Spare parts #7 - Modifying A Twist Drill For Drilling Brass

Modifying A Twist Drill For Drilling Brass, by Clickspring

Drilling brass with a standard twist drill carries a hazard with it, that can be easily avoided with a simple modification to the drill bit. Its simple, fast and very effective.

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Abbreviated Transcript:

00:06 Brass is definitely one of my favourite materials to work with, its fun to turn and I love how it makes even the simplest tools look interesting.
00:13 But it does have one drawback, and that's the tendency for cutting tools to grab when cutting it.
00:20 This is usually avoided by using cutting tools with zero, or in some cases even a negative rake. But when it comes to twist drills, we're presented with a problem.
00:32 They're manufactured with a positive rake, and if we use them as is on brass, we're going to have some serious issues.
00:39 The drill will grab, and screw itself into
the work. Ruining the part, and possibly causing a nasty injury. Fortunately there's an easy fix.
00:48 Take the drill bit and position it parallel to the surface of an abrasive stone like this india stone.
00:53 With just the cutting lip in contact, and maintaining the drill flat to the stone, give it a few gentle strokes.
01:01 In no time at all you will have made a tiny little flat on the cutting lip. Do the other cutting lip too, and the mod is complete.
01:10 It doesn't need to be very wide, maybe 0.2 of a mm, but that's enough to transform the cutting geometry to zero rake, and make drilling brass a completely different experience.
01:21 As the drill breaks through to the wood underneath, there's not even the slightest grab at the work.
01:29 The chips are different too, and you can see the second hole is a huge improvement on the first one.
01:34 The modified bits will still drill other materials, but I prefer to keep a separate set that I reserve solely for working on brass.
01:40 Now if the hole is critical I'll often clamp
a workpiece, just to give me an even better shot at getting the best result.
01:49 But whether the work is clamped or hand held, if the material being drilled is brass, this modification is essential.

Modifying A Twist Drill For Drilling Brass, by Clickspring

[aqs]

I had to chuckle when I saw your drill bit box simply labeled with a marker after watching you put so much care and effort into everything else you use for your workshop.

[junglejammer]

Great tip Chris. It also works great on drilling plastics. Especially brittle plastics like acrylic. Sometimes called Plexiglas or Perspex.

[spot]

This top is a total game changer, as an amateur hobbyist, learning as I go it has made a massive difference to me when drilling brass. So a big THANK YOU!

[ExtantFrodo]

This mod helps immensely when drilling plastic too.

[SwitchAndLever]

Great tip Chris! Will plant this firmly in the back of my head until I work on brass the next time!

[dnngskn]

This is a great safety tip. I've seen several people get hurt for not doing this very thing. I always warned my shop employees to do this simple task first and some would not and learned the hard way as brass will really grab with positive rake. Great job clickspring.

[gfvt]

Thank you for this video, it is not often that I have to drill brass but I remember how miserable it was to shear off a tiny drill bit in a piece of metal you had already invested time in. Your videos are not just educational but also entertaining, many of the tricks to doing a job will serve me well in my own projects.

[rongineer]

Just used this technique to drill some 932 bronze. Worked great!! Thanks!

[comictrio]

I was taught this by an elderly man in the first machine shop I worked at. Modifying the drill like this is simple and highly effective. I can't wait to see the completed clock.

[davidjames]

My eyes don't do justice to how amazing your videos are.

[fishkiller]

Makes perfect sense.I have ALWAYS clamped brass/copper, even tin to the wood and used bits right out of the box.
Ingenious remedy for "snagging".
Thanks M8.

[Unknowngamer]

I wish this modification had been known to me in high school. I tried drilling a bunch of small brass inserts with regular high speed steel drill bits on a drill press, and even though the work was in a vice and the vice was clamped to the table, it still bound up and nearly took my hand off.

[PapaGleb]

Wow big thanks. I mainly work with brass myself and this has always been an issue. Now I know how to solve it. Big thanks again!

[drawvenmusket]

Thank you for teaching me how to fix this problem for drills and brass, I have been warned of this grabbing in other peoples's videos but never before given a good fix for the problem now all I need to remember to do is mark the index box for brass only lol

[horvathjanos]

Dear Sir! I am a great admirer of the work of professional work and professional way recorded video. You know something I have not seen elsewhere. Thank you for sharing these videos with others. Welcome to Hungary.

[johnsutcliffe]

I did this to a 16mm drill bit to stop it grabbing whilst drilling out flogged 14mm holes in a truck chassis to fit 16mm bolts. Worked a treat.

[ErnieNoa]

Best video I have seen for this tool modification. I have always wondered what books were talking about negative rake. Looks like I need another set of drills just for brass.

[markwilliamson]

Hi Chris, it's little tips like that, from you guys that mould us beginners in to better machinists, I have already made the same stack alignment tool for my quick change tool post, and put it up on FB, s, machining YouTube Chanel, I'm loving your work, Thank you 👍🏻

[duncanmcharg]

G'day Chris, and thank you for this tip. The very next day after watching it, I was able to put this into action with a tiny wax chuck I was making (also inspired by your clips to make one for my tiny 1950s model engineers lathe). The small pilot hole was an unaltered twist drill, and dove through to 'side B' and distorted the hole a little; the full size hole was with one altered according to your advice, and went through cleanly and without any fuss. Thanks
Duncan

[lunaticvulpine]

I wish i had known that years ago. I find that most copper alloys tend to have some grab. a few years back I was boring out some shibu ichi, and I swear i could feel that moment when the bit grabbed onto the working stock. Thanks for this awesome mod :D