Countersink??

[Crow#21957]

I've had terrible luck with countersink bits.
Got one from a hardware store and one from track. Done one hole with each and they were shot. Chattering and not cutting.
My uni bit was ok until I misplaced it.LOL
Is there a certain brand I should look for?
What speed should I run them at?
Thanks

 

[The Crisco Kid]

The only way I've been able to use a counter sink, like on buttplates, tangs, etc. is to grind the cutting edge off 5 of the 6 flutes. As I understand it, a counter sink with evenly spaced flutes will chatter. One with a single cutting edge seems to work well. I use a dremel tool to just relieve the cutting edges and leave the rest of the flute for support.

 

[Crow#21957]

The counter sinks I've bought have only had two cutting edges.

 

[hawkenhunter50]

https://www.muzzleloadingforum.com/threads/why-do-my-countersinks-look-horrible.146284/
Lots of info in the above thread. Learned some useful info, thanks for bringing up the question.

 

[2shute]

Take a look at chatterless countersinks. I had the same problem until I started using them.

 

[Hatchet-Jack]

Hardware store countersinks never worked for me. My teacher suggested this one. It cuts smooth. No chatter.

 

[HSmithTX]

I would just about guarantee you are running them too fast, HSS you need to be running a max of maybe 100SFM. I would also just about guarantee the castings you are running them in are WAY harder than you think and WAY WAY harder than they need to be or should be. Anneal your castings and run them very slow, decent pressure and try to get a thin continuous chip off them, they will last basically forever. Too little pressure will destroy the edges almost as fast as running them too fast, and when each edge is cutting they won't chatter.

 

[Crow#21957]

To anneal them just heat them to a darkish red and let air cool???

 

[Flintandsteel]

Just like everything else, you get what you pay for.
I’ve bought multiple “sets”, and was never satisfied with the results.
Bought two of the MA Ford countersinks, and was amazed! Cut fast, and very clean. Of course I paid more for each of them, than I did for the sets.

 

[Hatchet-Jack]

To anneal them just heat them to a darkish red and let air cool???

For brass you can just heat it red and quench it in water, or let it air cool.

 

[Crow#21957]

Sand cast steel???

 

[Sidney Smith]

I find counter sinking easier by just using two different drill bits. One the size of the screw or bolt shank, the other the diameter of the head.

 

[user 34300]

I make 2 or 3-flute cutters that duplicate the screw shape, major diameter, and add a pilot section. I run them slow and well lubed. The result is excellent.

I would never use a countersink for a screw head. I do use them to break the edge of a tapped hole.

IF you look at a nice gun carefully, the screw recess has parallel sides, then the countersink section. It is not all counter sunk at the same angle. To get the screw to sit flush with a plain countersink the diameter of the cut needs to be larger than the screw. That looks bad to my eye.

 

[Kevin Houlihan]

IF you look at a nice gun carefully, the screw recess has parallel sides, then the countersink section. It is not all counter sunk at the same angle. To get the screw to sit flush with a plain countersink the diameter of the cut needs to be larger than the screw. That looks bad to my eye.

I use "center drills" and achieve exactly what Scot@4570 is talking about. I pick a center drill that is one size smaller than the screw head. I get a countersink below and straight sides for the recess. Then I turn the screw in a drill w/ a file held against it and get a perfect sized match between the screw head and the recess.
Kevin

 

[russellshaffer]

I have had great results with single flute countersinks. You will most likely have to order them from a machinest supply. Don't use a regular drill bit - they are made to cut holes and will grab and go way too deep. For machine tools, if MSC doesn't have it it probably doesn't exist.
https://www.mscdirect.com/
For limited use and iffy quality there is always ebay. There is some good stuff there if you are careful.

 

[Pete G]

Put a piece of paper between the tool and your part.

 

[Comfortably_Numb]

Put a cleaning patch under the counter sink when you do it. No more chatter.