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Author: Subject: Any Countersunk bit experts?
loggyboy

posted on 17/12/11 at 07:22 PM Reply With Quote
Any Countersunk bit experts?

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?
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iank

posted on 17/12/11 at 07:30 PM Reply With Quote
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]





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RAYLEE29

posted on 17/12/11 at 07:32 PM Reply With Quote
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





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RAYLEE29

posted on 17/12/11 at 07:34 PM Reply With Quote
ohh just seen the above pic and indeed they are shallow.
Ray





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big-vee-twin

posted on 17/12/11 at 07:55 PM Reply With Quote
I used a standard coutersunk drill with csk rivets- no problems





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loggyboy

posted on 17/12/11 at 08:25 PM Reply With Quote
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.

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trikerneil

posted on 17/12/11 at 08:25 PM Reply With Quote
An ordinary drill bit usually has an angle of 118°.

HTH

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loggyboy

posted on 17/12/11 at 08:31 PM Reply With Quote
IN which case these must have close to a 140-150 degree pitch, its really very shallow.
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andrew-theasby

posted on 17/12/11 at 08:33 PM Reply With Quote
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.
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Theshed

posted on 17/12/11 at 09:12 PM Reply With Quote
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.
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loggyboy

posted on 17/12/11 at 09:14 PM Reply With Quote
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!

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steve m

posted on 17/12/11 at 09:23 PM Reply With Quote
Can you not re cut a normal drill bit to the angle you require?
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TAZZMAXX

posted on 17/12/11 at 09:28 PM Reply With Quote
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.

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steve m

posted on 17/12/11 at 09:45 PM Reply With Quote
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

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paulf

posted on 18/12/11 at 09:14 AM Reply With Quote
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

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rusty nuts

posted on 18/12/11 at 10:05 AM Reply With Quote
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 ??
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Neville Jones

posted on 19/12/11 at 12:55 PM Reply With Quote
Cromwells do countersink cutters in various angles covering near everything used as standard in industry.

Cheers,
Nev.

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loggyboy

posted on 19/12/11 at 01:24 PM Reply With Quote
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!

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v8kid

posted on 19/12/11 at 01:40 PM Reply With Quote
http://www.cromwell.co.uk/browse?page=7

Cheers!





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loggyboy

posted on 19/12/11 at 01:51 PM Reply With Quote
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.

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v8kid

posted on 19/12/11 at 05:36 PM Reply With Quote
Works for me!

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





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