Long thin ellipse

[gasman]

Having just gone through the 2 pages of items from searching on the word 'ellipse' on this forum I know this has been discussed a fair few times... but does anyone know how to cut a long thin ellipse with a router?
The problem with the various jigs seems to be that you can only make fat ellipses ie where there is not much difference between the 2 diameters - about 12 inches is as big as the trend jig (which I have) can manage. So does anyone know any other methods? I need to make an ellipse 1300x500mm and although I could easily cut that by hand and then use a spokeshave I want to run an ebony inlay into the edge all round afterwards exactly the same distance from the edge all round. Thanks for helping

 

[9fingers]

I would make a template slightly smaller than your finished size and the use a selection of guide bushes in the router for the edge and the inlay.

The template is possibly best made by drawing - 2 pin and string method and then cutting/finishing to the line.

hth

Bob

 

[JohnBrown]

I cut a couple of elipses a few years back using a method I found somewhere on the web(I can't find it now!). Basically, you make your own jig that works in almost the same way as the cruciform offerings from Trend etc.: Attach a trammel to the router. Screw a couple of ball-races to the trammel. The ball-race closer to the router runs on the bottom edge of the workpiece, or a board clamped to the workpiece. The other ball-race run in a routed slot fixed at 90 degrees to the bottom edge of the workpiece. Ball-races are to found on ebay, or at Clas Ohlson - I bought a pack of 8 intended for inline skates for slightly more than the cost of a single unit.

 

[JohnBrown]

OK, I saved the video on my computer, it's a .WMV file and it's around 20mB.
Sadly, I can't find it on the internet, or I'd post a link. I've no idea if it's possible to attach a .WMV file to a posting here, but I'd be happy email it to you.

John

 

[Steve Maskery]

Steve
You correctly identify the problems with aspect ratio of such an ellipse - the trammel falls out of the cruciform, doesn't it?

When I made this mirror:

I made an MDF template by hand, finishing with a spokeshave. The rebate was cut with a single-point router fence. Whilst I wouldn't recommend a SINGLE-point fence you could make one with two points quite close together so that it runs smoothly around the edge. Yes, I know that there will be a very slightly greater width at the points of the ellipse than at the sides, but it's tiny and not noticeable to anyone (unless they inspect your work with a digital vernier).

Cheers
Steve

 

[gasman]

Steve what were the dimensions of your mirror as I need to make one similar-looking to this in a while. Maybe I could use the same template for the table and the mirror....
Also I like the 2-point idea - also thanks Bob a v good idea. Sounds like I should cut a template maybe a coupe of inches smaller then final size and one or other of those ways should work
Great ideas thanks very much
Best wishe
Mark

 

[Steve Maskery]

Steve
The frame is 1560 tall by 450 wide. The frame width is 60mm.

If you make something like this be careful about how you draw the concentric ellipses. For a start, there is no such thing as a concentric ellipse - they are either concentric or elliptical but they can't be both.

My cheval is elliptical around the outside edge and the inside is parallel to that, then the rebates are parallel to the inside and the bevelling is parallel to the edge of the mirror. The result is that the mirror itself is quite pointed and this is very noticeable at the "point" of the bevel.

What I would do next time is make the inside of the frame the true ellipse and make everything else parallel to that. We live and learn (the hard way, sometimes).

Cheers
Steve

 

[gasman]

Thanks very much Steve - the name's Mark by the way!

 

[Steve Maskery]

the name's Mark by the way!

Oops, sorry! I think we also have a Gasman Steve, just getting confused...

S