Cutting a hole/drilling in cast iron.. whats the best way?

[Evan Purple240zt]

I do have a big drillpress at my disposal. This cast iron exhaust manifold is one hard dude.

 

Any tips or tricks? I am cutting a hole for a pipe to add a wastegate.

 

Evan

[Warren]

I simply used a bi-metal hole saw...went through it with no problem, straight, clean and true. Took a little while, but with a good drill (not a cordless) you shouldn't have any problem.

[Evan Purple240zt]

Thanks Warren, this is gonna be some work definitely. Ill have to get the right size hole saw.

 

To complicate things, its not really on a flat surface.

 

Evan

[Roostmonkey]

I second Warrens method. Jig the manifold up into the desired orientation to the drill/saw and clamp it down tight to the press's bed and an uneven/nonflat surface wont matter.Go slow at first to establish a good straight hole

[Evan Purple240zt]

Alright, I really don't have a good way to jig it up so its gonna take a bit.

 

Can I drill with a holesaw without using a pilot bit? This manifold is divided, and I am cutting the hole where the pilot bit would not be able to penetrate completely so it would be drilling pretty deep for no real reason.

 

Evan

[Warren]

It still shouldn't be that hard to do, as once the holesaw has 2 points to drill between it should stay straight enough to continue. I did mine freehand, with the pilot bit protruding only 3/8 - 1/4" past the end of the holesaw itself and it stayed true. Just take your time and remember, a holesaw can jerk the drill right out of your hand (if you're using a hand drill) if it binds, so keep it as straight as possible. It did, however, take quite some time to drill through it.

 

Everyone says that the exhaust manifold is cast iron, but I believe it's properties to be more along the lines of cast steel. If you grind on it, it turns shiny like steel, not black like iron. If you weld on it, it takes the weld just like steel. I'm not totally convinced that it is in fact iron, but that's just from my experiences. Your (and others') mileage may vary.

[Evan Purple240zt]

Thanks warren!

 

Evan

[johnc]

Use a pilot bit and use lots of cutting fluid/lube. Keep that hole saw cool and don't spin it too fast.

[Careless]

if you have one of those jigs for making hole cuts in round tubing, you can probably use it to square up your drill, and drop it down straight onto the work piece...

 

you have a drill press, so it's not needed.

[Evan Purple240zt]

Thanks guys, the drill press is at work. The maintenance guys at the building where I work are very cool so they will let me use it.

 

They seem to know what they are doing, maybe Ill just ask them to do it for me.

 

Evan

[Evan Purple240zt]

I ended up doing it with a holesaw and a hand drill. Decided it would be too big of a pain to make it stay where I wanted it in the press.

 

Warren hit the nail on the head, slow, and WD40 worked well as a lubricant.

 

I drilled an 1/8" pilot an followed it up with a 5/16 then the holesaw.

 

Evan