How to drive large auger bit with 7/16" Powerdrive Hex shaft

[Joe Jensen]

I need to bore 11/16" holes through some turned legs that are 16 1/4" long. I bought a bit that's basically perfect, except that I assumed the 7/16" Powerdrive Hex shaft would fit the 5/8" Chuck on my drill press but it does not. I have googled a lot and I can't find an adapter to let me drive that bit in my drill press. I might be able to make it work by driving it with a 7/16" socket mounted to the drill press with an adapter but that will just just drive it and not let me pull the bit up to clear chips. I also though about tack welding a cheap socket to the bit. Other ideas? I need something that will work to drill holes in two legs. Also the legs are made from some scarce reclaimed wood and I really can't wreck them.

[Brice Rogers]

I'm a bit perplexed. If I did the math correctly, a 7/16 hex should measure around 0.495 measured from peak-to-peak (as opposed to measuring from flat to flat). And you say that you have a 5/8" chuck. What am I missing? I don't doubt that you have an interference, but I don't understand why a 7/16 hex shaft doesn't fit into a 10/16" chuck.

Is the interference small enough that you could grind off the points of the hex and still chuck down on the original flats?

[Tom M King]

your chuck may be bent to not allow it to open all the way. I have one on a 1/2" right angle drill, and had to hammer it back into round. I think someone tightened it with a hammer on the chuck key.

[Joe Jensen]

Oops, made a mistake. It's actually a 5/8" HEX and it for sure will not fit a 5/8" chuck. It's over 11/16" point to point.

[Bill Dufour]

I bet the chuck or drill is actually metric and they chose a common fraction close to the real size.
Bill D.

[Grant Wilkinson]

I would epoxy a 5/8" socket to the drill bit. If the socket is 3/8" drive, use a 3/8" short extension, chucked in your drill press to drive it. I've done similar things with smaller sockets and bits and it has worked fairly well.

[Bill Space]

If I am understanding the dilemma right, I would probably file the points of the shaft enough to allow it to fit in the chuck.

You would still have six flats, any three of which the chuck should grab.

Sorry if my my mental image is off target! :)

[Bill Dufour]

Sounds like you are measuring wrong. A hex is measured across the flats, the 11/16 measurement is not used.
Bill D.

[Rod Sheridan]

As Bill indicated, you're measuring the hex incorrectly.

A 5/8 hex will fir in a 5/8 chuck, are you sure the chuck is fully open?

Maybe it needs cleaning and lubricating?

Regards, Rod.

[mreza Salav]

Holes are to be drilled along the lengths of the turned legs? how about put the bit into a chuck on your lathe and do it on the lathe?

[Ronald Blue]

I think the problem is the hex measures 5/8" as stated however the issue is the 11/16" from point to point will not slip inside a 5/8" hole. So in effect it's like trying to stuff a 11'16" shank in a 5/8" hole.

[Kyle Iwamoto]

I think the problem is the hex measures 5/8" as stated however the issue is the 11/16" from point to point will not slip inside a 5/8" hole. So in effect it's like trying to stuff a 11'16" shank in a 5/8" hole.

The points should fit in between the chuck jaws as mentioned before. True, you can't fit a 11/16 point to point inside a 5/8 hole, but a chuck is different.
I'm in the camp that says you have a metric chuck that is smaller than 5/8 or it's not open all the way and could use some WD-40 or whatever you like to use to clean it up a bit...... It should work.

[Greg R Bradley]

I'm still trying to believe that there actually IS a drill bit with a 5/8" hex drive. Never seen or heard of that as a standard drive. 7/16" quick connect is a standard.

[Bill Space]

The points should fit in between the chuck jaws as mentioned before. True, you can't fit a 11/16 point to point inside a 5/8 hole, but a chuck is different.
I'm in the camp that says you have a metric chuck that is smaller than 5/8 or it's not open all the way and could use some WD-40 or whatever you like to use to clean it up a bit...... It should work.

EXCEPT that the end of the chuck has a circular hole that the jaws of the chuck move in and out of. If that hole is 5/8”, there is no way a hex shaft with a point to point width of larger than 5/8” is going to fit, as you said. Can’t see how a chuck with a 5/8” opening is different than a 5/8” hole...

Perhaps the OP can enlighten us a little more.

[Bradley Gray]

For 2 holes I would buy a spade bit with extension.

[Ronald Blue]

The points should fit in between the chuck jaws as mentioned before. True, you can't fit a 11/16 point to point inside a 5/8 hole, but a chuck is different.
I'm in the camp that says you have a metric chuck that is smaller than 5/8 or it's not open all the way and could use some WD-40 or whatever you like to use to clean it up a bit...... It should work.

I just checked my 1/2" chuck and it will accept 1/32" over 1/2". That's what I expected. Apparently 5/8" chucks are different? Not to my recollection from my machinist/tool and die days. I give Joe the benefit of the doubt that he knows what he's talking about. I think he can knock the points down and it will still run true and chuck up securely.

[Ronald Blue]

EXCEPT that the end of the chuck has a circular hole that the jaws of the chuck move in and out of. If that hole is 5/8”, there is no way a hex shaft with a point to point width of larger than 5/8” is going to fit, as you said. Can’t see how a chuck with a 5/8” opening is different than a 5/8” hole...

Perhaps the OP can enlighten us a little more.

My point exactly Bill. A chuck isn't different. They still have a hole that is the final limiting factor in what will chuck up in it. In my experience you can get usually a 1/32" larger than the rated capacity. The hole is what prevents going any larger.

[Joe Jensen]

Checking back in. The 5/8" chuck I have will accept a 5/8" diameter round and no larger. The 1/2" chucks and the 3/8" chucks are also limited to those sizes. Nothing bigger than 5/8" will fit.

I gave up and ordered another bit that has a 1/2" round shank. My bad in the first place for not noticing the shank when I ordered. I seriously considered welding (epoxy was a better idea) a socket on the shank but I was worried about runout and I also need to be able to pull the bit back out of the wood while running to clear chips so I figured I'd have to weld a cut off extension onto the socket.