Drilling cast iron?

I have a table saw with two stamped metal wings. I found a cast iron table from an old saw at a garage sale for $3. Cleaned up it should make a great wing.
Unfortunately it only has holes on three sides, and I need them on all four. (Since both it an my saw are craftsman, I am hoping the other holes line up, but better check before I do any new drilling...)
Any advice on drilling additional holes? I have an industrial drill and a big pile of drill bits I got when a tool shop went out of business, but it looks pretty thick. I know I have to keep oil on the surface, anything else?
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Cast iron is relatively easy to drill. Make sure that the holes are where you want them. Use a center punch to give yourself a good starting point. Use a good fresh bit about a 3/16 drill bit. Keep steady pressure and a slow speed. As long as the bit is making chips or curls everything is fine, just concentrate on steady pressure and drilling straight. It should go through fairly quickly. Follow with the appropriate bit for the size bolt you are using.
You probably do not need lubricant.
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Keep the whole world singing . . . . DanG (remove the sevens) snipped-for-privacy@7cox.net

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the post from DanG is correct, but one caution is that thin section castings sometimes can have chill spots, which are very hard. If you have a hole that is particulary difficult, and the drillbit dulls, chill iron is probably the culprit. If that hole location is a must, you may need to use a carbide bit, slower rpms, and some lubricant.

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holes
a
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castings
location
Ermm........
Slower rpms is generally not advisable when using carbide tooling........
Not gonna get into the "why" part of the deal here--so you hafta just trust me on it this time is all, but in short, I guess I'll just add.......Ker-blang!!!
--

SVL



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PrecisionMachinisT wrote:

Heh, missed that. Correct. Frank
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PrecisionMachinisT posted for all of us....

I would be interested either here or in email. Thanks!
--
Tekkie

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A masonry carbide bit, or something special?
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A traditional type carbide twist drill is hard to find in retail (and expensive) so I think you could try it with a new masonry point. Cast iron doesn't need much in the way of chip control geometry. Try it first with a regular drill bit, though. The iron might machine like butter :)

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bill a wrote:

Most often it will. If a masonry bit is required it could be a disaster without a pilot hole. Masonry bit are usually flat on the tip (in center) so *that* part doesn't really cut and it will often elongate the hole and wander.
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toller wrote:

Couple more things from an old machinist. Make sure your drill does not have a flat spot in the webbing. If it does it needs a pilot hole or it will want to wander. With cast iron, even water is a suitable coolant.
Frank
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I had no troubles drilling holes in 50's vintage craftsman table saw, to add a Jet fence. Sharp bit, and center punch should be all you need.
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Use a slow speed and make a dimple in the iron before drilling. You could make a ring of clay around the drill area to keep a small pool of oil. It should bore easily.
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The type of cast iron used for a saw table is not hard to drill and lubrication is not required either. Just mark your positions with a center punch and take your time.
--

Larry Wasserman Baltimore, Maryland
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snipped-for-privacy@fellspt.charm.net (Lawrence Wasserman) wrote in wrote:

I should think that using lubrication would be better for your drill bits. Unless you only use them once and dispose of them after one use.
--
Jim Yanik
jyanik-at-kua.net
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wrote:

Lubricant/coolant is not needed for cast iron.
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wrote:

Correct - it will just create mud.
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wrote:

Thank you for the affirmation. I feel like more of a man now.
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