Blind keyway broaching

[chedderhead]

Does anyone have any good suggestions for what process to use to rapidly broach a keyway (approx 1/4&quot in a 1 1/2" dia. blind hole? E.D.M. would be too slow of a process to be cost effective.

Thanks in advance for any help you can give.

 

[mytwotoes]

Assuming you have access to a Bridgeport or CNC mill.
Lock the spindle in place so that it does not rotate.
Mount a short as possible boring bar that has a 1/4"
square with a 45 degree angle. You will have to grind
clearance on the lathe bit. With your part centered
in a vise and your tool bit mounted, move x axis toward
the ID of your part, set your z depth for the blind keyway. If you are using a bridgeport type mill you may have you use the handle to take the shallow cuts to depth. If you
use a cnc mill you may program the head to come down to depth, go back up move x (depth of next pass) repeat.
I have done this on several occasions and it works great.

 

[ornerynorsk]

Your first concern was cost effectiveness? You must have a large number of parts, send them to a broaching shop for the quickest, cheapest, and most accurate job.

 

[gbent]

I have single point broached many keys in CNC machines. If you are going to manually broach it with the quill of a Bridgeport, make sure you use the worst machine in the shop. It is a little slow, but it saves a secondary op.

You will need a relief at the bottom of the keyway to allow the chip to break free. A groove all around the part works good, as there is no part index. Another solution is a drilled hole from the side for chip relief.

In the old days, it would have been cut on a shaper.

 

[Viktor]

This operation is called SLOTTING not broaching. Broaching cannot be used inherently for blind holes. Viktor

http://viktorastakhov.tripod.com