Is there a "kink" for setting up a slitting saw to saw through
round bar stock along the axis, so that the slot is exactly
across a diameter? (I presume this to be a similar problem to
setting up accurately for cross-drilling)

This is actually a Ham Radio application; I wish to make
up some very large banana-type plugs from the 1/4" round
bar stock that I have in small quantities. For this, I will need
to saw two diameters in a cross shape, and then splay
out the leaves slightly to make a springy and rubbing contact.

"Airy R.Bean" wrote in message
...
Is there a "kink" for setting up a slitting saw to saw through
round bar stock along the axis, so that the slot is exactly
across a diameter? (I presume this to be a similar problem to
setting up accurately for cross-drilling)

This is actually a Ham Radio application; I wish to make
up some very large banana-type plugs from the 1/4" round
bar stock that I have in small quantities. For this, I will need
to saw two diameters in a cross shape, and then splay
out the leaves slightly to make a springy and rubbing contact.



I put the saw mandrel in a lathe chuck and made a block with a hole and
setscrew to mount on the cross-slide. Did this to slit the threaded end of a
bolt - it has a countersunk hole lengthways through it and when a smaller
screw is thightened it locks the threads. This bolt is the mount for a
ball-turning attachment; I wanted to be able to lock the mounting bolt at
the right clearance without having it cock or move sideways, so a locknut
and a setscrew were both out.

I had to thread the hole through my block, but you don't need that. If you
wanted to get fancy you could make a shouldered sleeve with your setscrew
holding the stock, drill a hole in the shoulder, and two holes in the block
for a pin to set your 90 degree cuts.

In article , Airy R.Bean says...

Is there a "kink" for setting up a slitting saw to saw through
round bar stock along the axis, so that the slot is exactly
across a diameter?

Just set the part up in the vise, and touch off on one
side using something like cigarette paper. Then advance
across the workpiece half a diameter plus have the
width of the saw blade. That will get you within a
few thou, becuase they do cut slightly oversize.

Jim


--
==================================================
please reply to:
JRR(zero) at pkmfgvm4 (dot) vnet (dot) ibm (dot) com
==================================================

Thanks for your ideas - it's always the way that there's more
though and effort needed to be put in to make the jig than
to make the device in which you're interested!

"jtaylor" wrote in message
...
I had to thread the hole through my block, but you don't need that. If
you
wanted to get fancy you could make a shouldered sleeve with your setscrew
holding the stock, drill a hole in the shoulder, and two holes in the
block
for a pin to set your 90 degree cuts.

"Airy R.Bean" wrote in message
...
Is there a "kink" for setting up a slitting saw to saw through
round bar stock along the axis, so that the slot is exactly
across a diameter? (I presume this to be a similar problem to
setting up accurately for cross-drilling)

This is actually a Ham Radio application; I wish to make
up some very large banana-type plugs from the 1/4" round
bar stock that I have in small quantities. For this, I will need
to saw two diameters in a cross shape, and then splay
out the leaves slightly to make a springy and rubbing contact.



Assuming you are using a vertical mill so that the slitting saw is
horizontal, and the work is fixtured horizontal (vee block perhaps):

a/ Measure height of top of stock with vernier height guage, subtract
half the stock thickness, and add half the slitting saw thickness -
set the height guage to the resultant figure.

b/ Adjust quill of mill so top of slitting saw just touches the height
guage and lock the quill.

You now have the slitting saw bang on centre of the work.

AWEM

"Airy R.Bean" wrote in message
...
Thanks for your ideas - it's always the way that there's more
though and effort needed to be put in to make the jig than
to make the device in which you're interested!

"jtaylor" wrote in message
...
I had to thread the hole through my block, but you don't need that. If
you
wanted to get fancy you could make a shouldered sleeve with your
setscrew
holding the stock, drill a hole in the shoulder, and two holes in the
block
for a pin to set your 90 degree cuts.


If you're making more than half a dozen it'd be worth it.

Airy R.Bean wrote:
Is there a "kink" for setting up a slitting saw to saw through
round bar stock along the axis, so that the slot is exactly
across a diameter? (I presume this to be a similar problem to
setting up accurately for cross-drilling)

This trick assumes you have the slitting saw in a vertical mill, the bar
is horizontal, and the slitting saw teeth are straight (i.e.. not
staggered like a wood saw blade).
Adjust the position of the bar and saw so that, by eye, the blade is
just about touching the fattest part of the bar. Interpose a vertical
6" steel rule between the bar and the saw and move the table to very
gently pinch the rule. Unless you were lucky and set the saw exactly on
the fattest part, the rule will no longer be vertical. Adjust the hight
of the saw until the rule is truly vertical - you will be amazed at how
accurately the blade is then at centre hight.

--

Regards, Gary Wooding
(To reply by email, change feet to foot in my address)

Now, that's interesting, because it is a variation of the technique
for setting up for cross drilling (except that then the ruler is in
see-saw mode)

"Wooding" wrote in message
...
Airy R.Bean wrote:
Is there a "kink" for setting up a slitting saw to saw through
round bar stock along the axis, so that the slot is exactly
across a diameter? (I presume this to be a similar problem to
setting up accurately for cross-drilling)

This trick assumes you have the slitting saw in a vertical mill, the bar
is horizontal, and the slitting saw teeth are straight (i.e.. not
staggered like a wood saw blade).
Adjust the position of the bar and saw so that, by eye, the blade is
just about touching the fattest part of the bar. Interpose a vertical
6" steel rule between the bar and the saw and move the table to very
gently pinch the rule. Unless you were lucky and set the saw exactly on
the fattest part, the rule will no longer be vertical. Adjust the hight
of the saw until the rule is truly vertical - you will be amazed at how
accurately the blade is then at centre hight.

I have to make up about 14 such plugs.

(Although a nagging voice inside suggests that I should
also consider the "Binding Post" approach together with
spade terminals)

"jtaylor" wrote in message
...
"Airy R.Bean" wrote in message
...
Thanks for your ideas - it's always the way that there's more
though and effort needed to be put in to make the jig than
to make the device in which you're interested!
"jtaylor" wrote in message
...
I had to thread the hole through my block, but you don't need that.
If
you
wanted to get fancy you could make a shouldered sleeve with your
setscrew
holding the stock, drill a hole in the shoulder, and two holes in the
block
for a pin to set your 90 degree cuts.

If you're making more than half a dozen it'd be worth it.

Damn! I knew I should have purchased that digital
height gauge at the club sale, especially as it was only
£10!

The only difficulty otherwise with what you suggest is
the tendency of slitting saws to bend under the slightest
lateral force, but thanks anyway.

"Andrew Mawson" wrote in message
...
"Airy R.Bean" wrote in message
...
Is there a "kink" for setting up a slitting saw to saw through
round bar stock along the axis, so that the slot is exactly
across a diameter? (I presume this to be a similar problem to
setting up accurately for cross-drilling)
This is actually a Ham Radio application; I wish to make
up some very large banana-type plugs from the 1/4" round
bar stock that I have in small quantities. For this, I will need
to saw two diameters in a cross shape, and then splay
out the leaves slightly to make a springy and rubbing contact.
Assuming you are using a vertical mill so that the slitting saw is
horizontal, and the work is fixtured horizontal (vee block perhaps):
a/ Measure height of top of stock with vernier height guage, subtract
half the stock thickness, and add half the slitting saw thickness -
set the height guage to the resultant figure.
b/ Adjust quill of mill so top of slitting saw just touches the height
guage and lock the quill.
You now have the slitting saw bang on centre of the work.

"Airy R.Bean" wrote in message
...
Is there a "kink" for setting up a slitting saw to saw through
round bar stock along the axis, so that the slot is exactly
across a diameter? (I presume this to be a similar problem to
setting up accurately for cross-drilling)

The simplest way I know to locate a line on top of round stock is this:
(BTW, you don't have to switch from vertical to horizontal modes to make it
work.)

Mount the stock parallel to the mill table, and dead-level, with the
"working end" solidly in your mill vise, and enough overhang for the
slitting saw to clear the vise when you're working on the _side_ of the rod.

True up the work with your longitudinal travel, so it's _pretty_ good. A
thou. is OK, you don't need it to tenths.

With any-ol' side-cutting bit, slowly close in on the side of the work until
the bit just kisses the metal. Then make a longitudinal cut for however far
you want the slit to go.

You've now marked a line and flat that is parallel to the axis of the rod,
and perfectly centered on the horizontal diameter of the rod.

Without removing the work from the vise, you can switch to your slitting
saw, and true up the saw to the line you've just marked -- then cut.

LLoyd

"Airy R.Bean" wrote in message
...
Is there a "kink" for setting up a slitting saw to saw through
round bar stock along the axis, so that the slot is exactly
across a diameter? (I presume this to be a similar problem to
setting up accurately for cross-drilling)

This is actually a Ham Radio application; I wish to make
up some very large banana-type plugs from the 1/4" round
bar stock that I have in small quantities. For this, I will need
to saw two diameters in a cross shape, and then splay
out the leaves slightly to make a springy and rubbing contact.


Doesn't need to be "exactly" because it's the diameter that is more critical
than the position of the slot - I suspect even as much as just less than the
thickness of the slitting saw off centre would not be a problem.

I made a connector (female as opposed to your male) for an old radio by
slitting brass tube. Hacksaw and vice produced good enough accuracy for an
excellent operational performance.

Steve

I made a connector (female as opposed to your male) for an old radio by
slitting brass tube. Hacksaw and vice produced good enough accuracy for an
excellent operational performance.

How about making a square fixture to hold the round part with two slits
to guide the saw blade?

I have found that a good fret/jewelers saw very handy for cutting small
items. I find it very difficult to cut 1/8 drill rod with a hacksaw
but easy with a fret saw. They cut faster than you expect.

Lay the round bar stock in a Vee and put it under the saw so the saw just
touches the highest part of the rod. As long as the stock is round you'll
have a tangent to the diameter and all you need to do is start slotting,
half in two.
There used to be lots of banana plugs for sale on eBay and hamfest, quicker,
easier, and cheaper than DIY.

--

73
Hank WD5JFR
"Airy R.Bean" wrote in message
...
Is there a "kink" for setting up a slitting saw to saw through
round bar stock along the axis, so that the slot is exactly
across a diameter? (I presume this to be a similar problem to
setting up accurately for cross-drilling)

This is actually a Ham Radio application; I wish to make
up some very large banana-type plugs from the 1/4" round
bar stock that I have in small quantities. For this, I will need
to saw two diameters in a cross shape, and then splay
out the leaves slightly to make a springy and rubbing contact.

On Thu, 13 Jan 2005 13:13:17 -0000, "Airy R.Bean"
wrote:

Is there a "kink" for setting up a slitting saw to saw through
round bar stock along the axis, so that the slot is exactly
across a diameter? (I presume this to be a similar problem to
setting up accurately for cross-drilling)

This is actually a Ham Radio application; I wish to make
up some very large banana-type plugs from the 1/4" round
bar stock that I have in small quantities. For this, I will need
to saw two diameters in a cross shape, and then splay
out the leaves slightly to make a springy and rubbing contact.

I usually use a 5C collet spin index, as
http://www.use-enco.com/CGI/INSRIT?PMAKA=235-6011
This makes it easy to get the two cuts 90 deg apart.

I set the height as Jim Rozen suggested. A hint there is to touch the
slitting saw as close as possible to the center, where it is supported
by the mandrel. That minimizes any flex in the saw when "touching" for
zero. I have a dial indicator mounted on the quill of my mill, so I
just lower the quill 1/2 dia + 1/2 saw thickness, lock it and cut.

Once you have the height set, it's easy to rotate 90 deg for the
other cut, then pop the piece out, reload another blank, and make the
next one. Shouldn't take 20 minutes to make 14 of them, once set up.
A set of holes and a tapered pin in the spin index makes it easy to
hit any increment of 1 degree with accuracy sufficient for most
purposes.

Those spin indexes are also handy for making hex heads or wrench flats
on round things, drilling cross holes at various angles, lots of
uses. One of the better $29.95 I ever spent!

In article ,
says...
On Thu, 13 Jan 2005 13:13:17 -0000, "Airy R.Bean"
wrote:

Is there a "kink" for setting up a slitting saw to saw through
round bar stock along the axis, so that the slot is exactly
across a diameter? (I presume this to be a similar problem to
setting up accurately for cross-drilling)

This is actually a Ham Radio application; I wish to make
up some very large banana-type plugs from the 1/4" round
bar stock that I have in small quantities. For this, I will need
to saw two diameters in a cross shape, and then splay
out the leaves slightly to make a springy and rubbing contact.

I usually use a 5C collet spin index, as
http://www.use-enco.com/CGI/INSRIT?PMAKA=235-6011
This makes it easy to get the two cuts 90 deg apart.

I set the height as Jim Rozen suggested. A hint there is to touch the
slitting saw as close as possible to the center, where it is supported
by the mandrel. That minimizes any flex in the saw when "touching" for
zero.

If the slot has to be located very accurately and the the saw is very
thin it can be difficult to tell the difference between just touching
and a few thousandths beyond. In this case I'll set up test indicator
stuck to the mill head on a mag base and with the probe tip touching the
saw on the opposite side of the saw from where it will contact the work.
A tiny amount of flex in a thin saw is easier to detect this way than
with a zig-zag.

If you're working this close it's a good idea to mic the saw. I've found
they're usually a bit oversize and often have burrs on the teeth when
new that will cause them to cut oversize. A few swirls on a piece of 600
grit on a surface plate will knock the burrs flat and result in a cut
closer to nominal. Note that I'm talking here about jeweler's or
slitting saws that have no set.

Ned Simmons

Set it on center, set your depth of cut, set your speed and feed, cut. What
more do you want?

"Airy R.Bean" wrote in message
...
Is there a "kink" for setting up a slitting saw to saw through
round bar stock along the axis, so that the slot is exactly
across a diameter? (I presume this to be a similar problem to
setting up accurately for cross-drilling)

This is actually a Ham Radio application; I wish to make
up some very large banana-type plugs from the 1/4" round
bar stock that I have in small quantities. For this, I will need
to saw two diameters in a cross shape, and then splay
out the leaves slightly to make a springy and rubbing contact.

That's the question, how do you set it on center?

--

73
Hank WD5JFR
"CW" wrote in message
...
Set it on center, set your depth of cut, set your speed and feed, cut.
What
more do you want?

"Airy R.Bean" wrote in message
...
Is there a "kink" for setting up a slitting saw to saw through
round bar stock along the axis, so that the slot is exactly
across a diameter? (I presume this to be a similar problem to
setting up accurately for cross-drilling)

This is actually a Ham Radio application; I wish to make
up some very large banana-type plugs from the 1/4" round
bar stock that I have in small quantities. For this, I will need
to saw two diameters in a cross shape, and then splay
out the leaves slightly to make a springy and rubbing contact.

On Fri, 14 Jan 2005 01:46:43 GMT, "Henry Kolesnik"
wrote:

That's the question, how do you set it on center?

Hi Hank,

It seems it's not how, but how well. The how is trivial. The how
well is more a matter of a stock of ¼ inch which is sacrificed to
lumbering gross tools. Modern machines just make errors faster when
it is obviously within the scope of simpler hand tools and jigs. More
time has been expended in the sterile scribblings of what could be, in
place of actually getting it done.

73's
Richard Clark, KB7QHC

That's a good idea - I must otherwise admit to being lazy when
it comes to the possibility of NOT doing things with a hand saw!

"Charles A. Sherwood" wrote in message
...
I made a connector (female as opposed to your male) for an old radio by
slitting brass tube. Hacksaw and vice produced good enough accuracy for
an
excellent operational performance.

How about making a square fixture to hold the round part with two slits
to guide the saw blade?

I have found that a good fret/jewelers saw very handy for cutting small
items. I find it very difficult to cut 1/8 drill rod with a hacksaw
but easy with a fret saw. They cut faster than you expect.

The biggest off-the-shelf bananas that I have seen are
4mm. In any case, doing things for yourself is what
differentiates the Radio Ham from the CBer!

"Henry Kolesnik" wrote in message
m...
There used to be lots of banana plugs for sale on eBay and hamfest,
quicker,
easier, and cheaper than DIY.

How do you propose to set it on "center"? (English speakers
spell that as, "centre"!). That is the nub of my enquiry.


"CW" wrote in message
...
Set it on center, set your depth of cut, set your speed and feed, cut.
What
more do you want?
"Airy R.Bean" wrote in message
...
Is there a "kink" for setting up a slitting saw to saw through
round bar stock along the axis, so that the slot is exactly
across a diameter? (I presume this to be a similar problem to
setting up accurately for cross-drilling)
This is actually a Ham Radio application; I wish to make
up some very large banana-type plugs from the 1/4" round
bar stock that I have in small quantities. For this, I will need
to saw two diameters in a cross shape, and then splay
out the leaves slightly to make a springy and rubbing contact.

"Airy R.Bean" wrote in message
...
How do you propose to set it on "center"? (English speakers
spell that as, "centre"!). That is the nub of my enquiry.


Well, if you have "stock", and it's a small thing of which you're making
many, you get a method that allows both measured increments and a locking
system. You do a test, and adjust, so that once it's good enough, you just
shove the stock in and slice it.

If it's a one-off that has much time/money/work already into it, you use the
same arrangement but plan and measure as best you can first.

Stupid boy.

"jtaylor" wrote in message
...

"Airy R.Bean" wrote in message
...
How do you propose to set it on "center"? (English speakers
spell that as, "centre"!). That is the nub of my enquiry.


Well, if you have "stock", and it's a small thing of which you're making
many, you get a method that allows both measured increments and a locking
system. You do a test, and adjust, so that once it's good enough, you
just
shove the stock in and slice it.

If it's a one-off that has much time/money/work already into it, you use
the
same arrangement but plan and measure as best you can first.

Airy R.Bean wrote:
The biggest off-the-shelf bananas that I have seen are 4mm.

I've got some that are about 0.3 inches in diameter.
--
73, Cecil http://www.qsl.net/w5dxp


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On Thu, 13 Jan 2005 13:13:17 -0000, "Airy R.Bean"
wrote:

Is there a "kink" for setting up a slitting saw to saw through
round bar stock along the axis, so that the slot is exactly
across a diameter? (I presume this to be a similar problem to
setting up accurately for cross-drilling)

This is actually a Ham Radio application; I wish to make
up some very large banana-type plugs from the 1/4" round
bar stock that I have in small quantities. For this, I will need
to saw two diameters in a cross shape, and then splay
out the leaves slightly to make a springy and rubbing contact.

You might get a better result with less trouble by using tapered plugs
rather than cross-cut pins. Get a #4 taper pin reamer to ream the
"jacks", set up your lathe to cut the mating taper on the plugs.
The nominal dia of the large end of a #4 taper pin is .250"
The taper is .250" per foot. This is about 1.19 deg included angle,
which would be a "self locking" taper providing very good contact if
you got the taper right.

You could also just buy taper pins, solder them to the ends of bits of
shaft and copper-plate them.

There are various methods. First, you have to specify what kind of equipment
you are using. You never did say. BTW, American speakers spell it center. We
left England so we were free to do it a better way.

"Airy R.Bean" wrote in message
...
How do you propose to set it on "center"? (English speakers
spell that as, "centre"!). That is the nub of my enquiry.


"CW" wrote in message
...
Set it on center, set your depth of cut, set your speed and feed, cut.
What
more do you want?
"Airy R.Bean" wrote in message
...
Is there a "kink" for setting up a slitting saw to saw through
round bar stock along the axis, so that the slot is exactly
across a diameter? (I presume this to be a similar problem to
setting up accurately for cross-drilling)
This is actually a Ham Radio application; I wish to make
up some very large banana-type plugs from the 1/4" round
bar stock that I have in small quantities. For this, I will need
to saw two diameters in a cross shape, and then splay
out the leaves slightly to make a springy and rubbing contact.