.... broach a hex hole in mild steel.

Anyone see a problem with this method?

I have two parts sent to me that already have a .250" hex
in them, and my friend wants them opened up to .375" hexes.
I tested one, and it drilled out very easily and nicely.

My plan right now is to make a shaping cutter to fit my
Bridgeport Shaper/Slotting Head that has the width of
one flat of the hex (.217"), place the piece in a 5C collet,
the collet in a hex shaped collet block for easy indexing
in the vise, and broach/slot the hole to a hex shape.

Warnings? Admonitions?
Vulgarities? Suggestions?
A better idea?

Thanks,

Weyland

I should mention that the holes are .625" deep and are blind
holes, so through broaching using a hex broach isn't an option.

Best,

Weyland

I should mention that the holes are .625" deep and are blind
holes, so through broaching using a hex broach isn't an option.

You were good to go until you mentioned a blind hole. You need relief at the
end of the stroke for the shaper to work. It might be possible to drill your
hole, then take a woodruff cutter at the bottom of the hole to enlarge
clearance. Or if the part will fit in a lathe, make up a groove tool. Or,
can you have a thru hole and then weld a plug back in?

Karl

On 13 Jan 2006 17:34:16 -0800, "Weyland"
wrote:

I should mention that the holes are .625" deep and are blind
holes, so through broaching using a hex broach isn't an option.

Best,

Weyland


Wobble Broach. Though the shaper head works good

Gunner

The aim of untold millions is to be free to do exactly as they choose
and for someone else to pay when things go wrong.

In the past few decades, a peculiar and distinctive psychology
has emerged in England. Gone are the civility, sturdy independence,
and admirable stoicism that carried the English through the war years
.. It has been replaced by a constant whine of excuses, complaints,
and special pleading. The collapse of the British character has been
as swift and complete as the collapse of British power.

Theodore Dalrymple,

Karl Townsend wrote:

You were good to go until you mentioned a blind hole. You need relief at the
end of the stroke for the shaper to work. It might be possible to drill your
hole, then take a woodruff cutter at the bottom of the hole to enlarge
clearance. Or if the part will fit in a lathe, make up a groove tool. Or,
can you have a thru hole and then weld a plug back in?

Hi Karl,

Yes, I can hold it in the lathe.
(that's where I got the idea to use the hex collet
holder to index it while using the slotting head.)
I can certainly use an ID grooving tool
to create some relief at the bottom of the hole.
(thanks, not sure I would've thought of that)

No, I can't drill through and plug.
This is a finished part that can't be undone.
(they're two magneto rotors.)
I'm helping my friend by adapting them for him.
Basically, there's a .375" hex that interfaces with, and drives, the
rotor.
While the existing hole is .625" deep,
it only engages the driving hex for about .437".

Best,

Weyland

Gunner wrote:

Wobble Broach. Though the shaper head works good

Actually, it was during my searches before posting
that I saw you recommend this approach to another,
some time ago, calling it rotary broaching.

Great stuff, to be sure, but not
economically feasible for doing two of these.
(unless someone wanted to let me rent one for a day) (:)

After doing moreresearch and examining a bunch of broached
hexes today, I've come away with the impression that many (if not most)
tools are shaped to a point (the corner of the hex) to include half of
each side of a "flat" of the hex and are rotated to complete the
operation.

Can you see anything wrong with my
simply doing it by broaching the flats only?

Best,

Weyland

Two words
Chisel
BFH

On 14 Jan 2006 15:21:39 -0800, "Weyland"
wrote:


Karl Townsend wrote:

You were good to go until you mentioned a blind hole. You need relief at the
end of the stroke for the shaper to work. It might be possible to drill your
hole, then take a woodruff cutter at the bottom of the hole to enlarge
clearance. Or if the part will fit in a lathe, make up a groove tool. Or,
can you have a thru hole and then weld a plug back in?

Hi Karl,

Yes, I can hold it in the lathe.
(that's where I got the idea to use the hex collet
holder to index it while using the slotting head.)
I can certainly use an ID grooving tool
to create some relief at the bottom of the hole.
(thanks, not sure I would've thought of that)

No, I can't drill through and plug.
This is a finished part that can't be undone.
(they're two magneto rotors.)
I'm helping my friend by adapting them for him.
Basically, there's a .375" hex that interfaces with, and drives, the
rotor.
While the existing hole is .625" deep,
it only engages the driving hex for about .437".

Best,

Weyland

bore them out round..and install a ID hex sleeve?

Gunner


The aim of untold millions is to be free to do exactly as they choose
and for someone else to pay when things go wrong.

In the past few decades, a peculiar and distinctive psychology
has emerged in England. Gone are the civility, sturdy independence,
and admirable stoicism that carried the English through the war years
.. It has been replaced by a constant whine of excuses, complaints,
and special pleading. The collapse of the British character has been
as swift and complete as the collapse of British power.

Theodore Dalrymple,

On 14 Jan 2006 15:27:47 -0800, "Weyland"
wrote:

Gunner wrote:

Wobble Broach. Though the shaper head works good

Actually, it was during my searches before posting
that I saw you recommend this approach to another,
some time ago, calling it rotary broaching.

Great stuff, to be sure, but not
economically feasible for doing two of these.
(unless someone wanted to let me rent one for a day) (:)

After doing moreresearch and examining a bunch of broached
hexes today, I've come away with the impression that many (if not most)
tools are shaped to a point (the corner of the hex) to include half of
each side of a "flat" of the hex and are rotated to complete the
operation.

Can you see anything wrong with my
simply doing it by broaching the flats only?

Best,

Weyland

Nope..should work..but you do need someplace for the chip to go at the
bottom of the hole.

See my previous post about boring and sleeving

Gunner

The aim of untold millions is to be free to do exactly as they choose
and for someone else to pay when things go wrong.

In the past few decades, a peculiar and distinctive psychology
has emerged in England. Gone are the civility, sturdy independence,
and admirable stoicism that carried the English through the war years
.. It has been replaced by a constant whine of excuses, complaints,
and special pleading. The collapse of the British character has been
as swift and complete as the collapse of British power.

Theodore Dalrymple,

....
This is a finished part that can't be undone.
(they're two magneto rotors.)
I'm helping my friend by adapting them for him.
Basically, there's a .375" hex that interfaces with, and drives, the
rotor.
....

I think there's a MURPHY'S LAW that states the probably of F%^$ing up is
porportional to the value of the part.

This looks like a touchy job. I think I'd make two for practice before doing
the real thing.

Good luck

Karl

Gunner wrote:

bore them out round..and install a ID hex sleeve?

That's actually a pretty good idea
that I'll keep in mind if I fsck them up...

Thanks,

Weyland

Karl Townsend wrote:

I think there's a MURPHY'S LAW that states the probably of F%^$ing up is
porportional to the value of the part.

You ain't just whistling Dixie there, Karl~!
I'm *SURE* there's such a law.
In fact, I'm sure I've experienced it in action...

This looks like a touchy job. I think I'd make two for practice before doing
the real thing.

Thought of that, too, but appreciate you bringing it up.
I've already drilled a few pieces of stock to
practice on and set up the Shaping/Slotting head with.

I've never actually used this thing, but got it as part of my
deal when buying the Bridgeport, and have refused to part with it
despite *numerous* generous offers because I knew this day was coming.

This will either be fun or maddening...

I should take pictures.

Best,

Weyland

Gunner wrote:

Nope..should work..but you do need someplace for the chip to go at the
bottom of the hole.

I'm thinking along these lines -
The difference per side is .062".
I should be able to sneak up on it, taking .005"
(or even less, maybe) per cut, fairly quickly and easily.

This should accomplish two things -
I won't get bored and try to rush it through.
And I should be able to stop after each cut,
and break and clear the chip out of the hole.
(dental pick and air)

Wishful thinking? We'll find out...

Best,

Weyland

Easy,
Plunge EDM

Bob

wrote:
Easy,
Plunge EDM

Normally, I'd agree, but there's two concerns here -
There's only two parts, so it's likely not economic.
Also these are magneto rotors (highly magnetic and needed
to stay that way) and likely to be damaged by the EDM.
I've seen magneto rotors demagnetized by simply
hooking up a motorcycle battery incorrectly.

Keep'm coming, though.

Thanks,

Weyland

In article .com,
says...

Gunner wrote:

bore them out round..and install a ID hex sleeve?

That's actually a pretty good idea
that I'll keep in mind if I fsck them up...


Hex sleeves are available in many sizes in small increments disguised as
sockets.

Ned Simmons

Ned Simmons wrote:

Hex sleeves are available in many sizes in small increments disguised as
sockets.

Ned, that is very clever indeed, and I can say
that I most certainly would not have thought of that.
I know where to go if I end up needing one.

Thanks,

Weyland