Drilling Holes In 3mm Galvanized Steel Straightforward?

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pollys1dad
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Drilling Holes In 3mm Galvanized Steel Straightforward?

Post by pollys1dad »

I'm thinking hole sizes from around 8mm- 15/20mm. I have a decent quality, newish, floor standing pillar drill. What are the best type of drill bits to use for this and technique of drilling?, speed to run bits will steel heat up, deform?
Thanks.
arborist
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Re: Drilling Holes In 3mm Galvanized Steel Straightforward?

Post by arborist »

The difficulty with drilling thin material with a twist drill is that it will try to screw itself into the material as it breaks through the bottom of the hole. The drill bit thinks it is a woodscrew.

For that thickness, and above 14mm diameter, I would use a hole saw. They are like a hacksaw blade made into a circle so the speed should be the same as you would use a hacksaw (slow). Lubricant helps (a solid, wax-type is less messy).

Depending on the exact diameter requirements, a step drill might perform better than a twist drill on the smaller diameters.

Whatever you do, back the metal sheet up with a piece of plywood and clamp them both down. Be aware of the drill's desire to screw itself in and ease up pressure on the quill handle, even to the extent of applying upwards pressure to resist the drill bit's wayward behaviour.
pollys1dad
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Re: Drilling Holes In 3mm Galvanized Steel Straightforward?

Post by pollys1dad »

OK, thanks for the reply.
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NP317
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Re: Drilling Holes In 3mm Galvanized Steel Straightforward?

Post by NP317 »

I recommend using a step drill for thin metal drilling.
They are quite controllable and easy to use.
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Harold_V
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Re: Drilling Holes In 3mm Galvanized Steel Straightforward?

Post by Harold_V »

NP317 wrote: Mon Nov 28, 2022 3:50 pm I recommend using a step drill for thin metal drilling.

I tend to agree, as thin material tends to drill three sided when a twist drill is employed.

H
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pollys1dad
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Re: Drilling Holes In 3mm Galvanized Steel Straightforward?

Post by pollys1dad »

Will a step drill provide good results in 3mm galvanized steel sheet? I don't need to drill out a pilot hole? Do I use cutting fluid, paste with a step drill?
Thanks.
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Bill Shields
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Re: Drilling Holes In 3mm Galvanized Steel Straightforward?

Post by Bill Shields »

Not sure on the step drill

For 3mm (.125") I would use a hole saw based on the size recommended
Too many things going on to bother listing them.
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NP317
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Re: Drilling Holes In 3mm Galvanized Steel Straightforward?

Post by NP317 »

I'm leaning toward Bill Shields recommendation of a hole saw for the thicker materials.
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pollys1dad
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Re: Drilling Holes In 3mm Galvanized Steel Straightforward?

Post by pollys1dad »

OK, does anyone have experience of using a hole saw in 3mm steel, does a galvanized coating make steel even harder? Any tips on using a hole saw in intended application?
Appreciated, thanks :)
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Bill Shields
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Re: Drilling Holes In 3mm Galvanized Steel Straightforward?

Post by Bill Shields »

GALVANIZING (zinc) is not a problem unless you put a cutting torch to it.

go slow with lots of lube, as with any hole saw.
Too many things going on to bother listing them.
arborist
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Re: Drilling Holes In 3mm Galvanized Steel Straightforward?

Post by arborist »

Bill Shields wrote: Tue Nov 29, 2022 11:17 amFor 3mm (.125") I would use a hole saw based on the size recommended
He says in the original post that he wants from 8mm to 20mm diameter. The smallest hole saw that Starrett make is 14mm (9/16th of a freedom unit).

---

To the OP: you are in a good position having a drill press as the driving force behind whatever cutting tool you choose. Slower will always be better. That same advice extends to your own arm on the handle.

In anything above 1/2" (13mm), a hole saw is likely to be cheaper than a twist drill. Starrett are good; Bosch also good but use a non-standard arbor; Abracs (Toolstation) or Erbauer (Screwfix) will do the job.
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Re: Drilling Holes In 3mm Galvanized Steel Straightforward?

Post by jcfx »

Aside from the step drill NP317 mentions there are also rotabroaches, basically smaller versions of
annular cutters. Step drills and rotabroaches have been my go to for making small holes in thin materials.

https://www.blairequipment.com/rotabroach-cutters
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