[SML] question for router wizards

[Steven Hood]

The ellipse with string would work for the first one,  but scaling up would 
be harder. My first instinct would be to use a CAD program to sort my first 
one, then do an offset by the distance you like. As Paul1 said, a jigsaw 
would be less wear on the bits.
That said... I was thinking about making a router base with several 
concentric rings with circles you drop into place or remove to change the 
offset from the bit. You'd need a circle cutting template for the router, 
but you could make a series of incrementally larger of just about anything 
by swapping the circle in the base...
Steven R Hood


On December 17, 2016 7:13:54 PM Dale Farmer via Stagecraft 
<stagecraft at theatrical.net> wrote:

> On 12/17/2016 4:40 PM, Bill Conner via Stagecraft wrote:
>> 4 different ellipses - the axis changes every 90 degrees -  so the
>> ellipsograph seems tricky for a more or less two time use.  It is like
>> guide collars - only probably 2 1/2 to 3 inches apart.  I'll have the
>> "corners" of the mdf I plan to use the template, grid and jig and belt
>> sander, and thought I could make bases out of that.  Rough cu,. attach
>> to router, plunge, and then use router with bit locked down as the
>> pivot to turn base against on a band saw or another router.  Ought to
>> be pretty round and centered.
>>
> If I'm recalling my woodworking class from 40 or so years ago, you can
> easily draw an ellipse on the wood by putting a nail at each focus, then
> using a loop of string to constrain your pencil, just draw the thing.  I
> don't have a formula to calculate the length of the string, as the class
> was back in 7th grade woodshop, and we were making plaques for something.
>    Could scale it up to a loop of rope to constrain the router somehow?
> Or just cut it out with a jigsaw then sand it down to the desired
> dimensions?
>
> --Dale
>
>
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