Drilling Aluminum

[tpolley]

This is probably a dumb question.

I've been drilling a lot of aluminum in recent years. I've noticed that the drill bit seems to always walk, or drift to one direction as it cuts thru the aluminum giving a crooked hole. It hasn't been an issue because I've always been pre drilling for screw holes, but last evening i was trying to drill an accurate hole and it ended up being crooked as **** because the bit drifted as it cut thru the 3/16 aluminum. The hole was right on my measurement on the side i penetrated, the opposite side it was g.d. 1/16 inch off.

Oh, and I've been using a cordless drill. Drill bit size in this particular example is #1, or .228, or just under 1/4". But this would apply to other sizes, also.

So, short of using a drill press and a vise, or taking the part to work and using the scotchman ironworker, is there a trick to drilling a more accurate hole in aluminum with a handheld drill? Should i pre drill with a smaller bit?

 

[jeejay]

I think graduated drilling with numerous smaller bits (or a graduated bit) is best on the bits (along with lubricating them), and removing less metal at a time with each is less likely to throw it off as much. There are also drill guides for every size bit up to half-inch. A vise or clamp would help with that too, of course.

 

[rockwithjason]

the biggest thing i have found is not to rush it. guys lean on the drill with all their gut and the pressure will cause it to walk. lighter pressure and pre drill with a smaller bit. center punch will help too

 

[jeejay]

Another thing to try, this looks to be a good deal on a punch set (half off at the moment). I'd think using graduated punches at least before starting with a larger bit would help guide it (but then I'd still want to use a drill guide to line up a punch). Drill speed might play a factor too, more torque with lower speed (or battery power perhaps) could mean more resistance to keeping it aligned. And using high speed steel bits would go along with that notion.

 

[600SL]

Always start with a pilot hole. For the total time required to drill the hole you will save time and increase accuracy.

Good sharp bits, for several reasons.
1) It makes the job easier so you pay more attention to alignment.
2) Balanced sharpening on each drill flute keeps the drill from walking

Drill guides or drill bushings with a suitable holder.

http://www.mcmaster.com/#drill-bit-guides/=13t05d5

http://www.mcmaster.com/#standard-drill-bushings/=13t05vg

I use and recommend the drill doctor. It doesn't sharpen bits perfectly but it does a reasonable job and keeps you from running to the hardware store to drill one hole.

 

[beakie]

if you want a straight hole you need a good guide, or you need to use the drill press.

handheld drilling will never be perfect.

 

[ipdaley]

Lubricant helps top. For aluminum, use kerosene. Also that set of bits folks use for 20 years are dull. If that is 3003 Al, it gums up bad. Kerosene and sharps bits are the best you can do.

 

[04chase]

center punch for sure will keep you on target

ive been using irin turbomax drill bits as well and they seem to work pretty good on aluminum with the split tip

 

[Wanna Ride]

Drill press is going to be MUCH more accurate than a handheld. Speed and feed are your friends.

In anything critical, or of any thickness, you really need a rigid setup, to insure straight, round holes.

 

[larry_g]

.

The hole was right on my measurement on the side i penetrated, the opposite side it was g.d. 1/16 inch off.

Take your bit from the drill motor and put it back in the hole and then check it with a square. If it is not perpendicular with the face then your not holding the things correctly. As said above get or make a drill guide. Get a block or 2 or 3 and drill , on a drill press, the common holes thru it. Now when you have to drill a hole like above you use a clamp to hold the drill guide to the plate and then do your drilling. The through hole in the guide will help you to stay vertical.

An example ;
http://www.evenfallstudios.com/toolworks/drilling_aids/screw_predrill_square_guide.html

At the very least have a square sitting next to your hole to be drilled so you have a reference line/plane to follow.

lg
no neat sig line

 

[zkling]

Use a center punch and or a center drill or spotting drill.

 

[jimbbski]

If you drilling something as thin as 3/16 I would use a step drill. They make nice round holes and even chamfer the hole if you use the next size up part of the drill a bit. But a sharp drill bit and a center punch to start is not a bad idea.

 

[Superbec]

I think graduated drilling with numerous smaller bits (or a graduated bit) is best on the bits (along with lubricating them), and removing less metal at a time with each is less likely to throw it off as much. There are also drill guides for every size bit up to half-inch. A vise or clamp would help with that too, of course.

completely useless on aluminium under 1/2

Punch it hard