Going with recommendations here I recently picked up a Hougen Magnetic
drill with the intent to drill 1"+ diamter holes through 4" square,.
1/4" thick stainless steel(316L), and I'm just now discovering that
there is an MT2 Rotabroach Arbor that one can use to seat the annular
cutters to a lathe tailstock.(I have a Micro-Mark 7 X 14).

That would save a lot of time.(And would have saved money if I were
aware of that sooner).

So I figured I'd ask if anyone here has had any experience using a
Rotabroach(Annular) cutter in a lathe.

Any advice would be appreciated.

Thanks a lot.

Darren Harris
Staten Island, New York.

Assuming your lathe can go real slow, no reason it won't work.

I'd be sure and use LOTS of coolant or cutting oil, go real slow 50 or 100
RPM and keep the pressure up. If you work harden that 316, you'll be sorry.
One advantage of using a standard drill bit would be that's its not as big a
deal to resharpen and try again.

Karl

I have never used a rotabroach in a lathe, but I think you need to
understand some things about Morse tapers.

The Morse taper in your tailstock is held in place by friction.

As your cutting tool approaches the tapers diameter, the tools friction
eventually overcomes the friction of the taper and spins it. This will screw
up your tailstock socket, the taper on the arbor and probably your cutting
tool.

Drill presses solve this problem by using the tang on the end of the taper
to prevent rotation. Lathes (because of the screw that feeds the tailstock
barrel) don't have this feature.

Were you cutting something else, I would say you might get by using light
cutting pressure. Stainless, however, requires a "Low speed, High feed"
approach to cutting. The object being to make each tooth cut deep enough to
get under the work hardened surface left by the preceding tooth. This
strategy requires you to push the cutting tool into the stainless as hard as
you can and not let up on the pressure until you are through.

Bottom line, if you have enough horse power, it will work but you need to
devise an additional strategy to keep the arbor from rotating. Milling a
couple of flats on the arbor, clamping a wrench on the flats and letting the
wrench handle ride on the compound is one approach.

Paul K. Dickman

wrote in message
oups.com...
Going with recommendations here I recently picked up a Hougen Magnetic
drill with the intent to drill 1"+ diamter holes through 4" square,.
1/4" thick stainless steel(316L), and I'm just now discovering that
there is an MT2 Rotabroach Arbor that one can use to seat the annular
cutters to a lathe tailstock.(I have a Micro-Mark 7 X 14).

That would save a lot of time.(And would have saved money if I were
aware of that sooner).

So I figured I'd ask if anyone here has had any experience using a
Rotabroach(Annular) cutter in a lathe.

Any advice would be appreciated.

Thanks a lot.

Darren Harris
Staten Island, New York.

I have done this a lot- works great, and its lots quicker than using a
twist drill.
Like he said- slow speed, lots of coolant.

Thanks everyone.

The lowest speed of the lathe is 100rpms and it is rated at .47hp. I'd
just have to decide on what coolant to use.

As far as the wrench handle riding on the compound. I assume that you
are referring to the compound slide. The Rotabroach cutter has a two
inch max. hole depth, so if I want to use it for thicker material that
may pose a problem.

What about making a special tool holder? Though a Morse Taper #2 tool
holder is on my shopping list, perhaps a tool holder can be made
*specifically* for the cutter itself. That way I can use the power feed
to get the consistency I'd need for drilling Stainless steel.

And I wouldn't have to buy one of those expensive and hard to find MT2
Rotabroach Arbors. It appears that the only place to get them is
abroad: http://cgi.ebay.com/ws/eBayISAPI.dll...tem=7591467410

But if anyone know of another place I'd appreciate a pointer.

Thanks a lot.

Darren Harris
Staten Island, New York.
************************************************** ************************************************** **
Paul K. Dickman wrote:
I have never used a rotabroach in a lathe, but I think you need to
understand some things about Morse tapers.

The Morse taper in your tailstock is held in place by friction.

As your cutting tool approaches the tapers diameter, the tools friction
eventually overcomes the friction of the taper and spins it. This will screw
up your tailstock socket, the taper on the arbor and probably your cutting
tool.

Drill presses solve this problem by using the tang on the end of the taper
to prevent rotation. Lathes (because of the screw that feeds the tailstock
barrel) don't have this feature.

Were you cutting something else, I would say you might get by using light
cutting pressure. Stainless, however, requires a "Low speed, High feed"
approach to cutting. The object being to make each tooth cut deep enough to
get under the work hardened surface left by the preceding tooth. This
strategy requires you to push the cutting tool into the stainless as hard as
you can and not let up on the pressure until you are through.

Bottom line, if you have enough horse power, it will work but you need to
devise an additional strategy to keep the arbor from rotating. Milling a
couple of flats on the arbor, clamping a wrench on the flats and letting the
wrench handle ride on the compound is one approach.

Paul K. Dickman

wrote in message
oups.com...
Going with recommendations here I recently picked up a Hougen Magnetic
drill with the intent to drill 1"+ diamter holes through 4" square,.
1/4" thick stainless steel(316L), and I'm just now discovering that
there is an MT2 Rotabroach Arbor that one can use to seat the annular
cutters to a lathe tailstock.(I have a Micro-Mark 7 X 14).

That would save a lot of time.(And would have saved money if I were
aware of that sooner).

So I figured I'd ask if anyone here has had any experience using a
Rotabroach(Annular) cutter in a lathe.

Any advice would be appreciated.

Thanks a lot.

Darren Harris
Staten Island, New York.

wrote:

Thanks everyone.

The lowest speed of the lathe is 100rpms and it is rated at .47hp. I'd
just have to decide on what coolant to use.

As far as the wrench handle riding on the compound. I assume that you
are referring to the compound slide. The Rotabroach cutter has a two
inch max. hole depth, so if I want to use it for thicker material that
may pose a problem.

What about making a special tool holder? Though a Morse Taper #2 tool
holder is on my shopping list, perhaps a tool holder can be made
*specifically* for the cutter itself. That way I can use the power feed
to get the consistency I'd need for drilling Stainless steel.

And I wouldn't have to buy one of those expensive and hard to find MT2
Rotabroach Arbors. It appears that the only place to get them is
abroad: http://cgi.ebay.com/ws/eBayISAPI.dll...tem=7591467410

But if anyone know of another place I'd appreciate a pointer.

Thanks a lot.

Darren Harris
Staten Island, New York.
************************************************** ************************************************** **
Paul K. Dickman wrote:

I have never used a rotabroach in a lathe, but I think you need to
understand some things about Morse tapers.

The Morse taper in your tailstock is held in place by friction.

As your cutting tool approaches the tapers diameter, the tools friction
eventually overcomes the friction of the taper and spins it. This will screw
up your tailstock socket, the taper on the arbor and probably your cutting
tool.

Drill presses solve this problem by using the tang on the end of the taper
to prevent rotation. Lathes (because of the screw that feeds the tailstock
barrel) don't have this feature.

Were you cutting something else, I would say you might get by using light
cutting pressure. Stainless, however, requires a "Low speed, High feed"
approach to cutting. The object being to make each tooth cut deep enough to
get under the work hardened surface left by the preceding tooth. This
strategy requires you to push the cutting tool into the stainless as hard as
you can and not let up on the pressure until you are through.

Bottom line, if you have enough horse power, it will work but you need to
devise an additional strategy to keep the arbor from rotating. Milling a
couple of flats on the arbor, clamping a wrench on the flats and letting the
wrench handle ride on the compound is one approach.

Paul K. Dickman

wrote in message
groups.com...

Going with recommendations here I recently picked up a Hougen Magnetic
drill with the intent to drill 1"+ diamter holes through 4" square,.
1/4" thick stainless steel(316L), and I'm just now discovering that
there is an MT2 Rotabroach Arbor that one can use to seat the annular
cutters to a lathe tailstock.(I have a Micro-Mark 7 X 14).

That would save a lot of time.(And would have saved money if I were
aware of that sooner).

So I figured I'd ask if anyone here has had any experience using a
Rotabroach(Annular) cutter in a lathe.

Any advice would be appreciated.

Thanks a lot.

Darren Harris
Staten Island, New York.




Why can't you just put them in a boring bar toolholder? You don't have to bear
on the flats. Or get an Aloris toolholder that takes 5C collets and hold them
with a collet. I don't like the tailstock idea, I like the toolholder idea.

GWE

wrote:

Going with recommendations here I recently picked up a Hougen Magnetic
drill with the intent to drill 1"+ diamter holes through 4" square,.
1/4" thick stainless steel(316L), and I'm just now discovering that
there is an MT2 Rotabroach Arbor that one can use to seat the annular
cutters to a lathe tailstock.(I have a Micro-Mark 7 X 14).

That would save a lot of time.(And would have saved money if I were
aware of that sooner).

So I figured I'd ask if anyone here has had any experience using a
Rotabroach(Annular) cutter in a lathe.

Any advice would be appreciated.

Thanks a lot.

Darren Harris
Staten Island, New York.

I can't see you saving time by using your lathe, the motor
is a toy by comparison with the drill.
You'd be better off setting the drill up on a steel plate
& clamping your ss plates to it. If your plates are of uniform
length & width, simple stops would speed it up even further.

Tom

I would use the mag drill as well- the lathe I use the rotobraoch in is
7hp.
..47 hp changes things a bit.

We drill holes with the mag drill in non magnetic stuff all the time-
we have a piece of 1/2" x 4"mild steel flat bar, about 3 feet long, and
bolt or clamp it to a workbench, with spacers under it so it is above
the material we are drilling. The mag drill sticks to the flat bar, but
drills what ever we put under the flat bar- stainless, aluminum, you
name it.

Tom wrote:
wrote:
Going with recommendations here I recently picked up a Hougen Magnetic
drill with the intent to drill 1"+ diamter holes through 4" square,.
1/4" thick stainless steel(316L), and I'm just now discovering that
there is an MT2 Rotabroach Arbor that one can use to seat the annular
cutters to a lathe tailstock.(I have a Micro-Mark 7 X 14).
....
I can't see you saving time by using your lathe, the motor
is a toy by comparison with the drill.
You'd be better off setting the drill up on a steel plate
& clamping your ss plates to it. If your plates are of uniform
length & width, simple stops would speed it up even further.

I agree with Tom's comments.

I think you'll need to do finish boring, anyway, after
drilling through with the lathe. If you're making very
many parts, it will be faster having a rough drilling
setup on one machine (the Rotabroach) and boring on the
other (the 7x14).

Re the 7x14's 100 rpm min speed, for 30 rpm mods see
http://www.mini-lathe.com/Mini_lathe...htm#slow_speed
I don't know if that will apply to your lathe - the page says
newer machines don't need the mod - but I'd look inside the
speed control anyway and try some adjustments.

The headstock probably is MT3, vs the MT2 tailstock taper.
For heavy drilling on the 7x14, consider using a rotating,
MT3-taper drill bit, with the work fastened to the compound.
-jiw

James Waldby wrote:
Tom wrote:
wrote:
Going with recommendations here I recently picked up a Hougen Magnetic
drill with the intent to drill 1"+ diamter holes through 4" square,.
1/4" thick stainless steel(316L), and I'm just now discovering that
there is an MT2 Rotabroach Arbor that one can use to seat the annular
cutters to a lathe tailstock.(I have a Micro-Mark 7 X 14).
...
I can't see you saving time by using your lathe, the motor
is a toy by comparison with the drill.
You'd be better off setting the drill up on a steel plate
& clamping your ss plates to it. If your plates are of uniform
length & width, simple stops would speed it up even further.

I agree with Tom's comments.

I think you'll need to do finish boring, anyway, after
drilling through with the lathe. If you're making very
many parts, it will be faster having a rough drilling
setup on one machine (the Rotabroach) and boring on the
other (the 7x14).

Re the 7x14's 100 rpm min speed, for 30 rpm mods see
http://www.mini-lathe.com/Mini_lathe...htm#slow_speed
I don't know if that will apply to your lathe - the page says
newer machines don't need the mod - but I'd look inside the
speed control anyway and try some adjustments.

The headstock probably is MT3, vs the MT2 tailstock taper.
For heavy drilling on the 7x14, consider using a rotating,
MT3-taper drill bit, with the work fastened to the compound.
-jiw

The maximum diameter hole I can drill using my Rotabroach is 1-3/8",
but I'll need to make holes that are about 2-3/4" in diameter. and
accurately centered holes at that.

Even after I build a set-up for the Rotabroach(which would include a
positioning jig for the 4-1/2" square plates I'll be drilling), I can't
see how it would be faster than on the lathe. And if I have to do
finish boring anyway, then that makes the lathe even more convenient,
becausse the work would be already in place.

So I guess the big issue is if a 1/2hp motor strong enough to deal with
1/16" thick stainless steel.

Thanks.

Darren Harris
Staten Island, New York.

wrote:

James Waldby wrote:
Tom wrote:
wrote:
Going with recommendations here I recently picked up a Hougen Magnetic
drill with the intent to drill 1"+ diamter holes through 4" square,.
1/4" thick stainless steel(316L), and I'm just now discovering that
there is an MT2 Rotabroach Arbor that one can use to seat the annular
cutters to a lathe tailstock.(I have a Micro-Mark 7 X 14).
...
I can't see you saving time by using your lathe, the motor
is a toy by comparison with the drill.
You'd be better off setting the drill up on a steel plate
& clamping your ss plates to it. If your plates are of uniform
length & width, simple stops would speed it up even further.

I agree with Tom's comments.

I think you'll need to do finish boring, anyway, after
drilling through with the lathe. If you're making very
many parts, it will be faster having a rough drilling
setup on one machine (the Rotabroach) and boring on the
other (the 7x14).

Re the 7x14's 100 rpm min speed, for 30 rpm mods see
http://www.mini-lathe.com/Mini_lathe...htm#slow_speed
I don't know if that will apply to your lathe - the page says
newer machines don't need the mod - but I'd look inside the
speed control anyway and try some adjustments.

The headstock probably is MT3, vs the MT2 tailstock taper.
For heavy drilling on the 7x14, consider using a rotating,
MT3-taper drill bit, with the work fastened to the compound.
-jiw

The maximum diameter hole I can drill using my Rotabroach is 1-3/8",
but I'll need to make holes that are about 2-3/4" in diameter. and
accurately centered holes at that.

Even after I build a set-up for the Rotabroach(which would include a
positioning jig for the 4-1/2" square plates I'll be drilling), I can't
see how it would be faster than on the lathe. And if I have to do
finish boring anyway, then that makes the lathe even more convenient,
becausse the work would be already in place.

So I guess the big issue is if a 1/2hp motor strong enough to deal with
1/16" thick stainless steel.

Thanks.

Darren Harris
Staten Island, New York.

Hang on a minute, that doesn't relate to your original post above,
you've gone and changed all parameters of what you want to achieve.

Tom

wrote:

Tom wrote:
wrote:

James Waldby wrote:
Tom wrote:
wrote:
Going with recommendations here I recently picked up a Hougen Magnetic
drill with the intent to drill 1"+ diamter holes through 4" square,.
1/4" thick stainless steel(316L), and I'm just now discovering that
there is an MT2 Rotabroach Arbor that one can use to seat the annular
cutters to a lathe tailstock.(I have a Micro-Mark 7 X 14).
...
I can't see you saving time by using your lathe, the motor
is a toy by comparison with the drill.
You'd be better off setting the drill up on a steel plate
& clamping your ss plates to it. If your plates are of uniform
length & width, simple stops would speed it up even further.

I agree with Tom's comments.

I think you'll need to do finish boring, anyway, after
drilling through with the lathe. If you're making very
many parts, it will be faster having a rough drilling
setup on one machine (the Rotabroach) and boring on the
other (the 7x14).

Re the 7x14's 100 rpm min speed, for 30 rpm mods see
http://www.mini-lathe.com/Mini_lathe...htm#slow_speed
I don't know if that will apply to your lathe - the page says
newer machines don't need the mod - but I'd look inside the
speed control anyway and try some adjustments.

The headstock probably is MT3, vs the MT2 tailstock taper.
For heavy drilling on the 7x14, consider using a rotating,
MT3-taper drill bit, with the work fastened to the compound.
-jiw

The maximum diameter hole I can drill using my Rotabroach is 1-3/8",
but I'll need to make holes that are about 2-3/4" in diameter. and
accurately centered holes at that.

Even after I build a set-up for the Rotabroach(which would include a
positioning jig for the 4-1/2" square plates I'll be drilling), I can't
see how it would be faster than on the lathe. And if I have to do
finish boring anyway, then that makes the lathe even more convenient,
becausse the work would be already in place.

So I guess the big issue is if a 1/2hp motor strong enough to deal with
1/16" thick stainless steel.

Thanks.

Darren Harris
Staten Island, New York.

Hang on a minute, that doesn't relate to your original post above,
you've gone and changed all parameters of what you want to achieve.

Tom

How do you figure?

I mentioned 1/16" thick stainless steel which is actually part of the
same project. I still need to drill the 1/4" thick S.S. But the 1/16"
thick pieces are 4-1/2" square, whereas the 1/4" thick pieces are 4"
square.

I think a 5" chuck should hold both sizes.

Thanks.

Darren Harris
Staten Island, New York.

Where?