Countersink recommendation?

[JD1]

I need to countersink some holes in the top of my welding table, using a cordless drill. I don't have a mag drill. I have a countersink for wood but of course that won't work. I'm unfamiliar with countersinks for metal and would like some suggestions.

I assume cobalt or titanium but is the fluteing the same as the ones for wood or are the metal ones built differently?

[M J D]

You need to match the angle of the screws your using. 82 degrees is common. Keo makes pretty good countersinks.

[mla2ofus]

It may not exactly match the angle but I used a 3/4" metal drill bit for the bolts on my welding table. I don't know how well your cordless drill will do it.
Mike

[Mac's Crew]

Weldon makes a decent chamfer tool... don't know about cost.

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[Fnord5]

How many holes?
If it's not too many I've had good luck with the Irwin brand countersinks.. on fairly thin materials at least

https://www.lowes.com/pd/IRWIN-5-Pie...YaAo2aEALw_wcB

[psacustomcreations]

Aaron from the Youtube channel 6061.com is a member here and stops by occasionally.

He did a video on the different types of countersinks. This may help you:

[Chad86tsi]

one thing to consider in design is the depth of the relief just behind the cut edge. I have 2 countersinks that i use regularly, one I use to de-burr holes, the other for actual countersinking. The steeper relief allows more material removal, works more like a drill bit. The shallow relief cut on the bit makes the bit far more stable, yields a chatter free concentric cut, but doesn't advance once it starts to load up. Both are 6 cut edges. I got the one I use for countersinking at :
https://www.mcmaster.com/countersinks

you can choose the angle to match standard bolts.

The one I use for deburring I got at a hardware store, Irwin brand. It will countersink in aluminum, but not in steel. I think it was designed for wood. Get a popper one for the job, they work so much better than all the other jerry-rig options.

Edit, just watched the video above, the last one used is the one I got at Mcmaster. I used it in 1045 steel, it help up till I hit a hard impurity in the steel. I was able to save it by sharpening with a wet diamond cutoff wheel (designed for tile). Even after I had to re-work it by hand, it still works better than any other for the task.

[2strokeforever]

These are great
https://toolguyd.com/blog/wp-content...-Drill-Bit.jpg

[JD1]

Very interesting video above. Unfortunately you have to pay to subscribe to his site in order to see the part numbers and he was working on aluminum. The ones mentioned at McMaster didn't seem to be exactly the same. I looked up the Keo ones mentioned and they're available on Amazon. Got a lot of good reviews. I'm not sure how a zero flute countersink works but I may give that one a try.

[Bob-O]

Try Mcmaster -Carr or Fastenal

[shortfuse]

These are great
https://toolguyd.com/blog/wp-content...-Drill-Bit.jpg

Link doesn't work, 404 error code

[BrooklynBravest]

I have found MA Ford single flute to be the cleanest cutting for me. I bought an amazon one just because I needed one in a hurry and it cuts like garbage.

I also bought a 6 flute and even in a real rigid setup it chatters. Maybe better on soft metals but not steel.

Very interesting video above. Unfortunately you have to pay to subscribe to his site in order to see the part numbers and he was working on aluminum. The ones mentioned at McMaster didn't seem to be exactly the same. I looked up the Keo ones mentioned and they're available on Amazon. Got a lot of good reviews. I'm not sure how a zero flute countersink works but I may give that one a try.

I ordered the 6 flute referenced above after watching his video. As stated, not good on steel... He is hand drilling too, I get chatter in a collet with it.

[wb4rt]

I have used a center mill in my drill press to counter sink. They come in different sizes and last a long time. The short size and the thick body seem to do a good job. Of course you need to match bolt to bevel.

[JD1]

I ordered the 6 flute referenced above after watching his video. As stated, not good on steel... He is hand drilling too, I get chatter in a collet with it.

The engineer from Keo that answered my email said that chatter usually means the RPM's are too high. I don't know myself, not real experienced with countersinks.

Fastenal has a location here and they're showing a number of different 82 degree cobalt Keo countersinks on their site. I may call them Monday and see what's in stock, then run over there.

[Mac's Crew]

I have some KEO countersink cutters... not bad but not sure of the price either... they are at work so I didn't have to pay for them.



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[M J D]

The engineer from Keo that answered my email said that chatter usually means the RPM's are too high. I don't know myself, not real experienced with countersinks.

Fastenal has a location here and they're showing a number of different 82 degree cobalt Keo countersinks on their site. I may call them Monday and see what's in stock, then run over there.

Those should work out good for your project. I believe what that engineer said is spot on. My Milwaukee mag drill has the variable speed rheostat that lets it turn at rpm below 100 and no chatter even with large sizes. I'm not a fan of Fastenal but they are convenient, just check some prices on Amazon or elsewhere first.

[2strokeforever]

[farmersammm]

I had trouble getting a countersink to cut well, despite it being advertised as "chatter free".

I found that the best way to run the things is with a variable speed hand drill. My mill won't go below 230rpm, and they chatter like a chipmunk.

The cut was reasonable, and I mean reasonable with a caveat, when run at low rpms...….maybe 20ish rpms.

Then I got creative, Hell more like desperate, and ground a tool for the boring head.



Not terribly bad for 230rpm without coolant (oil only). I won't use any coolant when running my boring head

Main thing was...……..it was precise centering, and depth......not possible with a hand held drill.

I never took a pic of the grind geometry, but can if anybody's interested in trying this approach.

[ct from shawnee]

That is the best one right there used one yesterday !

[ct from shawnee]

That is the best one right there used one yesterday !

[JD1]

I asked the Keo engineer about that one, I was going to get it for my project. He said they're mainly for deburring and one with flutes will remove more metal. So I'm going with some version of flutes.

[metalman21]

I find that type works great in aluminum for a full countersink, but not great in steel. Its basically a single cutting edge.

[CAVEMANN]

I never liked a countersink that has more than one cutting edge or flute, we commonly called them a UNIFLUTE & I think that is also a name brand of the ones we had & used, or it may have just been the type. It seems that more than one cutting edge induces vibration/chatter into the mix, especially if the flutes are concentric/evenly spaced on the countersink.

[metalman21]

The single flute countersinks work great in the lathe, mill and the drill press. When they are sharp of course. I work the machines on the slow side.
I've had mixed results with the multiple flutes, some good and some chattered. If it really has to be good I'll take the time figure out what works best before I do the parts.
The statement previously made about speeds does have a lot to do with it.I

[lotechman]

Some things to consider:
The material that the countersink is made of is very important.
High speed steel ( Mushet steel) is over a hundred years old and there is still crappy versions of high speed steel but in general you will be able to countersink mild steel.

When you see "titanium" it is a selling gimmick that fools people. What you want is high speed steel that has a thin coating of titanium oxide giving it that distinctive color. That coating is amazing how it helps the cutting edge hold but once the coating is worn away you have just a regular high speed steel cutting edge. You have to hope when buying cheaper titanium cutters that it is not just carbon steel with a titanium coating because that is a total rip off. I recently bought some 20 odd drill bits from China with tianium oxide coating and when I tried to drill a piece of mild steel the end just wiped off. They ripped of another stupid round eye LOL The price was just too good to be true.

Cobalt steel in most cases if it is reputable brand indicates that the cutter is made of a high speed steel composition with the addition of cobalt in the alloy. They definitely give you a superior cutting edge that will still be there after a sharpening. Walter makes a great cobalt alloy drill bit but if you are drilling a cockeyed hole the whole drill bit can shatter they are so hard. Even on a drill press if your work is not secure or you ask the drill bit or countersink to bend it will be all over suddenly with cobalt alloy.

Carbide is really the way to go but you have to have deep pockets and a very rigid setup. If you fracture a carbide cutter or drill bit everyone will hear you crying as you realize how much money you tossed away.

That covers the alloys and then you can look at the different shapes and configurations.
For countersinking steel get your speed down and use a cutting oil if it is convenient. You can always raise your speed later but if you start out at too high a speed, in second, you will dull the cutting edge and lose on the total life of the cutter.