I have a need for some 4" circles of 1/8" steel. They have to be pretty flat.
They will wind up with a central hole of 5/8". (Tolerance here is about 1/32",
not really machinist tolerances.) If I could think of a clever way to hold them
by the 5/8" hole really solidly, I might be tempted to try grinding up a
trepanning bit - how hard can it be?

I suppose I could try cutting them with a circle template and a plasma cutter,
or I could make up a bandsaw circle jig and try cutting them on the bandsaw
(don't have a 24tpi blade though) or even borrow someone's hole saw and try
banging them out in one go on the mill. I don't have access to a blanking press.
I only need 3, so it isn't worth having them laser cut.

I have a few days before I need them. What's the easiest way to cut these?

Grant Erwin
Kirkland, Washington

"Grant Erwin" wrote in message
...
I have a need for some 4" circles of 1/8" steel. They have to be pretty
flat. They will wind up with a central hole of 5/8". (Tolerance here is
about 1/32", not really machinist tolerances.) If I could think of a clever
way to hold them by the 5/8" hole really solidly, I might be tempted to try
grinding up a trepanning bit - how hard can it be?

I suppose I could try cutting them with a circle template and a plasma
cutter, or I could make up a bandsaw circle jig and try cutting them on
the bandsaw (don't have a 24tpi blade though) or even borrow someone's
hole saw and try banging them out in one go on the mill. I don't have
access to a blanking press. I only need 3, so it isn't worth having them
laser cut.

I have a few days before I need them. What's the easiest way to cut these?

Grant Erwin
Kirkland, Washington

How about this approach:

1. Rough-cut the circles (a bit oversized) with your favorite cutter
2. Drill a 1/2" hole at the centerpoint of each circle blank
3. Cut the head off of a 1/2" bolt (with a smooth shank) and chuck it in
your lathe
4. Put a nut on the bolt and run it up tight then put the 3 blanks on and
use another nut to clamp them. [Washers optional]
5. Turn to size
6. Re-drill center hole to 5/8"

You DID say you wanted EASY, didn't you?

.... I suppose I could try cutting them with a circle template and a plasma
cutter,
or I could make up a bandsaw circle jig and try cutting them on the
bandsaw (don't have a 24tpi blade though) or even borrow someone's hole
saw and try banging them out in one go on the mill. I don't have access to
a blanking press. I only need 3, so it isn't worth having them laser cut.

I have a few days before I need them. What's the easiest way to cut these?


I needed a whole pile of similar size a while back. Also needed a tighter
spec on size and round. Anyway, I just cut up a bunch of octagons ruff on
bandsaw. Drilled center hole. Then took a piece of all thread and bolted a
whole stack on the lathe though the spindle center hole. Turn to size.

Karl

On Sat, 16 Jul 2005 13:00:07 -0700, Grant Erwin
wrote:

I have a need for some 4" circles of 1/8" steel. They have to be pretty flat.
They will wind up with a central hole of 5/8". (Tolerance here is about 1/32",
not really machinist tolerances.) If I could think of a clever way to hold them
by the 5/8" hole really solidly, I might be tempted to try grinding up a
trepanning bit - how hard can it be?

I suppose I could try cutting them with a circle template and a plasma cutter,
or I could make up a bandsaw circle jig and try cutting them on the bandsaw
(don't have a 24tpi blade though) or even borrow someone's hole saw and try
banging them out in one go on the mill. I don't have access to a blanking press.
I only need 3, so it isn't worth having them laser cut.

I have a few days before I need them. What's the easiest way to cut these?

Grant Erwin
Kirkland, Washington
Lessee Grant, you have a plasma cutter and a lathe. Rough cut the
steel with the plasma cutter. Then put in your 5/8 hole accurately.
Then chuck a 5/8 dowell pin in the lathe leaving .350 sticking out.
Slide the plates on it. Use a live center to press a plate against
your stack of plates that you slid onto the dowell pin. Turn to size.
You need a pretty good live center for this. But pressure turning
works well and is fast to setup. Take light cuts so the plates don't
catch. I used to do a repeat job on an 18" swing lathe where I would
stack up 20 each of 1/4 aluminum rough cut plates. These plates did
not have through holes in the center. I just pressed them against the
chuck jaws with a live center to hold them for turning.
ERS

A plasma torch will cut to that accuracy. Make yourself a washer template
and burn the center hole first. If your edge distance on the torch is say
half inch your center hole on the template would be 1 5/8 and your outside
diameter would be three inches. My first inclination is to hole the
template with a magnet but it may give problems with the plasma cut.
You also could make yourself up a radius cutting attachment to clamp to
your plasma torch much like people use with a oxy acetylene torch.
Randy


"Grant Erwin" wrote in message
...
I have a need for some 4" circles of 1/8" steel. They have to be pretty
flat. They will wind up with a central hole of 5/8". (Tolerance here is
about 1/32", not really machinist tolerances.) If I could think of a clever
way to hold them by the 5/8" hole really solidly, I might be tempted to try
grinding up a trepanning bit - how hard can it be?

I suppose I could try cutting them with a circle template and a plasma
cutter, or I could make up a bandsaw circle jig and try cutting them on
the bandsaw (don't have a 24tpi blade though) or even borrow someone's
hole saw and try banging them out in one go on the mill. I don't have
access to a blanking press. I only need 3, so it isn't worth having them
laser cut.

I have a few days before I need them. What's the easiest way to cut these?

Grant Erwin
Kirkland, Washington

Grant Erwin wrote:
I have a need for some 4" circles of 1/8" steel. They have to be pretty
flat. They will wind up with a central hole of 5/8". (Tolerance here is
about 1/32", not really machinist tolerances.) If I could think of a
clever way to hold them by the 5/8" hole really solidly, I might be
tempted to try grinding up a trepanning bit - how hard can it be?

I suppose I could try cutting them with a circle template and a plasma
cutter, or I could make up a bandsaw circle jig and try cutting them on
the bandsaw (don't have a 24tpi blade though) or even borrow someone's
hole saw and try banging them out in one go on the mill. I don't have
access to a blanking press. I only need 3, so it isn't worth having them
laser cut.

I have a few days before I need them. What's the easiest way to cut these?

Grant Erwin
Kirkland, Washington


A jig saw with a good blade will do the job in a few minutes. True up
the edges with a grinder after cutting.

Gary Brady
Austin, TX

You could use a 4 1/4 hole saw to cut them from flat plate and then enlarge
the pilot hole to 5/8- then put a 5/8 bolt and nut through the hole and
turn the OD to size

"Grant Erwin" wrote in message
...
I have a need for some 4" circles of 1/8" steel. They have to be pretty
flat.
They will wind up with a central hole of 5/8". (Tolerance here is about
1/32",
not really machinist tolerances.) If I could think of a clever way to hold
them
by the 5/8" hole really solidly, I might be tempted to try grinding up a
trepanning bit - how hard can it be?

I suppose I could try cutting them with a circle template and a plasma
cutter,
or I could make up a bandsaw circle jig and try cutting them on the
bandsaw
(don't have a 24tpi blade though) or even borrow someone's hole saw and
try
banging them out in one go on the mill. I don't have access to a blanking
press.
I only need 3, so it isn't worth having them laser cut.

I have a few days before I need them. What's the easiest way to cut these?

Grant Erwin
Kirkland, Washington

On Sat, 16 Jul 2005 13:00:07 -0700, Grant Erwin
wrote:

I have a need for some 4" circles of 1/8" steel. They have to be pretty flat.
They will wind up with a central hole of 5/8". (Tolerance here is about 1/32",
not really machinist tolerances.) If I could think of a clever way to hold them
by the 5/8" hole really solidly, I might be tempted to try grinding up a
trepanning bit - how hard can it be?

I suppose I could try cutting them with a circle template and a plasma cutter,
or I could make up a bandsaw circle jig and try cutting them on the bandsaw
(don't have a 24tpi blade though) or even borrow someone's hole saw and try
banging them out in one go on the mill. I don't have access to a blanking press.
I only need 3, so it isn't worth having them laser cut.

I have a few days before I need them. What's the easiest way to cut these?

Grant Erwin
Kirkland, Washington

I had to make 6 circles recently, 1/8" thick, 6" diameter. They needed
to be nice, so I always intended to lathe turn them. Trouble is, when
I've done it before using a plasma cutter and a compass-style circle
guide, the smallest variation in the angle of the torch head while
cutting left the blanks just inaccurate enough to be a pain to turn on
my small lathe. So this time I cut them square from 6" wide flat
stock, center drilled the squares, and mounted them on my quick and
dirty turntable, which was cobbled for a previous project from a
modified $10 HF boat winch . Added an adjustable arm to hold the torch
head locked in position, and started cranking. It worked so well that
I almost could have skipped the lathe turning. You'd think the
winch-turntable would need a separate ground to the material, but the
current carries through the gear train and bushings without problem.
It's overkill for 1/32 accuracy, but you might find it useful for
other projects. Very low tech, here's a photo
http://www.citlink.net/~wmbjk/images/winchturntable.jpg

Wayne

"wmbjk" wrote in message
...
I had to make 6 circles recently, 1/8" thick, 6" diameter. They needed
to be nice, so I always intended to lathe turn them. Trouble is, when
I've done it before using a plasma cutter and a compass-style circle
guide, the smallest variation in the angle of the torch head while
cutting left the blanks just inaccurate enough to be a pain to turn on
my small lathe. So this time I cut them square from 6" wide flat
stock, center drilled the squares, and mounted them on my quick and
dirty turntable, which was cobbled for a previous project from a
modified $10 HF boat winch . Added an adjustable arm to hold the torch
head locked in position, and started cranking. It worked so well that
I almost could have skipped the lathe turning. You'd think the
winch-turntable would need a separate ground to the material, but the
current carries through the gear train and bushings without problem.
It's overkill for 1/32 accuracy, but you might find it useful for
other projects. Very low tech, here's a photo
http://www.citlink.net/~wmbjk/images/winchturntable.jpg

Wayne

Great idea, I like the way you think!

I had to make 6 circles recently, 1/8" thick, 6" diameter. They needed
to be nice, so I always intended to lathe turn them. Trouble is, when
I've done it before using a plasma cutter and a compass-style circle
guide, the smallest variation in the angle of the torch head while
cutting left the blanks just inaccurate enough to be a pain to turn on
my small lathe. So this time I cut them square from 6" wide flat
stock, center drilled the squares, and mounted them on my quick and
dirty turntable, which was cobbled for a previous project from a
modified $10 HF boat winch . Added an adjustable arm to hold the torch
head locked in position, and started cranking. It worked so well that
I almost could have skipped the lathe turning. You'd think the
winch-turntable would need a separate ground to the material, but the
current carries through the gear train and bushings without problem.
It's overkill for 1/32 accuracy, but you might find it useful for
other projects. Very low tech, here's a photo
http://www.citlink.net/~wmbjk/images/winchturntable.jpg

Wayne

Funny, I'm working on a small winch too! I am going to simply remake the drum,
but different. Then I'm planning to cut the gear off the original drum and weld
it onto this one.

The design is for a table hoist system for an H-frame hydraulic press. I'm
modifying the winch to reel cable in and out both sides instead of just one,
then I'll mount it in the middle of the top and make pulleys on the top corners
and hang the cables from brackets on the outside of the H frame. Hope it works.

Grant

I just made a big specialized washer out of some 3/8 thick material
that I had on hand. I needed a 1.5 inch hole, but first drilled a hole
5/8 inch in diameter as I have a mandrel made of some 5/8 rod that is
threaded for an inch or so. I just use two nuts and clamp whatever
between them. I was not trepanning, but it works well enough to turn
the outside.

Dan

After getting the outside done, I chucked the disk in the lathe and
bored out the inside with a fairly large boring bar.

Grant Erwin wrote:
If I could think of a clever way to hold them
by the 5/8" hole really solidly, I might be tempted to try grinding up a
trepanning bit - how hard can it be?


I only need 3, so it isn't worth having them laser cut.

I have a few days before I need them. What's the easiest way to cut these?

Grant Erwin
Kirkland, Washington

"Eric R Snow" wrote in message
...
snip---

Lessee Grant, you have a plasma cutter and a lathe. Rough cut the
steel with the plasma cutter. Then put in your 5/8 hole accurately.
Then chuck a 5/8 dowell pin in the lathe leaving .350 sticking out.
Slide the plates on it. Use a live center to press a plate against
your stack of plates that you slid onto the dowell pin. Turn to size.
You need a pretty good live center for this. But pressure turning
works well and is fast to setup. Take light cuts so the plates don't
catch. I used to do a repeat job on an 18" swing lathe where I would
stack up 20 each of 1/4 aluminum rough cut plates. These plates did
not have through holes in the center. I just pressed them against the
chuck jaws with a live center to hold them for turning.
ERS

Yep! Works just fine. I've used that system for so many years I've lost
track.

Harold

How about a hole saw??
in a drill press?
cheap tool
a good one would do the job just fine wouldnt it?


Doug


"Grant Erwin" wrote in message
...
I have a need for some 4" circles of 1/8" steel. They have to be pretty
flat. They will wind up with a central hole of 5/8". (Tolerance here is
about 1/32", not really machinist tolerances.) If I could think of a clever
way to hold them by the 5/8" hole really solidly, I might be tempted to try
grinding up a trepanning bit - how hard can it be?

I suppose I could try cutting them with a circle template and a plasma
cutter, or I could make up a bandsaw circle jig and try cutting them on
the bandsaw (don't have a 24tpi blade though) or even borrow someone's
hole saw and try banging them out in one go on the mill. I don't have
access to a blanking press. I only need 3, so it isn't worth having them
laser cut.

I have a few days before I need them. What's the easiest way to cut these?

Grant Erwin
Kirkland, Washington

"Doug Schultz" wrote in message
news:M0mCe.1969525$6l.955770@pd7tw2no...
How about a hole saw??
in a drill press?
cheap tool
a good one would do the job just fine wouldnt it?

I'd be surprised to find a home shop type drill press that could run slow
enough to run a hole saw that size in steel.

Harold

Harold and Susan Vordos wrote:

"Eric R Snow" wrote in message
...
snip---


Lessee Grant, you have a plasma cutter and a lathe. Rough cut the
steel with the plasma cutter. Then put in your 5/8 hole accurately.
Then chuck a 5/8 dowell pin in the lathe leaving .350 sticking out.
Slide the plates on it. Use a live center to press a plate against
your stack of plates that you slid onto the dowell pin. Turn to size.
You need a pretty good live center for this. But pressure turning
works well and is fast to setup. Take light cuts so the plates don't
catch. I used to do a repeat job on an 18" swing lathe where I would
stack up 20 each of 1/4 aluminum rough cut plates. These plates did
not have through holes in the center. I just pressed them against the
chuck jaws with a live center to hold them for turning.
ERS


Yep! Works just fine. I've used that system for so many years I've lost
track.

Harold


Al cuts so nice with a plasma - vaporizes and powers the metal and it cuts.
I tried a small item on my CNC plasma - nice sharp edges.
Martin

--
Martin Eastburn
@ home at Lion's Lair with our computer lionslair at consolidated dot net
NRA LOH, NRA Life
NRA Second Amendment Task Force Charter Founder

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I'd be surprised to find a home shop type drill press that could run slow
enough to run a hole saw that size in steel.

Harold

Yep, Harold. Me too! Most folks don't view the hole saw as a machine
tool - one that has a specific range of speed and feed. The same with
trepanning-type circle "cutters". And reamers - aren't they all the same as
that tapered, sheet metal reamer Granpa used to use? I think the term
"cutter" is what sucks us in. If it says "cutter" anywhere on the label, it
must be easy and safe to use as scissors and other cutters we grew up with.

Bob (Please don't take me back to the old days) Swinney