Author Topic: Best design of 82 degree countersink ?  (Read 1974 times)

Offline Boo

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Best design of 82 degree countersink ?
« on: December 27, 2017, 01:54:27 PM »
Hi,

Question as title :  I'm looking for the best design of 82 degree countersink for use on alloy and steel.  I have a small set I bought but they suffer from chatter so I wondered whether anyone here has had good experiences with any particular design ?

Thanks,

Boo

Offline Mike OConnor

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Re: Best design of 82 degree countersink ?
« Reply #1 on: December 27, 2017, 02:19:41 PM »
Hello Boo,

My favorite counter sinks are made by Severance. I buy them from MSC here in the US. The HSS ones will work great in a home shop and they also make them in carbide. One thing I have found that helps to prevent chatter is to make sure the counter sinks have an odd number of flutes. The multiple flute type work best in steel and tough materials in my opinion. The single flute and the angled hole type are OK in non-ferrous materials, plastic and for woodworking.

Use the slowest spindle speed on your milling machine and cutting oil. If you do get some chatter, stop short on the depth and advance the depth stop a few thousandths. Then, put the spindle in neutral and rotate by hand while advancing the quill to the stop. Repeat until you reach final depth and the chatter can be removed.

For working with through holes and parts made from plate that need counter sinks, I have a set of piloted countersinks that work great. Purchased them from DoAll years ago who sadly are no longer in business. The cool thing about these is they drill the clearance hole and machine the 82 degree countersink in one operation.

Hope this helps.

Regards,
Mike
« Last Edit: December 27, 2017, 04:04:29 PM by Mike OConnor »

Offline Ramon

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Re: Best design of 82 degree countersink ?
« Reply #2 on: December 27, 2017, 02:23:04 PM »
Boo,

Chatter on C'sinks is usually a result of running too fast rpm - best results in c'sinking is always achieved using low rpm even in softer metals like Ali and Brass.

If you are experiencing an undulating sort of finish with radial marks up the side of the c'sink this can usually be removed by tearing a small square of emery cloth - finer the better as its more flexible - lay this over the hole cloth side down and bring the countersink bit down (at very low revs) with slow but firm pressure letting the cutting edges cut through the cloth. This helps even things out and usually this will take it back to a very smooth surface. This is of course using a conventional drill press as opposed to a fine feed on a mill though the same trick will get you out of trouble there too.

Hope that helps some - Tug
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Offline kvom

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Re: Best design of 82 degree countersink ?
« Reply #3 on: December 27, 2017, 02:29:50 PM »
X2 on low RPM.  I run my Chinese ones at 500 rpm most of the time.

Offline b.lindsey

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Re: Best design of 82 degree countersink ?
« Reply #4 on: December 27, 2017, 05:33:23 PM »
I have a set of M.A Ford single flute countersinks I have used for years on brass, aluminum, C.I, and steel. They seem to work well for me but as has been said use slow rpm's. As with drills and other cutting tools, the better name brands are work the extra up front investment IMHO.

Bill

Offline petertha

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Re: Best design of 82 degree countersink ?
« Reply #5 on: December 27, 2017, 06:25:24 PM »
I've heard odd number edges is better too, but for some reason most of big names seem to have even number? You would think if making 3 edges vs 4 or 5 vs 6 would save them some production cost & they cut better, then that would be the norm.

I've had my eye on these Dormer's but they aren't as popular around my parts
https://uk.rs-online.com/web/p/countersinks/6667422/

What is the opinion of the (pic) style with an edge made my angled hole through body. I haven't examined them too close but maybe they are a 1-edge cutter? I actually cant quite comprehend how they cut if there is no apparent relief. It looks like an angled body with the cutter hole???

Offline jadge

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Re: Best design of 82 degree countersink ?
« Reply #6 on: December 28, 2017, 11:35:22 AM »
I've had my eye on these Dormer's but they aren't as popular around my parts
https://uk.rs-online.com/web/p/countersinks/6667422/

That's what I use, up to 20mm diameter. Never had a problem with chatter using these cutters. I'll reiterate the need for low speed; I use ~500rpm, near the bottom of the high gear range on the Bridgeport. The other important factor is feedrate; I feed fairly fast. The cutting edge is relatively long, and you want it to cut not rub so don't pussyfoot around. If I'm doing a lot of countersinking I adjust the knee height on the mill to give the correct depth of countersink. Then I can feed fast up to the stop without worrying about creeping up on depth.

Andrew

Offline Steamer5

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Re: Best design of 82 degree countersink ?
« Reply #7 on: December 28, 2017, 01:05:46 PM »
Hi Pete,
 I use those too, work great. Like Andrew says low speed etc,

And for Andrew,
  Got any bright ideas on sharpening them correctly???
I have been using a diamond fish hook sharpener, this has a round side that fits the holes, sharpening from the back side, seems to work or at least improves them, but would like to be able to do them correctly....

Cheers Kerrin
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Offline Lew Hartswick

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Re: Best design of 82 degree countersink ?
« Reply #8 on: December 28, 2017, 03:16:24 PM »
I'll reiterate the need for low speed; I use ~500rpm, near the bottom of the high gear range on the Bridgeport.
I'm usually on the second speed up on high range for most of my work on the Bridgeport and when I do a csk I just drop into low range . Another + on the feed rate, don't "baby it". :-)
   ...lew...

Online Jo

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Re: Best design of 82 degree countersink ?
« Reply #9 on: December 28, 2017, 05:50:15 PM »
At the price of the Chinese countersinks is it worth sharpening them?

 :thinking: Mind you if they are loosing their edge they still might not last for long if you do...

Jo
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Online Dave Otto

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Re: Best design of 82 degree countersink ?
« Reply #10 on: December 28, 2017, 06:19:38 PM »
+1 for the MA Ford single flute countersinks, pretty much all I ever use. I have never been a fan of multi flute countersinks.
Lots of good tips here, keep the speed down and a slight dwell at the bottom to let it finish cutting. I program the dwell into my CNC code, but on a manual I like to come up to a hard stop at the proper depth then let it dwell for two or three turns.

Dave

Offline Art K

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Re: Best design of 82 degree countersink ?
« Reply #11 on: December 28, 2017, 09:39:12 PM »
I'm with Dave on the MA Ford countersinks, I use them a lot. Don't need to add the dito on speed you all covered that well. I have a set of the one's with a hole on them and have never used them so I cant speak for them. They were free so I cant complain. I used to have a cobalt three flute one that cut everything like butter. Its disappearance is the reason I took my toolbox home from work.
Art
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Offline jadge

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Re: Best design of 82 degree countersink ?
« Reply #12 on: December 29, 2017, 11:05:17 AM »
And for Andrew,
  Got any bright ideas on sharpening them correctly???
I have been using a diamond fish hook sharpener, this has a round side that fits the holes, sharpening from the back side, seems to work or at least improves them, but would like to be able to do them correctly....

I haven't needed to sharpen one yet, so no bright ideas. Rather than mess about with the T&C grinder I'd run a slip stone down the cutting edges, or buy a new one.

Andrew

Offline Steamer5

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Re: Best design of 82 degree countersink ?
« Reply #13 on: December 29, 2017, 12:54:00 PM »
At the price of the Chinese countersinks is it worth sharpening them?

 :thinking: Mind you if they are loosing their edge they still might not last for long if you do...

Jo

Hi Jo,
 I brought mine locally, Sutton from memory.....doing the w..k thing at the moment so cant go look!
I've used & abused them for a few years so they have held up pretty well! Using the diamond sharpener does improve them, probably just need to take a little longer to touch them up. Just thought somebody else may have come up with a better idea.

Cheers Kerrin
Get excited and make something!