Adventures in Steam Bending
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- čas přidán 5. 02. 2020
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There's a certain irony surrounding wood bending. Normally, woodworkers do everything they can to mitigate wood movement and prevent boards from bending, cupping and twisting. But sometimes we want a curved project part that simply can't or shouldn't be cut from a larger piece. There are two popular methods for bending wood: bent lamination and steam bending. With bent lamination, we saw a board into thin strips and glue the strips back together on a bending form with glue between each layer. This process is fairly predictable and you can do it with any species of wood. I have a video on that process here: • Bent Lamination
Steam bending is a very different beast. The process uses steam to transfer heat deep into the wood fibers, causing them to become more pliable for a period of time, long enough for us to clamp the workpiece to a bending form to grant it its new shape. A good analogy is curling hair. With moisture and heat, straight hair can be made curly and curly hair can be made straight. So it is with wood. But because every species is a little bit different, not all species take well to the bending process. Commonly-used species include Ash, Beech, Birch, Hickory, Red Oak, and White Oak. Furthermore, kiln dried wood is significantly more difficult to bend due to the hardening of the lignin imparted by kiln drying.
Since this process was completely new to me I decided to jump in head first, without doing a ton of research, and essentially setting myself up for some failures. But those failures helped me solidify my knowledge on the topic with actual experience and not just taking someone else's word for it. By the end of this experience, I had read numerous articles, watched tons of videos, and read two books on the topic including one I highly recommend: Wood Bending Made Easy by Lon Schleining: amzn.to/31ugzcS While I'm nowhere near an experienced steam-bender at this point, I do feel I have a much better understanding of what it takes to have repeatable successful steam bends. I also learned that I really prefer the predictability of bent lamination. But having both techniques as arrows in my quiver means I simply have more options when executing future projects.
Here's a summary of my personal conclusions. Keep in mind that all of these things warrant more testing and research:
• Soaking doesn't seem to be necessary for air dried lumber
• Steam a little longer than the literature recommends
• Compression straps appear to almost be a necessity. I say almost because I know lots of folks do bending without them.
• Give the piece plenty of time to dry on the form in a warm area.
• Kiln Dried just might be more trouble than it's worth for the occasional steam-bender.
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I'm a guitar builder, so the wood I'm bending is much thinner. Take this for what it's worth. In the guitar world, we have found that water isn't important for bending wood - HEAT is the thing which softens the wood. Steam can help to carry the heat into the wood, but the water just makes things go wonky, particularly if you have a piece of wood with complicated grain structure (anything which isn't perfectly quartersawn, with minimal runout). Now, we are bending thin pieces of wood, and we bend them around heated forms, but these days I use a spray bottle to moisten a side, wrap it in parchment paper (the stuff for the kitchen), and bend. Thicker wood will require more heating than this, but I'm not at all convinced that water is helpful in the process. Using something like the silcone heat blankets most guitar builders are using would be a great, albeit expensive, option.
Air dried lumber is a big deal, though. Either that, or make sure it has been acclimatizing to your shop for as long as possible - a year at least. Kiln dried lumber still has a lot of moisture in the cells of the wood, but most of the water has been driven out from between the cells. It's average moisture content is low, but it has pockets which is quite high. When the wood is heated enough for bending, these areas have very different plasticity, and you get a lot of spring back and checking. Air dried lumber dries more evenly, so when heated it has a more even plasticity.
Compression is extremely beneficial. It can make it possible to bend wood which is completely unsuited for bending.
That makes sense, since at 5000ft above sea level, his steam is significantly cooler than at sea level.
I left a separate comment earlier citing the Wood Handbook which basically agrees with what you say. I had also though about how, for example, the sides of an acoustic guitar are bent around a heated form without steaming. It is in fact the heat which "melts" the lignin in the wood and makes it plastic. The added water/moisture apparently just helps reduce the melting temperature and thus also the chances of damaging the fibers of the wood at prolonged exposure to high temperatures. The sides of a guitar are so thin, as you mentioned, that I think the heat simply takes less time to permeate the full thickness of the wood, so it can be safely bent with heat alone in a much shorter time without damaging the fibers. I suspect that if you tried this with a much thicker piece, you might end up degrading the fibers in the (much longer) time it took to fully heat and plasticize the board.
@@MechanicalMind7 Makes sense, though while we don't use steam, it is traditional to soak wood for 5-10 minutes before you bend sides. This has become far less common, though, because it will frequently cause highly figured wood (curly maple, curly koa, etc.; or some of the flat sawn stuff we sometimes have to use because customers can't understand that all available Brazilian rosewood came out of the burn pile from a factory 50 years ago, and should have ended up in a furnace) to create cross-grain cracks when bent. With highly figured wood, bending it almost dry is by far the most effective option, and it works so well with difficult wood that we may as well use it for easier wood as well. As I think I already said, for guitar sides I spray them with a spray bottle, wrap them in parchment paper to keep any resins from cross contaminating anything, and bend it around the mold with a silicone heat blanket.
how hot is the metal you bend around? Im wondering if heat blanket kits from webstaurant store witha cheapo temperature thermostat controller from ebay would be hot enough a with enough control heat blankets run 30-60 bucks
@@802Leith I've never really measured it, but the Watlow blankets I use can easily and quickly get up to about 500 degrees. I run them pretty much full on for bending, and then turn them down to "set" the bend at about 50% (or so) power for ten minutes.
You should search CZcams for 'engels coach shop steam bending'. This is a man that makes his living repairing old wooden wagons/coaches/sleighs/etc. Many of those require bending large pieces of wood. I think he has done some up to 2" thick. He also squashes the myth about steam bending kiln-dried lumber. Granted, his setup for bending is bigger than anything someone in a home workshop would have, but he is definitely an expert and has a lot to offer.
Tim Cerling agreed. He is a worthwhile watch for sure.
I bend short, thin pieces of kiln dried wood into circles and find that boiling works better than steaming and it's much quicker. Thanks for the video.
I bend fresh cut Ash branches straight to form cane shafts. Easy to bend with clamps and a tea kettle when wood is green. Then I put them outside and let them air-dry for about a year. Way easy to bend green wood with steam.
"Failure equals experience." Thank you. I needed to hear that today! Now back out to the shop.
Good judgement comes from experience....experience comes from bad judgement.
I just get my lumber from Homeless Despot, it comes pre bent.
😂🤣😂
Free of charge
Homeless Despot. Sounds like an AvE fan maybe?
Homer Simpson - "It's funny cause it's true"
Yup, I can make some really good spiral staircases from the lumber from the Orange or Blue box stores!
As a wood turner who uses the 'twice turned' method on many objects (boxes, bowls, etc.) where the rough-turned blank is air dried I can say there is a huge difference between air-dried and kiln-dried wood. There is more 'life' left in carefully air dried wood. It turns better and to me even looks better.
In my experience (51 years) of steam bending, double, triple, or quadruple the stated time in the steam box makes quite a difference. This makes the wood much more plastic and also seems to “anneal” kiln dried wood. I noticed the wood was still fighting you when you were clamping it. Great video! Thank you Marc.
How the temperature and time for steam?
Appreciate that advice Bill. I just tried (and failed) to bend a 2x6x48 piece of red cedar. I left it in my steamer at 200 degrees for three hours. This is my first piece (ever) so I wasn't sure what to expect in terms of bending effort. I read that it's possible to over-steam the piece but it sounds like you disagree. I'm getting ready to re-design my piece and leave these boards straight unless I can find a way to bend them the way I want to. Any advice?
@@rayrenteria5339 Replies on another thread were saying 400-500 degrees Fahrenheit, might be worth looking into the temps.
Hi Marc - great video - I've done a lot of steam bending almost exclusively with kiln dried timber (oak, ash, walnut, maple). Don't soak it! I've found the most important factors (in order) are ...
1: Strap. You are quite right, without a compression strap you will fail a lot!
2: Temperature in the box. Get as close to 100C as possible - below 95C is no good.
3: Steaming time. An hour per inch doesn't seem to come down in a linear way ie half inch takes longer than 30 mins etc.
4: Try to avoid grain run out on the bend.
You are right about drying too - I clamp mine in a drying form then put it in the oven (I bend much shorter peices than your sled!!) ... 3 hours at around 80C seems to give almost no spring back.
Like I say, this is just my own personal experience - as you rightly point out, trial and error is the best way to suss out what works for you - I have photos of piles and piles of bending fails to attest to that! Thanks again for your wonderful channel & keep up the good work.
I’m guessing that soaking the wood just adds more cold water that needs to be heated up, is that right?
Thanks for the informative comment.
Please post a video on bending.
Water boils at 212F at sea level, at 5000 ft it lowers to 203F(Denver 5100 to 5600 ish). This is the main factor in longer time needed in your steam box. Great Video, thanks.
You are The Best! all these other wood workers on CZcams are pure Yahoos!!Cheers from Toronto Canada!!
I took a class with Michael Fortune (master woodbender) a few years ago. He recommended only air-dried wood for steam bending. He also said that the bending strap is essential. As you pointed out, wood doesn't like to stretch, but is happy to compress. A strap of his design that is adjustable for any length board is available from Lee Valley. He claimed that there should be NO springback with steam bending. He had a 6/4 piece of walnut that he had bent around a 3" diameter form and it still fit snugly around the form. Amazing! His line was "once the wood is steam bent it thinks it grew that way".
Love this style of video probably one of my favorites all time
It was fun filming this way too. Glad you liked it.
Completely agree, my favourite video you have done, nice work.
My Uncle was an old school woodworker who used a lot of old time methods like steaming and also fuming. Steaming is ridiculously time consuming. He would tell me about pieces he would keep clamped in moulds for more than a month before releasing. Those cracks you show are indicative of rapid drying
I've heard there's a good steamer that's made in Cleveland but I still have to research it.
ryanern18 gross. But funny.
Tough to find a good research partner on that one
I'm pretty sure I've seen timber at my local hardware store that looks like that already. :)
What you referred to are especially good for boat making, rocking chairs and silos.
Yeah, but they call them studs.
@Dark Justice Ya I realized that when we had to go there and get wood for a new fence and gate.
I’ve seen stuff like that for sale too! Usually at the back of the rack, warped to hell and no one would touch it with a barge pole! Some shops really need to work on their quality control.
Have been reading a lot about steam bending and wood properties. To increase the chances of a good bend without cracks I recommend to superheat your steam to first try at 150 degrees celsius (more or less) and then try at around 200+ degree celsius. Continue to use your time rule + a little extra for good measure (just important to get the wood at a uniform temperature).
The reason I recommend this is because the substance that holds the fibers together in wood is called lignin, and this substance and its melting point is described in this one article (www.sciencedirect.com/topics/materials-science/lignin (3.5.1.3 Lignin) ) to have the following properties "Lignin has a glass transition temperature of about 90°C and melting temperature of about 170°C. Another article (bioresources.cnr.ncsu.edu/resources/thermal-softening-adhesive-properties-and-glass-transitions-in lignin-hemicellulose-and-cellulose/) make out lignin to have a "Softening temperatures of lignins ranged from 127-193°C. Birch xylan and pine glucomannan softened at 167° and 181’C, respectively."
To increase temperature, you could maybe take the exhaust gas from combustion and coil it with a copper pipe multiple times around the steam pipe and to increase heat transfer the steam pipe should also be from copper. You could also maybe route the exhaust gases directly into the steam box. I still recommend having the steam presence as the article (bioresources.cnr.ncsu.edu/resources/thermal-softening-adhesive-properties-and-glass-transitions-in-lignin-hemicellulose-and-cellulose/) state that "Sorption of water by lignin and hemicellulose caused pronounced decrease of the softening temperature-in some cases to as low as 54°C."
It would be really cool and interesting to see this experiment and see how it changes the bend. I would love to try myself but I am currently studying in a big city abroad and
wont be able to try it before the summer when I can go back to my home town where I have garage and equipment. But I dont want to wait that long! :)
Maybe if your able to superheat your steam to 200+ celsius you could try to bend pine wood? Know this wood is notorious to be hard to bend!
I've been seam binding for almost 10 years now and i still found this really interesting, i enjoyed your learning proses as a fond reminder of all of my tests and learnings. you've even made me rethink some of my methods.
For the bending form, you need a forming table, one with dog holes you can use for the form. You wouldn't have near the wasted sheet goods. You would only need a mandrel where the bend is, and dogs large enough to support the width of the work piece.
Metal working shops have forming tables like these, but one of those heavy workbenches all the woodworkers are building these days works almost as well.
Probably the cleanest shop I've ever seen. All the hanging tools are nice and shiny too.
At the furniture school I attended, two weeks was the minimum for drying in clamps on the moulds.
Very interesting. How thick were the laminates? I've done a lot of woodbending (in the '70's and '80's) I mostly used 1/8" laminates. I never used steam and didn't pay attention to if the wood was air or kiln dried. Some woods gave more spring back than others and I'd just adjust the bends to accommodate it. I'd soak the laminates in a sink overnight in hot/warm water, put the wet wood in the forms and let them dry out in the forms. Then I'd glue everything up with carpenter glue. I don't remember ever having cracking or splitting problems. Now I'll have to try it again leaving the wood in the forms for a couple of weeks.
At Denver the boiling point of water is about 10°F less than at sea level. This probably why you needed to allow the wood extra time in the steam box as your steam is at a lower temperature.
When I was in Jr. High School, it was before paper was invented, I built some sleds that had 2 skies shaped like a toboggan. I remember using 3/8" x 2" maple for the runners.
The method we used was to have a steel pipe with a cap plate welded on one end. I think the pipe was 8 or 10 inches. We built a frame to hold the pipe on a 30 ish degree angle. We used a propane burner on the downhill end of the pipe and filled the pipe with water deep enough to cover the part of the strips that were to be bent. The wood was kind of boiled/steamed, I guess.
We prepared the setup the day before we actually did the cooking and bending. The teacher lit the burner when he got to school in the morning at around 7 AM. We just put rags at the open end of the pipe to keep most of the steam/heat in the pipe. Mr. Black, the teacher, would add water during the process until it was my shop class time. My class was after lunch, 11:35. We took the strips out of the pipe and put them right on the form and bent them. They bent very easily. The wood boiled, soaked and steamed for about 4.5 hours.
After doing all of the clamping then adding more clamps, we moved the form to the coolest part of the shop and left them in the form for about a week. For the rest of the school day after my class was over, the teacher kept putting warm wet rags on the bends to keep them wet. I'm in Maine and the winter humidity is around 30 to 40 percent during the winter. Out of the 25 or 30 strips we bent that school year, we only had 2 or 3 break. I would say, don't try to cool it down and dry it out too quickly.
Kiln dried lumber is done with moist heat, steam but it is cooled slowly so it won't check.
Watching this video is very timely for me. I'm about to build an archtop window sash to replace an old broken sash in my house. I have the form built and am just waiting for the time to strip out the clear pine to bend. I forgot all about steaming the wood as opposed to just bent it cold.
I first lined my ply w/ 1" thick (pink) polystyrene/styrofoam insulation, adhered w/ construction adhesive. The insulation minimizes energy consumption/required steam, gets up to temp faster, and protects the plywood so it doesn't delaminate from steam/moisture. I think I also used treated plywood (not necessary); because the steam doesn't hardly get to to the plywood at all, I don't think any toxins are getting airborne from the steam process. Haven't tried the brass fittings, but might. I just used dishwasher drain hose (high temp tolerant) inserted into a hole.
I've heard from various sources over the years that the addition of ammonia to the steaming process helps with the bending.
Not directly from steam bending but I have found slow drying timber massively reduces the checking issues in green (wet) lumber. Drying it in front of a fire or even around central heating has caused major failures in many pieces of my lumber. Slow drying seems to allow for the stresses in the timber to balance out over time and has given my much better results. Thanks for the video.
A great educational video on steam bending Marc. It's critical to know why things go wrong rather than accepting the fact that air dried wood is preferred than kiln dried. I would hasten to say that the two that were soaked for several days were prone to further expansion to take up the water. The use of the steel strap compressor would have allowed the wood to take the simplest way to take up the expansion due to water logging. This allowed the the wood to separate through the length of the grain which was disguised due to the moisture content. When it dried out, those stresses in the grain would have dried out hence the visible splits. My thoughts. :-)
Check out the work of Bern Chandley, an Australian chair maker who specialises in windsor chairs. I know he does a lot of work with kiln-dried lumber. There seems to be a combination of factors that resulted in your failures. I don't think you let the pieces soak for long enough; you probably need seperate drying forms that reduce the inside contact area to allow even airflow; The stress fractures are from drying out too fast, same as for freshly felled lumber. If you wrap the piece in newspaper as it dries this can be avoided.
Poly bag steam bending, you can bend the wood while it's still steaming, then let it set still in the bag until it cools down.
Highly encourage you to check out "Tips from a Shipwright" and his steam bending material that is inches thick for a boat. Enjoy!
I've just done my first steam bent project.
Wish I watched this first.
I did see one item here. All the references I've seen say 1/4 sawn is much bigger deal than kiln vr air dried.
I used an old Turkey Deep Fryer for the steam generator👍👍
"We've just passed rare beef and smoked ham. On our way to poultry."
I'm now definitely getting the Meat Thermometer... for accuracy of course
Morning Wood Whisperer! Have been reading a lot about steam bending and wood properties. To increase the chances of a good bend without cracks I recommend to superheat your steam to first try at 150 degrees celcius (more or less) and then try at around 200+ degree celcius. Continue to use your time rule + a little extra for good measure (just important to get the wood at a uniform temperature).
The reason I recommend this is because the substance that holds the fibers together in wood is called lignin, and this substance and its melting point is described in this one article (@t (@t Lignin) ) to have the following properties "Lignin has a glass transition temperature of about 90°C and melting temperature of about 170°C. Another article (@t make out lignin to have a "Softening temperatures of lignins ranged from 127-193°C. Birch xylan and pine glucomannan softened at 167° and 181’C, respectively."
To increase temperature, you could maybe take the exhaust gas from combustion and coil it with a copper pipe multiple times around the steam pipe and to increase heat transfer the steam pipe should also be from copper. You could also maybe route the exhaust gases directly into the steam box. I still recommend having the steam presence as the article (@t state that "Sorption of water by lignin and hemicellulose caused pronounced decrease of the softening temperature-in some cases to as low as 54°C."
It would be really cool and interesting to see this experiment and see how it changes the bend. I would love to try myself but I am currently studying in a big city abroad and wont be able to try it before the summer when I can go back to my home town where I have garage and equipment. But I dont want to wait that long! Maybe you could try to bend pine as well if you are able to get the steam to +200 celcius! :)
I bent green oak for skin on frame kayak ribs. Approx. Section 35mm x 6mm. I insulated my steam box with an old carpet and insulated the steam hose by sheathing it in a corrugated plastic conduit. I managed to consistently achieve 100 deg C at the outlet end of the box within 5 mins.many of the ribs were quite V shaped but managed a suitable bend (free form) using a leather backing strap.
If you want to steam bend something like 1/4" you can use something as simple a a scuncii steam cleaner with a wide nozzle. Clamp one side onto the form an in a straight line get it wet and hot. Bend it slowly advancing where it is wet and hot as you go. Built a very nice back of a small wood boat that way. For thicker stuff a clear bag, and a metal 5 gallon gas can placed on a propane burner stand works well too. You can see the wood you are working with and the bag holds in the steam. You can clamp it in place once it's pliable and it will hold the form well when it's done.
I had to bend wood for some architectural models in grad school. My instructor told me to add some ammonia to my water bath and soak my pieces for 24-48 hours. Apparently the ammonia helps break down some of the binding elements of the wood fibers and makes the wood more plyable.
The thing I love about your vids, and why I subscribed however many years ago, is exactly that you've always had a scientific approach about knowledge. Failures are, like you said, part of learning.
Loved seeing the Firehouse Subs cup in the video. They are my go to sub place here in So Cal.
“I don’t think this thing is going to leak.” LOL 😂
Nice tutorial Marc. You are a very good teacher, explaining things in such a way that we can all benefit from them. Thank you.
Some much useful information. Thank you for sharing.
This video shows Mark’s science background. I splaud this kind of process.
My wife has an antique sewing machine cabinet that has three stacked drawers on both sides on the outer part of the cabinet that have curved sides to match the shape of the top. One drawer is completely missing so I need to make a new one and bend to wood to match the others. I have been looking at the Rockler steam bending kit, but I didn't know what kind of success it would provide. This is the first video that shows it in use, so I am now comfortable in purchasing it to replace that missing drawer. Then, if I can match the stain, we'll be in great shape.
When I did this, for canoe ribs, I had to soak the kiln dried oak from the borg for a week before steaming, and I still broke a lot of them.
My steam generator was a dollar store stock pot on an electric hot plate, that part worked. I put a fitting for a hose in the lid, and used some silicone rubber to strap the lid tight.
Been there done all that except my 1st attempt was steaming in the PVC tube. Then I used marine grade plywood for the box. I welded up some compression straps and used a portable winch to pull the strap to the form horizontally. Didn't work. Switched to a vertical setup with winch mounted to 20 ton press and it worked. Much harder with 2" thick material.
Thumbs up for the star wars impersonation lol
Good sense of humer.. easy to watch.
Again, excellent presentation!!!
Rosebud... (sorry --- at least I didn't say "we'll always have Paris")
Loved the video, Marc. The diversity of your content never ceases to amaze me.
You're quite right, failure is more important than success, we learn more from our failures.
My buddy and I make shaker boxes. Our steam box is foam lined to retain the heat. Our material is only about 1/8 thick. So the thicker material I am sure will require more soak time. And drying time.
Great video. Love that sled. Looking forward to seeing that make. An english channel (I'm over the pond) had a show called Grand Designs. All about people taking a different approach to creating their homes. One guy was building a semi-underground home and his roof was all bent wood. Cows would be walking on the roof of it so it took some time and experimenting for the carpenter to get it right. He laminated layer upon layer to achieve the strength. It was absolutely amazing. The channel is Channel 4. If ever you find an episode of it, it's worth a watch. Some amazing craftspeople and visionaries were visited throughout the run of that programme.
What series was this? I saw one house that used an inverted 'V' for the roof and they had no end of trouble with it.
@@TheOneWhoMightBe Can't remember which series it was sorry.
Thanks so much for this vid, and moreover, sharing the failures.
I really needed to watch this video today. I was working on a project where everything went from going right to complete failure. I was really down about it and after watching this you lifted my spirits. From about 14:00 to 17:00 you said word for word exactly how I felt. About how it feels like a lost day in the shop and all you feel is the failure. But then you shed some light and turned all that negative positive. I was just recommend to check out your channel and this is my first video I’ve ever watched on your channel and it’s exactly what I needed. I can’t wait to check out your other videos. Thank you!
Same.
I tried steam bending many years ago and never made it past the soaking phase. I used a PVC pipe as you did, but I put too much wood in there. With water, the wood swelled and nothing I could do would get it back out. I even hooked my car up to the end and tried pulling it out and it wouldn't budge. So....lesson learned, if you do this, watch how much wood you stuff in there to soak!
Maybe the short drying time in front of the fireplace made the wood split. A longer drying time in a cooler place might have prevented that from happening?
Fabric softener might help with surface tension, but will not soften the fibers - the liquids affect the electrostatic properties of clothing.
Great video. Thanks very much. I really like your presentation style.
Never used Kiln dried but I can tell you it's the lack of a compression strap in those early attempts. Wood fibers don't stretch at all, they will compress though. The compression strap forces the fibers to compress instead of stretching in any area. Another tip, you can use spacers to fill the gap if you are bending a shorter piece of wood than the strap you made. The key is that the wood must fit tightly or you will have bending problems. Wood that is thin enough can be bent without visible problems but will have a weaker structure than if you used a compression strap.
If you build your form with spacers in the middle instead of a solid piece of material it will dry faster, we allow it to dry in a humidity controlled space(drys too fast cracks too slow you wait forever) everything I have used has been kiln dried and didn't know there was a huge difference. I also use ratchet straps and blocks to start it on a form.It is heat more so then moisture, moisture really just carries the heat. we soak in warm water and about 4 hours for both 1/2 and 3/4. Just what works for me
I used an old coffee maker, a few feet of rubber fuel line, and a length of pvc like yours mounted slightly unlevel. The hose attached to the hot water outlet of the coffee maker, to the higher end of the pvc, and gravity slowly refilled the reservoir from the lower end of the pvc. I was shaping thin laminates of walnut oak and cedar(juniper). The cedar had a bi-product, unintentionally I'd extracted cedar oil and concentrated it by forgetting to turn it off
You don't have a failure. You've just found a way not to do it, (Thomas Eddison).
In your experiments try it with green timber.
You can use a heat gun to help keep the heat as your bending it on the curves. And it will help reduce the spring back.
Man i watch a lot of your Videos.
BUT! .....
This one is pure gold !
I've watched a few of your videos, but this is the first one where I've discovered you're here in Denver!
This video was published 3 years ago when we lived in Denver. If you watch a more recent video you'll see we are now in Missouri
Awesome stuff Marc, thanks for the info! 😃👍🏻👊🏻
Steam-wood bending seems fascinating and even more interesting after I watched this great video. ❤
Hi Marc, in my experience kiln dried timber seems to remove the natural tannins , (tannic acid present in oak), whereas air drying doesn’t seem to remove too much, so that when steaming and bending and then drying the wood doesn’t seem to split as much, if you get me. Hope this makes sense buddy. Great channel and videos mate, keep them coming! ATB Shaun
I watched this video with great interest. Important (I believe) details were shown to successfully recreate the wood bending process in any workshop. Personally, I would pay more attention to the steam heating process, including the increase in steam pressure (within reasonable and safe limits, of course), because I have the impression that it is not so much moistening the wood that facilitates bending, but above all a significant increase in temperature in the presence of steam, which is an efficient source of large the amount of heat.
I saw how do it years ago in wood factories. Pressure autoclaves with superheated steam were used, and the superheating itself took much longer - three hours for thick material. However, in this factory much longer and thicker elements with complex curves were bent. The material was formed using a specially adapted press which, in addition to shaping, also compressed the longitudinally formed material, so your metal strip is the right course of action, I think.
The principle of temperature rise TOGETHER WITH STEAM PRESSURE was the distinguishing feature of this technology. On the other hand, nobody was playing in the initial soaking of the material.
Very informative video. Many thanks for publishing and for very useful information.
Thankyou for this lesson, I benefited and learned from it, . . . . Chris, Norwich, England
You're welcome! :)
Good stuff. Thanks for the information.
This was a steamy video Marc
Excellent tutorial, very complete, very didactic
I've used a wallpaper remover steamer in the past for steam bending, and it looked exactly like yours from Rockler.
Very nice work and very precious advice
Now that you see the difference in waterlogging and steam saturation, you could research a couple of interesting things that have helped me. Japanese Saki ...no, really! AND, species grain characteristics. You can work Hickory or Elm right after cutting. I learned why them and almost no other. Good luck in your learning and sharing. Thanks
Hello , put the wood for one week in water, take it out and put it in aluminium foil and then steam for one hour, leave the aluminium foil on when you bending the wood . Love your program
Very insightful
Great video Marc!
This is info I really need to begin a lamp build for my sisters new house. Thank you for including your failure pieces, I will log that particular misstep in my little project diary!
BTW, I absolutely LOVE the "re-elect 'Goldie' Wilson sign!! BTTF was a childhood classic for me!
I liked it it was pretty simple and self explanatory
The steam time of about an hour per inch is after the wood comes up to temperature, not when you put the wood into the box cold.
You mentioned being in Colorado. Cooking time is likely going to be longer at that altitude I would imagine.
How long it takes to bring the wood up to temperature depends on the type of wood, the growth patterns in the wood, the bias in the grain when the wood was cut, the overall thickness, and probably about 12 million other minor variables, most of which aren't really important unless you're building parts for the space shuttle.
Keep in mind that you can overcook the lignin so more heat isn't necessarily better.
Maintaining heat through the entire process is important too so bending in a cold shop in winter when the humidity is very low will affect the bend. Keeping a steam generator spraying on the piece while you're working it helps, or if you're really brave, have someone with a high output weed burner torch brushing the piece. Otherwise, unless you want to build a sauna to work in then your options are limited.
You need to watch a video from, "Tips From a Shipwright" entitled, "How to steam bend wooden boat frames in plastic bags instead of a traditional steam box."
I was just going to leave this same comment!!! :) Lou bends pieces that are multiple inches thick using that amazing method! Many people seem to miss the point that woodworking is woodworking and we can all learn something whether it be from a cabinet maker, a ship builder or an aircraft builder.
Agreed best method I've seen, Tips from a Shipwright, 😇😇😇😇😇😇😇 and Dave Engles coach and wheelwrights.
@@PaulScott_ He also uses a steel can to boil the water and make steam. I think that gets much hotter than the plastic steamer that the Wood Whisperer is using here. Personally, I suspect that he needs a better steam box, made out of steel pipe and a steam generator like the one that Lou uses. But, that may be out of the scope of this project.
With a plastic bag is easy
Came here from that video. And no, I wasn't searching for steam-bending wood.
Others have commented like Tom R. on your form work. Make your two sides identical then put spacers/spokes from side to side. For example; if your "skis" are 3" make your spacers 8 or 9" x 1" x 3", glue and screw through the sides of the form into the end grain of the spacers. Place the spacers about every 2-3". This will allow air flow around the piece to speed drying. At the tip of the form make a starter clamp, a U shaped piece of plywood or a length of pipe secured to the outside of the form. Space this "starter clamp" so you can easily slip your ski tip under it. With the form secured to the bench with the spacers facing up put you hot wood under the starter and begin bending. As you bend clamp through the spacers in the center between the two skis using a clamp block that spans both skis. Always start at the end with the most bend and clamp to the other end.
Ditto, what many have said about more time in the steamer and more time on the form and V G wood if possible.
I did lot of bending for spiral stairs curved stairs, round/curved windows... We had good success with fabric softener alone but soak for 3+ days for 1/2". It comes out like a noodle and it is not hot and you don't have to hurry! Soak, bend, dry, then laminate.
I used to say to my students, "I have a lot of experience. You know what that means, right? It means I have made a LOT of mistakes." Then I would add, "I made those mistakes so you won't have to. You can make your own mistakes."
I like to use the thin laminations and glue. I made a demi-lune table 15 years ago out if yellow oak and 3/4" thick by 5 1/2" tall
glued up did not move when removed from the bending fixture.
Ty Very informative presentation.
I love your approach to learning this! thank you! can't wait to see that sled!
You're a good Dad... Hope your Kids love your work...
You can make a steam box out of ducting , end cap and hang rag over the open end. Use piece hardware cloth as riser. I have never soaked a piece of wood. Don’t use kiln dried, it is heat hardened and brittle. Green is always your best bet. I have not used a compression band but I do have couple hundred clamps. Use your moisture meter.
I watched 12 minutes of footage last night while going to bed and this morning while waking up I decided to watch the rest. At 13:10 I was literally startled and confused when you shaved and looked different in the matter of a frame lol. I'm awake now.
Long time listener, first time caller, a like and comment for the algorithm. Love your show.
I steamed some rocker for rocky chair. I found longer steam time as well with the same kit you used. I soaked over night. Used cherry Kilmed dried. I also found faster to get in clamps the better.
With kiln dried wood soak the wood to the point of being waterlogged. The extra water provided a more thorough heating.
Getting the steam hotter might help... I also think that you should leave the piece in the mold for an excess amount of time. If the rule is that you should steam for "1 hour per inch of thickness," I think you should consider leaving it in for 2 hours per inch of thickness. When you soak the wood for 24 hours, consider soaking it for 36 hours, and when you clamp the piece to the form, let it cool in place for twice the amount of time that you think it needs. Another suggestion, is to put some space, about 1/2" between each piece of the form. Consider placing a fan to blow some air between the form pieces. This would allow the piece to cool from both sides, and may eliminate some of the spring-back.
When it comes to steam bending if the wood is saturated with water it prevents the steam from penitrating into the full depth of the wood fibers so some moisture is preferred but wood that is waterlogged so to speak henders the steamming process
Good info 👍👍👍👍I was taught to use the compression strap in high school when laminating tight curves in thin materials without steam. Might of been overkill, lol but that's how he had me do it
thanks for sharing what you know, you know a ton.
If you're not already familiar with it, I find the Wood Handbook: Wood as an Engineering Material as a great overall technical resource that can cut through a lot of the internet BS and cut straight to the science. I have a pdf copy of the 2010 (centennial) edition on my computer, and Chapter 19 deals with specialty treatment of wood, including plasticizing (i.e. making it pliable for bending, including steam bending). Not sure if it has anything more than the book you recommend, but might be worth a read.
I've been thinking some more about this after reading the Wood Handbook, especially with regards to pre-soaking the wood. As explained at the beginning of Chapter 19,
"The matrix [lignin] can be thermoplasticized by heat alone, but the Tg [glass transition temperature, i.e. above which the lignin polymer softens] of the unmodified matrix is so high that some fiber decomposition can occur if high temperatures are maintained for a lengthy period. The Tg of the matrix can be decreased with the addition of moisture or through the use of plasticizers or softeners".
In other words, the mechanism by which wood is softened for bending is through heat, not necessarily moisture. The moisture merely aids to reduce the temperature necessary to "melt" the lignin. It seems to me that heating via steam provides the requisite moisture while also heating the board. By pre-soaking the wood, you are adding significant additional thermal mass to the board in the form of cold or room-temp water and likely raising its moisture content far beyond the recommended 25-30% cited in the Wood Handbook. Water has a very high specific heat, meaning it takes more heat energy to raise it to a given temperature. so it would take a water-logged board a much longer time in the steam chamber to reach the requisite bending temperature. I assume that the "rule of thumb" for how long to steam per unit of thickness is based on "dry" boards at typical moisture content, so using the same guidance for a water-logged board would likely fail to raise the water-logged board to the desired temperature in the same time (it would take much longer). That in combination with the problems with taking much longer to dry after forming, and the splitting issues upon drying, I suspect that pre-soaking is probably not only unnecessary but likely detrimental to the process.
Hi, can you please share the pdf for the book? I found some versions online but their chapter 19 is very different from what you shared, its called round timbers and something. It will be a great help if you can kindly share the pdf or at least point me to the right link so that i can purchase it. Thank you
@@DrShaggy I just found it by simply Googling "Wood Handbook, wood as an engineering material". It is a free publication by the US Dept of Agriculture so no purchase necessary (at least for electronic version):
www.fpl.fs.usda.gov/documnts/fplgtr/fpl_gtr190.pdf
Thank you!!
Those giant wide mouth F clamps at the end really aroused me.