Aluminium Drilling - Small Bit

[Bryan GD]

Hi everyone,

I am attempting to drill a 1.8mm diameter hole into aluminium. However, I find that the drill bits I'm using just keep on breaking. I am very inexperienced when it comes to machine work. I was told to use a quick spiral type drill bit (which I am using, think it was called that). Does any PLEASE have advice on technique, drilling speed, lubricant, drill bit type, etc.. cause these drill bits breaking all the time are beginning to be a pain in the butt. Thanks a lot.

Cheers

[Bryan GD]

Oh and the hole is about 6mm deep

[Med-Pac]

What are you using to drill your holes?

[guru]

1.8 or about .070" dia. going thru 1/4" plate is not a difficult job

chuck those hi-spiral drill bit in the collet , try 2800-3000rpm, feed at F5.0 ipm, peck every.050" -.062" and flood with soluble oil. Spot drill first to keep drill going straight not binding in the holes.

[Med-Pac]

Grade of alum. might be an issue also. 3003 and 5052 like to gum up the bit, 6061 is probably best for machining, 7075 is harder to drill and machine.

[tikka308]

I agree with Guru, although depending on the rigidity of the mill, 5IPM might be fast for the Z feed. I use a TAIG (small benchtop CNC mill) and usually drill closer to 2 IPM. Like guru said, spot drilling first, pecking the drilled hole, and coolant are all crucial.

[Bryan GD]

Thanks guys, things went a bit better today (pun not intended).

I forgot to mention one important thing: I'm not using a drill press, but a hand drill, which obviously makes it more difficult to keep the drill vertical when drilling.

[tikka308]

Bryan: I would avoid using a hand drill at all costs if you want to avoid problems when using small bits! Even with large bits, you're precision will be mediocre at best.

[Bryan GD]

Thanks tikka. I'm drilling into the one end of a 1000mm Al extrusion, and am having trouble setting the extrusion up so I can use the drill press. Unfortunatey I am working in a rather limited workshop. Seems like I might have to drill a lot more of these, so maybe it'll be best I take another look at using the drill press.

Cheers for now.

[recordist]

Also, if you weren't already, keep the length of the drill as short as possible.

[metalworkz]

You should be able to turn the drill press table out of the way and perhaps use an angle plate etc. as a guide. There are also drill guides that attach to a hand drill that I have implemented and found to be very usefull when using a portable hand drill to keep all the drilled holes perpendicular to the drilled surface. They are generally made from aluminum or zinc and are fairly light and manueverable compared to using something like a mag-drill. The hand drill-guide may be less favorable for drilling the ends of things as you probably have little surface to rest the base on, but even this can be worked around if needed by mounting the tube between 2 angle plates etc. You probably have already worked this out by the time I am posting, and I hope you have found and easy workaround.

[Cory]

Originally Posted by Med-Pac Grade of alum. might be an issue also. 3003 and 5052 like to gum up the bit, 6061 is probably best for machining, 7075 is harder to drill and machine.

I find 6061 to be much worse than 7075. 6061 is rather gummy as well. 7075 cuts much nicer IMO.