Update - (bad) experience with a workshop dehumidifier....

[ByronBlack]

Ian,

I think you may be over-complicating things a little. I've made a fair bit of furniture and guitars (which usually need very low MC) and have never worried about the moisture content too much - I always acclimatise the wood to its final destination for a few weeks (after dimension the wood close to its final size), and then bring it into the workshop to work on - if its a long project (in time) i'll bring the wood back into the house or wherever its going to go between session. So far I have had zero issues.

If you plan your projects to accommodate wood movement, then most of your problems are catered for.

As for your beech, I would have started making the base as soon as it was within a few percent of your shops natural MC, and while building the base, let the pieces for the top continue to dry, when you glue them up in a lamination, they really won't move too much once you have flattened them.

You really don't want to leave wide boards drying if at all possible as the likely hood of cupping is much greater, instead you want to rip them down to 1/2" or so of your final dimension, this means they dry quicker, and gets any movement out of the way ready for final dimensioning.

 

[jasonB]

That method is fine if you are making for yourself and can kondition the work in your house but you can't take a load of timber and leave it in stick in your clients house for a couple of months and then start working on it and poping back with bits every day.

You really need an area or whole workshop that is a close as possible to the average house conditions that would mean heating and possibly dehumidification but there are not many houses that have constant dehumidification or air conditioning so best to just keep it a room temp. Though I wouldn't want to work at the temps some of my clients keep their houses, would be like working in a sauna!

Aim to either keep some timber in stock or buy it as soon as the order is confirmed, hopefully you will be busy and have a few months waiting list. During this time the timber can be rough dimentioned and then stored in stick to aclimatise as best as possible.

I learnt this lesson early on when I started making furniture. I made a small table that had about 50 through tennons, made it all, applied finish and then bought it inside for a couple of days prior to delivery, all those tennon ends were sitting proud withing 48hrs and that was thin section 25x25 oak.

Jason

 

[ByronBlack]

That method is fine if you are making for yourself and can kondition the work in your house but you can't take a load of timber and leave it in stick in your clients house for a couple of months and then start working on it and poping back with bits every day.


Jason

Thats a good point Jason, if I were doing this work commercially, then it would make more sense to control the environment more as you suggest, but for personal or family projects, I think its easier to get away with stashing wood in cupboards/behind sofa's and under-beds...

 

[ondablade]

No question Byron but it would have helped if i had ripped down the beech when i got it, but unfortunately (a) i didn't fully appreciate that would have been a good idea (luckily it'll be OK as i have plenty of extra thickness), and (b) my shop is still stripped out awaiting completion of the wiring, ductwork and so on. (i got sucked into doing some consulting work, and then into refurbishment in a rental house for a tenant which has delayed me big time)

To yours Jason that's the point i think - it depends a lot on the specific situation. My thought is just that if i bite the bullet and seek to control %RH to 45% year round (heat in winter, AC in summer) so that everything tends towards 8% moisture then there's no rushing about. The question is whether or not this can be done fairly cost effectively, or not.

:wink: To get really picky. Go take humidity readings in the client's house, and adjust the shop accordingly....

 

[ByronBlack]

No question Byron but it would have helped if i had ripped down the beech when i got it, but unfortunately (a) i didn't fully appreciate that would have been a good idea (luckily it'll be OK as i have plenty of extra thickness), and (b) my shop is still stripped out awaiting completion of the wiring, ductwork and so on. (i got sucked into doing some consulting work, and then into refurbishment in a rental house for a tenant which has delayed me big time)

To yours Jason that's the point i think - it depends a lot on the specific situation. My thought is just that if i bite the bullet and seek to control %RH to 45% year round (heat in winter, AC in summer) so that everything tends towards 8% moisture then there's no rushing about. The question is whether or not this can be done fairly cost effectively, or not.

:wink: To get really picky. Go take humidity readings in the client's house, and adjust the shop accordingly....

Ian, are you planning on doing work commercially?

 

[ondablade]

Sorry Byron, i could have been clearer. Yes, I'm in the middle of setting up to go full time commercial.

I was fairly low level hobby and DIY woodworking with a Robland combo until late last year when i bit the bullet and starting upgrading my whole set-up. (including changing to separate Hammer machines)

Some of us have no sense...

 

[L Harding]

I basically agree with most that has been said, and although i dont go as far as keeping my shop humidity controlled, i do try and keep it at house temp (actually about 18C, the hottest i can work in) all year round.


However just to stick something into the mix, when i did my apprenticeship i was told that the workshop should be somewhere between the outside temp (and RH) the wood has been in at the yard (for however long since it was kilned) and that if its final surrounding. I.e. the clients house. The general basis being that this gives it time to acclimatise to the lower humidity slower and therefore stays more stable.

I know the counter argument for that is to just have it in the perfectly controlled shop for longer to get all this out the way, but we all know thats not really possible. Im normally about 2 months ahead with orders, but i rarely have the room to have stuff in stick for more than one job at a time, Plus 2 months is arguably not enough anyway, and i defiantly don't have room for a large wood store.

What we really need is the wood yards to control RH in there barns! Id pay an extra couple of quid per cube for that

Ill be very interested to see how much it will cost you to carry out your plans Ian



Luke


Luke

 

[ondablade]

Thanks for that Luke, sounds to me like it very nicely points up some issues where practical reality (detail) collides with basic theory. If we could air condition the world, then these details wouldn't be an issue. But we can't. (and as a German friend says 'the devil is always in the detail') Which is why a practical solution and a theoretical solution are not necessarily the same.

As you say there's the matter of conditions prior to the shop, the impossibly long time it would take to reach the correct conditions even resting in an air conditioned shop (which i guess is why kilns use high temperatures to force the drying cycle), what happens during transportation of the piece, and what really are the conditions over the year in the client's house.

A practical regime may well make use of air con equipment, but its going to force some compromises too. That said i suspect that if we're to do fine work the detail timber conditioning issues, and the opportunities presented by the availability of relatively cheap air conditioning equipment can't be ignored.

It'd be nice if we could figure out a practical regime in quantitative/scientific terms so that we knew why it worked, and what needs to be controlled.

Thinking about what you said:

The rate of drying or taking up of moisture - determined by how great the difference between the actual state of the timber, and the state it will reach if allowed to equilibriate in the conditions it finds itself in must be a fundamental issue.

Just surmising, but due to internal factors moisture presumably finds it's way out of wood at a fairly slow rate - which probably gets slower the thicker the wood. Which may well mean that if you dry very aggressively (apply external temp and humidity conditions that will suck the moisture out really quickly) the wood near the surface of the piece will dry faster than that deeper in - leading to internal tensions and likely warping and splitting if you try to go too fast.

It will of course all end up at the same moisture content and temperature in the end, but by the then the harm is done.

There's mentions about too that suggest that drying too fast causes 'case hardening' (no idea what that is) and other defects in the wood that also make it work much less nicely. (which may be why some say sir dried timber is nicer to work)

The other basic issue that arises from this must be that if as above you cut open a piece of wood that's partially dried but wet or dry inside relative to what the conditions have brought it's outer surface to then it has to warp immediately as a result of the release of the internal stresses caused by this moisture gradient.

If you then machine it true before its equilibriated it's got to move again afterwards as the newly exposed surfaces start to take up or lose moisture - again altering the gradient.

You mention temperature. It's not much talked about, but as well as greatly influencing drying rates it's surely got to act directly by causing expansion and contraction of the wood too.

I got budget quotes this morning for a small kiln set up, and for shop humidity control from Ebac's German division which i've not had a chance to look at yet. It's looking like a careful study of kilning and other drying processes is also going to be needed.

I'll be happy to share information as it comes available - but please be aware that this is a learning path for me so personal discretion is advised ...

 

[ByronBlack]

Ian, as you are doing this commercially, you can ignore my advice freely, but this is quite an interesting topic you have brought up, so keep us updated with your research into kilning and conditioning of wood as I sure we can all learn a little, so far I've been quite lucky with my lackadaisical approach and could probably benefit from your findings as you delve further into the subject.

 

[ondablade]

I wouldn't dare ignore advice born of experience Byron. It could be though that if you work primarily in small sections of a wood that is fairly stable, take precautions as you say and your supply is well dried that it's not such an issue.

My view is for sure a bit coloured by the aforementioned large planks of frolicsome and ever so slightly stroppy beech sitting in my shop.

I'll share as best i can what comes up from my diggings - but bear in mind i'm a mechanical engineer and manufacturing guy getting more seriously into woodworking with not a lot of experience, and little 'traditional' or trained background.

Good luck with your beech bench by the way. Maybe i should stall for a bit and wait for you to burn a trail...

PS thank you for the link to Koetter Jason.

 

[ByronBlack]

Ian, my current bench build unfortuantely won't be in beech, but the one I'm selling certainly is and that was a good experience building, I'll gladly pass on any info of my build of it to you if you need it when you come to build yours (unless less of course you want to rid yourself of bendy beech and buy mine

 

[ondablade]

Nice try Byron! :wink: