I will end my involvement with a thought about what is it that you are trying to put neat clean hole in. I cannot remember how many holes we drilled in concrete, watching to make sure that the bit did not wander and that the hole was the right depth before we tapped an anchor to just the right depth to hold big nasty telecommunication equipment. Rows and rows of it. I guess it just matters in the end as to what it is that you are trying to accomplish and how good/accurate that you need to be. I bet that we are all like minded when it comes such matters.
Well I hope you found a way by now, but making a drill guide and having everything secured together works pretty well.
For a small number of holes, a soft material like wood will work to keep the drill from glancing around. Other than that, having the right drill speed, and feed rate, cutting fluid or wax will help greatly. That’s assuming the drill geometry is correct for the application…
For a small number of holes, a soft material like wood will work to keep the drill from glancing around. Other than that, having the right drill speed, and feed rate, cutting fluid or wax will help greatly. That’s assuming the drill geometry is correct for the application…
The best way to cut large to medium-sized holes in material of this thickness is with a hole saw - a device made specifically for this purpose. They are available from a number of industrial sources, but I have always used McMaster-Carr. They are manufactured such that a single central mandrel will accept a variety of saw sizes, which are very easy to swap out. The mandrel has a 1/4" drill in the middle, which doubles for creating a pilot hole, and then as the pilot itself. In one of my former lives as a machinist, we used them extensively and they worked quite well. The actual cutters are made for a variety of materials, including aluminum. We found the best lubricant to be clear kerosine, but there are aluminum-specific cutting lubricants. Not using the correct lubricant may result in the aluminum gradually building up on the cutter. As always though, the work still needs to be clamped tightly!
As an aside, I use knockout punches for cutting holes in thin chassis material. They cut cleanly and are very easy to use. I made the happy discovery that the 1/2" (Nominal trade size for electricians) punch will pull a very serviceable hole for 9-pin tube sockets, and the 3/4" trade size does nicely for octals.
As an aside, I use knockout punches for cutting holes in thin chassis material. They cut cleanly and are very easy to use. I made the happy discovery that the 1/2" (Nominal trade size for electricians) punch will pull a very serviceable hole for 9-pin tube sockets, and the 3/4" trade size does nicely for octals.
Gives you a decent hole, but no guarantee it'll be very round, and the resulting finish will usually look like crap. There are nicer hole saws that have thicker walls and brazed carbide teeth with lots of relief... those ones are fun. I guess they're more accurately called annular cutters than hole saws.
https://karnasch.tools/en/all-produ...saws/easy-cut-5-carbide-tipped-hole-201020-p/
https://karnasch.tools/en/all-produ...saws/easy-cut-5-carbide-tipped-hole-201020-p/