Drill 4 x 28mm holes through 44mm thick aluminium

I need to drill 4 x 28mm holes through aluminium to make ballscrew nut mounts.... from 1-3/4" 44mm square bar.

Does anybody have any tips for doing this?

I'm thinking of using a good quality bi-metal holesaw.... Irwin/Bosch... at 545 rpm in the bench drill press... Drilling a 6mm pilot hole first... and possibly drilling two 6mm holes at opposing ends of the diameter to help with clearing chips.

Sure I would have to tackle the bar from both sides, but have no idea whether I would be fighting a losing battle, or whether cutting fluid would help keep the tool cool or have the opposite effect by making the chips gum up?

A hole saw will do it. but accuracy wont be great. A straight shanked boring head would be better if you can get a small one with a 12mm arbor to fit in the chuck. Theres no need to drill any holes other than the pilot hole..

Cutting fluid will help in either case... compressed air also works


Or ask someone nicely... hobnobs and/or beer often work ;)

This would be a nice little lathe job for anyone with a 4 jaw chuck and boring bar.

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Originally Posted by irving2008

A straight shanked boring head would be better if you can get a small one with a 12mm arbor to fit in the chuck. ... Or ask someone nicely... hobnobs and/or beer often work ;)

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Thanks Irving... Haven't seen hobnobs on here since that little spat a couple of weeks ago, which is sad as I really enjoyed his sense of humour... and benefitted from his contributions.

I will make use of a machining service that has access to a lathe and CNC, as that tooling looks expensive for now... Is a boring head and a fly-cutter one and the same thing?

I used an annular cutter with an adapter for it to fit the pillar chuck. Worked great. Or, you can buy a morse taper one for them.

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Originally Posted by WandrinAndy

Thanks Irving... Haven't seen hobnobs on here since that little spat a couple of weeks ago, which is sad as I really enjoyed his sense of humour... and benefitted from his contributions.

I will make use of a machining service that has access to a lathe and CNC, as that tooling looks expensive for now... Is a boring head and a fly-cutter one and the same thing?

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Essentially, tho a boring head is arguably more accurate as it holds a cutter at a known distance from the axis and is adjusted with a micrometer screw whereas a flycutter generally holds a bit of tool steel out at an angle. Boring heads generally allow you to bore deep holes; flycutters are usually used to cut circular holes in sheet of relatively low thickness..


If I could get at my mill or lathe I'd offer to do it for you, but at the moment I can't physically get at them .... :(

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Originally Posted by jonbabbz

I used an annular cutter with an adapter for it to fit the pillar chuck. Worked great. Or, you can buy a morse taper one for them.

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Didn't know those existed and it looks like they will clear the swarf quite well. What does the adapter you used look like/where can they be bought?

Nice little one here if you want a punt. USED C C CRALEY MFG CO. 1.1/2" BORING HEAD WITH ATTACHMENTS Direct From Myford | eBay

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Originally Posted by WandrinAndy

Didn't know those existed and it looks like they will clear the swarf quite well. What does the adapter you used look like/where can they be bought?

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They go through ali like butter. Ive seen the adapters on ebay before, or you can make one like mine on a lathe for nothing.

Attachment 7004

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Originally Posted by boldford

Nice little one here if you want a punt. USED C C CRALEY MFG CO. 1.1/2" BORING HEAD WITH ATTACHMENTS Direct From Myford | eBay

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I wouldn't bid on that since if an item has 'Myford' in the title you might as well multiply the price by ten!

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Originally Posted by Jonathan

I wouldn't bid on that since if an item has 'Myford' in the title you might as well multiply the price by ten!

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I can't really disagree with your comment. I was simply the first one I came across looking for one of the appropriate size.