Knot hole: fill or not?

[Paul F Franklin]

On what will be the bottom surface of one of the cherry desk tops I'm building, there is a knot hole. Roughly 3/4 in diameter and 5/8 or 3/4 deep in the 1" thick top. There is no sign of the knot itself on the top surface except for the circular grain pattern you would typically see near a knot. I've pressed on the area above the hole with a dowel and no sign of flex or weakness. It won't show on the bottom surface unless you climb under the desk, so my thought is to just leave it be. But I could fill it with epoxy if there is any reason to do so. I can't think of a reason, but thought it was work asking here. Fill or not?

[Zachary Hoyt]

If it was me I would drill a hole with a Forstner bit to the bottom of the knot hole and then cut a plug of cherry wood with similar grain direction to the rest of the board and glue it in, then cut it off flush and sand. Probably not necessary, but I'd feel better about it.

[Doug Garson]

I'd fill it for no other reason than it would be easy to do now, very hard to do after the desk is finished.

[Lee Schierer]

I would fill it. No need to get fancy since it is hidden. Use wood putty, epoxy, a dowel or appropriately sized piece of tree branch.

[Jim Becker]

I would do as Zachary mentioned...make it a round hole and fill it with a round plug of cherry with the grain oriented the same way as the board being repaired. It doesn't have to look pretty...just level with the surface. I'm sure you have some scrap cherry you can make the patch with hanging out... :)

[Jamie Buxton]

Is the knot stable? That is, is it going to stay there if you do nothing? Then I'd be inclined to do nothing. That's the way Mom Nature made that plank. If the knot isn't hurting anything, I'd leave it the way Mom made it.

[Ron Citerone]

I would pick out any loose material and then fill with epoxy.

[Frederick Skelly]

I'd fill it with epoxy and the scrape it flat.

[Dwayne Watt]

I am in the camp of filling knots with epoxy. Bottom line is there is usually no wrong answer to this question. Plug or fill are both very acceptable. Just depends what you like.

[lowell holmes]

If you do this and you don't like it, you can still drill it out and fit a plug in it.

[Paul F Franklin]

Thanks all! I wish I had thought to plug it (or asked here earlier) while the board with the knot hole was still rough; it would have been an easy job at the drill press. However, the tops are glued up, flattened, scraped, and sanded, and the knot hole is in almost exactly in the middle (of the bottom) of the 30 x 60 top, so no way to do it on the drill press. Being a chicken, I decided not to attempt to drill it with a hand drill, even with a guide, so I took the easy, and safe, way and just went with epoxy and all is well. Normally, I try to cut out such defects before glue-up, but since it was a wide board and the top of the board was pristine, and pretty, I left it be, knowing the defect would be on the bottom. But even though I don't really have a good reason for filling it, I feel better that it's done.

Jamie, the knot itself is gone....it was loose and I popped it out before thicknessing the stock to avoid any "excitement".

Thanks again, I really appreciate the advice I get here!

[Jim Becker]

Just as an aside, since you've already taken care of it, the alternative to drilling and plugging is to do a quick router inlay; again, keeping the patch so the grain is parallel with the table board grain.

[Doug Garson]

Jim's router inlay is also a good option where the knot hole will be visible. You can make it a feature rather than an attempt to hide a flaw by using a contrasting wood and an interesting shape. Here's a few examples in a table top I made a few years ago.


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[Jay Aubuchon]

Just out of curiosity, what bad thing might happen if the knot wasn’t filled?

[Jim Becker]

Jim's router inlay is also a good option where the knot hole will be visible. You can make it a feature rather than an attempt to hide a flaw by using a contrasting wood and an interesting shape.
I did that on our kitchen table...there was an odd-shaped knot in the cherry on one board that was actually missing. I did the fancy thing and used my CNC to both pocket it out in the exact, irregular shape of the missing knot and to create the inlay that replaced it. I used some purple heart for the knot-shaped plug with just enough allowance that the black CA I used to fill around the plug added even more interest. That whale looks great1

[Jim Becker]

Just out of curiosity, what bad thing might happen if the knot wasn’t filled?

In the OP's case, not likely anything...

[Tom Bender]

I disagree with you all. The unfilled knothole is stable. Filling it with something that may not move the same as the rest of the top could stress it and cause a crack in the good side.

And an unfilled hole may be an interesting detail for bored hands to discover.