Setting up slitting saw for round stock?
 

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.

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.

How would you set it up to be exactly cutting a diameter?

"Jack Painter" wrote in message
news:kWvFd.15549$B95.11334@lakeread02...
"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.
Hi Airy, couldn't you just use a grinding/cutting wheel to do this job?
Doesn't sound like you need any fancy jig to cut a slot or two into round
stock.

"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.


Hi Airy, couldn't you just use a grinding/cutting wheel to do this job?
Doesn't sound like you need any fancy jig to cut a slot or two into round
stock.

Jack

I'd put the bar in a vise and do it by hand, so what if you waste an inch of
stock at a time if you aren't happy with it? This isn't rocket-science
making a plug Airy, just have at it for Pete's sake. I could hold a tiny
Dremel-tool or a big 1/2" drive side-grinder steady enough to do what you're
asking with one eye closed.

"Airy R.Bean" wrote in message
...
How would you set it up to be exactly cutting a diameter?

"Jack Painter" wrote in message
news:kWvFd.15549$B95.11334@lakeread02...
"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.
Hi Airy, couldn't you just use a grinding/cutting wheel to do this job?
Doesn't sound like you need any fancy jig to cut a slot or two into
round
stock.

Sorry, but there is a parallel here with cross-drilling
of round stock. You only need to be a few thou out
for it to be very apparent that the hole is off-centre.

In trying to make a 4-leaf banana plug, with the additional
consideration that material is cut away by the saw or grinding wheel, I
expect that a few thou deviation would result in some leaves
of the plug being considerably weaker. In any case, there is
a certain degree of pride in setting out and achieving a
quality result if that result can be obtained with a few
moments of extra planning.

In any case, it is not the steadiness of hand that is the issue,
but the centring of the tool over the product.

"Jack Painter" wrote in message
news:s1wFd.15551$B95.14894@lakeread02...
I'd put the bar in a vise and do it by hand, so what if you waste an inch
of
stock at a time if you aren't happy with it? This isn't rocket-science
making a plug Airy, just have at it for Pete's sake. I could hold a tiny
Dremel-tool or a big 1/2" drive side-grinder steady enough to do what
you're
asking with one eye closed.

"Airy R.Bean" wrote in message
...
How would you set it up to be exactly cutting a diameter?

"Jack Painter" wrote in message
news:kWvFd.15549$B95.11334@lakeread02...
"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.
Hi Airy, couldn't you just use a grinding/cutting wheel to do this
job?
Doesn't sound like you need any fancy jig to cut a slot or two into
round
stock.

"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)