Hi,
About once a year I make about 200 disc out of MDF. These disc are
3.25 inch in diameter, 1/2" thick with an axial 3/8" hole. The rim of
the disc has a groove 1/4" deep and 1/4' wide around the circumference
so that from the side a cross-section looks like:
__ __
| | | |
| |__| |
| |
| |
| |
| |
| |
| |
| |
| |
| |
| __ |
| | | |
|_| |_|
I cut the MDF into squares and then gang cut these squares into
octagons. Up to this point things go fast. Next,I mount about a dozen
octagons at a time on a threaded rod which is held in a metal turning
lathe by a three jaw chuck and a live center in the tailstock. Things
do no have to be very precise so I can eyeball the side-to-side position
of the groove and use a stop to control the depth. My cutter is the
width of the groove. I have colored paper between the octagons so that
I can more easily see where to cut the groove.
Is there some easier way to do this? Molded solid platic probably
could work, but the cost for a small run might be high, I have thought
of using a hole saw and cut two thin (0.125") discs 3.25" diameter with
a hole saw and a 2.75 diameter disc that is 0.25 thick. But my
experience with hole saws usually involve lots of fighting to get the
disc free.
Any ideas? Thanks
Roger Haar
Roger Haar wrote:
> Hi,
>
> About once a year I make about 200 disc out of MDF. These disc are
> 3.25 inch in diameter, 1/2" thick with an axial 3/8" hole. The rim of
> the disc has a groove 1/4" deep and 1/4' wide around the circumference
> so that from the side a cross-section looks like:
>
> __ __
> | | | |
> | |__| |
> | |
> | |
> | |
> | |
> | |
> | |
> | |
> | |
> | |
> | __ |
> | | | |
> |_| |_|
>
>
> I cut the MDF into squares and then gang cut these squares into
> octagons. Up to this point things go fast. Next,I mount about a dozen
> octagons at a time on a threaded rod which is held in a metal turning
> lathe by a three jaw chuck and a live center in the tailstock. Things
> do no have to be very precise so I can eyeball the side-to-side position
> of the groove and use a stop to control the depth. My cutter is the
> width of the groove. I have colored paper between the octagons so that
> I can more easily see where to cut the groove.
>
> Is there some easier way to do this? Molded solid platic probably
> could work, but the cost for a small run might be high, I have thought
> of using a hole saw and cut two thin (0.125") discs 3.25" diameter with
> a hole saw and a 2.75 diameter disc that is 0.25 thick. But my
> experience with hole saws usually involve lots of fighting to get the
> disc free.
>
>
> Any ideas? Thanks
>
> Roger Haar
Think about a router with table. Groove cutters for routers are
available in sizes to suit your need.
The router table should come equipped with a miter fence, like a table
saw. You could mount a vertical pin on the miter slide bar to act as a
pivot for the drilled octagon blanks. Mount a blank on the pin, shove
it in to a stop, and rotate it with a suitable pusher -- keep fingers
out. A small plumber's helper would do for a pusher. Once set up, you
should be able to turn out two or three disks per minute.
Side benefit. This is a very good excuse to buy that router you've
always wanted.
Pat
Roger Haar wrote:
> About once a year I make about 200 disc out of MDF. These disc are
> 3.25 inch in diameter, 1/2" thick with an axial 3/8" hole. The rim of
> the disc has a groove
Easiest way to make disks is with a hole saw; your axial hole is a tad
bigger than the
pilot drills, so the hole and groove will probably need separate
operations.
Carbide-tip and high quality holesaws have proper tooth set and the
disks will come
cleanly free. Unlike square-then-cut processes, you will be able to
cut disks in
a hexagonal array (less waste) and might be able to get more from a
sheet.
I'd think of a lathe faceplate with a centering pin, perhaps just
clamped with
a live center; it'd be quick to unclamp and go to the next workpiece.
And if you can do it, grind a long 3/8" drill's tip to make a pilot
that matches
the holesaw's pilot, then the drill-out of the center is just a matter
of handheld
drilling in a drill press,
They wouldn't get stuck in this:
http://www.leevalley.com/wood/page.aspx?c=2&p=32275&cat=1,180,42316&ap=1
And you could gang them together, a stack of the smaller inner disk,
then a stack of the larger outer disk. You wouldn't have to adhere the
layers together either. If you started with 4"x4" squares, you could
use that shape to line them up on the DP against a fence and stop.
If the drill hole in the middle is 1/4 instead of 3/8, it would be easy
to mount a jig on the drill press to line up the disks exactly to drill
the holes out to 3/8.
Glue them up on the threaded rod in stacks. Mayme make wooden pieces
for the ends to distribute pressure, then crank down some nuts on the
threaded rod to act as clamps. The only problem I see with this is
squeeze-out polluting the 1/4" grooves. If you're careful, you could
probably eliminate that. Or you could use high-tack spray adhesive to
bond the three disks together.
brian
Roger Haar wrote:
>I have thought
> of using a hole saw and cut two thin (0.125") discs 3.25" diameter with
> a hole saw and a 2.75 diameter disc that is 0.25 thick. But my
> experience with hole saws usually involve lots of fighting to get the
> disc free.
Use a circle cutter which will leave a center hole for the axle too.
http://www.constantines.com/browseproducts/Wheel-and-Circle-Cutter.html
Then, on the router table get a slot cutting bit. Make a jig that fits
in the table slot and has a pin for holding the circle center. Setup a
stop on the table so you slide the jig forward until the slot cutter is
to the depth you want, then spin the circle.
Be careful to keep the circle from spinning out of control and wear a
mask if useing MDF.
Roger Haar wrote:
> Hi,
>
> About once a year I make about 200 disc out of MDF. These disc are
> 3.25 inch in diameter, 1/2" thick with an axial 3/8" hole. The rim of
> the disc has a groove 1/4" deep and 1/4' wide around the circumference
> so that from the side a cross-section looks like:
>
> __ __
> | | | |
> | |__| |
> | |
> | |
> | |
> | |
> | |
> | |
> | |
> | |
> | |
> | __ |
> | | | |
> |_| |_|
>
>
> I cut the MDF into squares and then gang cut these squares into
> octagons. Up to this point things go fast. Next,I mount about a dozen
> octagons at a time on a threaded rod which is held in a metal turning
> lathe by a three jaw chuck and a live center in the tailstock. Things
> do no have to be very precise so I can eyeball the side-to-side position
> of the groove and use a stop to control the depth. My cutter is the
> width of the groove. I have colored paper between the octagons so that
> I can more easily see where to cut the groove.
>
> Is there some easier way to do this? Molded solid platic probably
> could work, but the cost for a small run might be high, I have thought
> of using a hole saw and cut two thin (0.125") discs 3.25" diameter with
> a hole saw and a 2.75 diameter disc that is 0.25 thick. But my
> experience with hole saws usually involve lots of fighting to get the
> disc free.
>
>
> Any ideas? Thanks
>
> Roger Haar
Roger Haar wrote:
> Hi,
>
> About once a year I make about 200 disc out of MDF. These disc are
> 3.25 inch in diameter, 1/2" thick with an axial 3/8" hole. The rim of
> the disc has a groove 1/4" deep and 1/4' wide around the circumference
> so that from the side a cross-section looks like:
>
> __ __
> | | | |
> | |__| |
> | |
> | |
> | |
> | |
> | |
> | |
> | |
> | |
> | |
> | __ |
> | | | |
> |_| |_|
>
>
> I cut the MDF into squares and then gang cut these squares into
> octagons. Up to this point things go fast. Next,I mount about a dozen
> octagons at a time on a threaded rod which is held in a metal turning
> lathe by a three jaw chuck and a live center in the tailstock. Things
> do no have to be very precise so I can eyeball the side-to-side position
> of the groove and use a stop to control the depth. My cutter is the
> width of the groove. I have colored paper between the octagons so that
> I can more easily see where to cut the groove.
>
> Is there some easier way to do this? Molded solid platic probably
> could work, but the cost for a small run might be high, I have thought
> of using a hole saw and cut two thin (0.125") discs 3.25" diameter with
> a hole saw and a 2.75 diameter disc that is 0.25 thick. But my
> experience with hole saws usually involve lots of fighting to get the
> disc free.
>
>
> Any ideas? Thanks
>
> Roger Haar
I've had a couple of projects like this where I've cut two larger disks
and a smaller, then glued them together. If you've got a rigid drill
press or mill, General makes sort of a flycutter gizmo for trepanning
out circles, the local True Value and Ace stores have them. I replace
the center drill bit with a length of rod so the hole doesn't get
wallowed out. .25" MDF would be fast to cut, you might want to make a
bit ground out of some better stuff than the supplied cutter is made
of, good enough for wood, but not for abrasive stuff. The flycutter
gives you better control over diameter than a hole saw would and the
disks are easy to remove.
Stan
I think I would start by cutting strips of the MDF 3 3/8 wide X 48 long.
Next, I would draw a center line down the middle of the strip and walk of
center points with a set of dividers every 3.4 inches.
Set up your drill press with a fence and drill your blanks with the circle
cutter others have mentioned.
One thing others have not suggested is using a router bit with a bearing on
it to control the depth of the cut. This is a whole lot easier than rigging
a fence.
The slot can also be done on the lathe, easiest would be a metal lathe with
a mandrel set up, but the router would be the quickest way.
Last step would be to enlarge the 1/4" hole to 3/8". To do this I would
make a jig by screwing a piece of 1/4" or 3/8" to a sheet of 1/2" or 3/4"
and adjust your circle cutter so that the hole you make has an inside
diameter of 3 1/4 so your parts fit snug. With this clamped on your drill
press you should be able to drill out the pilot hole to size with no
problem.
I would recommend either a forstner bit or a brad point bit and to prevent
tearout, you might want to punch it half way and flip the disk over.
What are you using all of these disks for anyway?
--
Roger Shoaf
About the time I had mastered getting the toothpaste back in the tube, then
they come up with this striped stuff.
"Roger Haar" <[email protected]> wrote in message
news:[email protected]...
> Hi,
>
> About once a year I make about 200 disc out of MDF. These disc are
> 3.25 inch in diameter, 1/2" thick with an axial 3/8" hole. The rim of
> the disc has a groove 1/4" deep and 1/4' wide around the circumference
> so that from the side a cross-section looks like:
>
> __ __
> | | | |
> | |__| |
> | |
> | |
> | |
> | |
> | |
> | |
> | |
> | |
> | |
> | __ |
> | | | |
> |_| |_|
>
>
> I cut the MDF into squares and then gang cut these squares into
> octagons. Up to this point things go fast. Next,I mount about a dozen
> octagons at a time on a threaded rod which is held in a metal turning
> lathe by a three jaw chuck and a live center in the tailstock. Things
> do no have to be very precise so I can eyeball the side-to-side position
> of the groove and use a stop to control the depth. My cutter is the
> width of the groove. I have colored paper between the octagons so that
> I can more easily see where to cut the groove.
>
> Is there some easier way to do this? Molded solid platic probably
> could work, but the cost for a small run might be high, I have thought
> of using a hole saw and cut two thin (0.125") discs 3.25" diameter with
> a hole saw and a 2.75 diameter disc that is 0.25 thick. But my
> experience with hole saws usually involve lots of fighting to get the
> disc free.
>
>
> Any ideas? Thanks
>
> Roger Haar
>
In rec.crafts.metalworking [email protected] wrote:
>Roger Haar wrote:
>> About once a year I make about 200 disc out of MDF. These disc are
>> 3.25 inch in diameter, 1/2" thick with an axial 3/8" hole. The rim of
>> the disc has a groove 1/4" deep and 1/4' wide around the circumference
>> so that from the side a cross-section looks like:
--Just out of curiosity what's the application??
>Think about a router with table. Groove cutters for routers are
>available in sizes to suit your need.
--What he said, but I'd suggest using vacuum fixtures to hold each
part in place on a series of stages, each equipped with a template so that
the parts could be routed in steps, so you'd only have to change bits once
for each batch. I've done production work with routers and fixtures and this
is a reeeally fast method for multiple parts. As you move down the line
towards finished part you can make use of the evolving part shape to design
fixtures to hold it in different ways.
--
"Steamboat Ed" Haas : Proud to be the
Hacking the Trailing Edge! : family crackpot!
www.nmpproducts.com
---Decks a-wash in a sea of words---
Roger Haar wrote:
> Hi,
>
> About once a year I make about 200 disc out of MDF. These disc are
> 3.25 inch in diameter, 1/2" thick with an axial 3/8" hole. The rim of
> the disc has a groove 1/4" deep and 1/4' wide around the circumference
> so that from the side a cross-section looks like:
>
> __ __
> | | | |
> | |__| |
> | |
> | |
> | |
> | |
> | |
> | |
> | |
> | |
> | |
> | __ |
> | | | |
> |_| |_|
>
>
> I cut the MDF into squares and then gang cut these squares into
> octagons. Up to this point things go fast. Next,I mount about a dozen
> octagons at a time on a threaded rod which is held in a metal turning
> lathe by a three jaw chuck and a live center in the tailstock. Things
> do no have to be very precise so I can eyeball the side-to-side position
> of the groove and use a stop to control the depth. My cutter is the
> width of the groove. I have colored paper between the octagons so that
> I can more easily see where to cut the groove.
>
> Is there some easier way to do this? Molded solid platic probably
> could work, but the cost for a small run might be high, I have thought
> of using a hole saw and cut two thin (0.125") discs 3.25" diameter with
> a hole saw and a 2.75 diameter disc that is 0.25 thick. But my
> experience with hole saws usually involve lots of fighting to get the
> disc free.
>
>
> Any ideas? Thanks
>
> Roger Haar
>
If it works for you to assemble them and glue -- what about having your
blanks laser cut, and gluing them together using a 3/8" mandrel? This
will go a lot quicker for you, and having 600 pieces cut should spread
out the laser cutter's set-up and programming costs nicely.
--
Tim Wescott
Wescott Design Services
http://www.wescottdesign.com
Posting from Google? See http://cfaj.freeshell.org/google/
"Applied Control Theory for Embedded Systems" came out in April.
See details at http://www.wescottdesign.com/actfes/actfes.html
"Roger Haar" <[email protected]> wrote in message
news:[email protected]...
> Hi,
>
> About once a year I make about 200 disc out of MDF. These disc are 3.25
> inch in diameter, 1/2" thick with an axial 3/8" hole. The rim of the disc
> has a groove 1/4" deep and 1/4' wide around the circumference so that from
> the side a cross-section looks like:
>
> __ __
> | | | |
> | |__| |
> | |
> | |
> | |
> | |
> | |
> | |
> | |
> | |
> | |
> | __ |
> | | | |
> |_| |_|
>
>
> I cut the MDF into squares and then gang cut these squares into octagons.
> Up to this point things go fast. Next,I mount about a dozen octagons at a
> time on a threaded rod which is held in a metal turning lathe by a three
> jaw chuck and a live center in the tailstock. Things do no have to be
> very precise so I can eyeball the side-to-side position of the groove and
> use a stop to control the depth. My cutter is the width of the groove. I
> have colored paper between the octagons so that I can more easily see
> where to cut the groove.
>
> Is there some easier way to do this? Molded solid platic probably could
> work, but the cost for a small run might be high, I have thought of using
> a hole saw and cut two thin (0.125") discs 3.25" diameter with a hole saw
> and a 2.75 diameter disc that is 0.25 thick. But my experience with hole
> saws usually involve lots of fighting to get the disc free.
>
>
> Any ideas? Thanks
>
> Roger Haar
>
How long does it take to do them now?
Roger Haar wrote:
> Hi,
>
> About once a year I make about 200 disc out of MDF. These disc are
> 3.25 inch in diameter, 1/2" thick with an axial 3/8" hole. The rim of
> the disc has a groove 1/4" deep and 1/4' wide around the circumference
> so that from the side a cross-section looks like:
>
> __ __
> | | | |
> | |__| |
> | |
> | |
> | |
> | |
> | |
> | |
> | |
> | |
> | |
> | __ |
> | | | |
> |_| |_|
>
>
> I cut the MDF into squares and then gang cut these squares into
> octagons. Up to this point things go fast. Next,I mount about a dozen
> octagons at a time on a threaded rod which is held in a metal turning
> lathe by a three jaw chuck and a live center in the tailstock. Things
> do no have to be very precise so I can eyeball the side-to-side position
> of the groove and use a stop to control the depth. My cutter is the
> width of the groove. I have colored paper between the octagons so that
> I can more easily see where to cut the groove.
>
> Is there some easier way to do this? Molded solid platic probably
> could work, but the cost for a small run might be high, I have thought
> of using a hole saw and cut two thin (0.125") discs 3.25" diameter with
> a hole saw and a 2.75 diameter disc that is 0.25 thick. But my
> experience with hole saws usually involve lots of fighting to get the
> disc free.
>
>
> Any ideas? Thanks
>
> Roger Haar
>
I'd use a router and a circle cutting jig, sort of like a trammel point.
One operation for the intitial cutout, and another for the groove on
the edge. The circle cutting jig makes an exact circle but there's no
possiblility of gang cutting.
--
Gary Brady
Austin, TX
www.powdercoatoven.4t.com
I've got one of those cutters and it works very well for making round things
out of stock. I've even done 3/4" stock with no problems. Make sure that
you hold the material down firmly as the drill bit can walk about and
enlarge the hole even tho it is a special cut with no side cutting tooth.
--
Yeppie, Bush is such an idiot that He usually outwits
everybody else. How dumb!
On Mon, 16 Oct 2006 10:33:34 -0700, Roger Haar
<[email protected]> wrote:
>Hi,
>
> About once a year I make about 200 disc out of MDF. These disc are
>3.25 inch in diameter, 1/2" thick with an axial 3/8" hole. The rim of
>the disc has a groove 1/4" deep and 1/4' wide around the circumference
>so that from the side a cross-section looks like:
>
> I cut the MDF into squares and then gang cut these squares into
>octagons. Up to this point things go fast. Next,I mount about a dozen
>octagons at a time on a threaded rod which is held in a metal turning
>lathe by a three jaw chuck and a live center in the tailstock. Things
>do no have to be very precise so I can eyeball the side-to-side position
>of the groove and use a stop to control the depth. My cutter is the
>width of the groove. I have colored paper between the octagons so that
>I can more easily see where to cut the groove.
I think the way you're doing it is pretty effective. Instead of
cutting off the corners you might be better off ganging them into a
shorter stack and cutting them slightly oversize with a circle cutting
jig on the bandsaw.
To speed up the cutting of the grooves you could make a notched jig
for the tool rest that would control the position and depth of cut.
You could also make a "forked" cutter that would do two grooves at
once.
I can't see cutting them one at a time on a router table being faster.
-Leuf