Look at your workbenches!

[Al Navas]

I want to share the following with you, because it happened to me.


I heat the shop during Winter, using a forced air system. This creates a very dry heat that could result in bench tops not being as flat as we might need them. The following photos illustrate the current status of my workbench top - the total gap in the top photo is 1/8-inch, with the precision straight edge held flat on the back edge of the bench:


The bench top:


http://sandal-woodsblog.com/wp-content/uploads/2008/03/benchtop-1.thumbnail.png (http://sandal-woodsblog.com/wp-content/uploads/2008/03/benchtop-1.png)


The end cap:
http://sandal-woodsblog.com/wp-content/uploads/2008/03/benchendcap-1.thumbnail.png (http://sandal-woodsblog.com/wp-content/uploads/2008/03/benchendcap-1.png)


Of course, the dry air is likely to also affect everything else wood in the shop, such as your lumber and, by extension, any projects you are currently working on.


I recently bought a monitoring system, which will allow me to monitor the relative humidity in my shop using an inexpensive hygrometer that also monitors temperature. I believe I will be able to start using a humidifier when needed, to attempt to keep the humidity in the shop fairly constant.


You will find additional details and comments at my blog.



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[Peter Quinn]

I saw a steam generator system installed in the HVAC ducting in a TOH episode a few seasons ago. They claimed it was the most effective way to precisely control humidity during the dry months. Vastly superior to the foam wraped squirrel cage approach. Precise humidity levels were controlled with a hygrometer/controller installed in the conditioned space.

Recently had my Mahogony Martin guitar set up by a local luthier and he inquired about the humidity range of my home as it effects the instruments performance. Appearently he creates different tail pieces to maintain proper action for different seasonal humidity levels. He told me he had one of these steam generator humidifiers installed in his home/shop and it greatly stabilized his environment vrs using a portable humidifier.

In my basement shop LOW humidity is NEVER a problem!

[Marc Prudhomme]

al,
Thats nothing.You should of seen my newbie bench top I made last year.I made it out of a solid core door and I glued hardwood flooring to the top.I really should of took a picture of it but I was afraid I would be laughed right out of the forum.A picture would of been enough,no straight edge needed.It look like a 6 ft macaroni.I should say it looked like a 3 ft long macaroni 6 ft wide....
Marc

[Phil Thien]

al,
...but I was afraid I would be laughed right out of the forum...
Marc

We wouldn't laugh AT you, but WITH you.

My bench top is a solid-core door. It has been stable. I use a support in the middle to keep it from sagging. I has been solid, but I don't do a lot of hand-tool work, so I don't think neanderthals would approve.

[John Keeton]

Looks like the underside has lost more moisture than the top. Obviously, the change in humidity is the culprit, but probably aided by the top having some wax or other finish applied and the underside not. May want to apply something to the bottom surface to help minimize this effect.

[Al Navas]

...In my basement shop LOW humidity is NEVER a problem!
I have also heard of this type of system, Peter. But I know nothing about them - I will do a little research, as I am intrigued about how complex the installation might be. Thanks!





al,
Thats nothing.You should of seen my newbie bench top I made last year.I made it out of a solid core door and I glued hardwood flooring to the top.I really should of took a picture of it but I was afraid I would be laughed right out of the forum.A picture would of been enough,no straight edge needed.It look like a 6 ft macaroni.I should say it looked like a 3 ft long macaroni 6 ft wide....
Marc
NOW I want to see this one, Marc! No one will laugh AT you, but WITH you, as Phil said. Maybe we will learn from your experience. :cool:





Looks like the underside has lost more moisture than the top. Obviously, the change in humidity is the culprit, but probably aided by the top having some wax or other finish applied and the underside not. May want to apply something to the bottom surface to help minimize this effect.
No wax on this top, John. The vendor in the U.S. suggested to apply some sort of sealant to the underside.

However, most of the moisture loss takes place from the ends of the boards, not the edges. I will incorporate a yearly bench top flattening program, to coincide with the maintenance for the other tools.

Thank you all for your comments!


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[Peter Quinn]

It looked prety cool Al. Really a very simple addition to an existing system (of course they never give prices!) I thing they applied it as a retrofit. Maybe check the This Old House web site or a good HVAC man. I have forced hot water so its not an option for me.

[Al Navas]

It looked prety cool Al. Really a very simple addition to an existing system (of course they never give prices!) I thing they applied it as a retrofit. Maybe check the This Old House web site or a good HVAC man. I have forced hot water so its not an option for me.
I will have to look into this. I have no idea what size steam generator, but I imagine a small one will do the job. Headed over to TOH.

Thanks again, Peter!


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[Wayne Cannon]

A number of the left-over pieces from my flooring job turned pretzel, too. Most, amazingly, remained quite straight.

[Marc Prudhomme]

Sorry al,I burned it last year.Made a nice fire...
I have also heard of this type of system, Peter. But I know nothing about them - I will do a little research, as I am intrigued about how complex the installation might be. Thanks!





NOW I want to see this one, Marc! No one will laugh AT you, but WITH you, as Phil said. Maybe we will learn from your experience. :cool:





No wax on this top, John. The vendor in the U.S. suggested to apply some sort of sealant to the underside.

However, most of the moisture loss takes place from the ends of the boards, not the edges. I will incorporate a yearly bench top flattening program, to coincide with the maintenance for the other tools.

Thank you all for your comments!


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[Marc Prudhomme]

Was it Straight or a Pretzle???
A number of the left-over pieces from my flooring job turned pretzel, too. Most, amazingly, remained quite straight.

[Al Navas]

Sorry al,I burned it last year.Made a nice fire...

I cracked up at this one, Marc - thanks for the chuckle!


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[Will Blick]

Maintaining the same RH is only relevant when you hold the same indoor air temp. this is often overlooked....

wood reacts to grains of moisture in the air, not RH.

[Wayne Cannon]

Poor wording. Most left-over pieces remained quite straight. A half-dozen, however, warped as much as 8" over a four- to five-foot length, like reaction wood.

[Brent Ring]

Move West - Rocky Mountains - Everything is DRY here!

[Chris Padilla]

Consistent is what you what for your wood. Yes, it is nice and dry in Colorado but you can have the same problems...just the other direction! :)

California is dry in the summer, wet in the winter...wood is gonna move!

[Chris Friesen]

Wood reacts to grains of moisture in the air, not RH.

Not true. Wood wants to reach equilibrium moisture content, which varies primarily with RH and only secondarily with temperature. Read Hoadley if you don't believe me.

As an illustration...suppose you have a big stack of wood in equilibrium with freezing cold air at 40% RH, stored in a sealed room. If you heat the room, the air can hold more moisture, so the RH drops. Because of the higher temperature, the vapour pressure of the water in the wood rises, and water will escape the wood until it reaches a new balance with the air.

[Jules Dominguez]

Maintaining the same RH is only relevant when you hold the same indoor air temp. this is often overlooked....

wood reacts to grains of moisture in the air, not RH.

I don't think that's correct, Will. Temperature affects relative humidity, but I think it's the relative rather than the absolute amount of moisture in the air that drives the gain or loss in moisture in the wood. See p. 76 of Understanding Wood by Bruce Hoadley.

[David Giles]

Same problem here in Houston, Al. There's a 1/8" hump down the middle of the wood bench. But it was a good excuse to buy my first jack plane! That sucker will be flattened when I get back from vacation.

[Dennis Peacock]

al,
Thats nothing.You should of seen my newbie bench top I made last year.I made it out of a solid core door and I glued hardwood flooring to the top.I really should of took a picture of it but I was afraid I would be laughed right out of the forum.A picture would of been enough,no straight edge needed.It look like a 6 ft macaroni.I should say it looked like a 3 ft long macaroni 6 ft wide....
Marc

Now that's funny right there. :)
Marc, we wouldn't be laughing AT you...but we'd be laughing WITH you because many of us experience and do things like that with the same or even crazier end results. :o

[Al Navas]

Same problem here in Houston, Al. There's a 1/8" hump down the middle of the wood bench. But it was a good excuse to buy my first jack plane! That sucker will be flattened when I get back from vacation.
Thanks for your comment, David. What type of bench do you have? Did you make it, or did you buy it?

For whatever it's worth: Several people who know workbenches suggested I wait until late April-early May, well after the heating season has ended, before attempting any bench top flattening. What they fear is that, if done too early, one could end up with a low spot on the bench top.

I sharpened the iron in my Fulton #7, and have been making thin curlies on a test board in preparation for the flattening of the bench top.

I look forward to learning what your plans are, David. Thanks!


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