Countersinking bits

[Adrian Harris]

What do people use to countersink holes in aluminium ?

I used to have one which had around 10 cutting edges, which was supposed to be suitable for non-ferrous metals but it vibrated a lot, so didn't leave a good finish.

I'm currently using ones which are cone shaped with a single cutting edge but they are hard to keep centred on the hole, so sometimes the countersink isn't coaxial with the through hole.

Adrian.

[yves mouton]

Hi Adrian,

Most of the time i use a special countercink drill ( head with 3 cutting edges 90°)
or i also use a normal drill, depends how big the head of the screw is.

ps: see you ath the openday.

Regards Yves

[Armortek]

Hi Adrian

We use these:

http://www.mscdirect.co.uk/RUK-00020H/S ... oduct.html

keep the revs down and the pressure up.

Mark

[Eric Ho]

There are center drills/spot drills with 90 degree countersinks. The diameter of the center bit should be sized to fit. Eg. http://www.ebay.com/itm/7-No-7-3-OAL-90 ... 19c9421a1b

[yves mouton]

Hi Adrian

We use these:

http://www.mscdirect.co.uk/RUK-00020H/S ... oduct.html

keep the revs down and the pressure up.

Mark

Thats the same drill bit i use Adrian.
best regards Yves

[Liam Mahoney]

Hi Adrian

I use these http://www.machineryhouse.com.au/D1051 they have a much better cutting action than the 3 flute.

Liam

[Adrian Harris]

Thanks for the suggestions and links

Eric - That's an interesting idea to use a centre drill to keep things centred - I hadn't realised you could get 90 degree ones.

Liam - I've found some YouTube videos of these slanted hole bits and they do seem to cut nicely, though I'm not sure how they would get on with deepening an already countersunk hole. I'll certainly get one to try.

Adrian.

[Eric Ho]

Yes, the center drills are available in 82 deg and 90 deg versions. http://toolinghouse.com/plaintype82degr ... angle.aspx

Below are 60 deg, but lists the tip and body diameters. https://www.carbidedepot.com/formulas-centerdrills.htm

The trick is to have the pilot tip sized/undersized so that you don't remove any threads that may be there. The finish or smoothness depends on the cutting speed, pressure, and perhaps using a bit of oil/cutting oil.

[Derek Attree]

Hi Adrian
I use the same as Mark at work and at home they are the best.

Derek