Help with Roundover

[Darren Vass]

I'm working on building a subwoofer. I really like the box in the pic below, especially in nice veneer. It is a 20 inch cube with wall thickness of 1.5 inches, MDF. Does anyone have an idea of how to do the roundovers in the pic? Don't they look rather large? Just for perspective, the large circle hole is about 15 inches and the smaller one that is covered by the grill is 12 inches. Do you think I could do this with a router bit, table or hand held? Would you do the roundover on the completed box edge or can one do it on the preassembled box, so that when glued up, the roundover would be larger?

Thanks,

Darren

http://i1025.photobucket.com/albums/y313/dian1511/dsc5993.jpg

[Stephen Cherry]

This looks like a job for a shaper, but Whiteside makes some large roundover bits (1 1/2 radius) that may work. You might want to consider taking the bulk of the material with a table saw, mounting the router in a table and making a couple passes. And possibly even some sort of dust mask.

[Rob Woodman]

Darren, your limitation will be the size of round over bit you can buy that your router can handle while in a table. Large bits generally require a slower machine speed and for the router to be in a table and may require several passes to attain full cut. ( this is advisable in any case, even with large shapers)
The majority of the waste could be removed on the table saw to make life easier.

Alternatively, the whole job could be done by hand planing, then sanding to final shape. Long winded and hard work but do-able.:eek:

HTH Rob.

[Lee Koepke]

Cut some 'ribs' then use thinner veneer and bend it. You could also get a round post / large dowel and rip it down.

Just a couple of thoughts.

[Darren Vass]

Thanks for the ideas. It does seem that a router is going to be DIFFICULT. I'll look more into bending, perhaps with kerf cuts and also into a large dowel.

Thanks again,

Darren

[mark kosse]

That's a shaper job. If you could find a roundover to do that it would be kinda costly. A 3/4 Freud is 50.00.

Does the roundover need to be that big?

[Paul Atkins]

We built a bed long ago and it needed 6" radius corners, so we had a 12" cylinder turned and quartered it and used dowels or tenons to connect it to the straight parts. 1/8" bending ply applied to the whole thing and then veneered. Seamless and perfect.

[Stephen Cherry]

Another, low tech way to do this might find a piece of pvc pipe with an appropriate radius. and cut a length of the pipe into quarters.


Build the box square with extra mdf in the corners, trace the contour of the pipe onto each corner of the top and bottom. Then use a table saw to make cuts at a bunch of angles to get rid of almost all of the material. Then take some coase sandpaper and line the inside of the piece of PVC pipe with it and sand till smooth, with the edge of the box taking on the contour of the pipe.