Get a spiral cutting router bit to minimize tear-out. I got a really nice one from Woodcraft. Make sure the cutting head is long enough to cut through the thickness of the maple. I run routers backwards first (the direction the bit pulls as it cuts) before running it in the "right" direction to clean up the cut. This prevents tear-outs but be extremely careful the router can get away from you if you try and cut too much at once.

One idea: Pat Warner's book, "The Router Book", is a really good intro guide with lots of good safety-related information. (More than you'll get on the internet from hacks like me who neglect to mention male versus female templates...)

Another idea: a quirk at the bottom edge of the sink cutout (like the kerf you see at the underside of a traditional windowsill) would prevent water from travelling too far sideways. I think I'd do this with a scratch stock (google scratch stock quirk for pix/etc) with a small, slightly rounded fence.

Here is a link that might be useful: The Router Book

Hi Jon, I do know the block will move but I have not thought it would move enough to break the sealant, as far as I know most sinks are secured by clips with the silicone to stop water, but the clips should be similar for drop in installation. If the risk you proposed is true wouldn't it be just as risky to install a drop in sink in a butcherblock? Also the movement is distributed over the length of the caulk bead, so the tension per area (non techical term here) should be less than a full 1/4". Windows and door caulk can handle a movement of wood planks and they are not even fully silicone. Kitchen caulk like GE II is fully silicone. I think I have dealt with some of this stuff dried out and found it VERY elastic.

I have seen many folks here who has butcherblock and sinks mostly undermounted. That's not to say it will last long against moisture if not properly maintained.

I am however going to seal all edge with waterlox at least 5 coats.

The router will be bosch 1617 2.25HP with some reputable carbide bits that I could find...

poorowner,

When I make my MDF templates off the paper template, I adjust the size of the template during that layout. If I want the template smaller, I'll use transfer paper under The paper template and then trace a line 1/4" or so inside the template line.

If going the other way, I trace a line 1/4" outside the edge of the paper template.

Then I just use my regular flush cutting pattern bit.

Mongo

Sorry, I didn't mean to imply that the sink would fall into the cabinet when the sealant tears; it will, of course, be supported by clips or some other means.

You're right that the full 1/4" of movement wouldn't affect any one part of the seal. At a minimum, the front and back edges would see about 1/8" of movement, while the part towards the middle of the counter might be quite stable. Even so, 1/8" is a lot. Yes, silicone is stretchy, but when you're playing with a shred big enough to handle, you are not duplicating the forces that are in play when the sealant is pressed into a flat layer that's 1/16" or less thick.

Yes, the seals around drop-in sinks fail the same way, but the failure is further from the water, in a place less prone to cause problems.

I realize that people do mount sinks this way, and I think they're pretty to look at. I'm not saying your whole kitchen is going to implode, but I am saying that you can't expect this installation to be as long-lived and trouble-free as an otherwise similar installation in a stone countertop.

Jon gives good advice, you just need to be aware of the issues beforehand. Wood movement, type of wood, wood versus water.

That said, I have an 8/4 teak countertop in my kitchen, it's plank, edge glued (epoxy), with an undermount sink. The countertop is 2" thick by 30" deep, and about 18' long.

Can't recall how long it's been in...maybe 6 or 7 years? Still looks great. No issues. I hit it with mineral oil about every 4 to 6 months.

Mongo

Thanks, Mongo.

FWIW, the shrinkage/expansion numbers for teak are less than half those of hard maple.

OK, I have selected a farm style sink instead of a true undermount, so it is installed in the cabinet instead of attached to the countertop. Althought it is still considered to be undermounted, I plan on applying a bead of silicone bead from the outside, and joint can be redone down the road (hopefully without too much trouble)

I think that is one step away from the issues mentioned here.

A number of problems occur with wood and moisture.

No finish is completely vapor proof.
All the finish does is slow down the movement of water vapor.

If you have end grin butcher block (the end grain faces up) the cutout for the sink will be in side grain and not as prone to absorbing moisture.

The side grain 'butcher block' is not really butcher block (butcher's blocks use end grain for long life and it is easier on the knives).

The side grain on the face of the counter means that end grain will be exposed on two sides of the sink cutout.

End grain soaks up moisture quickly and easily.

You also need to consider movement of the wood.

The seal between the sink and counter will not remain water tight with more than a small fraction (think thirty secondths of an inch) of movement.

The farm style sink should eliminate most of the problems, but make sure you apply both some finish and seal the edges of the counter against the sink.

A gap and a cover strip would be even better.

jon,

Yup, the minimal (when compared to other commonly used species) tangential movement and the ability to resist water were two of the reasons I chose teak.

brickeye,

That's one of my semantic pet peeves...the difference between true butcher block versus edge-grain plank glue ups, and how people always refer to plank as butcher block.

Anyhow, here's a 4' square by 5" thick teak butcherblock...this thing is pretty much bulletproof.

Here's the kitchen sink cutout, it sits in the midst of about 17 or 18' linear feet of 2" thick by 30" deep teak countertop.

And since I'm on a teak kick, here's a teak tub deck...

...and a couple of teak bathroom countertops. The sink countertop has a slight bow front to it.

Mongo

That's nice mongo, where did you get the teak? Did you glue them up yourself?

Bought locally, well, "locally" as in a lumberyard about 25 minutes from where I live. General Woodcraft in New London CT.

Teak has skyrocketed here. Used to be able to get wide 8/4 planks about 5 years ago for $9 a bdft, now the wide boards are running upwards of $30 a bdft.

Epoxy and biscuits for the edge-glued plank tops, just epoxy for the butcher block.

Mongo