What kind of tool can I use to cut a 12" circle from plywood? These need
to be as close to perfectly round as possible. I have quite a few of
these to do.
I don't have a disc sander or a bandsaw for this. I have used a fly
cutter for smaller stuff, but I wouldn't want to use a 12" fly cutter if
they even make one.
Brian Elfert
"Brian Elfert" <[email protected]> wrote in message
news:[email protected]...
> Roy Smith <[email protected]> writes:
>
<snip>
> For one thing, I can't have a 5/8" hole in the center of the circle. A
> small hole would be fine, but not 5/8".
>
> I'm thinking about a Dremel or Dewalt cut-off tool with a circle cutting
> guide. About $80 total.
>
> Brian Elfert
Unless you have other uses in mind for either the Dremel of DW imo a circle
attachment for your existing router would be a better buy.
As I have a router table with a miter slot I have a scrap miter bar with
small screw that sticks up as a pivot, I put a stop at the requred radius
for the bar and then I can feed the work into the router.
You didn't say what thickness of ply you are working with but I found the
Dremel and similar size tools under powered for most any wood working job
unless using very small bits and/or very light cuts.
Bernard R
Bernard R
With a 1/4" tool bit in the router at the
http://www.patwarner.com/621_offset.html link you can set up & cut a
12.00" diameter circle in 2 minutes or less.
**************************************************************
> What kind of tool can I use to cut a 12" circle from plywood? These need
> to be as close to perfectly round as possible. I have quite a few of
> these to do.
>
> I don't have a disc sander or a bandsaw for this. I have used a fly
> cutter for smaller stuff, but I wouldn't want to use a 12" fly cutter if
> they even make one.
>
> Brian Elfert
DanG wrote:
>
> It depends a bit on the tools that you have. The easiest tools
> with which to work accurately would be a table saw or a router.
> Both of these will require a small pivot pin hole in the center of
> your finish disk....
Finish with a stationary belt or disk sander, with a similar jig,
for a sweet-looking finish.
"J. Clarke" <[email protected]> writes:
>It would help if you said what tools you _do_ have.
I have a router, shaper, table saw, drill press, and scroll saw.
Brian Elfert
Roy Smith <[email protected]> writes:
>mount it on the saw arbor. Lower the blade height adjustment until the
>entire workpiece is below the table. Take a sheet of 36 grit sandpaper
>and lay it grit-side down over the blade slot. Back it up with a piece
>of 3/4" plywood. Now turn on the saw and slowly raise the blade height
>adjustment. The sandpaper will grind the edge of the workpiece into a
>perfect circle.
For one thing, I can't have a 5/8" hole in the center of the circle. A
small hole would be fine, but not 5/8".
I'm thinking about a Dremel or Dewalt cut-off tool with a circle cutting
guide. About $80 total.
Brian Elfert
Brian Elfert wrote:
> Roy Smith <[email protected]> writes:
>
>
>>mount it on the saw arbor. Lower the blade height adjustment until the
>>entire workpiece is below the table. Take a sheet of 36 grit sandpaper
>>and lay it grit-side down over the blade slot. Back it up with a piece
>>of 3/4" plywood. Now turn on the saw and slowly raise the blade height
>>adjustment. The sandpaper will grind the edge of the workpiece into a
>>perfect circle.
>
>
> For one thing, I can't have a 5/8" hole in the center of the circle. A
> small hole would be fine, but not 5/8".
>
> I'm thinking about a Dremel or Dewalt cut-off tool with a circle cutting
> guide. About $80 total.
>
> Brian Elfert
Somebody already mentioned a circle cutting jig you can make out of
scrapwood to use with your router, so there is no need to shell out $80
for one. If you don't want to put any holes in your circular pieces,
you could temporarily glue on a scrap block that would hold the pivot
hinge. I made a rough drawing showing what I mean. It's not to scale,
and you'd probably want to include some washers and glue up a strip of
sandpaper between the pieces to keep it from slipping, but should be
good enough to give you an idea:
http://www.skunkduster.com/woodworking/circlejig.gif
Good luck!
-Rick
It depends a bit on the tools that you have. The easiest tools
with which to work accurately would be a table saw or a router.
Both of these will require a small pivot pin hole in the center of
your finish disk.
Table saw method:
If you already own a sled, great. It does not matter whether it
is one sided or on both sides of the blade. The center of the
disk that you want to make needs to be the radius distance away
from the blade. Square cut all your disks first. Install the
sled. Tack the piece to the sled with a pivot pin ( I usually use
a #4 finish nail on 3/4" material) Turn the square's corners off
the edge of the sled and cut them off, repeat until you have an
extremely rough beginning of a circle. Turn the disk in a circle
where the high corners are just bumping the blade, move the sled
forward slightly and repeat until you get to the full diameter.
You will get really true circles with reasonable finish. This
method is faster than working with a router in my opinion, though
I have both.
Router method #1:
Mount the router to a scrap of material. 1/4" Plexiglas or
plywood comes to mind. You can remove the router's plastic base
and reuse the machine screws to hold the base on the ply strip.
Run the router bit you intend to use through the ply. Measure out
the radius amount and tack onto your disk material at its mid
point. You will have to adjust the router's depth of cut 3 or 4
times for 3/4 material, but you can get extremely accurate disks.
Router method #2
If you have a router table, combine the thoughts from 1 and 2.
Hope this helps.
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Keep the whole world singing. . . .
DanG
"Brian Elfert" <[email protected]> wrote in message
news:[email protected]...
> What kind of tool can I use to cut a 12" circle from plywood?
These need
> to be as close to perfectly round as possible. I have quite a
few of
> these to do.
>
> I don't have a disc sander or a bandsaw for this. I have used a
fly
> cutter for smaller stuff, but I wouldn't want to use a 12" fly
cutter if
> they even make one.
>
> Brian Elfert
Brian Elfert wrote:
> What kind of tool can I use to cut a 12" circle from plywood? These need
> to be as close to perfectly round as possible. I have quite a few of
> these to do.
>
> I don't have a disc sander or a bandsaw for this. I have used a fly
> cutter for smaller stuff, but I wouldn't want to use a 12" fly cutter if
> they even make one.
>
> Brian Elfert
making just a few. Screw a piece of plexiglass to the bottom of a router
with a 1/4" sprial cut bit. Measure form the outside of the router to a
spot 6" away on the plexi and screw it to the center of the circle.
On 10 May 2004 01:15:19 GMT, Brian Elfert <[email protected]> wrote:
>What kind of tool can I use to cut a 12" circle from plywood? These need
>to be as close to perfectly round as possible. I have quite a few of
>these to do.
>
>I don't have a disc sander or a bandsaw for this. I have used a fly
>cutter for smaller stuff, but I wouldn't want to use a 12" fly cutter if
>they even make one.
You can do it with a jigsaw, scrollsaw or a router. You could probably get a
nice clean circle using a beltsander on it's side and a jig (after rough cutting
them). Maybe you could toss a stack of them on a lathe. Table saw might work
ok if you cleaned them up afterwards. What tools do you have?
JP
Router with a circle cutting base.
John
On 10 May 2004 01:15:19 GMT, Brian Elfert <[email protected]> wrote:
>What kind of tool can I use to cut a 12" circle from plywood? These need
>to be as close to perfectly round as possible. I have quite a few of
>these to do.
>
>I don't have a disc sander or a bandsaw for this. I have used a fly
>cutter for smaller stuff, but I wouldn't want to use a 12" fly cutter if
>they even make one.
>
>Brian Elfert
Brian Elfert wrote:
> What kind of tool can I use to cut a 12" circle from plywood? These need
> to be as close to perfectly round as possible. I have quite a few of
> these to do.
>
> I don't have a disc sander or a bandsaw for this. I have used a fly
> cutter for smaller stuff, but I wouldn't want to use a 12" fly cutter if
> they even make one.
It would help if you said what tools you _do_ have.
> Brian Elfert
--
--John
Reply to jclarke at ae tee tee global dot net
(was jclarke at eye bee em dot net)
Roy,
LOL You had me going there for a moment. I could just picture a piece of
plywood spinning four thousand RPM's and out of bounce.
Gary
"Roy Smith" <[email protected]> wrote in message
news:[email protected]...
> In article <[email protected]>,
> Brian Elfert <[email protected]> wrote:
>
> > Roy Smith <[email protected]> writes:
> >
> > >mount it on the saw arbor. Lower the blade height adjustment until the
> > >entire workpiece is below the table. Take a sheet of 36 grit sandpaper
> > >and lay it grit-side down over the blade slot. Back it up with a piece
> > >of 3/4" plywood. Now turn on the saw and slowly raise the blade height
> > >adjustment. The sandpaper will grind the edge of the workpiece into a
> > >perfect circle.
> >
> > For one thing, I can't have a 5/8" hole in the center of the circle. A
> > small hole would be fine, but not 5/8".
> >
> > I'm thinking about a Dremel or Dewalt cut-off tool with a circle cutting
> > guide. About $80 total.
> >
> > Brian Elfert
>
> In case it wasn't obvious, I was only joking. What I described is an
> entry for the Darwin Awards, not a technique I was seriously suggesting
> you try.
Ooops, make that out of balance. (No problem with it bouncing, all over the
shop.)
"Gary" <[email protected]> wrote in message
news:[email protected]...
> Roy,
>
> LOL You had me going there for a moment. I could just picture a piece of
> plywood spinning four thousand RPM's and out of bounce.
>
> Gary
> "Roy Smith" <[email protected]> wrote in message
> news:[email protected]...
> > In article <[email protected]>,
> > Brian Elfert <[email protected]> wrote:
> >
> > > Roy Smith <[email protected]> writes:
> > >
> > > >mount it on the saw arbor. Lower the blade height adjustment until
the
> > > >entire workpiece is below the table. Take a sheet of 36 grit
sandpaper
> > > >and lay it grit-side down over the blade slot. Back it up with a
piece
> > > >of 3/4" plywood. Now turn on the saw and slowly raise the blade
height
> > > >adjustment. The sandpaper will grind the edge of the workpiece into
a
> > > >perfect circle.
> > >
> > > For one thing, I can't have a 5/8" hole in the center of the circle.
A
> > > small hole would be fine, but not 5/8".
> > >
> > > I'm thinking about a Dremel or Dewalt cut-off tool with a circle
cutting
> > > guide. About $80 total.
> > >
> > > Brian Elfert
> >
> > In case it wasn't obvious, I was only joking. What I described is an
> > entry for the Darwin Awards, not a technique I was seriously suggesting
> > you try.
>
>
Brian Elfert wrote:
> "J. Clarke" <[email protected]> writes:
>
>>It would help if you said what tools you _do_ have.
>
> I have a router, shaper, table saw, drill press, and scroll saw.
Router's the obvious choice. Quick and dirty, find a scrap of something
long enough to serve as the circle guide and not too thick (piece of 1/8"
Masonite for example). Pull the plastic shoe off the base of the router
and use it to mark where you need holes in the new guide. Drill the holes
including the center hole (hole saw or Forstner is handy for that),
countersink the screw holes, screw the guide onto the router. Measure from
the edge of the bit however far you need to go to put your pivot hole--if
you're making a disk then measure to the inside edge of the bit, if you're
making a hole then remember to subtract the diameter of the bit. If you
can afford a hole in the center then drill one and drop a drill bit or nail
or whatever into it to act as a pivot. Cut--if you're cutting a disk go
clockwise, if a hole then counterclockwise. You may need to make several
passes.
If you can't afford a hole in the center then use a piece of scrap and stick
it down with double-sided tape.
From here you can get as fancy as you want.
If you've got the edge guide for the router you can make a piece that clamps
down on the guide-rods and has a projection that fits in your pivot-hole.
The Rotozips and the like work very nicely for plaster and drywall, but the
bits they provide for wood aren't all that good--they cut slowly and tend
to flex, not to mention they're down-spiral not up-spiral, so they tend to
push the dust into the groove instead of pulling it out. I haven't tried a
quarter inch spiral cut router bit in the Rotozip--if it's got enough power
to swing it it might work nicely.
> Brian Elfert
--
--John
Reply to jclarke at ae tee tee global dot net
(was jclarke at eye bee em dot net)
"Brian Elfert" <[email protected]> wrote in message
news:[email protected]...
> What kind of tool can I use to cut a 12" circle from plywood? These need
> to be as close to perfectly round as possible. I have quite a few of
> these to do.
>
> I don't have a disc sander or a bandsaw for this. I have used a fly
> cutter for smaller stuff, but I wouldn't want to use a 12" fly cutter if
> they even make one.
>
> Brian Elfert
Woodworker's Journal, January/February 2003, had an article on cutting
circles using a bandsaw. They showed the plans for a sled and the hardware
is available at Rockler.
For the sled I used a piece of MDO that I had and put a runner on the bottom
to ride in the table slot. On the top I routed a groove perpendicular to the
runner and screwed in a track that holds a pin point. Once in place, you
push the board forward until the pit is at the front of the blade. Now you
put a stop as this will give you the centerline for cutting.
The pin can be set at the radius you desire, the blank is put on the pin and
the sled is pushed into the blade until the stop hits. Now you just rotate
the blank and you get a circle cutout.
I thought it was a nifty idea so I built one, but never needed to cut a
circle until last week. At least I was ready! I made wheels for a chaise
lounge that I'm building now. They came out very nice, easy to do.
Ed
[email protected]
http://pages.cthome.net/edhome
On Mon, 10 May 2004 19:58:56 -0700, Rick Nelson
<[email protected]> wrote:
>Somebody already mentioned a circle cutting jig you can make out of
>scrapwood to use with your router, so there is no need to shell out $80
>for one. If you don't want to put any holes in your circular pieces,
>you could temporarily glue on a scrap block that would hold the pivot
>hinge.
Why not make a larger cutout from scrap, for which you can use a
center point. A bit of careful sanding, then use that as an outside
template for the router.
Bill.
In article <[email protected]>,
Brian Elfert <[email protected]> wrote:
> Roy Smith <[email protected]> writes:
>
> >mount it on the saw arbor. Lower the blade height adjustment until the
> >entire workpiece is below the table. Take a sheet of 36 grit sandpaper
> >and lay it grit-side down over the blade slot. Back it up with a piece
> >of 3/4" plywood. Now turn on the saw and slowly raise the blade height
> >adjustment. The sandpaper will grind the edge of the workpiece into a
> >perfect circle.
>
> For one thing, I can't have a 5/8" hole in the center of the circle. A
> small hole would be fine, but not 5/8".
>
> I'm thinking about a Dremel or Dewalt cut-off tool with a circle cutting
> guide. About $80 total.
>
> Brian Elfert
In case it wasn't obvious, I was only joking. What I described is an
entry for the Darwin Awards, not a technique I was seriously suggesting
you try.
In article <[email protected]>,
Brian Elfert <[email protected]> wrote:
> "J. Clarke" <[email protected]> writes:
>
> >It would help if you said what tools you _do_ have.
>
> I have a router, shaper, table saw, drill press, and scroll saw.
>
> Brian Elfert
Rough cut the circle oversize on the scroll saw. Drill a hole in the
middle of the piece the same diameter as the arbor on your table saw and
mount it on the saw arbor. Lower the blade height adjustment until the
entire workpiece is below the table. Take a sheet of 36 grit sandpaper
and lay it grit-side down over the blade slot. Back it up with a piece
of 3/4" plywood. Now turn on the saw and slowly raise the blade height
adjustment. The sandpaper will grind the edge of the workpiece into a
perfect circle.
OK, so it's not a very good way, but I'm in a strange mood this morning
:-)