Routing a wood slab

[peter]

Hi, I have to cut / route a 135cm circle into a slab of wood, 4.5cm. I have miniamal experience with routers. What sort of jig do I need to set up? Peter

[Upscale]

A circle cutting jig. You could make your own out of plywood or buy one of these. Take your choice. 4.5cm for the slab is almost two inches thick. Options are finding a router bit that is 2" in length, route one side and then turn the slab over, buy yourself a bit extender. Although I've heard of bit extenders, I've never used one and can't advise you on how well they work.

?c=1&p=40970&cat=1,43000

[peter]

I'll try and make something along the lines of the third option you offered.

Cheers and thanks again,

Peter pax

[Lobby Dosser]

Though I have not used a bit extender, I don't think one would do any good in this case. The bit extenders I've seen actually extend the Collet for ease in bit changing in a router table or getting full use of the bit with a fairly thick sub-base on a hand held machine. No matter the length of the bit 'extender', the actual bit remains the same length and the diameter of the collet of the extender is likely larger than the diameter of the bit thus preventing extension of the bit into the stock to a depth deeper than its length.

[bluemax1811-newsgroups]

You don't need a bit extender. You can buy a router bit that is long enough. Freud makes them. I am sure others do, as well. Just be sure that the length and plunge capabilities all work out so you can start at zero and plunge to your final required depth (about 1 3/4"). The Freud bit that is 2 1/2" long might stick out a bit, depending on your router, so starting the circle might be a challenge.

Bob

[George]

If you're speaking of "cutting" a circle rather than just routing a blind-bottomed circular pattern into a slab, find a bandsaw and do it right, with much less danger and effort. Circle-cutting jigs are pretty much the same all over, so a search would turn up many.

If you're speaking of the groove, you might also consider following the edge of a plywood template cut on that bandsaw and tacked to the middle. A nail hole in end grain is going to close pretty nicely. A trammel hole not quite as nice.

[gpdewitt]

You can also start your cut with the aforementioned jig, cutting mayby

1/4 or 3/8 deep, then rough cut at the OUTSIDE edge of the groove with a bandsaw or saber saw, then use a top bearing pattern bit to finish the edge in stages. Depends what tools and bits you have/are willing to buy.

[peter]

Thanks George. The hole is to fit a new sink. I've never done anything like this before. It should be beautiful when done. I hope. ;) The ply wood stencil is do-able, thanks.

[Lobby Dosser]

Assuming the body of the sink will overlap the edge of the hole, all you need to do is draw the circle, drill a hole inside the circle near the edge, and then cut out the circle with a jig saw. Unless you have a sink unlike others I've owned, you don't need perfection.

[peter]

The slab of wood is a bit thick for jig sawing. About 4.5cm. Could I plunge the power saw into the bottom side and cut / chisel out an area under the sink hole area, and then ?? jig saw or ?? route the final top hole?

Thanks for all the input. Who would have thought that 'makers' would find the time to share thier experience in a group on the net.

[Lobby Dosser]

I don't think we're talking the same tool. Common jigsaw blades are about

4 inches in length and you want to cut 4.5 centimeters which is about 1.8 inches.

Here are some examples:

Note the working length column. You'll see working lengths to about 5 inches.

Just in case we are talking different tools, here's a jig saw:

Hope this helps.

LD

[Lobby Dosser]

While I'm thinking about it, here are a couple more tips:

1. Sinks usually come with a paper pattern for the cutout - the waste bit. Cut out the pattern, tape it to the wood and draw a line round the outside. Then cut to the inside of the line. You could also spray some adhesive on the pattern, stick it to the wood and cut round it.

1. After you have cut a bit more than half the circle, make sure that the underside of the cut portion has some support, such as a board across the diameter clamped to the whole block. If the waste is not supported, you risk the final inch or so breaking free rather than cutting free.

2. Please don't take offense at this, but if you let everyone know right off What you are doing you are more likely to get to a better solution quickly. There are several regulars here who do this for a living and have waaay more experience than me. Something such as "I need to cut a circular hole in 4.5cm stock for a sink, how do I do this?"

Good luck with the project and let us know how you do it and the results.

LD

[peter]

I feel really greatful for all your assistance and effort. Thanks also for your patience. I love working with wood, and appreciate the help I find in this group. I will take more effort to detail my ideas. In other groups, they are not as receptive. I sometimes get flamed for not being the brightest.

This is a great group.

Peter pax

[Lobby Dosser]

I been flamed so much it's a wonder there's any fuel left anywhere.

Got that right!!