Green wood Roubo

[Evan Mansker]

I have a buckeye tree that is a couple of years old (down) that is relatively long and straight (20+ inch trunk to 16” over 40’). I’ve already slabbed it out roughly with a chainsaw (freestyle, no mill). I plan to flatten it with a router sled, then dimension with two cuts using a circular saw. The slabs are 6” thick and 6’+ long - fortunately I had gravity on my side to get them off the hill. I am planning on having two slabs for the bench top and I’m torn on whether to try and do a polyurethane edge glue or leave them as a split top that I can fill with seasoned wood after it’s dried for a few years. The wood is buckeye and I’m hoping to keep it 5+” thick for the top, will see how the flattening goes though. My questions:

1. For the slabs, am I setting myself up for heartache with the glue or should I do the split top? Ultimately I don’t want it to be a split top when the wood stops moving.

2. The frame is also green wood. I figured I’d do either drawbore mortise and tenon or through tenons with pegs, which would be better over time for joining the aprons to the legs? The top will be attached via sliding dovetail and through tenons that I usually see with roubo.

I have all the tools (I’m lucky), but I’m new to woodworking and am still learning quite a bit. Part of the reason for the sizing is I don’t have good luck with my jointer and planer, I tend to get better results hand planing. I figure I can use the machines to get my close and finish with hand tools but my current setup is maddening…

[John TenEyck]

Unless your shop is in an unheated building, those big thick pieces are going to split. If you build the bench from it before they split, it likely will rack in addition to splitting. I would set this project aside for several years while the wood dries, slowly, outdoors under cover. Build a bench from dry wood, even if only to bridge you through until this wood is dry.

The old saying about wood taking roughly 1 year to dry for every inch of thickness might not be totally accurate, but it will still take several years for those slabs to dry.

John

[Evan Mansker]

Unless your shop is in an unheated building, those big thick pieces are going to split. If you build the bench from it before they split, it likely will rack in addition to splitting. I would set this project aside for several years while the wood dries, slowly, outdoors under cover. Build a bench from dry wood, even if only to bridge you through until this wood is dry.

The old saying about wood taking roughly 1 year to dry for every inch of thickness might not be totally accurate, but it will still take several years for those slabs to dry.

John

My garage is unheated and I’m going to smother them in boiled linseed oil to slow the drying process. I know there is a risk here, but I can’t believe all wood workers in the 1700’s waited to work with dried wood. So this is as much exploratory as anything. I don’t mind learning and fixing mistakes.

[Kevin Jenness]

Knock yourself out, but be aware that those timbers are going to be on the move for years. You will be planing them on a regular basis to have a flat work surface.

I don't understand how you would combine attaching the top with through tenons as well as sliding dovetails. However you do it you need to allow the top to shrink in relation to the stretchers between the legs. I would advise against gluing the slabs together at this point. Be aware that the tenons will shrink within their mortises.

No doubt you will learn quite a bit about wood movement with this project. I am reminded of Tage Frid saying something like, "If you start out by building a hope chest, make it for small hopes."

"Good luck" has little to do with getting usable results from your machines. Your jointer and planer are basic to efficient millwork. Do some research in the archives here and/or get a capable mentor to help put those machines in working order.

[Cameron Wood]

I would plan on the slabs just sitting on the base without being fastened, so they can be worked on over time.

At least, with a hardness similar to poplar, that won't be too hard.

Also, I would leave the pieces long and seal the ends, but leave the rest unfinished.

[Andrew Hughes]

It a waste of your time to build something like a hand tool bench with green wood. Soaking it in boiled linseed oil will do nothing. The problem your facing is big pieces will shrink a lot.
Be patient pilgrim.

[Richard Coers]

Buckeye is incredibly soft and light weight. Not my idea of a good choice for a bench. Buckeye is 350 on the hardness scale, American basswood is 410, walnut is 1010, hard maple is 1450.

[Kevin Jenness]

Thanks for that, Richard. We don't have buckeye here, so I assumed it was a moderately dense wood. Is there anything to recommend it for a workbench?

[John TenEyck]

My garage is unheated and I’m going to smother them in boiled linseed oil to slow the drying process. I know there is a risk here, but I can’t believe all wood workers in the 1700’s waited to work with dried wood. So this is as much exploratory as anything. I don’t mind learning and fixing mistakes.

Believe what you want but the guys who made their living woodworking way back then knew a lot about how wood moved. You can see doors on churches, etc. that are 800 years old, all the way to high end, and I mean unbelievable, stuff made in France in the 1500 and 1600's that remains functional and still looks amazing. Green wood is fine for some chairs, benches, etc, but those guys learned as you are about to that green wood is completely unsuitable for anything with large cross sections that is joined together. Back then they could use air dry wood because buildings had no central heat. And you could use air dry wood for your bench.

One year per inch, outside, under cover, until it's air dry. What's air dry? 12 - 14% where I live in NYS. Why learn the hard way when folks here with years of experience are trying to help you avoid the pain of failure?

John

[Richard Coers]

Thanks for that, Richard. We don't have buckeye here, so I assumed it was a moderately dense wood. Is there anything to recommend it for a workbench?
Here is the chart I was using. https://www.bestbassgear.com/ebass/ideas/wood-hardness-chart-bigger-better-more-woods.html
Red or white oak are great choices. Even soft maple isn't too bad and is a great bargain option. Often has some figure too. Hard maple is better for wear, but much harder to dry in heavy stock and can be much tougher to hand plane to redress the top in 10 years. I used walnut and red oak for my bench.
491039

[Keegan Shields]

I know there is a risk here, but I can’t believe all wood workers in the 1700’s waited to work with dried wood.

I'm curious why you think this? Perhaps I'm misunderstanding what you plan to build.

Even firewood must be seasoned (dried) to bring the moisture content down for safe use in an indoor fireplace.

Using green wood to build something temporary (like a camp stool) or something rough (a split rail fence) certainly happened, but that's not fine furniture.

Given all of the time and effort that goes into building a Roubo workbench, I would use an appropriate species of wood (not buckeye) that has been properly dried.

You'll be much happier with the result.

[Bill Dufour]

Climate? They should dry in a few years outside, under shade, in the high desert.
Bill D.

[Kevin Jenness]

My garage is unheated and I’m going to smother them in boiled linseed oil to slow the drying process. I know there is a risk here, but I can’t believe all wood workers in the 1700’s waited to work with dried wood. So this is as much exploratory as anything. I don’t mind learning and fixing mistakes.

Better to learn from others' mistakes - you will make plenty of your own. What you need is a flat, stable, solid bench made of dry wood with vises and dogs to hold your work. By the time that buckeye is dry you will understand why building a bench from it now is a bad idea.

[William Hodge]

Soft wood can work out fine for a bench, depending on its use.

I have a 4' x 8' bench with a 5/4 Eastern White Pine top, on a sturdy flat frame made from 8/4 pine. My main use of the bench is hand tool work on sash and door parts, like hand planing, and carving, and sanding hundreds of sash. The soft wood is great for screwing down cleats for wedging work in place. Being able to shoot screws into the soft wood to hold work in place while sanding, hand planing, and carving is great. The Oak bench I have is better for glazing and vice work. The assembly bench is pine, but I put legs under the edge for pounding tenons into mortises.

I never understood why people build monolithic timbers into benches, apart from building an object of grandeur and appreciation from admirers.In professional shops, benches like that are more for flamboyant artists, rather than production workers. No knocks, my neighbor made a very good living as a flamboyant artist. He built a woodworking business making statement furniture and millwork, had a dozen people working for him at times, and is now retired wealthy after 40 years in the business.

Now wet wood, Yikes! The old inch per foot canard doesn't account for different drying conditions. I dry firewood from 30% down to 8% moisture content. This is the big stuff, 14" diameter, that I can't split. It checks like crazy, sun and wet wood equal movement. Look at any old timber framed building. Anything big is split all over. Wet wood is fine for rough framing, just nail it down before it can move much. That's why I don't stock much framing lumber. It moves all over sitting in the shop. Home Depot is my warehouse for that stuff.

[Evan Mansker]

I appreciate the thoughts here. I may leave it go as a floating top and forego the full roubo design for now.
In regards to the softness, somewhere I read that having a softer bench than the wood you work with is good because the bench will take the beating/denting instead of your project. Sounds like through tenons with pins/wedges are best for the framing, if I’m reading this right.

[Kevin Jenness]

If you are set on using green wood for framing, drawbored tenons will probably stay tight. Wedged through tenons will loosen as the wood shrinks and need the wedges tightened periodically.

If you keep your bench top clean and smooth it will not dent your work. Keep it waxed and pop the glue drips off with a scraper.