Hello all,

I am getting closer to doing the job that involves clamping open boxes,
DB 9 holes, etc. There will be some round holes, and my first thought
was a boring head. That would be overkill in precision capability, but
I'd like to learn how to use one, so it seemed reasonable.

The acrylic and facing problems came along, and a flycutter is
officially in transit (3/4 shanks). Can I (ab)use that as a hole saw?
Is it safe? Should I clamp the waste to avoid catching on the bit?

I still plan to get a boring head, but would rather wait a while to let
my wallet cool off a little. Another reason to wait on the boring head
is that I am not convinced I will take to flycutter. If it gives me the
creeps for facing, I might prefer a face mill to a boring head as my
next purchase.

Bill

Bill Schwab wrote in message
nk.net...
Hello all,

I am getting closer to doing the job that involves clamping open boxes,
DB 9 holes, etc. There will be some round holes, and my first thought
was a boring head. That would be overkill in precision capability, but
I'd like to learn how to use one, so it seemed reasonable.

The acrylic and facing problems came along, and a flycutter is
officially in transit (3/4 shanks). Can I (ab)use that as a hole saw?
Is it safe? Should I clamp the waste to avoid catching on the bit?

I still plan to get a boring head, but would rather wait a while to let
my wallet cool off a little. Another reason to wait on the boring head
is that I am not convinced I will take to flycutter. If it gives me the
creeps for facing, I might prefer a face mill to a boring head as my
next purchase.

It's very easy to make your own adjustable boring bars. A length of 3/4" or
bigger steel bar, drill a 5/16" or 3/8" cross hole at one end and drill and
tap for a grub screw to hold the cutting tool that goes in the cross hole.
If you drill the cross hole at 45 degrees to the shank instead of 90 degrees
to it then the non cutting end of the tool sticks up out of the way of the
workpiece i.e. you can use longer tools with more diametrical adjustment on
them. Cutting tools can be ground up from old milling cutters, drill bits or
use carbide tipped tools on round shanks which are cheaply available from
engineering suppliers.

Start your hole with the biggest drill bit or milling cutter to hand and
then enlarge it as required with the boring bar.

I've made loads over the years in various sizes to bore from 3/4" up to 4"
or more. Whatever size bar I use for the shank I generally turn a 3/4" end
on it and run it in an R8 collet.
--
Dave Baker

"Bill Schwab" wrote in message
nk.net...
Hello all,

I am getting closer to doing the job that involves clamping open boxes,
DB 9 holes, etc. There will be some round holes, and my first thought
was a boring head. That would be overkill in precision capability, but
I'd like to learn how to use one, so it seemed reasonable.

The acrylic and facing problems came along, and a flycutter is
officially in transit (3/4 shanks). Can I (ab)use that as a hole saw?
Is it safe? Should I clamp the waste to avoid catching on the bit?

I still plan to get a boring head, but would rather wait a while to let
my wallet cool off a little. Another reason to wait on the boring head
is that I am not convinced I will take to flycutter. If it gives me the
creeps for facing, I might prefer a face mill to a boring head as my
next purchase.

Bill

Depending on the construction of the fly cutter, you may not be able to
install a tool such that it will serve as a hole saw. Fly cutters are
generally intended for tools that somewhat parallel the face being machined.
If you have one that permits the tool to be installed at a right angle,
parallel to the spindle, it might serve your needs, but you may not have the
option to select the diameter you desire. An operation such as that is
called trepanning, where you remove a core piece without reducing it to
chips. It can be accomplished easier with a boring head, but even that can
be challenging---especially when machining tough materials like the majority
of the 300 series stainless alloys or the chrome moly series.

Regards clamping the piece that comes loose---it's usually a good idea to
use a slightly angled tool, so the cut will be quite thin at one edge, the
outer one preferred, so you don't leave a lot in the hole. When it's about
to break through, you stop cutting and remove it manually. By setting a
quill stop, that's easy. Often, when you break through, the core piece will
shift enough to bind and break the tool, so it's not a good way to get the
piece out. If stop cutting at the right point, it's real easy to remove
the core with a light tap of a hammer on one side. Needless to say, you
should be on parallels, not working off the table face. Be mindful of the
tapered edge remaining--it can be quite sharp if you stop at the right
place.

Using a boring head for fly cutting isn't likely to work much better than
using a fly cutter for trepanning. For one, it may not run smoothly if you
are running at reasonable speed. The advantage of fly cutting is the
ability to run fast, so your single point tool will permit a faster feed
rate. As mentioned in a different thread, you're limited by the tool's
ability to cut at the limits of the material, but some materials have
literally no restrictions. Aluminum, for example. If speed isn't a
concern, you might get away with the boring head, but I'd advise keeping the
slide locked to avoid movement sideways, under cutting pressure. Surface
finish would likely suffer otherwise.

If you don't have a boring head now, and you're debating between a face mill
and the boring head, that should be a no-brainer. Buy the boring head.
You can face mill with a fly cutter, which can be shop made with ease, or
even end mills, A face mill won't bore holes, so running without the
boring head would be the greater restriction.

Harold

Harold,

Using a boring head for fly cutting isn't likely to work much better than
using a fly cutter for trepanning. For one, it may not run smoothly if you
are running at reasonable speed. The advantage of fly cutting is the
ability to run fast, so your single point tool will permit a faster feed
rate. As mentioned in a different thread, you're limited by the tool's
ability to cut at the limits of the material, but some materials have
literally no restrictions. Aluminum, for example. If speed isn't a
concern, you might get away with the boring head, but I'd advise keeping the
slide locked to avoid movement sideways, under cutting pressure. Surface
finish would likely suffer otherwise.

I need to read this more and ask some more questions. However, my
question is not so much about using a boring head for flycutting, as it
is using either a flycutter or boring head to make large round holes in
thin steel and some truly awful gunk passing as metal: when cut, it
reduces to a mix of what seems like cast iron dust and razor sharp oat
meal - terrible stuff.

A hole saw might be the right answer, but I have relatively few such
holes to make, and have more faith in a carbide bit than the hole saws
at Lowe's.

All of that said, I might see the problem with the flycutter for the
job. I'll think it through some more and post again once I can explain
it. Boring bars can be had cheaply, and given that I don't care about
precision in diameter, I might do well to rig my own holder as suggested
elsewhere. Also, I can afford an import boring set; I was simply hoping
to put it off a while given the additional measuring tools I just
bought. No worries about the flycutter; it was cheap and I will
certainly get use out of it, so it was a great place to start for facing
if nothing else.


If you don't have a boring head now, and you're debating between a face mill
and the boring head, that should be a no-brainer. Buy the boring head.
You can face mill with a fly cutter, which can be shop made with ease, or
even end mills, A face mill won't bore holes, so running without the
boring head would be the greater restriction.

I bought a $27 (for about half price it turns out!) flycutter set and
some bits; they should arrive early next week. I reserve the right to
be scared silly of it (always thinking of "Lefty" and the blurry area),
in which case I might opt for the face mill. If the flycutter and I get
along (seems likely), then I agree the boring head would be next.

Thanks!

Bill

"Harold and Susan Vordos" wrote in message
...
An operation such as that is
called trepanning, where you remove a core piece without reducing it to
chips. It can be accomplished easier with a boring head, but even that
can

Harold,

Are there bits commonly available for trepanning in a boring head? If I
wanted to make one, how would it be shaped? I'd start with round stock so
that it could be mounted in the head, yes?

Regards,

Peter

Bill Schwab wrote:

I am getting closer to doing the job that involves clamping open boxes,
DB 9 holes, etc. There will be some round holes, and my first thought
was a boring head. That would be overkill in precision capability, but
I'd like to learn how to use one, so it seemed reasonable.
[...]

Non-standard sized large round holes?
Thin metal (steel or aluminum?) boxes?
Using a drillpress or a mill or something else?

What's the material? I'd use a punch press for the round and
db-9 holes, but d style punches are expensive.

Bill Schwab wrote:
Hello all,

I am getting closer to doing the job that involves clamping open boxes,
DB 9 holes, etc. There will be some round holes, and my first thought
was a boring head. That would be overkill in precision capability, but
I'd like to learn how to use one, so it seemed reasonable.

The acrylic and facing problems came along, and a flycutter is
officially in transit (3/4 shanks). Can I (ab)use that as a hole saw?
Is it safe? Should I clamp the waste to avoid catching on the bit?

I'm a big fan of punching sheet metal as opposed to drilling it. - GWE

Dave wrote:
Bill Schwab wrote:

I am getting closer to doing the job that involves clamping open boxes,
DB 9 holes, etc. There will be some round holes, and my first thought
was a boring head. That would be overkill in precision capability, but
I'd like to learn how to use one, so it seemed reasonable.
[...]


Non-standard sized large round holes?
Thin metal (steel or aluminum?) boxes?
Using a drillpress or a mill or something else?

On Thu, 26 Jan 2006 17:49:12 GMT, Bill Schwab
wrote:

Hello all,

I am getting closer to doing the job that involves clamping open boxes,
DB 9 holes, etc. There will be some round holes, and my first thought
was a boring head. That would be overkill in precision capability, but
I'd like to learn how to use one, so it seemed reasonable.

The acrylic and facing problems came along, and a flycutter is
officially in transit (3/4 shanks). Can I (ab)use that as a hole saw?
Is it safe? Should I clamp the waste to avoid catching on the bit?

I still plan to get a boring head, but would rather wait a while to let
my wallet cool off a little. Another reason to wait on the boring head
is that I am not convinced I will take to flycutter. If it gives me the
creeps for facing, I might prefer a face mill to a boring head as my
next purchase.

Bill


Hey Bill,

Fly-cutters are normally used to remove a light or relatively thin cut
of constant thickness across a flatted surface, controlled by a lead
screw to apply relatively constant positive pressure in the feed
direction(s), and the contact of the tool to the work is not large.

When you try to use the same fly-cutter to "bore" instead, it goes
very easily and rapidly for the first few thou, then the cutter starts
to cut over a greater and greater fever increasing face area as it
plunges. Doesn't work really well, and the "feed" control is not as
constant or steady as you'd like. ie: doesn't work worth a sh$t, and
"break-through" can be pretty exciting if you get that far, and edge
finish sucks.

A proper hole saw has lots and lots of teeth, so the chip load and cut
in Inches Per Revolution can be quite large, and the "surface" being
cut never changes as it "bores in", and break-through is both
controlled and even, and relatively good finish.

Now-a-days, even good (USA) quality hole saws for metal are not too
expensive, and very available. Maybe you could just borrow what you
need from a buddy?

Of course, there is always the old stand-by of edge drilling and
filing. Even edge drilling, knock out, and then fly-cutter boring to
size and finish. Works even better if you can clamp the metal in
between two sacrificial wood pieces, and gives you something to both
clamp to for work-holding and protects the work at the same time.

My two-bits worth.

Brian Lawson,
Bothwell, Ontario.

Greenlee punches can get expensive but they make clean holes. For round
holes the other option might be one of those multi-step hole cutters. I
don't like the flycutter/boring head idea.

Grant Erwin wrote:
I'm a big fan of punching sheet metal as opposed to drilling it. - GWE

Dave wrote:

Non-standard sized large round holes?
Thin metal (steel or aluminum?) boxes?
Using a drillpress or a mill or something else?

Bill Schwab wrote:

I am getting closer to doing the job that involves clamping open boxes,
DB 9 holes, etc. There will be some round holes, and my first thought
was a boring head. That would be overkill in precision capability, but
I'd like to learn how to use one, so it seemed reasonable.
[...]

If you are talking about enlarging an existing hole, it will work fine.
You may have to make multiple passes, re-setting the bit after each
pass. You will have to measure very carefully on the last few passes
if you need any real accuracy. All of which will take time.

The boring head, of course, will be a lot faster as you will just crank
out the slide after each pass.

If you don't have the central hole to start with, it's a lot more
difficult. You could grind up a trepanning cutter for a fly cutter
head, but it would be a lot of work to get the edges right for both
inside and outside cutting and it would only work for very thin stuff.
In the boring head you can hold the bit end on to the work, and can
therefore grind it a lot more effectively.

All of which is to say that you can often make do with what you have,
but that it won't necessarily be easy.

John Martin

"Peter Grey" wrote in message
.net...



"Harold and Susan Vordos" wrote in message
...
An operation such as that is
called trepanning, where you remove a core piece without reducing it to
chips. It can be accomplished easier with a boring head, but even that
can

Harold,

Are there bits commonly available for trepanning in a boring head? If I
wanted to make one, how would it be shaped? I'd start with round stock so
that it could be mounted in the head, yes?

Regards,

Peter


I was faced with this challenge years ago, when I built a gasketed filter
press for my gold refining operation. I had to cut about two dozen
washers from an unknown (austenitic) stainless material, roughly 3/16"
thick. Finished washers were roughly 3" diameter, with a bore of 1-1/2" as
I recall. The press is long gone now, having been sold along with the
refining business I sold when I retired, so I may be off on the sizes. No
matter, the principle remains unchanged.

I used a 3/8" HSS end mill shank, on which I ground what resembles a parting
tool for a lathe, with a slight cant to the cutting edge, so it would leave
a very thin section on one side of the part being removed (the washer), so
there was little material to machine afterwards. You stop cutting before
breaking through to avoid the tool binding on the part being removed from
the stock, and the thin section makes it easy to get the piece out. The
problems of cutting stainless in this fashion were difficult to overcome. I
ended up buying a BoeLube setup, which solved all the machining problems.
Sulfur oil alone wasn't adequate. That would likely not be true on other
materials.

One runs the boring head very slowly, using the finest feed. With a chip
breaker properly ground in the tool, it works great, but would certainly
become a serious challenge if the cut was very deep. There's considerable
chatter, due in part to the rather flimsy setup. You can often eliminate
the chatter with proper speed and feed selection, however.

One of the things you have to address is considerable side clearance on the
tool, where it must clear the radius of the cut on the outside edge of the
circle. The tool looks somewhat odd, but works fine. Should you decide
to try it, remember, the material you select for your tool will leave the
tool edge ahead of center unless you reduce it at the point of the cut to
the centerline of the tool. That the cutting edge is on center, or not,
has a serious effect on how the tool sees the material, and the relief
angles. Does this make sense to you? If not, lets talk. It's important
that you understand it well.

Harold

"Harold and Susan Vordos" wrote in message

One of the things you have to address is considerable side clearance on
the
tool, where it must clear the radius of the cut on the outside edge of the
circle. The tool looks somewhat odd, but works fine. Should you
decide
to try it, remember, the material you select for your tool will leave the
tool edge ahead of center unless you reduce it at the point of the cut to
the centerline of the tool. That the cutting edge is on center, or not,
has a serious effect on how the tool sees the material, and the relief
angles. Does this make sense to you? If not, lets talk. It's important
that you understand it well.



I think what you're saying is that if the entire cutting edge is to be
square to the cut, the tool itself may need to be curved, and the inside and
outside cutting edges will be on the centerline, making the edge look
"slanted" in relation to the rest of the tool (I suppose if the tool were
short enough that it wouldn't need to be curved, then one would get more
chatter...?). Unlike a bit where the cut is straight, although each relief
may look different, when measured in reference to its own cutting edge it'll
be the same as the other. Am I understanding this or have a disappeared
over the horizon on a tangent?

I just finished a job where a setup like this would have made sense. I was
drilling 2.250" holes in .250 6061 plate and then finishing them with a
boring head. I did 12 of them. The hole saw was pretty sloppy, and
although it wasn't all that important that the holes be of similar size, the
diameter of the holes made by the hole saw varied quite a bit. The goal was
to have holes with a decent finish and it would have satisfied my sense of
propriety if the first holes were accurate and finished well enough so that
passes with the boring bar were unnecessary. It's probable that I'll end up
performing this operation again, so I'm interested in how to do it quickly
and cleanly.

As always, thanks.

Peter

"Peter Grey" wrote in message
nk.net...



"Harold and Susan Vordos" wrote in message

One of the things you have to address is considerable side clearance on
the
tool, where it must clear the radius of the cut on the outside edge of
the
circle. The tool looks somewhat odd, but works fine. Should you
decide
to try it, remember, the material you select for your tool will leave
the
tool edge ahead of center unless you reduce it at the point of the cut
to
the centerline of the tool. That the cutting edge is on center, or
not,
has a serious effect on how the tool sees the material, and the relief
angles. Does this make sense to you? If not, lets talk. It's
important
that you understand it well.



I think what you're saying is that if the entire cutting edge is to be
square to the cut, the tool itself may need to be curved, and the inside
and
outside cutting edges will be on the centerline, making the edge look
"slanted" in relation to the rest of the tool (I suppose if the tool were
short enough that it wouldn't need to be curved, then one would get more
chatter...?). Unlike a bit where the cut is straight, although each
relief
may look different, when measured in reference to its own cutting edge
it'll
be the same as the other. Am I understanding this or have a disappeared
over the horizon on a tangent?

Sigh! Trust me to say something in such a way that I use up all the words I
know, but fail to hit on the point at hand.

OK----lets try it this way:

Boring heads (at least the ones I have) are made such that the centerline of
the cutting tool is the centerline of the head. For boring, that's exactly
where you want the tool to fall, due to the position of your boring tool.
For trepanning, that isn't the case. That means that when you make a tool
such as I described, the actual cutting edge will be in front of center
unless you grind away half of the shank you use to grind your tool. Does
that make sense? You'd grind what is a D configuration, with the
straight side of the D the cutting edge, which will parallel the slide of
the boring head. This tool, when installed in the boring head, would have
the cutting edge on the centerline of the head. You then grind away the
sides to establish the width of the tool, grinding greater relief on what
will form the outside of the circle you'll generate, so the tool clears the
circular slot it generates, and much less on the opposite side, for the same
reason. The tool should also have back clearance, so as it goes deeper
into the cut, it doesn't drag on the portion behind the cutting edge. In
simple terms, the point of contact, the cutting edge, will be the broadest
portion of the tool, with clearance in all directions ground on the tool.
Hope that makes it somewhat more clear. It's easy to do, just hard for me
to describe. One more thing to remember. Make the tool cut in a clockwise
direction, so you don't unscrew the boring head from its shank. The tool
you'll grind will be handed because one side has considerably more relief
than the other.


I just finished a job where a setup like this would have made sense. I
was
drilling 2.250" holes in .250 6061 plate and then finishing them with a
boring head. I did 12 of them. The hole saw was pretty sloppy, and
although it wasn't all that important that the holes be of similar size,
the
diameter of the holes made by the hole saw varied quite a bit. The goal
was
to have holes with a decent finish and it would have satisfied my sense of
propriety if the first holes were accurate and finished well enough so
that
passes with the boring bar were unnecessary. It's probable that I'll end
up
performing this operation again, so I'm interested in how to do it quickly
and cleanly.

I fully understand about the hole saw. They're a dreadful tool, although
they are good for opening a large hole. Like you, I've experienced various
sizes from the same saw, and am never pleased with the quality of the hole.

A note to remember. When you open a hole by the means I've described, it
may not come out really pretty. You'll have some trouble with chip flow if
your tool isn't perfect, and the cut well lubricated, so the size could vary
to some degree ( a few thou) from hole to hole, depending on if you have
chip problems, or not. Finish would be a reflection of chip flow and
lubrication. Bottom line-----if you want all the holes to have sharp,
square corners, with a nice finish, treat the trepanning operation in
keeping with what it really is-----a roughing operation. Shoot for a hole
that is somewhat undersized----maybe .020/.040", depending on how well it
goes. That will allow for a finish pass with a boring head after the
fact, providing a uniform hole and finish. That's called good workmanship,
and should be practiced unless the hole just plain doesn't matter.


As always, thanks.

Peter

You're welcome, Peter. Hope some of this helps. All of it has been used
with success, so if you have any particular problems, let me know. Could be
I've been through the same thing and may recall how I got around it.

Harold

"Harold and Susan Vordos" wrote in message
...
Sigh! Trust me to say something in such a way that I use up all the words
I
know, but fail to hit on the point at hand.

OK----lets try it this way:

Boring heads (at least the ones I have) are made such that the centerline
of
the cutting tool is the centerline of the head. For boring, that's
exactly
where you want the tool to fall, due to the position of your boring tool.
For trepanning, that isn't the case. That means that when you make a tool
such as I described, the actual cutting edge will be in front of center
unless you grind away half of the shank you use to grind your tool. Does
that make sense? You'd grind what is a D configuration, with the
straight side of the D the cutting edge, which will parallel the slide of
the boring head. This tool, when installed in the boring head, would have
the cutting edge on the centerline of the head. You then grind away the
sides to establish the width of the tool, grinding greater relief on what
will form the outside of the circle you'll generate, so the tool clears
the
circular slot it generates, and much less on the opposite side, for the
same
reason. The tool should also have back clearance, so as it goes deeper
into the cut, it doesn't drag on the portion behind the cutting edge.
In
simple terms, the point of contact, the cutting edge, will be the broadest
portion of the tool, with clearance in all directions ground on the tool.
Hope that makes it somewhat more clear. It's easy to do, just hard for
me
to describe. One more thing to remember. Make the tool cut in a
clockwise
direction, so you don't unscrew the boring head from its shank. The tool
you'll grind will be handed because one side has considerably more relief
than the other.

Yes. I understand your point now. That makes sense, as does the rest of
your post.

Regards,

Peter.

Dave,

I am getting closer to doing the job that involves clamping open boxes,
DB 9 holes, etc. There will be some round holes, and my first thought
was a boring head. That would be overkill in precision capability, but
I'd like to learn how to use one, so it seemed reasonable.
[...]


Non-standard sized large round holes?
Thin metal (steel or aluminum?) boxes?
Using a drillpress or a mill or something else?

Sorry - large holes, not necessarily non-standard, thin metal, one
steel, one a mix of various metalic substances. If I really get lucky,
I might be able to negotiate the steel out of existence, leaving just
the dusty/grity/disgusting metal that must be penetrated. That stuff
would probably yield to the cheapest of hole saws, assuming I can get
one of a suitable size (likely).

Bill

John,

If you are talking about enlarging an existing hole, it will work fine.
You may have to make multiple passes, re-setting the bit after each
pass. You will have to measure very carefully on the last few passes
if you need any real accuracy. All of which will take time.

Accuracy is not a big deal, which makes the discovery of an appropriate
hole saw reasonably likely. Hole saws are getting fairly good reviews
in this thread, which increases my confidence in them.


The boring head, of course, will be a lot faster as you will just crank
out the slide after each pass.

Dumb question: when you say a "pass", are you referring to: (1) set the
bar at a given radius; (2) quill down to contact; (3) slow feed until
breakthrough? Is the bar parallel or perpendicular to the spindle?
Does it matter?


If you don't have the central hole to start with, it's a lot more
difficult. You could grind up a trepanning cutter for a fly cutter
head, but it would be a lot of work to get the edges right for both
inside and outside cutting and it would only work for very thin stuff.
In the boring head you can hold the bit end on to the work, and can
therefore grind it a lot more effectively.

The stock is thin, so I have that going for me. I'll try to do some
reading on trepanning and then take another crack at this and Harold's
answer. Correct me if I'm wrong, but I think you guys are saying pretty
much the same thing.

Thanks,

Bill

Bill Schwab wrote:
John,

If you are talking about enlarging an existing hole, it will work fine.
You may have to make multiple passes, re-setting the bit after each
pass. You will have to measure very carefully on the last few passes
if you need any real accuracy. All of which will take time.

Accuracy is not a big deal, which makes the discovery of an appropriate
hole saw reasonably likely. Hole saws are getting fairly good reviews
in this thread, which increases my confidence in them.


The boring head, of course, will be a lot faster as you will just crank
out the slide after each pass.

Dumb question: when you say a "pass", are you referring to: (1) set the
bar at a given radius; (2) quill down to contact; (3) slow feed until
breakthrough? Is the bar parallel or perpendicular to the spindle?
Does it matter?


If you don't have the central hole to start with, it's a lot more
difficult. You could grind up a trepanning cutter for a fly cutter
head, but it would be a lot of work to get the edges right for both
inside and outside cutting and it would only work for very thin stuff.
In the boring head you can hold the bit end on to the work, and can
therefore grind it a lot more effectively.

The stock is thin, so I have that going for me. I'll try to do some
reading on trepanning and then take another crack at this and Harold's
answer. Correct me if I'm wrong, but I think you guys are saying pretty
much the same thing.

Thanks,

Bill

The hole saw is the way to go. If you need a better finish or a
different size, finish up with the fly cutter or boring head.

Your interpretation of "one pass" is correct. And the boring bar or
bit can be held in either orientation in the boring head - it all
depends on the size of the head and the size of the boring bar. For
smaller holes it will have to be parallel to the spindle.

Trepanning can be a difficult operation. In a way, it's like parting,
because both sides and the end of the tool are in contact with the
work. Which means no side rake. Since it's not as rigid as a typical
parting setup, back rake can also be a problem. And then, as you'll be
cutting a curve, you need different clearance angles on each side of
the bit.

I suggested that you could grind up a trepanning bit for a flycutter if
you lacked a boring head. That bit would have to have a tit on the
side to do the cutting - sort of like a bit that you might grind up to
cut a small internal thread. Maybe an Acme or square thread.

John Martin

According to Bill Schwab :

[ ... ]

Sorry - large holes, not necessarily non-standard, thin metal, one
steel, one a mix of various metalic substances. If I really get lucky,
I might be able to negotiate the steel out of existence, leaving just
the dusty/grity/disgusting metal that must be penetrated. That stuff
would probably yield to the cheapest of hole saws, assuming I can get
one of a suitable size (likely).

One thing to consider is that hole saws tend to make rather ugly
holes in metal -- at least based on use in a drill press.

What I always like for aluminum or steel panels is a Greenlee
Chassis punch -- but that can be *very* expensive.

And if you're working with the die-cast aluminum zinc boxes, I
think that the stresses of a chassis punch might lead to cracking.

What I've found to do a nice job of making clean holes in sheet
metal on a drill press is something called a "Roto-Bor". I have two
sets, covering a size range from about 1/4" to 1". They have a
spring-loaded pilot which fits into a center punch mark or a center
drill hole to precisely locate the cutter.

The cutter has two flutes for the smaller sizes, or four for the
larger sizes.

The major disadvantage of this is that as far as I can
determine, these are no longer made.

Note that using a boring head on the mill will not eliminate the
need for a hole to start with -- and the bigger the hole the better,
because a boring head is rather a rather slow way of removing material.
So, a hole saw to produce an undersized hole is a good thing to use
*with* the boring head.

Enjoy,
DoN.

--
Email: | 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 ---

"DoN. Nichols" wrote in message
ervers.com...
snip----

Note that using a boring head on the mill will not eliminate the
need for a hole to start with -- and the bigger the hole the better,
because a boring head is rather a rather slow way of removing material.
So, a hole saw to produce an undersized hole is a good thing to use
*with* the boring head.

Enjoy,
DoN.


You missed the part about trepanning, DoN. I've done it with outstanding
success. You can, indeed, create large holes without having a starter hole.
That was the point of our discussion above.

Harold

"Harold and Susan Vordos" wrote in message

You're welcome, Peter. Hope some of this helps. All of it has been used
with success, so if you have any particular problems, let me know. Could
be
I've been through the same thing and may recall how I got around it.

I had another thought/realization. One ouwld be able to use a higher
spindle speed with a boring/trepanning setup than with a hole saw (chatter
being a gating factor obviously), yes? This would be an advantage to those
of us with a minimum spindle speed of 330RPM... A VFD is looking pretty
good at the moment.

Peter

"Peter Grey" wrote in message
ink.net...



"Harold and Susan Vordos" wrote in message

You're welcome, Peter. Hope some of this helps. All of it has been
used
with success, so if you have any particular problems, let me know. Could
be
I've been through the same thing and may recall how I got around it.

I had another thought/realization. One ouwld be able to use a higher
spindle speed with a boring/trepanning setup than with a hole saw (chatter
being a gating factor obviously), yes? This would be an advantage to
those
of us with a minimum spindle speed of 330RPM... A VFD is looking pretty
good at the moment.

Peter


By nature of the design of the trepanning tool for this type of application,
the tool tends to be rather flimsy, which is part of the problem, so you are
likely to be well restricted by chatter. If not, so much the better. In
aluminum you should be able to achieve a good speed, so long as you can keep
the cut well lubed. That, or machine 2024, which is quite forgiving of dry
machining. Remember, my project was one of the worst case scenarios, a
tough grade of stainless, so I was very limited as to RPM. You may have
good fortune and not be so restricted.

Love to hear how it turns out when you give it a go. Can we count on a
report?

Harold

According to Harold and Susan Vordos :

"DoN. Nichols" wrote in message
ervers.com...
snip----

Note that using a boring head on the mill will not eliminate the
need for a hole to start with -- and the bigger the hole the better,
because a boring head is rather a rather slow way of removing material.
So, a hole saw to produce an undersized hole is a good thing to use
*with* the boring head.

You missed the part about trepanning, DoN. I've done it with outstanding
success. You can, indeed, create large holes without having a starter hole.
That was the point of our discussion above.

Yes -- but that needs greater skill in grinding the tool to go
into the boring head. Sometimes, it may be easier to use the hole saw
followed by the boring head with standard boring bars. After all, the
original poster does not yet have tool grinding skills. (Nor do I
remember whether he has even indicated that he has a bench grinder.)

Enjoy,
DoN.

--
Email: | 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 ---

"Harold and Susan Vordos" wrote in message
...
Love to hear how it turns out when you give it a go. Can we count on a
report?

Certainly, although it may be a while.

Peter

"DoN. Nichols" wrote in message
rvers.com...
According to Harold and Susan Vordos :

"DoN. Nichols" wrote in message
ervers.com...
snip----

Note that using a boring head on the mill will not eliminate the
need for a hole to start with -- and the bigger the hole the better,
because a boring head is rather a rather slow way of removing
material.
So, a hole saw to produce an undersized hole is a good thing to use
*with* the boring head.

You missed the part about trepanning, DoN. I've done it with
outstanding
success. You can, indeed, create large holes without having a starter
hole.
That was the point of our discussion above.

Yes -- but that needs greater skill in grinding the tool to go
into the boring head.

Yep, detailed instructions for which I provided, although they were directed
towards a different individual, one that hopes to use the process in the
near future. It has been a learning thing, of sorts, for those that
haven't been there. I was fortunate (?) to have visited the problem some
time ago and solved many of the issues.

Sometimes, it may be easier to use the hole saw
followed by the boring head with standard boring bars. After all, the
original poster does not yet have tool grinding skills. (Nor do I
remember whether he has even indicated that he has a bench grinder.)

Enjoy,
DoN.

Agreed. My conversation with Peter evolved well after the fact, and my
comments weren't necessarily directed towards Bill. Not that he might not
benefit, mind you. The trepanning method I discussed is a wonderful backup
for that special job that comes along and there's no reasonable method
otherwise. Good example might be the blanking of many round pieces from
plate or sheet, where a center hole may not be permitted, ruling out, or
seriously limiting a hole saw.

Grinding a tool for trepanning with a boring head does require some skill,
of that there's no question, but if I can master the technique, I can't help
but think that others can as well. What's important is to understand how it
cuts, and what clearances and rake are necessary. The rest is just applying
the concept to the tool. If a person can grind their own lathe tools,
there's very little difference in grinding a trepanning tool.

Harold

According to Harold and Susan Vordos :

"DoN. Nichols" wrote in message
rvers.com...

[ ... ]

Yes -- but that needs greater skill in grinding the tool to go
into the boring head.

Yep, detailed instructions for which I provided, although they were directed
towards a different individual, one that hopes to use the process in the
near future. It has been a learning thing, of sorts, for those that
haven't been there. I was fortunate (?) to have visited the problem some
time ago and solved many of the issues.

And it was nice of you to share that information.

Sometimes, it may be easier to use the hole saw
followed by the boring head with standard boring bars. After all, the
original poster does not yet have tool grinding skills. (Nor do I
remember whether he has even indicated that he has a bench grinder.)

[ ... ]

Agreed. My conversation with Peter evolved well after the fact, and my
comments weren't necessarily directed towards Bill. Not that he might not
benefit, mind you. The trepanning method I discussed is a wonderful backup
for that special job that comes along and there's no reasonable method
otherwise. Good example might be the blanking of many round pieces from
plate or sheet, where a center hole may not be permitted, ruling out, or
seriously limiting a hole saw.

Agreed. Though the Roto-Bor which I mentioned (if available)
could have the spring loaded pilot point on a small disk of sacrifical
metal placed over the workpiece. (But the shape of the cutting flutes
on it result in a sharp-edged disk, so they are better for holes than
making disks.

Grinding a tool for trepanning with a boring head does require some skill,
of that there's no question, but if I can master the technique, I can't help
but think that others can as well. What's important is to understand how it
cuts, and what clearances and rake are necessary. The rest is just applying
the concept to the tool. If a person can grind their own lathe tools,
there's very little difference in grinding a trepanning tool.

The primary thing is that you need a different trepanning cutter
for each size of hole, while a lathe tool will work through a wide range
of sizes. (I don't think that I saw this explicitly mentioned in the
discussion.) This means that I would probably not do the trepanning
unless it was a serious improvement over the alternatives possible with
my existing tooling.

Enjoy,
DoN.

--
Email: | 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 ---

"DoN. Nichols" wrote in message
rvers.com...
snip-----

The primary thing is that you need a different trepanning cutter
for each size of hole, while a lathe tool will work through a wide range
of sizes. (I don't think that I saw this explicitly mentioned in the
discussion.)

That's true, within reason. As the hole size increases, it's more
forgiving, but it can still be a problem. I covered it in principle in the
description without making mention that the tool would be different from
size to size.

This means that I would probably not do the trepanning
unless it was a serious improvement over the alternatives possible with
my existing tooling.

Enjoy,
DoN.

No doubt, when one has other means, they are likely to be better. The
point here is for someone that has no other means, but has a mill drill or a
knee mill, this opens door to an operation that otherwise may not be
possible. It's the main reason I did it in the first place. My objective
was to blank the needed "washers" for the filter press I was building. At
that point in my career, I had been away from the shop for considerable time
and had no interest in purchasing tools that would get used to manufacture a
specific item and perhaps never used again. By using my boring head and
some creativity, I managed to accomplish my task without buying unwanted
tools and or tooling. Overall, it was far and away faster and easier than
sawing the pieces, which would have been my next option. Another way to
look at the situation is it's Saturday afternoon and you can't buy your
needs. It's nice to have an alternate method for accomplishing what can be
a rotten task.

Harold

Harold, Don, everybody,

No doubt, when one has other means, they are likely to be better. The
point here is for someone that has no other means, but has a mill drill or a
knee mill, this opens door to an operation that otherwise may not be
possible. It's the main reason I did it in the first place. My objective
was to blank the needed "washers" for the filter press I was building. At
that point in my career, I had been away from the shop for considerable time
and had no interest in purchasing tools that would get used to manufacture a
specific item and perhaps never used again. By using my boring head and
some creativity, I managed to accomplish my task without buying unwanted
tools and or tooling. Overall, it was far and away faster and easier than
sawing the pieces, which would have been my next option. Another way to
look at the situation is it's Saturday afternoon and you can't buy your
needs. It's nice to have an alternate method for accomplishing what can be
a rotten task.

That captures the spirit(s) in which I asked the question. That, and a
simple minded curiosity as to whether the flycutter that is on the way
would do this job too. It's a long and sad story, but I should have a
bench grinder already, and it _might_ actually still be in good shape.
Failing that, I need to get one. The bigger concern is tricky tool
grinding; better to start on that adventure with simple stuff.

The replies taken together seem to favor a hole saw, possibly followed
by clean up with a boring head or flycutter. Suppose that I get a
slightly undersized hole saw or edge drill and take out the waste with a
buzz saw. Could I then reasonably/safely use the flycutter to drop
through the thickness to clean up the diameter? In the edge-drilled
case, there will be significant changes in the amount of metal being
removed; is that a problem? Below, there is a marginal ascii drawing of
what I have in mind. I think I ordered tool bits that will do it
provided enough waste has been removed.

I don't know why I expect troubles with a hole saw, I just do It
will probably work fine. If this were simply a matter of some extra
wear on a $6 carbide bit, I'd use the flycutter; since there's more to
it, the price of a hole saw seems justified. At least a cheap one, if
it will work on the steel, will pay for itself in a hurry if I don't
have to edge drill the hole.

Fair? Any recommendations on a hole saw?

Bill




/.........../
/.........../
/.........../
~......... /
-------+~......... /
///////|~~~~~~~~--
///////+-----+------------...
/////////////|
-------------+------------...

...... Bit
~~~~~ cutting edge of bit
//// section through work

According to Bill Schwab :
Harold, Don, everybody,

No doubt, when one has other means, they are likely to be better. The
point here is for someone that has no other means, but has a mill drill or a

[ ... ]

needs. It's nice to have an alternate method for accomplishing what can be
a rotten task.

That captures the spirit(s) in which I asked the question. That, and a
simple minded curiosity as to whether the flycutter that is on the way
would do this job too.

A flycutter as supplied would not, but with some custom bit
grinding, it might work for a reasonably small workpiece thickness.

It's a long and sad story, but I should have a
bench grinder already, and it _might_ actually still be in good shape.
Failing that, I need to get one. The bigger concern is tricky tool
grinding; better to start on that adventure with simple stuff.

Well ... to try to trepan with a fly cutter, you *will* need to
do some tricky tool grinding.

The replies taken together seem to favor a hole saw, possibly followed
by clean up with a boring head or flycutter.

I consider the boring head to be the better cleanup option.

Suppose that I get a
slightly undersized hole saw or edge drill and take out the waste with a
buzz saw. Could I then reasonably/safely use the flycutter to drop
through the thickness to clean up the diameter?

With the hole saw, and not too far under the desired size, yes.
As you point out, the edge drilled case would be somewhat different.

In the edge-drilled
case, there will be significant changes in the amount of metal being
removed; is that a problem?

Yes -- you will be performing an interrupted cut, which is more
stress on either the boring head or the flycutter --- and more so on the
flycutter I believe.

Below, there is a marginal ascii drawing of
what I have in mind. I think I ordered tool bits that will do it
provided enough waste has been removed.

I don't know why I expect troubles with a hole saw, I just do It
will probably work fine.

It will tend to produce a rather rough ID on the hole it
produces, based on my experience.

And a good thing to do to help a hole saw cut better (and not
clog up) is to drill one or more holes just inside the cut line, which
will let chips fall clear of the teeth more easily.

If this were simply a matter of some extra
wear on a $6 carbide bit, I'd use the flycutter; since there's more to
it, the price of a hole saw seems justified. At least a cheap one, if
it will work on the steel, will pay for itself in a hurry if I don't
have to edge drill the hole.

Fair? Any recommendations on a hole saw?

Leonix? Starrett?

[ ... ]

/.........../
/.........../
/.........../
~......... /
-------+~......... /
///////|~~~~~~~~--
///////+-----+------------...
/////////////|
-------------+------------...

..... Bit
~~~~~ cutting edge of bit
//// section through work

Do you intend to go all the way through, or to leave a shoulder
as shown there?

With the drilled holes to clear out the slug, the width of
material to be removed will be greater than with the hole saw -- at
least at some positions.

The angle of the bit will normally be more shallow than what you
have shown -- though that is probably more the limitations of ASCII
graphics than your mental image of the position of the bit. But
essentially, as you go deeper, the ground cutting edge on the bottom end
of the bit will not be the only thing which is contacting the workpiece.
You will add the sloped under-surface of the body of the bit, which is
not ground to cut, nor to have relief. This increases the amount of
cut, especially when you get to the projections between the holes which
you drilled to knock out the waste stock.

The knocking of that under surface can sometimes cause the bit
to tilt in the holder, and *that* will move the tip outward so it will
cut a larger circle than you were trying to cut. Since you will already
be down into the circle, this will probably jam the bit into the
workpiece, and attempt to pull it out of whatever is holding it in
place.

The bit on the boring head comes down vertically, and can be
ground to be fairly narrow if needed. Also, you can start with a
reduced diameter to make the first pass, so there is less stock under
the heel of the bit.

Granted -- you can grind a bit to follow a shape which will
approximate a trepaning bit for a boring head -- for fairly thin
workpieces.

Try something like this (again understanding the limits of
ASCII graphics in portraying the angle of the bit):

/ /
/ /
/ /
/ _ /
/ |
/________| --- this step must be greater than the
thickness of the workpiece

The actual angle of the bit will typically be less than 30 degrees to
the horizontal, so the necessary grind to clear the thickness will
probably weaken the bit somewhat more than is comfortable.

Back in the old days, a tool bit with a custom curve would have
been forged to make this easier to do.

Or -- Wayne Cook's special home-brew flycutter design could be
used, which holds the bit rather more vertical. But this is not typical
of a metalworking flycutter, though there are woodworking ones with an
adjustable arm which holds the bit vertical. Too much flex for
metalworking, however.

Good Luck,
DoN.
--
Email: | 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 ---

I made my flycutters/boring bars the same as Dave except I drilled and
reamed a 1/4 hole in the bottom end. Ream to a slip fit and use a dowel
slipped into the hole to measure over to the edge of the tool bit.
(Subtract half the dowel dia.)
Drill a 1/4 inche hole in the center of the work piece, install the
flycutter. Index the 1/4 dowel into the drilled hole and you stabilize
the tool to the workpiece. Hole will be dead nuts.
Remove the 1/4 inche dowel for flycutting, of course.
Oh, one more thing, you can slip a small spring over the 1/4 dowel to
hold the scrap down, if you wish.

Warren

Don,

That captures the spirit(s) in which I asked the question. That, and a
simple minded curiosity as to whether the flycutter that is on the way
would do this job too.


A flycutter as supplied would not, but with some custom bit
grinding, it might work for a reasonably small workpiece thickness.

Thin work I have going for me.


It's a long and sad story, but I should have a
bench grinder already, and it _might_ actually still be in good shape.
Failing that, I need to get one. The bigger concern is tricky tool
grinding; better to start on that adventure with simple stuff.


Well ... to try to trepan with a fly cutter, you *will* need to
do some tricky tool grinding.

Probably best left for later. That's ok.


The replies taken together seem to favor a hole saw, possibly followed
by clean up with a boring head or flycutter.


I consider the boring head to be the better cleanup option.

Unless I encounter other priorities, I will probably have one before my
"production run" of this design. For now, I need to clean up a few
holes, and really not all that accurately.



Fair? Any recommendations on a hole saw?


Leonix? Starrett?

Thanks.


[ ... ]


/.........../
/.........../
/.........../
~......... /
-------+~......... /
///////|~~~~~~~~--
///////+-----+------------...
/////////////|
-------------+------------...

..... Bit
~~~~~ cutting edge of bit
//// section through work


Do you intend to go all the way through, or to leave a shoulder
as shown there?

Through.


With the drilled holes to clear out the slug, the width of
material to be removed will be greater than with the hole saw -- at
least at some positions.

The angle of the bit will normally be more shallow than what you
have shown -- though that is probably more the limitations of ASCII
graphics than your mental image of the position of the bit.

My mental image is pretty limitedg, but yes, I realize the angle shown
is too steep.


But
essentially, as you go deeper, the ground cutting edge on the bottom end
of the bit will not be the only thing which is contacting the workpiece.
You will add the sloped under-surface of the body of the bit, which is
not ground to cut, nor to have relief. This increases the amount of
cut, especially when you get to the projections between the holes which
you drilled to knock out the waste stock.

Could that not be avoided by taking multiple passes to enlarge the hole?
I _think_ I understand what you mean, and I first started to realize
it from Harold's initial reply.


The knocking of that under surface can sometimes cause the bit
to tilt in the holder, and *that* will move the tip outward so it will
cut a larger circle than you were trying to cut. Since you will already
be down into the circle, this will probably jam the bit into the
workpiece, and attempt to pull it out of whatever is holding it in
place.

Agreed, that's a problem.


The bit on the boring head comes down vertically, and can be
ground to be fairly narrow if needed. Also, you can start with a
reduced diameter to make the first pass, so there is less stock under
the heel of the bit.

Granted -- you can grind a bit to follow a shape which will
approximate a trepaning bit for a boring head -- for fairly thin
workpieces.

Try something like this (again understanding the limits of
ASCII graphics in portraying the angle of the bit):

/ /
/ /
/ /
/ _ /
/ |
/________| --- this step must be greater than the
thickness of the workpiece

The actual angle of the bit will typically be less than 30 degrees to
the horizontal, so the necessary grind to clear the thickness will
probably weaken the bit somewhat more than is comfortable.

I think I follow. Suddenly it doesn't seem so bad, but the hole saw is
probably the way to go.

Thanks!!

Bill

According to Bill Schwab :
Don,

[ ... ]

A flycutter as supplied would not, but with some custom bit
grinding, it might work for a reasonably small workpiece thickness.

Thin work I have going for me.

That helps.


[ ... ]

I consider the boring head to be the better cleanup option.

Unless I encounter other priorities, I will probably have one before my
"production run" of this design. For now, I need to clean up a few
holes, and really not all that accurately.

O.K. Clean up *can* be done with a half-round file for just a
few holes.



Fair? Any recommendations on a hole saw?


Leonix? Starrett?

Thanks.

Hopefully, others will toss in more suggestions.
Do you intend to go all the way through, or to leave a shoulder
as shown there?

Through.

O.K.

[ ... ]

The angle of the bit will normally be more shallow than what you
have shown -- though that is probably more the limitations of ASCII
graphics than your mental image of the position of the bit.

My mental image is pretty limitedg, but yes, I realize the angle shown
is too steep.

Good enough. Just making sure. :-)


But
essentially, as you go deeper, the ground cutting edge on the bottom end
of the bit will not be the only thing which is contacting the workpiece.
You will add the sloped under-surface of the body of the bit, which is
not ground to cut, nor to have relief. This increases the amount of
cut, especially when you get to the projections between the holes which
you drilled to knock out the waste stock.

Could that not be avoided by taking multiple passes to enlarge the hole?

Yes -- with the problem that it is difficult to set a fly cutter
precisely to a given size, and with multiple holes and multiple passes,
you will have to do the same thing multiple times -- unless you fixture
the workpiece, do one pass for all workpieces, then increase and the
next pass for all, etc.

The boring head has a micrometer dial to give you repeatable
readings -- though it is still easy enough to get one turn off and be
too small (no real problem) or too big (I have yet to see a mill with an
"add metal back" feature. :-)

I _think_ I understand what you mean, and I first started to realize
it from Harold's initial reply.

Good.

[ ... ]

Granted -- you can grind a bit to follow a shape which will
approximate a trepaning bit for a boring head -- for fairly thin
workpieces.

Try something like this (again understanding the limits of
ASCII graphics in portraying the angle of the bit):

/ /
/ /
/ /
/ _ /
/ |
/________| --- this step must be greater than the
thickness of the workpiece

The actual angle of the bit will typically be less than 30 degrees to
the horizontal, so the necessary grind to clear the thickness will
probably weaken the bit somewhat more than is comfortable.

I think I follow. Suddenly it doesn't seem so bad, but the hole saw is
probably the way to go.

Thanks!!

You're welcome.

Enjoy,
DoN.

--
Email: | 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 ---

I have a flycutter made to make large holes using a drill press,
General was the brand, cost something like $7 or so when I got it.
IIRC, it'll do holes up to 4" or so in thin material. I've used it in
plexiglas and aluminum, it should be run SLOW. Got it at the local
hardware store, it was sold as a flycutter for making holes, not as a
milling attachment. It's got a pilot bit that I rplaced with a piece
of drill rod, I make the hole for it first, clamp things down and have
at it. Works well enough. It's about as precise as you could set the
radius.

Stan

wrote in message
oups.com...
I have a flycutter made to make large holes using a drill press,
General was the brand, cost something like $7 or so when I got it.
IIRC, it'll do holes up to 4" or so in thin material. I've used it in
plexiglas and aluminum, it should be run SLOW. Got it at the local
hardware store, it was sold as a flycutter for making holes, not as a
milling attachment. It's got a pilot bit that I rplaced with a piece
of drill rod, I make the hole for it first, clamp things down and have
at it. Works well enough. It's about as precise as you could set the
radius.

Stan


I used an identical cutter to open holes for 3" TA's and hubs in electrical
cans when I installed my 3 phase service, and drove it with a 1/2" Milwaukee
hand drill. With patience, it works great. It doesn't hurt if you can
grind good parting tools.

Harold