First workbench: dealing with large, solid knots in top. chisel out & inlay? Options?

[Fitzhugh Freeman]

A number of you were great help recently when I began planning out my bench. I got the Landis book and the newer Schwarz book as advised. A local woodworker with a sawmill sold me a 14" X 3" (after I plane it) by 16' long board of douglas fir for the top - it fits Schwarz' definition of the right wood for a workbench top... the biggest, driest stuff available right now. I got it for much less than any of the other options I priced out - it was one really really big cut-off scrap!

So, it's thick and heavy, long, and available. Only problem is it has some knots - maybe 7 or 8 total, each 1.5 - 2 inches across, super dense and solid. I'm doing this all with hand tools (all I have anyhow) and a limited selection at that.

No surprise, I'm having trouble planing the knots. I can plane them, but probably can't plane them and still end up with as flat a top as if I cut them out and fill them. So far I've had best results chiseling off a thin layer so I can plane without hitting them. Getting them even in the end will be a pain with this approach.

I'm considering chiseling out the top/surface portion of each knot - maybe a 1/4 or 1/2 inch, and filling the space with a thick veneer of more douglas fir. Is there a reason to remove them completely or deal with planing them?

If I do cut them out, is there a traditional/wise way to approach this, something equivalent to butterfly wedges for cracks? Should I just cut a rectangular plug, a diamond-shaped plug, or a round plug (a tad harder)? If I do, the grain should run parallel and the wood should be the same DF so it expands/contracts similarly, right?

What would you do?

[Jim Matthews]

Before cutting them out, see if they're right the way through the board.

You may be able to knock the knot right out with a hammer.
If the knot doesn't go through the board, try applying some oil directly to the knot before planing.

I think this is an idea I lifted from Jim Tolpin's writing, but I can't find the source.
It has worked for me, particularly in conjunction with a card scraper.

FYI - I get VERY good results scraping with a carbide scraper (http://www.highlandwoodworking.com/bahco1carbidescraperwholster.aspx) (sacrilege though it may be).
It makes sense, a hard blade for the hardest part of a board.

[Fitzhugh Freeman]

Thanks - I just tried hammering them out. I think it is just too thick, and the knots are super solid, didn't budge. I'd seen those carbide scrapers and wondered what type of things they'd be used for, makes sense. If I shouldn't chisel and plug w/ wood I'll try one.

[Zahid Naqvi]

Fitz, all you need is chisel out just enough off the top of the knots so that they do not interfere with planing. As a side note I have planed Ash (Doug Fir can't be harder than Ash) boards with knots in them, although difficult but not impossible. Considering we are talking a bench top some tear-out is acceptable. If you angle your plane some you should be able to plane right across the knots, granted you will need a lot more sharpening.

[Prashun Patel]

Are the knots small enough that you can turn them into dog holes? While maybe not centered, those locations might make great hold fast spots.

[Howard Pollack]

I'd flatten them as much as possible using whatever tool works (incl. electric sander) if they are not higher than the surrounding surface than simply ignore them, it they are higher lower them to the level of the surrounding surface or (gasp!) a bit lower. Who cares? It is a workbench -Howard

[Fitzhugh Freeman]

The holdfast idea - I'll gladly keep that in mind since the douglas fir is soft enough I was wondering if it would stand up to holdfast use over time. The knots are quite large enough to drill holes for bench dogs/holdfasts in, and one is probably going to end up in a perfect position to drill for a planing stop.

Thanks for the reality check, all of you... it is a workbench. Flat for a workbench doesn't mean a perfectly flat and uninterrupted surface like a perfect table top, it means it is really flat so work can sit on it. As long as they don't stick up they won't interfere, so I'll chisel out a little so I can plane the whole top properly.

I'd still like to hear of any thoughts about adding a veneer or plug - if there are any "right" ways of doing it, but I won't worry about that as a high priority.

[David Wong]

Knots are end grain, so they would not contribute any strength as a gluing surface. That means any plug would have to depend for glue strength on the depth of your plug, and how oversized your plug would be relative to the size of the knot. Digging out a knot and leveling it with hand tools is not going to be fun. This is a case where an electric router would be useful. If your wood is still a little on the wet side, the knot may end up proud, relative to the surface of the wood when it dry out more. Instead of a plug, maybe you could try to level the knot with epoxy?

I also have large knots in my douglas fir lumber I am using for my long suffering bench build. Fortunately, I am able to orient the wood to not expose any knots on the top surface.

[Mike Siemsen]

Your plane is probably set too rank to plane over the knots. It works fine in the surrounding wood but can't get through the knots. Set another plane up to deal with the knots, or take a finer shaving at the knots with the plane you are using. Don't waste time on inlaying just get it flat and start making something.
Mike

[Mike Olson]

Red Knot Good Knot, Black Knot bad Knot.
if the knots are red in color they are not going anywhere, just surface plane the majority of the wood and use some course sand paper on the knots if you have to.
If the knots are black or there is a black circle around the knots then you need to get rid of them as they will eventually loosen up.

One of my old bosses when i did construction had a few Knot terms that always stuck with me. The one above and then the other i like. Knots UP! He would always yell that before we started laying floor joists.

[Bruce Haugen]

Sorry to be such a heretic, but this sounds like a job for Mr. Belt Sandah. There are some things at which electrons excel. This is one.

[Terry Beadle]

The electrons comment is a good one. You can make a quick jig to set your electric router on. If you don't have one, you can usually buy one at a pawn shop super cheap. If you can't buy one, borrow one. Doesn't matter the size but bigger is better. Use the jig and router just on the knotty areas. You could recess the knots a bit but not more than 1/16th at a time IMO. Your bench is a key component of successful jointery. Keep it flat as possible. Check it a half dozen times a year and you'll learn what areas of the wood move more than others.

Some bench builders have even used such jigs and router to flatten the whole deck. I would not want to have to do that but it's a solution.

The jigs are simple. Two rails for the router face plate to ride on. Fairly thin but strong. A couple of stiles to keep the distance between the rails in control and away you go.

Good luck ! Pictures are a thrill !

[Wilbur Pan]

You don't have to do anything to the knots as has been mentioned above. But digging them out and putting a patch in of some sort is great practice for doing inlays. I've taken out some of the knots in my workbench for this very reason. The workbench looks better, although the patching process didn't improve the functionality of my workbench at all. This still didn't mean that it was a meaningless exercise.

And I would argue that if taking the knots out and patching them makes you feel better just because the bench looks better to you, that's more than enough justification to do it.

[Fitzhugh Freeman]

great range of responses, thanks!

I'm new enough to woodworking that I see building the bench as just as important as building the stuff I'll build on the bench, and am approaching the knots rather like Wilber did - a chance to learn something and have fun messing with wood.

The knots are very dark, so bad. And I hadn't thought about them being end grain, so not good for gluing, I knew I'd learn stuff if I asked.

I don't have any power tools. I've used a cheap narrow mortise chisel to whack out a level of the knots and plane down until I'm about to reach them, then repeat the process. There is a lot of leveling to do on this piece - the last foot has a trough from wandering a bit on the sawmill). It's easy to flatten the knot with a paring chisel or card scraper, but with the point made above that they could end up proud of the surface later I'll try inlaying over one.

I'd thought about epoxy, but figured a wood inlay would be nicer to my tools and easier to flatten again later.