Ellipse jig

[atgcpaul]

I didn't see a finished ellipse making jig so I'm posting the one I just finished.

I'm making a bent lamination that needs half of an ellipse as the form. My
attempts at using a fair sticking and nails were less than fair. I had trouble
cutting the shape and then sanding a fair edge. I wish I had an edge belt
sander.

Anyway, I looked closely at the Rockler jig and pretty much copied it.

http://images.rockler.com/tech/RTD10000285AA.pdf

The "keys" are 2" lengths of Rockler T-track. They slide in dado grooves that
are cut perpendicular to each other in some plywood. The keys are screwed
to the trammel so they can still freely spin but there is no side to to side
slop. To properly size your jig, you need to know how big your ellipse will be.
The length of the groove measured from the center to the edge must be at
least 1/2 the length of the difference between the major and minor axis.

In this picture you can see the base screwed to my future form and the
trammel laid on edge.




A shot of the jig on the base after cutting close to the line and before cutting
the final ellipse. Hand pressure at the center of the trammel keeps everything
happy.



Paul

[jhart]

Looks like it should work pretty well. Thanks for showing it Paul.

[pelligrini]

That's pretty slick. Thanks for showing.

We do some ellipses in our plans. I had a builder that needed a whole lot more info on laying the ellipse out. I handed him a drawing and said "this ought to do it." You should have seen his face when he looked at a drawing with just two foci dimensioned and a formula calling out the ellipse. He may have bit his tongue too, because he didn't say much. (I did have another drawing fully done using the string method.)

[gsmittle]

OT Response

I have that exact same Griz lam trimmer. How do you like it?

g.

[footprintsinconc]

cool! i think i will have to copy that one day when i have mastered straight cuts first!

[atgcpaul]

I bought the Griz router based on the Wood magazine review last year. It
took 3 visits to the Muncy store before they had it in stock.

It's great for what it is--a small router. It's well suited for these types of
jigs because it's small and easy to mount. It's important to cut away as
much waste as possible because the little motor will bog down and your bits
will dull faster.

I don't think I'll ever need to step up to the Bosch Colt. For half the price of
the Colt, I think I have a pretty nice tool.

[gsmittle]

I bought the Griz router based on the Wood magazine review last year. It
took 3 visits to the Muncy store before they had it in stock.

It's great for what it is--a small router. It's well suited for these types of
jigs because it's small and easy to mount. It's important to cut away as
much waste as possible because the little motor will bog down and your bits
will dull faster.

I don't think I'll ever need to step up to the Bosch Colt. For half the price of
the Colt, I think I have a pretty nice tool.

I bought it after reading the same review. I feel pretty much the same, it's a fine router for what it is. I saw Mythbusters use this same router to fabricate a card-throwing rig once. Cool!

I made Hylton's circle jig for my big router and the flush-trim baseplate for this one. I'll probably never buy a Colt, unless I get a router addiction

g.