drilling cast iron

I'm finally getting to assembling my table saw(s). I finished the mobile base today and scooted the unisaw onto the base. I had already attached the CI wing. So I attached the other CI wing and benchdog router table wing.
I'm making this:
----------------------------- Benchdog Router table ----------------------------- table saw wing 1 ----------------------------- cabinet saw ----------------------------- table saw wing 2 ----------------------------- contractor's saw ----------------------------- harbor freight router top -----------------------------
So the next step is to attach the contractor's saw to table saw wing 2 that was included with the contractor's saw. That's when I noticed that it's different from the wing that was included with the unisaw (tablesaw wing 1). Instead of a mating surface with holes drilled in it, there are no holes and it's painted with what looks like black powder coat. There's also a slight roundover on the corners.
So I have four choices:
1. don't bolt the contractor's saw to the rest of the top and position it on the mobile base in the right place.
2. take off that wing and buy another one with the holes.
3. position the contractor's saw where it goes and clamp the two tables together with C-clamps, making them godzilla tight.
4. sand off the paint on the wing, then drill some holes in the wing, then bolt them together.
I'm currently leaning toward #4. But I've never drilled cast iron before. How difficult is it? I don't have to tap it, just drill them oversize. There's threading in the contractor's saw table.
I plan to put a harbor freight router table extension on the other side of the contractor's saw, then build a cabinet under that to support that end of the table. Once I do that, I'll suspend the contractor's saw in the air with storage under it, sealing the CS for dust collection.
brian
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Cast iron is not steel; it drills very easily. I drilled mine when I put a extension wing router table on.
Try it in a harmless place first if you have doubts.

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TS tops typically drill very easily. Start with a punch to locate the center exactly. Move up to a 1/8" bit and progress up from there.

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<snip>

Due to the graphite inclusions in ductile iron, it's very easy to drill.
todd
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actually it drill rather well. Of coarse a drill press is best, but good results can be had with a hand drill. Possibly drill a small pilot hole, 1/8 " at first then your other hole: 5/16-3/8 as needed. "
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wrote:

I had to drill cast iron recently when making a propane burner for my forge, and it was as easy or easier than drilling mild steel (can't say with any real certainty, because the cast piece was a pipe elbow, and I was drilling into a curved surface- not something I do all that often with steel.) Taps easily, too. The only thing that gets tricky with cast iron is welding the stuff, but you're not doing that. It shouldn't be a problem.
*Do* remember that metal is not wood, and you need to drill at a low RPM, and use some cutting fluid (motor oil will work in a pinch, if that's what you've got.)
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Cast iron drills very easily. The only problem with it is that it can be a bit "grabby", like brass or copper. For a lot of holes, it might make sense to stone the cutting edges. Otherwise, just be careful when the bit breaks through the far side. And, if you want to drill a pilot hole, make it no larger than the the thickness of the drill web (the chisel point). No cutting oil is needed - the graphite in cast iron serves as a lubricant.
John Martin
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Thanks everyone. I'll try to drill it tonight.
brian
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