drilling cast iron

[brian lanning]

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:

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Benchdog Router table
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table saw wing 1
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cabinet saw
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table saw wing 2
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contractor's saw
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harbor freight router top
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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

[Mike Henderson]

No problem drilling cast iron with a standard twist drill. I use some oil during the drilling to cool the drill. Squirt it where you're going to drill, and stop part way through and squirt again.

Cast iron is just iron with a relatively high carbon content - maybe 4% compared to 1% or a bit less for regular steel.

Mike

[Kelly C. Hanna]

Use a slower drill speed, faster you go the faster the bit will wear.

[Gary Keedwell]

I would make sure your using a HSS (high speed steel) bit. It will stay cooler therefore less chance of dulling.

Gary K.

[Robert Mahon]

I would also "Dub" the cutting edge of the drill's flutes. If left as purchased, there is a chance the cutting edge will dig in and pull the drill into the iron. If using a hand-held drill motor, the drill could dig in an grab, causing the motor to exert a lot of reverse torque on your wrists.
"Dubbing" doesn't ruin the drill and often extends the useful life.

Use a good drill, like HSS as mentioned. The imports that work OK for wood will not hold up well.

Don't exert a lot of pressure because the drill may dig in and bind.

Other than that, drilling cast-iron is no problem and the refuse will be small flakes rather than stringy metal.

[Jim Becker]

Why not do the C-clamp thing to verify you really like the arrangement before you go to the trouble of drilling. And you mention mobile bases...this is going to be tougher with such a large and wide arrangement as you have to have everything exactly at the same height and in the same plane. Mobile bases are harder to shim... Of course, if it's ONE mobile base for everything, it may work fine.

[Ray Moser]

Years ago I built an auxiliary table for my Jet bandsaw. I had no trouble drilling and tapping the cast iron table to mount the add on. I use cutting oil whenever I drill iron or steel.

[David G Baker]

I also use cutting oil when using a hacksaw to cut metal. It cuts much quicker, smoother and straighter.
David B

[brian lanning]

Why not do the C-clamp thing to verify you really like the arrangement before you go to the trouble of drilling. And you mention mobile bases...this is going to be tougher with such a large and wide arrangement as you have to have everything exactly at the same height and in the same plane. Mobile bases are harder to shim... Of course, if it's ONE mobile base for everything, it may work fine.

Thanks to everyone who's responded.

It is one mobile base. It isn't really like the ones you go out and buy. I made it by half-lapping 2x4s into sort of a # shape. I designed it so it could support a cabinet at each end also. I was also worried about four casters supporting the weight. So I may add more.

Originally I was planning to put the contractor's saw base under the saw to support it while I was bolting everything together, then remove it when I had the cabinet in place.

Among other mistakes, I didn't measure the stand before making the base (d'oh) just the cabinet saw base. It has a wider stance so I have to cook up other temporary solution.

I'll post pics when I get it all together.

brian

[glenn bradley]

I held off for about a week drilling my CI wings to complete my TS build despite everyone here telling me it wasn't that tough. So I'll say just what they told me . . . it's not that tough; slow speed, a little oil, no problem.

[Roy Wall]

Good info on this thread!

For a slight hijack......if I wanted to tap 1/4-20 threads (example) into the cast iron....what size drill bit would be used first????

[Bill Simmeth]

For a slight hijack......if I wanted to tap 1/4-20 threads (example) into the cast iron....what size drill bit would be used first????

Roy, your example would call for a #7. There are several tap/drill reference charts out on the web. Here's a link to one: http://www.newmantools.com/tapdrill.htm

[roy knapp]

Use a number 7 highspeed drill bit.

[Roy Wall]

Bill and Roy,

You guys are good -- thank you!!

Roy --- nice to see you on the board...hadn't seen you in a while!

Bill - pm sent......

[Tom Andersen]

Drilling cast iron is more easy than steel, the chips come off like dust.