Broaching a hex hole
Broaching a hex hole
(OP)
I need some advise on how to broach a hexagon into a BLIND hole. The workpiece is 2" diameter, 22" long and I need to have a 3/4"AF hex Female hole put into both ends about 2" deep. Like a cap head screw. Can anyone advise me on how to do this?.





RE: Broaching a hex hole
-handleman, CSWP (The new, easy test)
RE: Broaching a hex hole
RE: Broaching a hex hole
EDM solves that problem, at the expense of speed.
Another possibility; through- broach a pair of short cylinders, press them into blind bored holes in the ends of the workpiece, and secure with threaded Dutch pins or plug welds or whatever.
Mike Halloran
Pembroke Pines, FL, USA
RE: Broaching a hex hole
Ted
RE: Broaching a hex hole
I have not failed. I've just found 10,000 ways that won't work." — Thomas Edison
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RE: Broaching a hex hole
James Spisich
Design Engineer, CSWP
RE: Broaching a hex hole
RE: Broaching a hex hole
RE: Broaching a hex hole
RE: Broaching a hex hole
From your comments blind hole boring or punching is a method but I have never seen "blind hole broaches or punches" are these available? or would I need to make myself? (BTW if the answer is make myself then I will be asking a whole load of other questions!!)
Assuming they are stuck well I dont mind about the chips remaining in the bottom of the hole.
RE: Broaching a hex hole
http://www.slatertools.com/rotary_broaching.htm
RE: Broaching a hex hole
A place I worked at used to have a "Polygonal Hole Drilling Attachment"; it made a lot of noise but produced pretty good holes, hexagons were much better and sharper than squares which had slightly rounded corners, but I don't think that they recommended going much deeper than twice the AF distance, so that may rule it out for you.
It was made by Watts Brothers Tool Works in Wilmerding PA and I believe they're still in business, may be worth asking them if they still make them and if they can go deeper now.
I saw a CNC turning centre producing hex holes fairly recently (Dianichi, I think) using a rotary tool in a driven tooling station, so I guess that it's the same principle but without the noisy guide plate!
RE: Broaching a hex hole
Griffy
RE: Broaching a hex hole
RE: Broaching a hex hole
Cheers
Greg Locock
SIG:Please see FAQ731-376: Eng-Tips.com Forum Policies for tips on how to make the best use of Eng-Tips.
RE: Broaching a hex hole
Blind-hole broaching
Blind-hole broaching violates two broaching principles: the tool does not pass completely through the work piece, and it must be withdrawn backwards over the broached surface. But it can be done when necessary. The job usually involves a series of short push broaches, each slightly larger in diameter than the preceding tool. These short push broaches are mounted on a circular indexing table that rotates under or over the work piece; the broaching machine pushes the work piece over the tool, withdraws it, and then waits for the next broaching tool to index into position.
http://holdenventures.com/BD.aspx
RE: Broaching a hex hole
If you need the two inch diameter on the end then press the sockets into a hole drilled in each end. Then weld the exposed ends.
RE: Broaching a hex hole
It was just an idea, please don't shoot me.
Greetings
RE: Broaching a hex hole
My machine tools book dates from the mid-seventies. It has a section describing a system for drilling square, hexagonal, octagonal and other weird shaped holes. The photos are courtesy Watts Brothers Tool Works.
Try searching Google for Watts Brothers Tool Works, and for Reuleaux triangle.