Need to modify HSS? broach

[aribert]

I need to broach an 1/8 inch keyway in a 7/8 bore. I have an 1/8 inch broach - acquired with a small lot of items at a grinder shop auction. Problem is that the broach is more than 7/8 inch wide. I know I could use my lathe carriage as a shaper - I have tried a couple of times in the past to use the carriage to shape with no success. I could buy a new import broach for about $40 (unless I was willing to wait a month or more, then I could buy it for half as much). So I am interested in removing stock from my existing broach. I tried a knowingly somewhat dull carbide endmill and got more rubbing than cutting. I presume the broach is HSS or similar. How could I mill it? If not milling, I could hack off the majority of the excess with zip discs and then would need to grind the hacked off surface smooth - I don't have a surface grinder. I could cover the mill knee ways and put a grinding wheel on an arbor in the mill - mill highest speed is about 5K rpm. Ruining the broach is of no concern - it owes me nothing and if I can't use it when needed, it is of no value. Other ideas?

[Doozer]

Wire EDM.

-D

[nc5a]

I suggest you buy a standard push broach. What you have pictured is a specialty broach, ie no taper in the body, only in the cutting teeth. My 1/8" standard push broach body measures roughly 3/8" at the small end and 1/2" at the large end. Make it easy on yourself and get a standard broach and bushing.

[cijuanni]

I suggest you buy a standard push broach. What you have pictured is a specialty broach, ie no taper in the body, only in the cutting teeth. My 1/8" standard push broach body measures roughly 3/8" at the small end and 1/2" at the large end. Make it easy on yourself and get a standard broach and bushing.

Yes it looks like a modified keyseater broach, and a dull rusty one at that.

[dian]

what problems do you have with broaching on the mill or lathe? especially such a small slot?

[J Tiers]

what problems do you have with broaching on the mill or lathe? especially such a small slot?

Not speaking for the OP, but broaching/shaping a slot on the lathe always seems like lathe abuse to me.

As for the mill, does not apply.

[LKeithR]

I suggest you buy a standard push broach. What you have pictured is a specialty broach, ie no taper in the body, only in the cutting teeth. My 1/8" standard push broach body measures roughly 3/8" at the small end and 1/2" at the large end. Make it easy on yourself and get a standard broach and bushing.

Exactly. That broach has certainly seen better days and it will require a lot of modification to make
it work right. It will require a custom bushing as well. Just not worth the trouble...

[dian]

Not speaking for the OP, but broaching/shaping a slot on the lathe always seems like lathe abuse to me.

As for the mill, does not apply.

i would rather see it the other way, but i gues it depends on what size of machines we are talking about. the lathe rack just seems more robust than a quill feed.

[Doozer]

i would rather see it the other way, but i gues it depends on what size of machines we are talking about. the lathe rack just seems more robust than a quill feed.

I believe the rack pinion gear in the apron is the weak link there.
Put the slotter tool in an offset boring head, held in the tailstock
would be more rigid, less strain on the works.

-Doozer

[JoeLee]

Wire EDM.

-D

If he doesn't have a grinder it's doubtful he has an EDM. I would buy a new broach.

JL...............

[JoeLee]

I believe the rack pinion gear in the apron is the weak link there.
Put the slotter tool in an offset boring head, held in the tailstock
would be more rigid, less strain on the works.

-Doozer

Unless you have a real big heavy duty lathe I wouldn't even think of using my lathe in that manner. I would make a bushing and smack or press the broach through using the appropriate shims.

JL...............

[reggie_obe]

Maybe someone in arbert's neck 'o the woods can loan him a broach and bushing.

[Doozer]

If he doesn't have a grinder it's doubtful he has an EDM. I would buy a new broach.

JL...............

That was my sarcasm show.

-D

[J Tiers]

I believe the rack pinion gear in the apron is the weak link there.
Put the slotter tool in an offset boring head, held in the tailstock
would be more rigid, less strain on the works.

-Doozer

And that would be even slower.... competitive with a hammer, cape chisel, and file.


He has the wrong tool for the job, and that's no error.

[Doozer]

You're right Jerry.
Use a chisel.
Perfect.

-D