[kevinro]

I have a 'standard' keyway broach setup (broach tools with collars and shims) and an arbor press. I know how to do this method.

Is there a CNC method I don't know about? Specifically, I am cutting a 3/32" into a .375 diameter hole in a wheel hub that is .5" deep (through the entire way).

Just wondering if a tool exists that I could do this with the CNC machine.

Never hurts to ask.

Kevin

[SCzEngrgGroup]

Yes, there is. Take a piece of steel rod, drill a cross-hole through it, near one end. Drill and tap an axial hole in the end. Insert a small lathe tool (I use 1/8" square HSS), through the cross hole, and put a screw in the end hole to lock it in place. You now have a broach. Put that in the spindle, and run it up and down in the hole you want to put the keyway in, moving it a few thou further from the hole center with each pass. This is the only way I've ever cut keyways. Even just doing it manually in a drill press takes only a few minutes.

Regards,
Ray L.

[DareBee]

You could use a tool called a rotobroach

[dbrija]

Yes, there is. Take a piece of steel rod, drill a cross-hole through it, near one end. Drill and tap an axial hole in the end. Insert a small lathe tool (I use 1/8" square HSS), through the cross hole, and put a screw in the end hole to lock it in place. You now have a broach. Put that in the spindle, and run it up and down in the hole you want to put the keyway in, moving it a few thou further from the hole center with each pass. This is the only way I've ever cut keyways. Even just doing it manually in a drill press takes only a few minutes.

Regards,
Ray L.

That's a problem on a Tormach as there is no spindle braking. One could come up with a way to hold the spindle motionless to solve that... Then you are good to go.

[SCzEngrgGroup]

That's a problem on a Tormach as there is no spindle braking. One could come up with a way to hold the spindle motionless to solve that... Then you are good to go.

I've done it on my knee mill, without using the spindle brake. Once you get started, it guides itself. You could easily add some kind of guide rod coming off the broach, to prevent the spindle from rotating. But, in my experience, it's not necessary.

You can also do the same thing on a lathe, just mounting the broach in the tool holder.

Regards,
Ray L.

[kevinro]

You could use a tool called a rotobroach

Isn't a rotobroach used for boring a hexagonal hole? I am looking for a key to fit onto a keyed shaft.

[kevinro]

I've done it on my knee mill, without using the spindle brake. Once you get started, it guides itself. You could easily add some kind of guide rod coming off the broach, to prevent the spindle from rotating. But, in my experience, it's not necessary.

You can also do the same thing on a lathe, just mounting the broach in the tool holder.

Regards,
Ray L.

Any thoughts on programming CNC to do this? I realize I would have to align the broaching tool manually so it was aligned with say the Y axis.

I was thinking a series of drill operations each say .01 in a linear progression along the Y axis, but I am unclear how to prevent the spindle from turning on. If someone else has blazed this trail already, I am eager to follow!

Kevin

[hoss2006]

Sure, it's been done before.
There is a video of a tormach cutting splines in a similar fashion but couldn't find it.
Here's a few others.
Hoss

[ame=http://www.youtube.com/watch?v=7vxjCEwsQK4]Z Axis Broaching - YouTube[/ame]

[ame=http://www.youtube.com/watch?v=ThLyK3WPiWE]PH Horn Internal Broaching - YouTube[/ame]

[ame=http://www.youtube.com/watch?v=iO81YZsUc_4]Broaching a keyway Haas VF-7 - YouTube[/ame]