How to question (cut out for sink)

[Craig D Peltier]

Hi I have to cut an oblong hole in a 1.75 thick walnut top for an undermount sink.
What I was thinking of doing is. Using a 5 inch jig saw blade.Cutting it proud by 1/4 inch. Then using a template with a edge trim bit ( I have a big one with top mounted bearing).
Is there another way?
Im a little dumbfounded how to make the template and it be perfect lines. I was thinking of having it C&C'd.
Top is 48x118. Its a kitchen island.
Im also making a curve cut on one side (10 feet). I was going to use same method but no template? Curve goes in about 8 inches I think.

THANKS

[Dennis Montgomery]

You may want to rough cut with a circular saw. It will take a long time to cut it with a jig saw. I have done a lot of top mount sinks this way.

[Craig D Peltier]

You may want to rough cut with a circular saw. It will take a long time to cut it with a jig saw. I have done a lot of top mount sinks this way.

Its undermount sink. Also I can cut a curve for the long 120 inch section with it.
The opening for sink will be quite small, maybe 18x18.

[NICK BARBOZA]

I think your on the right track with jigsaw then flush trim bit in the router. as for the template i would use MDF and trace the pattern that comes with the sink and cut it out and clean it up to that size. any sink i have ever installed usually comes with a pattern, othewise, use the sink itself to make the pattern. Post some pics when your done.


good luck
Nick

[Craig D Peltier]

I think your on the right track with jigsaw then flush trim bit in the router. as for the template i would use MDF and trace the pattern that comes with the sink and cut it out and clean it up to that size. any sink i have ever installed usually comes with a pattern, othewise, use the sink itself to make the pattern. Post some pics when your done.


good luck
Nick

Looked in box, no paperwork at all ( was looking for template). Theres no cutouts its basically a hammered copper basin only. I have to drill some holes outside of it for faucet etc.
Ill give it more thought of cleaning it up using a MDF template.
Thanks

[Tom Klass]

A lot times the template is part of the cardboard box that the sink came in. The box is perf'd where you cut it out or trace it out on a pc of card board as a template.
Tom

[Jim Becker]

Craig, many copper sinks like that don't come with any templates...the one we used in our new wet bar was that way. The fabricator took the sink and made a template for the cuts.

I'll second the suggestion of rough cutting the hole with whatever tools you find convenience to do so and then using a template you create from the sink, pattern route the opening smooth and true. That may require multiple passes to get the depth...and at some point the previously routed pass becomes your template for subsequent passes, depending on your cutter and it's bearing configuration.

[Matt Ocel]

FYI -

If you rough cut it with a circular saw, you should cut it on the bottom side.

You can cut it on the top side with a jig saw using a down stroke blade.

[Craig D Peltier]

A lot times the template is part of the cardboard box that the sink came in. The box is perf'd where you cut it out or trace it out on a pc of card board as a template.
Tom

Box is perfed where it sits in. I will take a look at it. Thanks for the tip.

[Ken Fitzgerald]

Craig,

Use the perf template to cut the hole and make the jig.

The jig could easily be 1/4" or 1/2 plywood.

You could make one of two types of jigs....an "inside" jig or an an "outside" jig. On the inside jig...the jig would represent the outline of the area you want to cut out. The inside jig would be easier to sand ....to make smooth but..you have to becareful while routing to insure you don't stray away from the jig and cut in areas you don't want to remove.

An outside jig....the guide bearing rides on the inside of the jig but if you stray from the jig....no big deal.....you were going to remove that area anyway. The one catch....it's a little more time consuming to smooth the area where the guide bearing will be riding....

Good luck with you project!

[Craig D Peltier]

Craig,

Use the perf template to cut the hole and make the jig.

The jig could easily be 1/4" or 1/2 plywood.

You could make one of two types of jigs....an "inside" jig or an an "outside" jig. On the inside jig...the jig would represent the outline of the area you want to cut out. The inside jig would be easier to sand ....to make smooth but..you have to becareful while routing to insure you don't stray away from the jig and cut in areas you don't want to remove.

An outside jig....the guide bearing rides on the inside of the jig but if you stray from the jig....no big deal.....you were going to remove that area anyway. The one catch....it's a little more time consuming to smooth the area where the guide bearing will be riding....

Good luck with you project!

Thanks for taking the time to0 explain the nuances of both. It helps. I was thinking half inch mdf for an outside jig. Making the jig perfect is what worries me.

[Tom Veatch]

I guess I'm a little curious as to how perfect the cut has to be. Will the cut edge be visible? Isn't there some width of flange/overlap/sealing surface between the sink and the countertop that hides the cut edge.

My ignorance in this area is monumental as I've never had the pleasure of trying to install a sink/countertop/etc.

[Jim Becker]

Tom, for an undermount sink, the cutout is absolutely visible and must be finished. There isn't any part of the metal sink above or on top of the counter. The flange of the sink is mounted to the underside of the counter.

[John Lucas]

There is another way, short of having the template from the mfr. First cut the hole with about 1/4" left to remove to the exact line. I then attached the sink using the undermount clip hardware and set my router bit bearing to the top of the sink. If your sink has striaght sides for the first 1/2" or so, this can work. You do want to be sure that the bottom of the cutter is NOT in contact with the copper (duh). I will admit it was scary to start but then went very smoothly and the final cut was dead on.

[Craig D Peltier]

There is another way, short of having the template from the mfr. First cut the hole with about 1/4" left to remove to the exact line. I then attached the sink using the undermount clip hardware and set my router bit bearing to the top of the sink. If your sink has striaght sides for the first 1/2" or so, this can work. You do want to be sure that the bottom of the cutter is NOT in contact with the copper (duh). I will admit it was scary to start but then went very smoothly and the final cut was dead on.

Interesting idea. This top is 1.75 thick. I have a 2 inch bit with bottom bearing this might work.
Customer told me the perfed box in this case isnt the template.I yet to verify.