Cutting rings and circles from plywood

[Les Toombs]

I have a set of plans for a simple paddle wheel boat, that I bought
from RCM Magazine. They are very good plans with plans for
everything, including the boat, paddle wheel, drive system, with
building and finishing instructions.

My problem is that I am a novice and do not know how to cut perfect
rings and circles from plywood. The plans use 1/64, 1/32, 3/32, etc
plywood for the paddle wheel rings, hubs and for the drive belt
pulleys.

If anyone could give me some ideas I would really appreciate it.

Thanks


Les Toombs

[Dallinson]

Les.
Cutting really clean circles can be a problem.
If you want a hand operated method then I would suggest that you get a
gadget called an OLFA CIRCLE CUTTER. Good if your ply is not too thick. Use
the second option if it is thicker.
I can do no better than quote from the Squires catalogue.
FIRST OPTION
"Olfa circle cutter is a high quality cutter specially designed for cutting
accurate circles in plywood, carpet, leather, corrugated card, hobby board
etc. The diameter is adjustable from 7 cm to 30 cm and the depth of cut is
also adjustable allowing materials of various thickness to be cut. The
cutter uses 18mm snap-off blades.". Squires Code No OCMP-2, and a pack of
spare blades is code OLB-10B Cost approx 25 Pounds UK.

SECOND OPTION
If you want to get into cutting circles in thicker material using power then
you want hole cutter.
Again I quote the Squires catalogue:-
Hole Cutter with combination shank for use with a hand brace or power drill.
Speed range 200 RPM when cutting holes above 90mm, increasing to 800 RPM for
40mm diameter holes. The cutter has a wing nut for easy adjustment,
graduated beam and hardened pilot point. For wood and plastics maximum
cutting depth is 30mm. Cutting range 40mm to 120mm. The code number for that
is 48527, cost approx 16 English pounds. From bitter experience you will
need to clamp the work piece very firmly and then use a very fine feed when
running this thing, or it will dig in and destroy itself and the work-piece.

If your local shop doesn't have either of the above then you can get them
mail order from Squires.
An E-mail to sales@squirestools.com should get you moving. Obviously I
don't guarantee anything, but it is a start.
Hope it works out and you get your paddles round.
Best regards
David

[Dallinson]

Les.
I forgot to say that when using either cutter always make a cut, say quarter
to half way through, on one side before turning over and finishing the cut
from the other side. This eliminates any problem with uneven breakthrough
giving rise to splitting or splintering of the ply and ensures that both
sides are super clean. My feeling is that the OLFA cutter would be best bet
for the thickness of ply you are talking about.
Regards
David

[Randal R Largent]

Hi Les,
Is this boat a sidewheeler or stern?
Can you share the issue #etc, and how to get a set of the plans for the
wheels?
Thanks,
Randy

[Les Toombs]

The Boat is a sternwheeler, small (18") overall. but it looks like
you could easily double the size.
The plan are available from
www.rcmmagazine.com

You can go to their plans page
then "By Catagory" > Power boats > Name "Poho"

Plans # 993
RCM 5-87
$8.00 plus $4.00 shipping (I ordered on web and received them in
about a week)