Metalworking (rec.crafts.metalworking) Discuss various aspects of working with metal, such as machining, welding, metal joining, screwing, casting, hardening/tempering, blacksmithing/forging, spinning and hammer work, sheet metal work.

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Default Rotary Broaching

Now I know the easiest way to do what I want is with a push broach and make
them as two pieces, but I want to make some specialty hex drivers with a one
piece body. That leaves me with rotary broaching. The thing is I am not
going to make a bunch of them so buying a rotary broach holder or spending a
day making one isn't all that wise of use of my time or money. However once
I was setup to do it rotary broach inserts are a lot cheaper than push
broaches.

Recently I had need to do some cross drilling that would have been easiest
with a preset cross drill on the lathe. Its slow and tedious to center up
and drill the part on the mill, but of course I can do it. I don't have to
do it often so again making a cross drill for the lathe isn't good use of my
time.

Then I had an aha moment. Make it fairly robust and use it for rotary
broaching as well. Centering would be a little tedious, but getting my 1
degree back angle from center would be dead easy to do after that. Then
lock down all the gibs not in use and advance the carriage. I doubt it
would ever work on the mini lathe or the small lathe, but maybe the PM1440
could handle it.

If I can use the same tool for both applications it almost makes it worht
making one. I might still know where to find it by the next time I need it.
Driven with hand held drill when cross drilling and of course driven by the
stock when rotary broaching.

I don't think I've ever cross tapped stock in the lathe, but if I don't see
why I could not add enough functionality to do that too if I need to.

So what's wrong with it? I know rotary broaching takes a lot of power. The
lathe is big, but its only 3HP. Flex in the compound, cross slide, and
carriage could be an issue. If a spacer is used internally in the cross
dril that rides on a thrust bearing I think the drill itself could take it.
I also considered bronze bushing with a 1/2 shaft collet chuck because the
bronze can take so much force.



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Default Rotary Broaching

"Jim Wilkins" wrote in message
news
"Bob La Londe" wrote in message


I added the other groups to clutter them up the way they do to us.
--jsw


STOP THAT! LOL. I've been posting metal working questions and projects to
try and get people thinking about our craft again now that the political
**** storm has subsided a little.

The flex you talk about to get an angle has the same affect as a 1 degree
angle with a rotary broaching tool.

The idea with the tool post cross drill part is if its left adjusted in a
tool holder I can just drop it in place and drill a cross hole with no
setup. 10 seconds vs 2 minutes or more to take it off and transfer it to
the mill. I've got three parts I have made that require cross drilling and
might wind up being small scale production parts. One would benefit from a
turning operation afterwards. I can mount a collet in the lathe, but I am
leaning towards putting the 4 jaw on and leaving it in place for all the one
off projects.

Actually the mini lathe CNC conversion may get a 3C collet closer and get
used for some of those parts, but the conversion is only half done and
customers just won't pay me unless I promise to make their parts. LOL. I
am leaning towards also CNCing the small lathe with a 3C collet closer as
well.



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Default Rotary Broaching

"Bob La Londe" wrote in message
news
"Jim Wilkins" wrote in message
news
"Bob La Londe" wrote in message


I added the other groups to clutter them up the way they do to us.
--jsw


STOP THAT! LOL. I've been posting metal working questions and
projects to try and get people thinking about our craft again now
that the political **** storm has subsided a little.

The flex you talk about to get an angle has the same affect as a 1
degree angle with a rotary broaching tool.

The idea with the tool post cross drill part is if its left adjusted
in a tool holder I can just drop it in place and drill a cross hole
with no setup. 10 seconds vs 2 minutes or more to take it off and
transfer it to the mill. I've got three parts I have made that
require cross drilling and might wind up being small scale
production parts. One would benefit from a turning operation
afterwards. I can mount a collet in the lathe, but I am leaning
towards putting the 4 jaw on and leaving it in place for all the one
off projects.

Actually the mini lathe CNC conversion may get a 3C collet closer
and get used for some of those parts, but the conversion is only
half done and customers just won't pay me unless I promise to make
their parts. LOL. I am leaning towards also CNCing the small lathe
with a 3C collet closer as well.


Can you lock the spindle while you drill?

Mine locks by engaging the back gears but there's detectable play in
the gears and bull pin.

I bought a router motor to mount on the tool post and then realized it
wouldn't handle the range of operations I do to round parts on the
mill, especially cutting large wrench flats, and the setback to allow
for a drill chuck + bit would make the mount too wobbly.

--jsw


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Default Rotary Broaching

On 2016-12-01, Bob La Londe wrote:
Now I know the easiest way to do what I want is with a push broach and make
them as two pieces, but I want to make some specialty hex drivers with a one
piece body. That leaves me with rotary broaching. The thing is I am not
going to make a bunch of them so buying a rotary broach holder or spending a
day making one isn't all that wise of use of my time or money. However once
I was setup to do it rotary broach inserts are a lot cheaper than push
broaches.


Yes. Recent experience -- in MSC, a Dumont 1/4" square push broach
is $101.??, and a 1/4" rotary broach is about $60.00.

Recently I had need to do some cross drilling that would have been easiest
with a preset cross drill on the lathe. Its slow and tedious to center up
and drill the part on the mill, but of course I can do it. I don't have to
do it often so again making a cross drill for the lathe isn't good use of my
time.


Hmmm ... for cross drilling -- have you ever seen the tailstock
tool for the purpose? A Morse-taper mounted round pad with a V-groove
across it. Just slap the workpiece (assuming cylindrical) into the V,
and with a drill chuck in the headstock spindle, drill away. I've seen
them in old _How to use a Lathe_ books. Either the Atlas/Craftsman one,
or the South Bend -- if not both.

I would actually like to have one of those myself.

As for centering up on a mill -- the same trick as used for
aligning tailstock and headstock centers can be used. A piece of thin
material -- a 6" pocket scale, or a razor blade, and you can tell which
side is getting the center of the bit by which way the thin piece tilts.

Of course -- another trick which I have read about, but not yet
tried, is to drill the center of the round stock in the lathe with the
size bit desired, then part it off, and when dross-drilling time comes,
put the round stock in a vise with the round parted off part on top.
Use the hole in the parted off piece as a drill bushing to get the bit
truly on center.

Then I had an aha moment. Make it fairly robust and use it for rotary
broaching as well. Centering would be a little tedious, but getting my 1
degree back angle from center would be dead easy to do after that. Then
lock down all the gibs not in use and advance the carriage. I doubt it
would ever work on the mini lathe or the small lathe, but maybe the PM1440
could handle it.


Likely -- ideally with the compound removed and the tool bolted
directly to the cross-slide. This eliminates several locations for
play.

If I can use the same tool for both applications it almost makes it worht
making one. I might still know where to find it by the next time I need it.
Driven with hand held drill when cross drilling and of course driven by the
stock when rotary broaching.

I don't think I've ever cross tapped stock in the lathe, but if I don't see
why I could not add enough functionality to do that too if I need to.


For the drilling and threading, you would want the spindle
locked as you are describing it. Or -- if using a variant of the V-pad
in the tailstock, you want a releasing tap holder in the lathe chuck or
collet so you don't tap too deep.

So what's wrong with it? I know rotary broaching takes a lot of power. The
lathe is big, but its only 3HP. Flex in the compound, cross slide, and
carriage could be an issue. If a spacer is used internally in the cross
dril that rides on a thrust bearing I think the drill itself could take it.
I also considered bronze bushing with a 1/2 shaft collet chuck because the
bronze can take so much force.


I have no experience with the rotary broaching (though perhaps I
should get that). However, I just did some broaching in A2 drill rod
using a 1/4 square broach. After making a fixture to hold the drill rod
vertical and setting it up in a 3-ton arbor press (and broaching a hole
which was 3/4" long) I got about half way through before I could not put
enough weight on the lever (my 3-ton does not have the ratcheting lever
arm -- and one of my own arms is still recovering from being broken a
couple of years ago), so I had to move it to the 20-Ton Harbor Freight
Hydraulic press to finish. This with Molybdmium DiSulfide grease as a
lube.

So -- if the rotary broach takes more force, I don't want to
play. :-)

Enjoy,
DoN.

--
Remove oil spill source from e-mail
Email: | (KV4PH) Voice (all times): (703) 938-4564
(too) near Washington D.C. | http://www.d-and-d.com/dnichols/DoN.html
--- Black Holes are where God is dividing by zero ---
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Default Rotary Broaching

On 2016-12-01, Bob La Londe wrote:
"Jim Wilkins" wrote in message
news
"Bob La Londe" wrote in message


I added the other groups to clutter them up the way they do to us.
--jsw


STOP THAT! LOL. I've been posting metal working questions and projects to
try and get people thinking about our craft again now that the political
**** storm has subsided a little.


Good for you!

Enjoy,
DoN.
--
Remove oil spill source from e-mail
Email: | (KV4PH) Voice (all times): (703) 938-4564
(too) near Washington D.C. | http://www.d-and-d.com/dnichols/DoN.html
--- Black Holes are where God is dividing by zero ---


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Default Rotary Broaching

"DoN. Nichols" wrote in message
...
...
Hmmm ... for cross drilling -- have you ever seen the tailstock
tool for the purpose? A Morse-taper mounted round pad with a
V-groove
across it. Just slap the workpiece (assuming cylindrical) into the
V,
and with a drill chuck in the headstock spindle, drill away. I've
seen
them in old _How to use a Lathe_ books. Either the Atlas/Craftsman
one,
or the South Bend -- if not both.

I would actually like to have one of those myself.


I have one that I never used, so I just went through the motions
without turning the lathe on. I don't like having to swap the hand
holding the work against the vee to reach the power switch on the
headstock while the spindle is running and the drill is in the hole.
Backing out the tailstock could let the work spin. It seems as
dangerous as hand-holding a small part on a drill press.

--jsw


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Default Rotary Broaching

On 2016-12-02, Jim Wilkins wrote:
"DoN. Nichols" wrote in message
...
...
Hmmm ... for cross drilling -- have you ever seen the tailstock
tool for the purpose? A Morse-taper mounted round pad with a
V-groove
across it. Just slap the workpiece (assuming cylindrical) into the
V,
and with a drill chuck in the headstock spindle, drill away. I've
seen
them in old _How to use a Lathe_ books. Either the Atlas/Craftsman
one,
or the South Bend -- if not both.

I would actually like to have one of those myself.


I have one that I never used, so I just went through the motions
without turning the lathe on. I don't like having to swap the hand
holding the work against the vee to reach the power switch on the
headstock while the spindle is running and the drill is in the hole.
Backing out the tailstock could let the work spin. It seems as
dangerous as hand-holding a small part on a drill press.


Add a foot switch to stop the spindle. (It helps if you have a
relay-switched spindle motor with buttons -- there you just need to add
a NC switch in series with the stop switch.

Enjoy,
DoN.

--
Remove oil spill source from e-mail
Email: | (KV4PH) Voice (all times): (703) 938-4564
(too) near Washington D.C. | http://www.d-and-d.com/dnichols/DoN.html
--- Black Holes are where God is dividing by zero ---
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Default Rotary Broaching

"DoN. Nichols" wrote in message
...
On 2016-12-02, Jim Wilkins wrote:
"DoN. Nichols" wrote in message
...
...
Hmmm ... for cross drilling -- have you ever seen the tailstock
tool for the purpose? A Morse-taper mounted round pad with a
V-groove
across it. Just slap the workpiece (assuming cylindrical) into
the
V,
and with a drill chuck in the headstock spindle, drill away. I've
seen
them in old _How to use a Lathe_ books. Either the
Atlas/Craftsman
one,
or the South Bend -- if not both.

I would actually like to have one of those myself.


I have one that I never used, so I just went through the motions
without turning the lathe on. I don't like having to swap the hand
holding the work against the vee to reach the power switch on the
headstock while the spindle is running and the drill is in the
hole.
Backing out the tailstock could let the work spin. It seems as
dangerous as hand-holding a small part on a drill press.


Add a foot switch to stop the spindle. (It helps if you have a
relay-switched spindle motor with buttons -- there you just need to
add
a NC switch in series with the stop switch.

Enjoy,
DoN.


Like the lathe milling attachment it seems to be a workaround for
those who don't have other machine tools. It provides only hand layout
and punch mark accuracy lengthwise.

Long ago I cast a white metal bolt-down vee block for my drill press
that served the same function. The drill bit holds the block centered
while tightening the bolts. Before the bit breaks through I raised the
bit and work and turned the work onto the flat tops to give clearance
underneath.

-jsw


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Default Rotary Broaching


"Jim Wilkins" wrote in message
news
"Bob La Londe" wrote in message
news
"Jim Wilkins" wrote in message
news
"Bob La Londe" wrote in message


I added the other groups to clutter them up the way they do to us.
--jsw


STOP THAT! LOL. I've been posting metal working questions and projects
to try and get people thinking about our craft again now that the
political **** storm has subsided a little.

The flex you talk about to get an angle has the same affect as a 1 degree
angle with a rotary broaching tool.

The idea with the tool post cross drill part is if its left adjusted in a
tool holder I can just drop it in place and drill a cross hole with no
setup. 10 seconds vs 2 minutes or more to take it off and transfer it to
the mill. I've got three parts I have made that require cross drilling
and might wind up being small scale production parts. One would benefit
from a turning operation afterwards. I can mount a collet in the lathe,
but I am leaning towards putting the 4 jaw on and leaving it in place for
all the one off projects.

Actually the mini lathe CNC conversion may get a 3C collet closer and get
used for some of those parts, but the conversion is only half done and
customers just won't pay me unless I promise to make their parts. LOL.
I am leaning towards also CNCing the small lathe with a 3C collet closer
as well.


Can you lock the spindle while you drill?


Yes, I have a foot brake that cuts power to the motor and stops the spindle.
I figured if standing on the foot bar was to much hassle I could add a bar
or catch to it.


Mine locks by engaging the back gears but there's detectable play in the
gears and bull pin.


Yeah, mine too.


I bought a router motor to mount on the tool post and then realized it
wouldn't handle the range of operations I do to round parts on the mill,
especially cutting large wrench flats, and the setback to allow for a
drill chuck + bit would make the mount too wobbly.


Somethings are just easier on the mill. I admit that. My big mill is
actually pretty good inspite of being 35 years old. I do sometimes CNC mill
round parts with it. They usually come out within .0015 of round if I go
modestly slow. Often better Obviously external hexes are easy on the mill.
I even thought about doing a modified internal hex where the flats of the
driven object ride on internal CAM lobes like a lot of the multi size
wrenches we have started seeing in the last couple decades. My issue with
that was that its really really slow to mill out something like that for an
1/4" hex with the necessary 1/16" end mill.

My plan is to use a straight shank ER collet chuck. It goes in bearings or
bushings in a chuck of steel mounted directly in the tool holder. That's a
pretty solid setup. Its used for high speed spindles. I'm so into the idea
now I plan to build a couple of them. (there goes my efficiency) Atleast
one each with bushings and bearings. Any drive connection flex will be a
near non issue as the chuck itself will be right up against its support
bearing rather than suspended out from it. The big issue will always be the
drill bit flex.



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