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What's the best way to attack a hex hole on a slotter?

rklopp

Diamond
Joined
Feb 27, 2001
Location
Redwood City, CA USA
Assuming I have an indexing table, what is the best way to cut an internal hexagon on a vertical slotter? Should I grind a 120° V cutter and go after the corners, a flat cutter and go after the flats full-width, or a narrower flat cutter and go after about half a flat at a time and traverse to machine the whole flat? This is to make a 1/2"-across-the-flats hex hole in Durabar about 0.7" thick starting from a 0.503" hole, with the end result being the same as I'd get shoving a standard 1/2" hex broach through the hole (but without buying and busting a 1/2" broach for lack of a press with enough headroom).
 
Do the flats - it's easier on the machine and cutter,...………..and machinist 'cos you have the across flat hole to use as a witness ;)

Narrower cutter is also easier on the machine and gives you a bit of wriggle room IME ''funny things'' can happen with shapers n slotters

Oh & Durabar = a doddle
 
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Wouldn't you drill the corners first ?

Then proceed to drill/bore the center out ?

Then bring in the shaper ?
 
He didn't tell us about his slotter, but for a real slotter I wouldn't worry until I was pushing over 3/4 wide in pre-hard.
 
My slotter is an attachment that goes on an Aciera F5 mill. I would in fact worry before I was pushing a 3/4" wide cutter in pre-hard...or aluminum for that matter. ;-) I would put the slotter in the same league as the Bridgeport E head, but a little more rigid and with a lot more motor behind it.

Thanks all for the suggestions.
 
Do the flats - it's easier on the machine and cutter,...………..and machinist 'cos you have the across flat hole to use as a witness ;)
Narrower cutter is also easier on the machine and gives you a bit of wriggle room IME ''funny things'' can happen with shapers n slotters
Oh & Durabar = a doddle

Normally, I'm in default agreement with you, Sami. On this one though, I don't think it really matters given the job. Gonna be a doddle, either way. Frankly, if he's the indexer I'd almost rather the 120° tool, simply for being able to clean the corners more nicely. The only reason I'd favor the flat's for the easier tool to make.
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I don't have the cutter but have everything else needed to rotary broach it. With the cutter I could rotary broach it faster than you can set up the slotter.
 
Broach the hole

Normally, I'm in default agreement with you, Sami. On this one though, I don't think it really matters given the job. Gonna be a doddle, either way. Frankly, if he's the indexer I'd almost rather the 120° tool, simply for being able to clean the corners more nicely. The only reason I'd favor the flat's for the easier tool to make.
icon14.png

There shall be better chance of success to bore a hole in the work piece and make a O1 60-62 Rc broach with an undercut pilot on the front of the broach. If you require close tolerance, make an additional finish broach .0025 larger than the first. I know you said your shop lacks a press, but a press for your use should be available at any auto parts store. Press a little at a time, remove the broach; file away the chip and press again until your through the hole.

Comments?

All the best,
Roger
 
AF means "as f¥€<" on most of the internet. As in "Just make any tool and index six times. Easy AF."

That might be the source of the "Across the Flats" confusion.
 
I would just drill the corners and mill the hex, maybe a little bit of file work or could use the slotter to tickle out the remainder.

For some applications, I'd purchase a deep hex impact socket and cut the hex end off, and press fit it into the part. But a hex socket might be a bit loose on the 1/2", however it will resist wear better than the iron itself.
 
You having some sort of a laugh - or just taking the piss?

'Muricans are not familiar with AF stamped on the wrenches since they don't use Whitworth wrench size system :D

(A Whitworth wrench is sized according to the diameter of the shank of the bolt, not the head)
And then you have the old Whitworth and new or BSF sizes... so wrench stamped 1/2" BSW fits to 3/4" AF bolt head. Depending on bolt itself could be 1/2" or 9/16" diameter :nutter:
1/2" BSW = 9/16 BS(F) = 3/4" AF :crazy:
 
That may be true, but taken in context of a discussion concerning dimensions Across Flats, I knew what Limy meant as soon as I read his post.
 
I would just drill the corners and mill the hex, maybe a little bit of file work or could use the slotter to tickle out the remainder.

For some applications, I'd purchase a deep hex impact socket and cut the hex end off, and press fit it into the part. But a hex socket might be a bit loose on the 1/2", however it will resist wear better than the iron itself.

Quick layout shows 1/16" corners, use .250 endmill will leave .041 sliver to file off.
 

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