Cutting mahogany countertop for farmhouse sink

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Forum topic by 03Protege posted 06-20-2018 01:51 PM 529 views 0 times favorited 6 replies Add to Favorites Watch
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2 posts in 744 days

06-20-2018 01:51 PM

Hello everybody,

My first post here, I first want to say what a great wealth of knowledge is here on this forum. I have been lurking for several months and this website has been immensely helpful. I now have a task I couldn’t find a solution for (searching wrong terms maybe?) so I decided to finally join on and make a post.

I am making Vanity tops and my kitchen island top out of African Mahogany and I am running into a roadblock in my head on how I am going to cut out for my farmhouse sink.

It was supplied with a cutout template and I planned on building a large plywood jig to clamp down and cut everything out with my Makita router. My island top will be approximately 1.5-1.6” after I finish planing.

The problem now is finding the appropriate bit to this, I was hoping to find a 1/4” straight cut bit that I could use but the only bits long enough I can find are 1/2” diameter. I would really prefer a smaller bit due to the inside corners, I would prefer to get a nice tight radius there instead of the more gradual radius the 1/2” bit would leave.

It appears that these smaller bits may not be strong enough to make in my desired length so I am kind of stuck not knowing what to do.

Attached are some pictures of a smaller vanities and a counter top.

Thanks in advance!

6 replies so far

View sawdustdad's profile


379 posts in 1653 days

#1 posted 06-20-2018 03:08 PM

1/2 inch bit is 1/4 inch radius. Don’t see why this would not work? If it’s a problem, then use a saber saw to finish the cuts into a square(ish) corner(s).

I’d cut the whole thing with a saber saw if it’s going to be covered by the sink. If the edge is actually exposed (not sure how the sink fits) then rough cut with the saber saw and then route to a template to achieve a finished edge.

-- Murphy's Carpentry Corollary #3: Half of all boards cut to a specific length will be too short.

View 03Protege's profile


2 posts in 744 days

#2 posted 06-20-2018 03:23 PM

Well that helps a ton, I assumed a 1/2” diameter bit was a 1/2” radius profile (right word?). Obviously now that i am thinking about it a radius is half the diameter. DUH!

The sink mounts below the counter so the cut will be exposed which why I am trying to use a router and template, I’m very scared what damage I can do with a jig saw. Cutting the corners out after the rest is routed wouldn’t be too bad though.

Thanks for the advice.

View jonah's profile


2119 posts in 4066 days

#3 posted 06-20-2018 03:31 PM

I’d go with a jigsaw to remove 95% of the material, then a router to clean it up. You’d never want to make the initial captured cut with a router if you didn’t have to. Far better to clean up an edge with a pattern bit or even just a straight bit and an edge guide.

View jonah's profile


2119 posts in 4066 days

#4 posted 06-20-2018 03:32 PM

It goes without saying to make a practice piece out of scrap plywood to refine your technique. You obviously don’t want to screw it up.

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John Smith

2419 posts in 930 days

#5 posted 06-20-2018 03:50 PM

have you given any thought to WATERPROOFING the bottom
and all holes cut in it for the faucet fixtures ?
if not treated properly, the end grain will be like a sponge
and ruin all your hard work with water stains.

onboard boats, we drill the hole 1/4” larger than required for the fixtures
and fill it with epoxy – after it cures, drill the size required for the pipes.
that way there is a 1/4” collar between the pipe and any bare wood.
an ounce of prevention – - – - as the saying goes.



-- I am a painter: that's what I do, I like to paint things. --

View Rich's profile


5602 posts in 1357 days

#6 posted 06-20-2018 04:08 PM

On my bathroom vanity, I glued it up with much of the opening to begin with. At $25/bdft I didn’t want to waste any more wenge than I had to. Like the previous posts said, make a template out of 1/4” plywood to ensure you have a perfect fit with your sink, then trace it onto the counter top and cut just shy of the line. Attach the template and route it smooth. You can use a top-bearing or combination (bearings top and bottom) flush trim bit, or a bushing, but if you do the bushing, you need to account for the difference between its OD and the router bit. A typical setup uses a 5/8” bushing and 1/2” bit, so the template will need to be 1/16” larger than the opening you want.

The flush trim bit is much easier.

-- Half of what we read or hear about finishing is right. We just don’t know which half! — Bob Flexner

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