drilling stainless steel

[schapiro1]

I want to fit a weldless ball valve on my brew kettle. How difficult is it to drill stainless steel? What bit should I use? How high from the bottom should I drill?

[Sven]

Here is what I have learned.

1. Use a step bit
2. Use a punch to get started. I just used a nail and hammer, it doesn't have to penetrate just leave a modest dent.
3. Lube! Olive oil works well and you most likely have it around
4. Drilling stainless is pretty easy, just don't go too fast.

[el_stevis]

Every time I see a post on drilling stainless people seem to use step bits. The how-to in BYO last month said the same thing. Their take was that it leaves a smoother surface. Is that the only reason?

Thanks,
Stevis

[Sven]

This is a visual answer so I'll try my best to describe it.


Much like a candy cane with its red and white stripes a drill bit is fashioned the same way except instead of "red" areas there are instead "voids". These "voids" can bite into your material causing it to rip and tear.
If you have ever drilled metal you have most likely have seen little pig tail like metal shards, if you graduate your sizes to quickly those little shards become big shards and may even get hung up on your drill and possibly cause you to "rip" the material you are drilling, rendering it useless.

So you can get away with not using a step bit as long as you manually change up your bit size about every 1/8th inch.

Sven

[el_stevis]

Totally makes sense. Thanks, Sven!

Cheers,
Stevis

[schapiro1]

How high from the bottom of the kettle should the center point be?

[Petedadink]

Having worked as a machinst for too long, Step drills are an easy way to make a large round hole with home tools (hand drill) . Compared to standard cold rolled carbon steel Stainless is harder and if you cut too fast or without lubricant you will run the chance of work hardening the stainless and dulling your drill. Take your time and it comes out just fine.
Using a standard 7/8 spade drill it can be done . A major pain but it can be done, A step drill will also add a slight countersink and break the sharp edge that will be produced and giving a smoother hole to work with.

[Push Eject]

A recent post on this very subject on the brewboard lends the following information:

• Drill stainless with slow speed and high pressure (in practice I would say 'firm' pressure)
• Lube your bit (oil you say? Nah, water... see the next item).
• Cool the metal. Running water works for this; have your kid hold the hose while you drill.

So in reality, oil on your bit is fine if you go slowly and pause to let the steel cool after each step. If you want to just get it done, use running water to keep the steel cool.

Aluminum is a different story. Use soap on your bit when drilling aluminum and a firm block on the back of your material.

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