Drill through thick cast iron

[zingo]

I have a small project where I need to drill some 10 mm holes in approximately 5 mm thick cast iron. Are there any miracle drill bits for this (that won't wear out after one hole)? I can understand if water cooling is needed while drilling.

 

[nino]

Hole saw or regular drill bits should work, right?

 

[atomlab]

Buy a drill of good quality. And use it at low speed with moderate pressure so it lasts for many holes.

I have very good experience with DeWalt extreme 2.

 

[cpalm]

If you use proper drill bits, it's not a problem. For 10 mm, it's probably best to do it in at least two steps, i.e., start with a smaller drill bit. Then use oil for lubrication and the right speed so it doesn't get too hot.
The best option is if you could get hold of a machine with a magnetic stand so you can apply some force to the drill.

 

[zingo]

If you use sensible drills, it's no problem. For 10 mm, you should probably do it in at least two steps, i.e., start with a smaller drill. Then oil for lubrication and the right speed to prevent it from getting too hot.
The best would be if you could get hold of a machine with a magnetic base so you can apply some force to the drill.

Ok, thanks. That's kind of what I was thinking.
What type of oil?

 

[Mattias Andreasson]

Ok, thanks. That's kind of what I thought. What type of oil?

Cutting oil to be precise, but many probably use whatever they have. Motor oil, WD-40, bicycle chain oil, etc.

 

[Dan1891]

Cutting oil if you want to be precise, but many probably use whatever they have. Motor oil, WD-40, bicycle chain oil, etc.

I've been wondering about this, is the primary function of the oil to lubricate? Or to cool? Or both?

 

[cpalm]

I've been thinking about this, is the primary function of oil to lubricate?

To lubricate so that there is less friction and less heat generation.

 

[zingo]

Lubricate to reduce friction and heat generation.

I have plenty of chainsaw oil. Could it also be suitable for drilling?

 

[Workingclasshero]

Hello
I rarely use oil or other sticky substances when drilling in iron.
But it's good to do so, of course, especially if you can't sharpen drills.
It's more important to know what you're going to drill with, i.e. what equipment you have to perform the work.
Indoors, outdoors, etc.?
Visible holes, painted surface, etc.?
Answer that so we can help even better.

 

[Violina]

"Thick cast iron"

No... But as already mentioned, start with a smaller drill bit (MAX 5mm) and drill through first. Then a 10mm.

Not chainsaw oil, it's too thick.

If it's going to be painted, no oil with silicone in it.

Small drill bit - high speed

Larger drill bit - lower speed

And remember to also press firmly when drilling... otherwise, you won't cut with the drill bit, it will just create friction (and heat)

Recommend Dormer drill bits (or similar) HSS

If it's cast iron, be even more careful with the drill bit (since it is often harder)

 

[toolman77]

Check what kind of tip the 10mm drill bit has. If it has a split point with a "mejeslbit" in the middle that doesn't cut, you need to pre-drill. Otherwise, you'll have to press the chisel through the material.

10mm in 5mm thickness is not a problem. Keep in mind that you should run at low speed and high pressure. Another option with thin material like 5mm is to use a step drill.

 

[Lilllen]

One thing that probably everyone in the thread knows but I haven't seen anyone mention is that one reason you don't want it to get hot is that the iron then hardens and becomes much harder to drill through. So if you start with a dull 10mm drill at high speed and don't press hard, it's not so easy afterward even if you've bought the right drill.