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Any Countersunk bit experts?
loggyboy - 17/12/11 at 07:22 PM

I want to countersink some of my rivets, but the rivets have a very shallow angle. Most counter sunk drill bits (or even just larger drill bits) seen to have a close to 45degree pitch. Am i right in thinking that a 90degree counter sunk is 45degrees on each side? In which case do i need a large or smaller pitch to get a shallower angle?

iank - 17/12/11 at 07:30 PM

Silly question, but you are using countersunk (CSK) head rivets?

Which look like this


IIRC they need something like a 120degree countersink.

[Edited on 17/12/11 by iank]

RAYLEE29 - 17/12/11 at 07:32 PM

Hi, the normal countersunk rivets are already 90 degrees personally they are the only ones ive ever seen.
where did you get the shallower ones from are they special for thin sheet or something?
Ray

RAYLEE29 - 17/12/11 at 07:34 PM

ohh just seen the above pic and indeed they are shallow.
Ray

big-vee-twin - 17/12/11 at 07:55 PM

I used a standard coutersunk drill with csk rivets- no problems

loggyboy - 17/12/11 at 08:25 PM

quote:
Originally posted by iank
Silly question, but you are using countersunk (CSK) head rivets?

Which look like this


IIRC they need something like a 120degree countersink.

[Edited on 17/12/11 by iank]

Almost identical, just a sealed version in alluminium.
Im using the counersunk ones on the areas I want to cover with vinyl so the vinyl lays flat.

trikerneil - 17/12/11 at 08:25 PM

An ordinary drill bit usually has an angle of 118°.

HTH

Neil

loggyboy - 17/12/11 at 08:31 PM

IN which case these must have close to a 140-150 degree pitch, its really very shallow.

andrew-theasby - 17/12/11 at 08:33 PM

there are 90, 100 and 120deg rivets available, if you want to check them, compare them upto a light against a woodscrew which are normally 90deg, and a drill bit iirc should be 51deg each side ie 102deg. if its neither of them it ll be 120deg.

Theshed - 17/12/11 at 09:12 PM

What size are your rivets - i might have what you need. I countersunk most of my rivets using a "microstop" (google for images) I have various countersinks for it. Aircraft rivets are usually 100 degrees. I have some 130 degree cutters but largish.

loggyboy - 17/12/11 at 09:14 PM

Cheers guys, will have a compare.
Typically, being specilist it looks like im gonna have to spend over the odds for a tool il use only a few times!

Robert Charles 14mm x 120 TiN 7 flute Countersink | eBay

steve m - 17/12/11 at 09:23 PM

Can you not re cut a normal drill bit to the angle you require?

TAZZMAXX - 17/12/11 at 09:28 PM

quote:
Originally posted by steve m
Can you not re cut a normal drill bit to the angle you require?


A 2 fluted cutter is more likely to chatter than a 3 fluted one which most C'SK bits are. Also, proper countersink bits have very shallow relief on the back so are less aggressive cutting than a drill bit.

steve m - 17/12/11 at 09:45 PM

cool,

i was only asking a question, off what i would of possibly done !!!

just as well, as i would off buggered up the material

Steve

paulf - 18/12/11 at 09:14 AM

You can use a drill bit by first grinding it to the correct angle and then grinding a small flat on each front cutting edge to remove the front rake angle, it will then be ok for countersinking ally etc without snatching but wont cut hard materials very well.However if I had a lot of holes to do I would buy the correct bit.
Paul

rusty nuts - 18/12/11 at 10:05 AM

Placing a piece of emery tape between a modified drill bit and the hole to be countersunk normally stops any chattering. Might be worth trying on a piece of scrap ??

Neville Jones - 19/12/11 at 12:55 PM

Cromwells do countersink cutters in various angles covering near everything used as standard in industry.

Cheers,
Nev.

loggyboy - 19/12/11 at 01:24 PM

quote:
Originally posted by Neville Jones
Cromwells do countersink cutters in various angles covering near everything used as standard in industry.

Cheers,
Nev.


DO you have a link?
When i search their site I find only 90 degree ones and cant seem to access lots of the site, search engine seems fecked!

v8kid - 19/12/11 at 01:40 PM

http://www.cromwell.co.uk/browse?page=7

Cheers!

loggyboy - 19/12/11 at 01:51 PM

quote:
Originally posted by v8kid
http://www.cromwell.co.uk/browse?page=7

Cheers!


quote:
Your search did not match any products.
Please try alternative keywords or a more general search.

v8kid - 19/12/11 at 05:36 PM

Works for me!

Go into the site, put countersink into the search box, at the bottom of the page click page 7.