elliptical hole jig or template? Help request

[MusicMan]

I need to cut three elliptical holes in the back on the lap harp that I am constructing (see separate thread). The material is hard maple, 12 mm thick and the ellipses will be roughly 50 x 75, 75 x 100 and 100 x 150 though these are not critical (and may change a bit).

I thought it would be easy enough to find elliptical hole router templates, but I can't find anything suitable. I don't particularly want to lash out the price of a commercial jig for cutting just three holes, nor the construction time to build my own jig.

Does anyone know a source for suitable templates? Or would anyone who owns a suitable jig like to cut me the templates for a suitable price? Or lend me the jig for a bit?

I can't scroll saw it or use the bandsaw now as I have glued it onto the sides of the soundbox! I do know how to construct ellipses so I guess the alternative is to draw them out, cut roughly with a jigsaw and do a lot of hand filing. Or maybe make a jig by hand and then rout it.

Thanks for any input

Keith

 

[RobinBHM]

is this any help?

It doesnt look like much construction time

-maybe it could be used to machine an mdf template that you could then use with a template guide bush.

 

[CHJ]

Know anyone local with a CNC router that can cut you a template.?

As you say easy to draw, not so easy to get he darn things printed to exact scale.

 

[Phil Pascoe]

https://www.blocklayer.com/oval-templates.aspx

 

[monkeybiter]

This link might help show the usual ellipse jig for a router. Not done it yet but they look simple enough to make and use, wether you can use it direct on your work piece or to make a template.
https://youtu.be/KlJr1aqBXxA

 

[MusicMan]

Thanks all.
Robin BHM, you didn't include a link!
Phil.P, that'll be handy if I have to print it and cut by hand.
Monkeybiter, I saw that one but I think my ellipses are going to be smaller than can be managed with this jig (even than the Trend mini-ellipse jig).

CHJ that's an idea. Anyone with a CNC router like a small job? I could probably manage with one template and some router bushes.

 

[Droogs]

If you are looking to make true elipses then you need to make a device called an "Archemedies Trammel". It's not difficult and should take about 30 mins with a table saw. I have 3, one for each of my routers.- a dremel type tool that sits in a veritas plunge base, one for my Katsu-Makita 700 rip off and one for my 1/4" collet Trend. There are plenty of builds on lumberjocks.

heres a wee vid on youtube to give you the general idea.
https://www.youtube.com/watch?v=KlJr1aqBXxA

 

[monkeybiter]

Errrr.....
Two posts above your Droogs...

 

[RobinBHM]

Here it is....

http://www.woodweb.com/knowledge_base/A ... ipses.html

 

[MusicMan]

Droogs, monkeybiter - I'm aware of this jig but not clear how to make or use it for ellipses that are comparable in size or smaller than the router itself? Looks to me as if they can only do ellipses significantly larger than the router.

Keith

 

[SteveF]

http://www.calicocraftparts.co.uk/oval- ... laque.html

may be of use, a bit of messing around but may help

Steve

 

[MusicMan]

Thanks SteveF, that's a workable solution! I have just had a very kind offer from a member to make me an elliptical template for a router, so may have an easier solution, but I appreciate the suggestion and information.

cheers, Keith