Drilling larger holes in aluminium, or any metal

[penberth3]

...I've seen the term used - what is a pillar drill, as opposed to a bench drill - or are they one and the same thing?

I think its two names for the same thing, only difference is the floor mounted version has a taller pillar.

 

[penberth3]

...On site - when we had to drill large holes in girders ( like 12mm thick - 25mm hole ) we hired a magnetic base pillar drill - still just a rotary pillar drill, and the bits supplied were very odd !
They worked like a hole cutter - ie one was left with a plug from the middle - but had a sort of moving sleeve. They worked like a dream ! Any hire shop would know what they were. As said - the drill was a normal rotary drill - but may have had a special chuck ?

Already mentioned in a post - "Rotabroach" is a common trade name for these.

 

[penberth3]

You could try a stepped drill. Cheap as chips on ebay so you need't worry about knackering them.

OK for thin sheet but the OP mentions 15mm thick material.

 

[Neeves]

OK for thin sheet but the OP mentions 15mm thick material.

I was going to query that - I can see how they work on a few mm - but could not see how you could drill a 20mm hole in say 15mm plate with a max diameter of the stepped drill bit of 25mm. You answered the question, can only drill upto the seize determined by the steps.

Thanks

 

[thinwater]

This is what I thought I needed, to buy, but did not know what it was called.

Thanks

Jonathan

I assumed you already knew about or had what you are calling "blacksmith drills' (called "reduced shank drills" in the US). Yup, they will grab like a bastard when they break through. A light drill press (bench-top drill) will probably just stall. It can work, and the work better be double clamped and no hands near it. If it does not work, a hole saw will work in aluminum up to considerable sizes.

 

[Neeves]

I assumed you already knew about or had what you are calling "blacksmith drills' (called "reduced shank drills" in the US). Yup, they will grab like a bastard when they break through. A light drill press (bench-top drill) will probably just stall. It can work, and the work better be double clamped and no hands near it. If it does not work, a hole saw will work in aluminum up to considerable sizes.

I have small ones, upto 15mm - but not the sizes I need. And I had no idea what they were called.

A rotating bit of metal locked into a, even slowly moving plate of metal (or the drill bit is slow, the metal quite fast!), is a significant hazard

I have hole saws of the right sort of sizes. My first option is to try them.

Thanks to all

Jonathan

 

[Neeves]

Unfortunately (for me) I'm not an engineer so I'm not sure. 15mm is quite deep but they say they will cut SS so aluminium should be ok, I've found in the past aluminium clogs up files quite easy but I imagine taking it easy and lifting it out each mm or so would keep the teeth clean.

Colbalt drills are fantastic compared to anything else, it's all I buy now.

I think anything beefier would really require a mill with a cutting head.

I've made a start with a 20mm hole saw, with out any issues. Well not quite right - the first hole-saw I used was too blunt, but the other of an identical size was better - so I'm progressing with the better of the 2. I'm using WD40 as it is easy to apply and drill at the same time. It is going to take some time, I'm operating at a very slow speed but enough pressure to keep cutting but not locking up the drill, which is why I have only made a start. I am drilling for short periods and cleaning the swarf.

I don't think it would work for holes much bigger than 25/30mm - or you would need the patience of Job, its slow enough with a 20mm hole. For larger diameter holes you would need one of the other options suggested (and as I had the hole-saws I went the cheaper and easier option ).

Very many thanks for ALL of the advice, I might not have followed everything everyone said - but have filed it away for larger holes in the future.

Jonathan

 

[DinghyMan]

Already mentioned in a post - "Rotabroach" is a common trade name for these.

Yep, I have a collection from 12mm to 50mm plus adaptors for the drills and other machines I have. You can easily cut a 50mm hole in 1" steel using a pillar drill as they only cut a small part, like the hole saws but much better and a but thicker, and the smaller ones can be used happily in hand drills even for stainless.