Work bench legs

[Joe Fabbri]

Hi guys,

I've been meaning to build a decent, sturdy workbench for a while. I don't want anything fancy really. I'd like to build it as inexpensively as possible, and I'd like to use up as much scrap lumber I have around the house that I can. Anyway, I have a few pressure treated 4x6's that I'm thinking of using for the legs. They're pretty old, probably 20 years old, and they're straight and very heavy, so I'm tempted to use them. I'm thinking that since they're this old and haven't twisted, it's probably okay to use as a leg, though I know a lot of people seem to laminate bench legs, when they want them thick.

The only problem I see is one side of each 4x6 has some checking running consistently down the middle (where it's near the center of the tree, I guess). Some are fairly shallow, and others a little deeper (towards the ends of the boards). My question is would you guys use them if you're not worrying about looks, or are they likely to continue cracking when put into use?

Could I fill the checks with glue, and maybe attempt to clamp it with heavy duty c-clamps? Anyone every try this with good results?

I suppose I could just laminate the legs, but it just seems like a waste of very heavy and straight wood not to use them.

I also have a few very old and heavy pressure treated 2x8s for stretchers, so I was tempted to just make the whole base out of this old lumber.

Anyone here use solid beams for legs with okay results?

Joe

[Rob Fisher]

I would not use any pressure treated lumber. It tends to be corrosive to metals. The newer stuff more so, but the old stuff is as well.

[Chuck Walker]

Pressure treated lumber is also fairly toxic if the dust is breathed when working it. I personally only use pressure treated stock for out of doors and even then reluctantly.

[Bill Houghton]

You can never make cracks like that go away. But old barns were framed with timbers that had that sort of checking, and they stood up for 100 and more years. I'd pay attention to placement of the checks to minimize likelihood of opening, but use them.

I do have a concern about having pressure treated wood where you'll come into constant contact with it. If they're 20 years old, they're probably treated with arsenate-based chemicals, and you don't want to be absorbing those chemicals. If you do make your bench from them, I'd put a heavy coat of paint on the legs and stretchers.

[Joe Fabbri]

Thanks for the replies, guys.

Yeah, I understand the concern. I figured for the base, though, which I wouldn't really contact much at all, and which the tools wouldn't touch much, it would be okay. But I know what you mean. I wish they weren't treated. The beams were outside for a while, and I think it's the consistent wetting and slow drying that might have kept them straight all these years. I'm thinking that a lot of the chemicals may have worn out. Do you guys know on average how long the old pressure treating lasts?

Bill, I was thinking of old barn beams myself. Almost everyone you see has a lot of checking.

Joe

[john brenton]

For the checking you could try banding it with some thick gauge "plumbers tape" (not teflon tape, but the galv. Band with holes in it. I don't know much about the toxins in pressure treated, but maybe paint would seal it in?

[Andrae Covington]

The beams were outside for a while, and I think it's the consistent wetting and slow drying that might have kept them straight all these years. I'm thinking that a lot of the chemicals may have worn out. Do you guys know on average how long the old pressure treating lasts?

There are about twelve different levels of pressure treated wood depending on the intended use, such as "Interior Dry", "Ground Contact, Extreme Duty", "Marine Use, Southern Waters", etc. The amount of chemical treatment and subsequent expected lifespan vary accordingly. Wood infused with chromated copper arsenate (used until 2003) can last 40 years. Of course actual lifespan in any given field condition varies. Even after 40 years, I would be reluctant to conclude that all the arsenic is gone. That said, tests have shown that rain and weathering do release the arsenic:


Meanwhile, in 1996, far from the lab bench, a Connecticut chemist, David Stilwell, began crawling around back yard decks throughout New England. A year later, he reported that the soil under and around pressure-treated structures contained concentrations of arsenic far in excess of background levels, and in some cases, far in excess of the clean-up standards for Superfund sites. More than sixty years after Kamesam's humanitarian invention, Stilwell discovered that chromium does not serve as such an effective binding agent after all. Eventually, the arsenic and copper leach out. Especially if the wood is rained on.


I do have a concern about having pressure treated wood where you'll come into constant contact with it. If they're 20 years old, they're probably treated with arsenate-based chemicals, and you don't want to be absorbing those chemicals. If you do make your bench from them, I'd put a heavy coat of paint on the legs and stretchers.

It appears that a penetrating oil-based sealer may offer better protection than paint:


As an additional step, you may consider applying a sealant every year. Some studies suggest that applying a penetrating coating (such as a water or oil-based sealant or semi-transparent stain) at least every other year will limit the amount of arsenic that leaches out. It is not recommended to use paints or urethanes that will peel or that require the wood to be sanded. Keep children away when applying oil-based products.

The EPA is studying the effectiveness of 12 sealants to see whether they keep the arsenic from being rubbed or washed off the wood, and how often they need to be applied. Interim results show that a penetrating, water or oil-based sealant or stain should be applied at least once a year. (As of January 2007, full results from the EPA study had not been released.)

If you are thinking of using a sealant, note that sanding or pressure-washing the CCA-treated lumber may not be a good idea, even if it is recommended on the sealant label! Sanding will scatter particles of arsenic in the air. Pressure-washing could increase the leaching of arsenic out of the wood.

[Kent A Bathurst]

Aww, jeez...here we go again.

First - after 20 years, the splits in the 4x6 timbers have stopped growing. If you want to, you could reinforce with some galvanized lag screws. I would build the base out of those timbers and the 2x8 without hesitation.

Second - when working with any type of preservative-treated lumber, don't inhale the dust, don't burn the scraps, don't eat the scraps. After all that time, the wood is fully dried, and you could paint it if you want to.

Third - Your bench will be indoors. All the stuff about penetrating sealers, leaching, pressure washing, etc. has to do nothing whatsoever to do with your situation - that deals with treated lumber outdoors in the elements.

And last - Once more unto the breach, or let them fill up the wall with our English dead...........I will climb on my soapbox again. The entire blow-up over the arsenic turned out to be nonsense. For every study claiming elevated levels there are many, many more studies - officially-funded, organized, and sanctioned scientific studies, as opposed to crawling around in backyards and playgrounds - that say the opposite. You need to understand the opera behind why the chromated copper arsenic chemical is no longer used for routine residential applications : The whole hoo-haw started about the arsenic in the ground. Well-intentioned groups, without legitimate science behind them, started beating the drums.

The Big Box Boys were looking at a big PR problem, if not a sales problem as well. More specifically - if you look only at the Big Two - HD & Lowes - who was going to blink first? - anyone that moved to the alternatives readily available at that time would gain some PR points, but would get hammered on the sales side, because those alternate chemicals are more costly - the price of the treated lumber was going to have to increase a noticeable amout. They didn't want to bet against the consumer, and they didn't want to bet on the consumer.

The EPA had nothing in their holster on either side of the issue, but were getting hammered by those groups, their elected representatives, and the press. So - in one of the all-time classic bureaucratic moves, the EPA simply let the 5-year approval on the chemical [the same 5-year cycle for many commercially used chemicals] expire - without comment. They simply did not renew the approval. So - the CCA was out - for everyone, and all suppliers changed, and all retailers changed, and all the prices went up at the same time, and the EPA did not have to take a position.

In the cold, sober, light of dawn - well after all of this went down, the actual "science" came in and the conclusions were that there was no evidence to drive the elimination of the CCA. Too late. The best, lowest-cost product ever, with many many decades of proven results, was gone. Almost.

The CCA is still, AFAIK, permitted for a number of applications. Below-grade wooden foundations. Agricultural applications [fences, pole barns, etc.] [I]where the livestock lives. Water contact and immersion - ie - seawalls, piers, docks, etc - where the chemical is in constant contact with the water that is supposed to cause the leaching, and the water where the kids swim and the seafood lives.

And so it goes...........Build the bench. Don't eat the scrap. Paint it if you want to. Drive some galvanized screws through the splits of you want to. The smart move from an environmental standpoint is to use it, not pitch it - "reduce, reuse, recycle".

[Gary Kman]

Tough break for the big box stores when the cost of fasteners increased several fold when CCA was fazed out.:cool:

[Kent A Bathurst]

Generally speaking, it doesn't bother them a bit - as long as all competitors have to provide the same, higher cost fasteners or PT lumber. However, there is some price-elasticity of demand at work - somewhere, the higher costs caused some folks to pass on new or upgraded outdoor projects.

[Kurt Cady]

Hey Kent,

Did you build that soapbox with handcut, variable spaced dovetails?!? :) :) :) :) :)

[David Keller NC]

Joe - I have a chemistry background (PhD in CHE). Kent is 100% correct. There is no reason not to use the PT wood for the base of your bench. In fact, if you have a basement workshop that's on a concrete floor, PT would be much preferred for the legs.

Corrosion of fasteners by PT wood is also not of concern to you. The corrosion referred to with PT wood is in an outdoor or wet location, and the new PT wood is far more corrosive than CCA wood. My original bench that I cobbled together in grad school has CCA PT legs, and plain steel metal bolts for the stretchers. There has been no corrosion for over 20 years, so I think you're safe.

For the checks, fill these with glue mixed with sawdust. Regular old PVA glue will do just fine. If you don't like the looks, you can fill it with black-dyed epoxy, but that's a pricey option (epoxy is expensive, relatively speaking, to PVA glue).

BTW - breathing any wood dust isn't good, but you'd have to work in a mill that was constantly cutting and milling PT wood to have a major concern about exposure to arsenic and chromium. In fact, many, many locales in the US have measurable arsenic concentrations in potable water. These are typically wells, but some municipalities have low levels as well. In addition, many soils in the US contain arsenic, mercury, selenium and chromium, all of which are toxic and/or carcinogenic in high concentrations, but do not cause problems at low levels (in fact, selenium is an essential nutrient at low levels - you can't live without it). Garden vegetables as well as farm crops are grown in this soil, and there are measurable concentrations in the resulting produce. But that doesn't mean they are dangerous to eat.

So use the PT wood for the legs. In fact, use the PT wood for the whole bench. You might be at risk of a back injury from building your bench (or an amputation if you're using power tools), but heavy metal toxicity isn't one of the risk factors. ;)

[Kent A Bathurst]

Kurt..........Nah........PT lumber and galvanized fasteners :p

[Kent A Bathurst]

David - hotdamm.

Finally - 35 years too late, a CHE says I got something 100% correct. I coulda used that grade back in college, pal :D

[David Keller NC]

Ha! Well, consider yourself as getting an "A" in appropriate risk analysis. We could easily start a topic on risk analysis and the human condition that makes all of us so terribly bad at it in the off-topic forum.;)

[Kurt Cady]

Kurt..........Nah........PT lumber and galvanized fasteners :pHahaha. Touchè

[Terry Beadle]

I used some 4 X 8 treated pine for the legs and cross bars on my work bench 12 years ago. Absolutely no problems. There is some checks but it's cosmetic and not comsmic ! Hoot! Anyway, These PT legs are heavy, strong, and the bench does not move. Very good value IMO.

I will probably replace my bench top which is a rock maple japanese inspired wide beam design with tool tray and back side removable trays some time in 2020. It's that stable and over all cost was well under $150. Bolted thru tenons and dove tailed slip joints have all worked out great. It took a while to build but it's done the job for a dozen years and seems to get better the more little tuning things I've done to it. In retrospect, I wish Mr. Schwartz's bench book had been written sooner as I would have adopted some features from that. And, if and when I replace the top, I will just mount the new one on the old legs with out question.

Bottom line: I would not hesitate to use PT 4/8 or 4/6 lumber for legs and cross bracing.

[Joe Fabbri]

Hi David and Terry,

Thanks for your input. I thought about filling the cracks with sawdust and glue mixture, preferably sawdust from the same wood used (for color). I'm not sure if it would look better to merely leave the checks though, rather than have it looked filled. Would filling it with sawdust/glue strengthen it really, though? Or is it only aesthetics? Also, is there any issue trying to glue pressure treated wood? I've heard something about that.

And yes, I figured that since the bench will be sitting in the garage, which has a concrete floor, it would be best not to put untreated wood directly on concrete. I'm also considering a trestle design to keep the end grain off the floor as well. Unfortunately I'm one timber short of being able to make the whole base in a traditional trestle style. I may have to use some 4x4 untreated for the top of the trestle, under the bench top.

Terry, it's good to hear you haven't had any problems using solid legs that large. You must have a very sturdy bench with those 4x8's. And here I was thinking that the 4x6's might be overkill. Do you by any chance have any pictures of the bench you built? Did you use 4x8's for the stretchers as well?

Joe

[Kent A Bathurst]

After all this time, the lumber is bone dry [I'm assuming its been stored indoors]. In that case, glue will be OK. I think its just aesthetics - you won't put any noticeable strain on those big boys, unless you park your car on top of the bench.

[David Keller NC]

Hi David and Terry,

Thanks for your input. I thought about filling the cracks with sawdust and glue mixture, preferably sawdust from the same wood used (for color). I'm not sure if it would look better to merely leave the checks though, rather than have it looked filled. Would filling it with sawdust/glue strengthen it really, though? Or is it only aesthetics? Also, is there any issue trying to glue pressure treated wood? I've heard something about that.


The sawdust & glue mixture will actually strengthen the piece of wood, but as Kent said, it's overkill in a bench leg, so it's primarily cosmetic. The "glue" issue with PT has to do with the chemicals and moisture in the wood interacting with polyurethane glue - it foams like crazy. But this applies to new PT wood, which yours is not, and you're not contemplating using polyurethane glue for this project anyway (are you...). :)

[Terry Beadle]

Mr. Fabbri :Here are the photo's you requested.208948208949208950

[Joe Fabbri]

Hi guys,

David, that's good to know about the polyurethane glue. I would just use regular glue anyway, but I'll keep it in mind if and when I deal with any new pt wood in the future.

Terry, the wood was outside for a while (I don't even remember where they came from, my father had them), but I brought it inside last year when I decided I would use them for the bench. So it's been at least a year inside my garage. So I think it's dry enough, right?

Anyway, Terry, that looks like a no-nonsense bench. Thanks for sharing the photos. I like the idea of dovetailing the top of the leg. I was thinking of running the leg tenons up through the mortises in the top trestle and then extending them into shallow mortises in the bottom of the bench top, to keep the top tight side to side. With a heavy enough top the weight should keep it down, and it might be better than simply lag screwing the top to the base. What do you think, guys?

Joe

[Kent A Bathurst]

Joe - regarding "...extending them into shallow mortises in the bottom of the bench top, to keep the top tight side to side."

I think you might want to consider expansion/contraction. The top will move side-to-side, but the base will not. I built my bench with lag screws up through elongated holes in the upper end rails [looks like Terry's bench doesn't have them].

Also - on the glue - brand new PT wood is relatively soaking wet. The polyurethane would be fun to watch, as David pointed out, but I don't think much of anything will adhere to it until it dries. And - after 19 years air drying outdoors, and one year indoors, I think you are good to go.

[Terry Beadle]

I did use bolts to anchor the top to the base cross pieces. They are slotted but not by much as the deck top expands up and down not side to side as the beam components are quarter sawn. The bolts do enough to keep the top from never moving...so far ! Hoot! They are not torqued to the n'th degree either. I was shooting for a cross between a Japanese beam and a Frank Klause bowling alley plank. So far it's worked.

You are right. It's a no nonsense bench as when I built it I was more concerned with movement whilst planing/sawing/chiseling etc. This bench does not move unless I put my full weight against it and even then.... It shows the signs of a dozen years of projects but it takes just a few minutes to keep true to a very slight ( and I mean very slight ) concavity using only card scrapers. I check it with a Starrett straight edge and it stays very flat.