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hard steel? Answered

How can I cut and drilling old bed frames without dulling blades and bits?

2 Replies

randofoBest Answer (author)2017-02-01

First, you need to get drill bits intended for hardened steel (Cobalt with HSS high speed steel - or carbide tip).

You will want to lubricate what you are drilling with lots of cutting coil to increase lubrication and reduce heat.

Not sure how big of a hole you are drilling, but you will likely want to start with a smaller pilot hole (say 1/16 - 1/8). With a small drill bit like that, you will want it to spin relatively fast.

When drilling, you should probably employ peck drilling (apply pressure for a moment, release for a moment, and then repeat).

This should work, but may take a little trial and error if you don't know exactly the type of metal you are dealing with.

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dougs116 (author)randofo2017-08-06

You need to understand what is happening right at the tip of your drill when you drill ferrous steel. You have friction which causes heat, you have oxygen which when added to the very hot steel causes the drilled piece to begin to "case harden" just under the point of the drill. The harder you push the more friction and heat, the now red (near molten steel) will at this point either destroy the bit or if the metal is thin push on through with a very messy hole which will require much work to de burr, Also, the hole is most likely not where it is supposed to be because under all the pressure the bit has bent and the point had walked one way or another. Understanding the above is important to being successful, knowing an additional trick will make you drill like a master machinist. Someone who has more time than myself needs to do a instructional on this:

This works best on a drill press.

1. Set the speed for the material being drilled, slower is better.

2. Mark the drill hole with a center punch.

3. Set up you project in proper clamp or vise, making sure that everything is centered and secure.

3. Place a quarter sized puddle of RTV or silicone sealer on the center punch mark. The RTV or silicone's job is to keep all oxygen away from the drill point.

4. Start the drill press and slowly drill the hole with smooth downward pressure.

You will discover that the hole will be true, smooth, and will require very little if any de burring.

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