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Blog...wood bending

Bending Wood the Wrong Way, by Christo, 3/19/24

Here is a response I gave to a wood artist wanting to bend compressed wood across the grain (the weak direction) to form the curve of the leaves.

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We have all seen cupped wood  as a plank that is all but unusable. It is the result of uneven tension in the plank, and often made worse by poor drying technique. But what if you want to do it on purpose? Most wood will split along the grain when you try to bend it that way. Compressed wood will bend that way a little, but choose the ones with cross linked grain like Elm, Sassafras or Hackberry. They will hold together better. Use some kind of form if you can with a depression curve in the back and a round over curve in the front. Press the wood between them. This will even out the bend compared with trying to do it by hand. But you can certainly do it by hand too.

Try heating up the wood in a microwave to make it warm before bending. Use about 30-40% power setting and try 30 seconds at a time. Too much and you will dry it out and prevent it from bending. Also use the microwave to dry the parts. Just keep adding 30 seconds of heat and adjust the shape every 30 seconds in your hands until it is so dry you can't bend it in your hands anymore. Once most of the moisture is removed, it gets too hot to touch. Quit drying around that point or you can burn it. 

You can put the cold wood into a form as described above, wrap it tightly with elastic bands, and cook it slowly in the microwave. As it heats and softens, it will take the shape of the form. Then continue heating to dry it. Drying time has to be experimental, because you are also drying that formwork. If you have any tight angles, consider carving them from thicker stock that is tapered, combined with bending.

The Hackberry planks are usually labelled "Ash or Grey Elm". They look the same as ash, but with cross linked grain. Red Elm planks are also good. As is Sassafras. If you want to try any of the other bends, bow, twist, crook, compressed wood is your answer for a perfectly stable part, once dried.


The making of Woody. by Christo, published 15/16/18


Woody is a creation of Shimoda Design for Steelcase. Pure Timber is the fabricator. This is a good example of a fairly complex architectural project. Joey Shimoda is a LA architect and owns a mid size design firm. He designed an organic wooden trellis at the request of Steelcase, a previous client. Pure Timber was asked to fabricate the trellis because that's what we do, and we did so in Gig Harbor WA. The client is in Chicago so we built Woody to be disassembled and installed by a large local millwork company named Bernhard Millwork that was familiar with the building. This was of some importance because the building is a significant Chicago landmark. At 4,000,000 sq ft (about 30 Costcos), The Chicago Merchandise Mart was the largest building in the world when it opened in 1930. It is also a union building, and Pure Timber could not bid the installation, and manage union labor in Chicago. The general contractor is Bushman Construction, and owner Matt Bushman took a very strong personal interest in the project. He managed it from start to finish. 

The trellis had a design spec that made it more than a bit challenging to build. It was to be bisected by a glass wall, and that wall curves back and forth through the installation. There is also a sliding door that bisects part of Woody. Half of woody is in the Steelcase showroom, and half is in the common hallway. The ceiling heights are different on both sides of the glass wall. The building is nearly 90 years old and has been renovated so many times that no one really new what was behind the plaster. Anchor points, sofits, drop downs, and bracing had to be built on site, while Pure Timber fabricated the trellis.

Here is an early rendering of what Woody was meant to look like. It is very alien looking in this image, but became very organic looking in solid ash....



 The lower point shows the separation for the curved glass wall, which extends through the entire 100' length of the trellis.


There were months of updates in the computer model. We were actually well into the build before the model was fully locked down. Even then, new issues were discovered on site that affected what we had to build. The above image shows a more organic rendering of Woody.






Running a creative business. by Christo, published 12/30/2017

Running a small manufacturing operation in the US has turned out to be both possible and rewarding. From an early age, probably 13, when I took my first part time job in a wood turning factory for $1.25/hr (about what some overseas woodworkers make today), I wanted to own and run a factory. Making things went back generations for my family, and I needed to do it too. A factory gives you scale, repeatability and leverage to grow. However, in the end I shunned the factory approach and created a studio style operation. This was more suitable for my interest in one-off and custom work. Everyone at Pure Timber works on everything, and especially what they want to work on. I am one person that has quite a few ideas, but I don't have all the ideas. My employees have some. And my customers have a lot. Together, we can do things I couldn't accomplish on my own. So I have achieved some leverage in my business. To some extent, it lets me focus mainly on the creative side of the business. I say mainly, because there is a lot of paperwork, and sales and customer service. I don't find that work very creative. I am happiest building something, and one day maybe I'll be able to offload some of the non creative, but essential, operations to others. Recently, we completed a large trellis project for a Chicago client. It has taken 4 months of my life, and I want to do it again. It has been the most rewarding project to date, probably because the design was truly organic, and required our compressed wood to accomplish. It couldn't have been built in wood without it. In a few weeks I'll visit Chicago for the opening, and get some awesome images of it. For now, here is a teaser...



Bent plywood and notes on building contemporary furniture. by Christo, published 1/03/2014


The term bent plywood can be confused with wood bending. It's bent wood after all isn't it? Well, it's not solid wood bending like we specialize in at Pure Timber. It is really bent sheets of veneer that are laminated together in a curved form with glue between the layers, and cured under heat and pressure to fix the shape. Bent plywood should really be called molded veneers. The technique makes a very strong and stable product. It can be made very thin, like for curved chair seats that are less than 1/2" thick. But you can't take a sheet of plywood and bend it (some minor exceptions). Laminated veneers are very useful for building contemporary furniture and contemporary parts that have very tight corners, often combined with long straight sections. The technique is mostly confined to two dimensional shapes. You can't 3D bend veneers, except to a very small degree - such as a slightly scooped chair seat. 

Pure Timber LLC does bend plywood and laminate veneers into curved plywood shapes if that is the best technique to make the part. But foremost we are solid wood benders. And we specialize in extreme 3D bending, something that bent plywood can't be used for. So if you come to us with a contemporary design that is more suited to bent plywood, we may refer you to another company like Plyforms in Michigan. Keep in mind that laminated veneer tooling is very expensive, and suited to high volume production. You won't be able to prototype your designs in bent plywood because of the high up front costs for tooling. Sometimes, we will prototype this type of product in our solid wood bending style, so that you can have a physical prototype of your design.

Solid wood bends are often thicker than curved plywood shapes to achieve strength and stability in the same design. Keep in mind though that our 3D bending gains great strength from the shape, so it doesn't always need to be thick. But if you want to build a very thin and 2D solid part, that has long straight sections and tight corners, stability is lost. One reason for this is that bending wood doesn't very much want to be straight. So if you have a long straight section in your design, with a tight curve at the end of it, the bending wood has to be able to make that curve. We engineer our bending wood so that it stretches out when you bend it. That is the secret of why it works. If you don't bend it, like in a long straight section, it still has that potential energy or strech engineered into it. It will be pretty stable if fully dried, but it has potential energy in it that you didn't use up by bending it. And that potential energy can be released by having a straight line turn into a slightly squiggly or bowed line later. This is a problem in building contemporary furniture that often has a lot of parallel lines. They have to stay parallel to look good. One way around the problem is to go thicker with the bending wood, so we can often adapt our technique to suit your design.

When thinking about using Cold-Bend hardwood for prototyping, consider that it is more suited to organic shapes - shapes without many straight lines, and with 3D bends instead of 2D bends. Contemporary 2D bent parts are better made from laminated veneers.


The business of engineering Cold-Bend hardwood, by Christo, published 12/30/2014

236-compwood-machine.jpgOnce in a while someone asks me if they can make Cold-Bend hardwood at home. It is sometimes from someone that finds a $100 plank of extreme bending wood too expensive, and sometimes from someone who might like to be in this business. Either way, it is a reasonable question. I would really like to have a partner/competitor out there to help grow this market. I am so under the radar of architects and designers, my preferred customers, that it feels like the chance of connecting with them in time to design something really original, sculptural, and in solid hardwood is pretty low. The best time to start working on a new project is when it is still in the conceptual stage, where we can do some consulting and help to create something very unique, that can be built in our 3D organic sculptural style. Problem is, almost no one else can build it, so there are not many people thinking about what we do.

To get back to what starts it all - engineering hardwood to be "extreme" bendable, I'd like to discuss what it takes to do it. Our investment in it is somewhere around one million dollars in equipment and development time. If you are lucky enough to be in the earnings area that you know what it costs to support one million, such as with a million dollar mortgage for example, you will know that it costs nearly $100,000 per year to service a million dollar investment/debt/mortgage. That is just debt service, and that doesn't include making it, storing it, selling it, etc. We don't actually sell you that much product as engineered wood, so most of it goes into in-house projects. And this is where the real value of our raw material comes in. It allows us to make things for our customers that they couldn't otherwise get made in solid hardwood (maybe plastic or steel or aluminum, but not hardwood). That is our "value add".

When I made the commitment to manufacture Cold-Bend hardwood about 10 years ago, we were thinking more along the lines of what the equipment cost, which was a lot, but no where near the real cost, I found out. After two years of having someone else run the equipment, and suffering with low yield and high losses, I took the equipment over personally and have run it almost exclusively ever since. I treated it like a graduate degree level experience, something I have done twice formally, and know the steps to take. So I eventually graduated with my advanced "degree" in wood science in the school of hard knocks-my shop. This took about two more years, and I learn more every year. This year, I had an epiphany where I finally understood something that happens during wood compression, that is completely invisible, but wrecked so much clear lumber. This was in my tenth year, and I finally understood something about wood compression, that maybe, probably, no one else in the world knows.

So to answer the question about how to make compressed wood at home, you'll need about half a million in equipment, and then half a million and several years in development. We can build and sell you the equipment, and I can shorten and lessen the second part of that equation as a technical consultant to you, but so far, no one else has decided to take on the challenge. I've worked out the soft costs so that I could pass them on, but the hard costs of the equipment are still there. And the market is small, though would grow faster with others in the industry. I can think of a lot of ways to use compressed wood, but you can think of more, that I never would have. And the business would benefit from the extra dimension of more brains working on similar, but ultimately different things.

Since almost no one is going to take up the challenge of making Cold-Bend hardwood, me excepted (and maybe you), we make it available for your projects, whether it be small scale like jewelry making or wood turning (I mean small scale in that we can't sell you much wood if you make jewelry or put handles or vines on wood turnings), or large architectural scale projects, my perrsonal favorite. BTW, wood turnerrs are among our most creative users, and I love to see what you do with our engineered wood, even if you don't use that much of it. I'm not just in business to sell engineered wood. This business means much more to me than that. I want to see what you can do with it too, because I can't think of everything, and I want to see what else can be done with it.


Looking back on 2014, by Christo, published 12/28/2014

As the calendar changes over to 2015, I'm thinking about how well things went for my business in 2014, and also how things went for my customers in 2014. Every year since the beginning of the "great recession", optimism has been predicted for the coming year. Mostly, it had been unfounded, at least until one or maybe two years ago. Now, as employment has risen (though underemployment is still rampant), and prices have stabilized and perhaps climbed a bit, I can say I agree that things are looking better in the economy. And more projects in specialty woodworking, where I focus, are breaking ground. One way I gauge the next year is how many cool projects hit my inbox. They dried up in early 2009, were sporadic for years after that, but now I am seeing more cool projects on the horizon. We get a chance to help direct their development, value engineer them sometimes, and make sure they are buildable when it comes to wood bending, our specialty. 

brian-buchik-2.jpgWe have been building a lot of chairs lately. These are custom, one-off chairs. I believe that what is happening is that designers are wanting to go out on their own, and are coming up with organically shaped furniture. This is very hard to build, but we specialize in it, and I think we are found and invited to bid on the project. Often the project is underfunded and it never gets off the ground. But we have worked on a number of terrific examples too. It is costly to have a new chair prototyped. All formwork and bending forms has to be paid for on that one piece. Sometimes we can use that same formwork for future chairs, so it may eventually mitigate the up front cost. Some of you may be building one-off furniture too, perhaps to try out your own designs. Here is how I approach pricing one-off furniture...

We take an estimate of hours that the project will take and add the cost of materials we expect to use. In addition, we estimate the tooling and formwork needed and add that to the expected cost. If engineering is needed on our side, we may have to invoice for it, but usually that part is taken care of by the time we get the project. Often we have a lot of back and forth up front about what can be built, and this usually influences the design a bit. This up front work is not usually paid work though, and it is a problem when too many of these kinds of projects get discussed, value engineered, then not built. We may have to start working on a consultant basis for the early stages work, but so far we haven't done it, because it isn't how we get paid. We get paid to build things, and that is how I like it. I'd prefer not to make it too complicated up front.

After pricing a chair like this, it is often cheaper for the designer to buy someone else's chair at Design Within Reach, or Hive Modern. The designer should expect the first chair that is being built to be more expensive than a similar quality retail chair in a specialty shop that is built in the hundreds at a time. Low end production chairs sell for about $2,000 to $3,000 or more, and a one-off of a new design is probably going to be close to double that cost, for the first chair.

It takes time to bring the cost down on a custom project like this. Let's say I give the customer a budget number of $5,000 for their chair. That is often thought to be a lot of money to own one chair, so I have to hope the customer understands that this is the only one in the world, and the first one is the hardest to build, always. Usually at this point, they will want to know what it will cost if I build 10 of them, 50 of them or 100 of them at a time. They are thinking about whether the project is worth pursuing. Unfortunately, without putting time into the project, it is difficult to predict how the product will scale. And if we are building it, most likely it is a very difficult project, and it will have to sell in the upper end of the retail price point for that type of product. Which brings volume down. And costs up. So it is a tough thing to give a number up front as to what the piece will cost to produce down the road. Probably some of you have this issue too.

It is tempting to do backwards math on the product to come up with what it should cost to build. If the market will bear $3,000 per chair, then it has to be built for $1,500 or less. If the first one costs $5,000 to build, how many have to be built at one time to get the price down to $1,500 or less? The customer would like an answer to that question, but the answer is a difficult one to give. Lets say the answer is 100 chairs at a time. But now that 100 chairs are going to hit the market, will they still command a price of $3,000 each? At this point I have to admit that I know more about making things than selling them. I know I can make them for a certain price, but I don't know if you can sell that many for a profit. And around it goes. So we tend to start small, the customer has to sell high, and the volume will be low. If the seller develops a good sales channel for their chair, then we can start to take out costs as production increases.

I started out talking about 2014 so I want to end on a note about that. We had a good 2014. Our employees stayed with us because we work on cool things (with one exception - I had a young architect working for me for the last 2 1/2 years and now he is moving out of state. He commuted 40 miles each way to work for me, so I think he found something he liked about the job. Good luck Austin.). I enjoyed the year because I got to build things I really liked and I sent them out into the world. Our market is still mostly out of state and out of country, but that makes sense to me. We are pretty much the only ones doing this kind of work, so much of it is going to go abroad. If our order paterns are any indication, some of you also had a good 2014, and are enjoying the cool type of work you can produce with our bendable hardwoods. I'm here to help when you need it.


November 23, 2014: Curved Walls Project

dscn0069.jpgWe have been very busy this past year building 16 curved solid elm walls for Fidelity Financial Services buildings in North Carolina. The walls are about 30' long each, and 9' tall. We are fabricating the parts at our facility in Gig Harbor, Washington, and shipping to the customers site for installation. The project is designed by BHDP architects and we worked with the firm from the earliest design stages to ensure the architects vision was met.

We have the elm fresh sawn for us in Indiana then shipped to us for partial drying, then bending, followed by complete drying. Those dry bent planks are then dimensioned, surfaced and machined on one of our arch molders for the tongue and groove and chamfer profiles. There are a lot of steps to go from log to wall. Some of the interesting steps you may want to take not of are the following...

  1. The fresh sawn planks are stickered for drying from green to about 20% MC. We use a dehumidification kiln
  2. These "half dry" planks are machined oversize
  3. Approximately 10' planks are autoclaved and then compressed so that they come out as 8' planks (with stretch built in)
  4. These stretchable planks are bent over forms and dried in their new shape to about 7% MC.
  5. Still oversize, the dry bent planks are surfaced on all 4 sides using three different production sanders, including a "chair back" sander we added this year. The chair back sander allows us to precisely thickness sand curved parts.
  6. Tongue and groove and chamfer profiles are machined in an "Arch" molder. The molder is specially equipped to manage tall planks
  7. Face size on the planks is 5 3/8" + the T&G
  8. The planks are finished at 150 grit and shipped to our customer in North Carolina for spray finish and installation.


October 9, 2013 by Christo: Leaf Chair


Beverly Hills architect and designer Gulla Jonsdottir commissioned Pure Timber to take her vision of a chair shaped like a leaf, and convert it into an ergonomic sculptural chair. We are now nearly complete with the second chair (added in 2014 - we built a third, and a fourth). The first went to a client in Malibu, CA and the second is going to NY, NY. It is built using a modified boat building technique called strip planking. It works because of our extreme bendable hardwoods. The chair is made up of a middle rib layer, and front and back layers strip planked with Cold-Bend hardwood. Shown below is a work in progress picture with only the first center rows of the back layer installed to show the middle rib layer.

This building method is laborious, but produces a most unique product, and I have to say, it is great fun to build. Retail price on this chair is somewhere north of $20,000.







September 5, 2013 by Christo: Wooden Boat Show


This year we took a booth at the Port Townsend Wooden Boat Festival. One of the largest festivals of its kind in the country, vendors travel from distant locals

to join the fun and show their products related mostly to heritage boat building. I've attended numerous times since Port Townsend is only a little over an hour from my home in Gig Harbor, and is a very pleasant location. Recently, The wooden boat association completed a $10 million complex for their school, museum, ship chandlery and small boat storage, right on the edge of the magnificent Boat Basin harbor. We were invited to set up in this gorgeous boat shop (after promising to provide constant wood bending demonstrations). The space was phenomenal. Any wood worker would make this their dream building. Every one of the 10,000 guests expected in a fair weekend had to walk past our booth to get into the rest of the show.

What we do is not typical woodworking or even marine in nature. But we use a lot of traditional boat building techniques in our projects, and we have participated in many heritage wooden boat restorations and other related projects. So we had quite a bit of "eye candy" on hand to thrill viewers. This included a work in progress "Petal Chair" for Beverly Hills architect Gulla Jonsdottir, and a diamond ribbed boat shell I built 10 years ago.

Our near constant wood bending demonstrations delighted and amazed 1000s of viewers. The demonstration was of our "knot" bend. In short, we take a strip of our compressed hardwood, about 3/8" thick and 1" wide, x 48" long. This we bend into a wooden knot, by hand, in about 30 seconds. The wood is of course cold when we do this. At one point, I had six burly guys looking over my shoulder, all with either amazed looks or simply uncontrollably delighted grins.

The most frequent response was "I had no idea this could be done with wood", and our most frequent answer is that it is "part of our marketing campaign to keep it quiet". Which really means we have no marketing campaign and toil in obscure anonymity most of the time. Which we like to do. Normally our customers have to discover us on their own, or hear about us via word of mouth. But this time we came out of hiding and showed thousands of people in one weekend what we can do. Many took home our demonstration bent knots, unfinished, for the low show price of $20, while in galleries they sell for up to $150.

I think I'll plan to do ICFF next. It is just too fun to watch people’s faces when they see our wood bend. Jaws literally drop. Over and over again we get the same jaw dropping or uncontrollable smile responses. But maybe we don't want to be out their too much. We like working best with those customers who have "discovered" us and show a kind of delight in the potential they see in our techniques.






September 22, 2013 by Chris Mroz: Pendant Lamps and Horn Speakers

sunflower-pendant-1.jpgI'm experimenting with a new type of pendant lamp shade. It has a horn shape at the top, and then bends away at bottom into many tendrils. I have the idea that this shape could also be adapted for acoustic horn speakers. These are the fantastically expensive and beautiful speakers made by companies like Oswalds Mill Audio and Acoustic Horns. The shape is good for a pendant now, but if I extend the horn, get the right length and angles, it could work with the kind of compression drivers used for midrange and higher horns. Paired with a suitable woofer, it could make for a stunning and functional art speaker. I may contact Bill Wells at Acoustic Horn, or Jonathan Weis at OMA to discuss a collaboration.











August 2013 by Chris Mroz: Thick Guitar Sides and Thick Drum Shells


For several years I have experimented with making sides for guitars really thick. Let's say I have a solution that is looking for a problem. I talk to any luthier I can that has used thicker than normal sides. Of course, we can bend solid wood thicker than anyone else in the world, so I look for applications where a product could benefit from being thicker. A good example is our snare drum shell. Steam bent shells are about 1/4" to 5/16" thick. Laminated shells can be any thickness, but they give up certain qualities with the multiple layers of glue. The holly grail of solid wood shells for Drum Workshop, our main customer for thick solid shells, was to make a thick shell from one piece of wood. You can do this by hollowing out a log, but it is a terrible waste of wood, and it creates a very fragile instrument. Log shells are inherently weak, as the wood has next to no cross grain strength. By bending the wood, the strength of the fiber is exactly where it needs to be.

As the drum shell gets thicker, pitch goes up. Drum Workshop tells me that volume is high too on these shells, and John Good at DW says a rim shot on these shells is so loud it'll take the top of your head off. I'm assuming that is a good thing. If you want to see more about this from John Good at DW Drums, take a look at his video here...  https://puretimber.com/videos/ .

One year while I was wandering around the giant NAMM music show, I started to think about applying what we do with drum shells to guitar sides. Some luthiers laminate sides to make them stiffer. This could reduce the need for bracing. And I'm told stiffer sides may reduce sound loss to sides that are flexing.

The luthier Sheldon Schwartz in Toronto thought that my thick sides might save a lot of work when he has to laminate to get stiff sides. As far as I know he hasn't made any sides like this, but he does use Cold-Bend hardwood for purflings.

Other luthiers have built instruments with thick sides so that they don't have to put in side bracing or even linings. Obviously this simplifies the build. I'd like to see though if there is any benefit to sound as there is in drum shells.

In the current issue of American Luthier, there is an interview with master luthier Fabio Ragghianti from Italy. There were pictures of a thick walled guitar made from kerfed cabinet grade mdf materials. I contacted him and told him I could make thick sides like that in a solid, up to 3/8" thick for a cutaway model. He was intrigued. I followed up by sending him two sets of thick sides. One set of walnut and one of quarter sawn sycamore. he liked what he saw and asked for backs so that he could make them into instruments and test them. Hopefully we can take this next step. _________________________________________________________________________________________________________

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