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Navyblue 9th April 2012 05:19 PM

What are these drill bits called?
I apologise if this isn't the right forum to ask.

What are these drill bits called?.

I am trying to search for alternate supplier (as they are on holiday) but not sure of the right keyword. Are they any good for steel chassis? And how do they compare with stepped bits? I'm trying to cut holes for tube socket btw.

Ronsonic 9th April 2012 05:25 PM

Those are hole saws.

For tube sockets in steel I think punches will prove longer lasting and give a better result. .

simon7000 9th April 2012 06:20 PM

They are quite inexpensive as they show carbide teeth. They must be used in a drill press at a slow speed (300 RPM or so). To cut steel you should use a cutting fluid. The traditional fluid is a mixture of kerosine and lard. The steel should be backed up by something solid such as a hardwood board. Also be sure the steel is clamped to the drill press table.

A stepped drill bit will also work but is more expensive and is not carbides so it dulls much faster.

A chassis punch is good for thin steel typically under 2 mm. But good ones are expensive, but mine are still quite good after 40+ years. I do sharpen them before each use!

SoNic_real_one 9th April 2012 06:23 PM

Hole-punch tools make cleaner holes.

Navyblue 11th April 2012 03:12 PM

Thanks guys. :)

Are these any good?

PChi 11th April 2012 04:26 PM

The Q-MAX sheet Metal Punches that I am familiar with look a little different than the Ebay ones. They don't have a large hexagonal head part. Check out for hopefully genuine ones.
The picture shows one part of the punch off centre which concerns me. Also the quality of the steel is all important. Q-Max and Greenlee are well respected. It depends how much you trust the seller.

KatieandDad 11th April 2012 04:30 PM

The Q-Max punches are fine. That one only looks off-centre because the cutter isn't inside the cutting ring in the photo.

Make sure you grease them up well each time you use them.

Navyblue 11th April 2012 05:06 PM

On this side of the globe, it looks like eBay is my best bet.

Where do I grease it? The screw thread? Or both that and the metal that I am cutting?

KatieandDad 11th April 2012 05:13 PM

The thread needs to be heavilly greased as it will be put under enormous pressure during cutting, the face of the cutter also needs to be greased.

Any old car grease will do.

simon7000 11th April 2012 05:21 PM

I use a high grad oil on the threads, such as Mobil 1. It reduces wear and friction. On the cutting edges you want a different lubricant, kerosine and lard oil is good, Tapmagic is better.

Be sure to sharpen the punch before each use. I use a sheet of 400 grit silicon carbide sandpaper. Place one side of the punch flat on the paper and trace a figure 8, then do the other cutting side. Rotate the punch half a turn and do it again. Keep repeating until you don't notice any change in the drag of the tool.

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