across the street. If I ever get to take it anywhere, I can probably fit it into the back of a van without taking it apart, though I will want to un-hook the weight first I should think. :)
Maximum range on those baseballs is about 100' I'm afraid. I've heard accounts of smaller/lighter trebs doing better, so maybe I don't have mine properly tuned yet.
Tomorrow I'll throw half a brick with the thing and see if I can beat your 50' throw. :)
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On Sat, 09 Aug 2003 02:27:05 -0400, Silvan

You need to account for the beam inertia too.

Nearer 200' now - with the big counterweight !
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Andy Dingley wrote:

I have no idea how to calculate that, so we'll just skip it. It's more than plenty enough to throw a baseball. I hate sewing, and I made a sling that can't fit anything larger than a baseball, so a baseball it is.
I wonder how you'd factor in the roller bearings when calculating arm inertia. I gather these things aren't usually built that way. The arm is ~2" wide along the pivot axis, but the contact patch is much narrower, since the only bearing surfaces are a couple of 1/4" thick roller bearings. Very low resistance; very smooooth. If I put a fixed weight on the bottom and give it a good shove, it will rock back and forth for 20 minutes.

I got to about 70' with half a brick. But your machine is much larger than mine. From ground to the top of the hook is 60".
Anyway, there are lots of trebuchets out there in the world that are bigger/stronger/faster/cooler than mine, but there's only one like this one, and I designed and built the thing myself, and it kicks ass, no matter what anybody else says. :)
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On Sat, 09 Aug 2003 15:10:03 -0400, Silvan

Download the programs WinTreb or TrebStar

My one started with an axle of 3/4" tube, then bent that during testing. Nw it runs with solid 3/4" steel. Don't underestimate the forces around that pivot ! (like they did on Scrapheap Challenge)

Absolutely !
BTW, the last couple I made were mangonels, not trebs (twisted rope, not a weight) One had a 9" arm, for my 8 year old, and the other had a 12" arm for a friend's birthday. http://www.jarkman.co.uk/catalog/random/onager.htm
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Andy Dingley wrote:

And run them on what?
I haven't found any trebuchet software for Linux. Actually, I just looked again, and there _is_ something, but SourceForge is being uncooperative at the moment.

Mine is only 5/8" but it's serious stuff. I couldn't drill a hole in it. When I tried to mark the starter dimple with my center punch, I ruined my center punch. I never could get a bit into it.

I've thought about building one of those myself, but I think I have to draw the line somewhere, and that's it. Using archaic technology is fun, but for the scale of machine I have to build, I'd be surprised if a torsion bundle is worth the effort compared to bungee power.
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On Sun, 10 Aug 2003 01:16:25 -0400, Silvan

Wine ?

A torsion bundle works better when scaled down than either a weight machine (especially) or a bungee.
Nylon bricklayer's line is the best I've found. Horsehair is more in period.
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Silvan wrote:

Constrain the payload to approximate size and mass of a USDA grade A extra large hen's egg: good aerodynamics, harmless, but still lots of fun. What range could you achieve with a modest treb?
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Dr. Rev. Chuck, M.D. P.A. wrote:

Hmmm... Now why didn't I think of that? We don't eat a lot of eggs, and I'll bet there are still eggs in the fridge left over from last winter's cookie baking season. Maybe I'll decorate the gigantic concrete wall beside my house. :)
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JackD wrote:

Be damn hard to crank it up though, I'd think.
Hard on the suspension too.
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I'd use oil, slow speed, and not over 1/4". Drill a hole in some iron, or maybe use one of your rails, and clamp it so the hole is where you want to drill. That will get you started and keep the bit from skating. Wilson

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