Chamfering/countersinking

[PT Doc]

I need to chamfer holes after drilling. I bought a single flute that is 1/2" in diameter. I need a larger one and see so many variations. Some have just a hole, some single flute then there are 4 and 6 flute. Do any of these work better than others. This will be used for mild steel. Thanks

[vpt]

I am interested as well for a good chamfer tool. I normally use a bigger drill bit to chamfer holes but it doesn't leave a perfect nice finish.

[Mike Folks]

Weldon single flute countersinks come in several degree angles. Aerospace uses them in 100 degree sizes, to deburr drill holes in Aluminum. They also work great in wood.

http://dewitt-tool.com/csinks_weldon100d.aspx

[Juergenwt]

How many? If you are just making a limited number than just use a three corner (triangular) file - sharpen the front end on all three sides and de-burr / c''sink by hand. Takes a little practice but works on all diameters and is fast.

[macona]

I have never had good luck with anything but a single flute. The best are MA Ford, in my not so humble opinion.

Multiflute always chatter on me.

Standard angle for flat screws is 82 degrees.

[Paul Alciatore]

I have tried various types and personally like the O flute countersinks best. These are the ones that are roughly cone shaped with a single hole drilled through them at about a 45 degree angle to the axis. They seem to be better at eliminating chatter then the one flute ones which have a straight cutting edge. I think the curved cutting edge does the trick.

Be careful to buy good quality as the geometry of these O flute countersinks is a bit tricky to get the proper relief behind the cutting edge. Some cheap imports are shaped/sharpened incorrectly and wind up with no relief so they cut poorly or not at all.

They come in a variety of sizes and you can buy sets of three or more to cover the range that you need. Another advantage is that you can easily sharpen them. You can stroke them across a stone while rotating them to touch them up. But you should not remove too much from the exterior surface. When they need a serious sharpening, you can use a round stone in a Dremel type tool inside the hole to restore a good cutting edge.

[J Tiers]

The beef I have with countersinks is the fact that most if not all of the ones I have tried, including the "0 flute" types, still throw up a burr on the OD in many materials.

Then I need to deburr the OD of the countersunk hole, for which there seems to be no adequate tool.

Somewhere there must be a good countersink, because I see good clean c-sinks done in steel and aluminum. I just have not found one yet, and I have a lot of different types.

[Royldean]

Multiflute always chatter on me.

Have you tried the staggered flute type (claim to be chatterless)? I haven't......

[Jaakko Fagerlund]

If it is sharpened properly and used properly, it doesn't raise a burr. Have fought numerous times with this at work and even slightly dull will raise the burr. I have a few different size countersinks with 3 cutting edges, all the shanks have been modified to have 3 flats so that they won't spin in a hand held drill. Battery operated drill, countersink in and zap-zap-zap, nice clean hole edges very fast I don't even bother trying to use the mill or the drill press or lathe to swap it there, just move the tool away from the work and have at it with the hand held drill. Much quicker.

Edit: If a multiflute chatters, then the mounting isn't rigid, too much speed is used or the feed is just too little or one or more of the flutes are not sharp or sharpened unequally.

[Dr Stan]

I've always preferred 0 flute csk's. One thing to keep in mind with any csk is the cutting speed as it needs to be much slower than a similar sized drill bit.

[PT Doc]

Thanks for the info. Will check out enco and look for a zero flute.

[Jim2]

Somebody on here said that putting a thick rag or doubled-up rag over the hole then using the countersink prevents chattering. I've tried it a few times, and it helps a lot.

Jim

[PT Doc]

Seems like the 3/4" single flute countersink would work on a verity of hole sizes. Is this true or do they need to be sized closer to the hole size? I'll be using the 82 degree just in case I want to use a countersink screw at some point. Thanks

[Stepside]

Most countersink tools are a PIA at the best. I have a fine collection of different type aquired in the hunt for one I liked. What I have found is that speed needs to be quite slow both in RPM and feed. The material needs to be held rigidly not hand held in "kinda" the correct location. What I use to deburr is either a hand-held deburring tool or a carbide ball shaped burr fixed in a handle. The burr idea I stole from somewhere on this forum. both deburring operations I usually do with the part in the vise or held in my hand. To countersink for screws my favorite at the moment are the ones with the angled hole used with slow speed and cutting fluid.

[Toolguy]

Severance tool makes countersinks and deburring tools that have alternating axial flutes and angled flutes. These cut a smooth surface and last a long time. As already mentioned, slow RPM and oil or coolant make the best results, but can be used dry.