Proof is in the Pudding - Wedging Tenons

My pudding is pistachio, what's yours? That makes no sense but that is what just came to me when I looked at my photos.

What am I talking about? Well an interesting little thing that I came upon when wedging through tenons has proven to be true and not just theoretical. I think it was about a year or two ago that Pete Galbert was talking about glueing only one side of a wedge when putting them in. I hadn't given it much thought as being anything ground breaking but once he started talking about it I realized that this was in fact what I had been doing and was significant to the longevity of chair joinery.

Why glue only one side of a wedge. I started doing it as I recall because I had heard about someone actually splitting the end of a tenon before assembling it with the mortise. I don't remember who it was. But the idea was that the tenon would have a weak area in it so that when the seasons changed the moisture content of the wood, thus expansion/contraction would happen, the stresses would simply spread the split in the tenon rather than break the glue joint.

So basically I figured that if you only glued one side of a wedge then the other side would serve as the weak part of the joint and spread rather than stress and break the glue joint. So here is the proof that it actually works. My house has been really dry. All my wood flooring has gaps between the boards and the humidity has been down around 10-20%. After coming from humid south east Texas this is all new to me.

Look at what the joints on my settee have done. One is the leg tenon coming through the seat. The other is the tenon coming through the handhold. One side of the wedge has opened up rather than there being a failed glue joint.
Very interesting, is it not.

By the way, I have been doing a lot of reading and editing of Pete's book that is due out this year. This post didn't start out as a way to plug Pete's book but I have to say that if this sort of stuff interests you then trust me you will love this book. It is packed with, among other things, little nuggets like this.

Danish Modern Chair Joinery - Møller Style Joints

I got a little nudge to follow up on something I promised to talk more about which is how to do those joints in Danish furniture where the rails meet at the same height on a post of a chair leg.

From the first time I made these chair joints until now I have made them the same each time in designs that require this type of joint. I have not had one fail yet. Honestly I had wondered for a long time just how the factory made there joinery. Turns out it is the same. I discovered some photos of an antique one that was for sale and the joint had come apart and there was my answer. I don't think it takes a real genius to figure this out but it is nice to have confirmation when you see a factory example of it to confirm you aren't making substandard joinery.

So I will let the pictures speak for themselves especially since I am heading out of town for the weekend and my time is a bit crunched.

By the way I do cut the mortise on the slot mortiser. You could use a router as a substitute but couldn't make any recommendations on how to use one of those things.

Here is an example of an assembled joint from a Møller style bench. You can see the typical thicker portion of the post at the joint height. This helps add more meat to the joint and a shoulder surface for support of racking forces.

Below is how the joint intersects in the middle of the post. The mortises make an X if you viewed a cross section of the post. I place the rail that is shown vertically as the front to back rail and the horizontal as the left to right rail. This way the front and back rails "pin" the side rails in the mortise. I think of it as a sort of back up if the glue joints weaken. There is plenty of glue surface in these joints as well. Surprisingly strong.

Some additional views below.

Above is the joint before shaping. I carve off the corners and then finely rasp the surface to match the shape and thickness of a piece of cord.

I have found no faster way to round down the tenons to match a slotted mortise than a no.6 grain rasp. On that note I prefer round as opposed to square mortises here because I think the joint is less likely to split out when stresses are applied to the joint.

For reference the tenon is 3/8" thick by 1-7/8" high (I think?) and the post are 1-1/2" square at the joint. 

Give it a try and let me know what you think.

Weaving Hans Wegner's CH25 - Photo Series

So here it is. I know that this is an often searched for and requested topic when it comes to weaving Danish furniture. I have seen the forum topics myself from several years back while trying to acquire the details on the subject. As with many of these things I decided maybe I just need to be the one to figure it out and share it.

So, here are a lot of photos showing the basic bones of the process. This is not a "how to" or a "step by step" but it will get you the basis if you examine the what and where and what order I am on, etc. I would like to give a more thorough explanation but due to time this will have to be it for now. Hope it helps some.

Oh and thanks to my wife for coming down and shooting some photos, otherwise I wouldn't have the seat weaving part. I shot the back portion, thus no me in the pictures.

Weave the front and rear rails as you would a Danish cord pattern of this sort. I hate saying that because there is no proper instruction on how to do this correctly out there. There is a way to wrap the rails while working from the roll rather than taking a bundle and going around and around the rail but I have never seen anyone explain it. I will at some point but for now wrap the front and rear rails and string the cord from front to back as you know how. Then work the weave left to right.

Work the cord over and under and pull through. By the way I have seen instruction that say the initial front to back weave is to be left loose. WRONG. It must be pulled tight. Not tight like a guitar string but definitely not intentionally left loose. The left to right weave is left just loose enough to make a nice up and down wave pattern through the initial front to back cord. If the left to right pattern it is pulled too tightly then it will not pack in neatly.

The return weave is wrapped around a steel bar that runs from front to back. Notice the steel wire that goes between the bars to keep them from bowing and keeps the tension balanced across the seat weave. This is critical that you don't use cord nails here instead. They will cause the outer rails to twist and eventually, very likely, split out somewhere or at least compromise the structural integrity.

Another bottom view for clarity.

There are slots in the rails for cord to go around where joinery would interfere with the cord. This is a block glued on to create space for the cord to go around the arm joint. Notice the cord areas are recessed so that the cord ends up just proud of the surrounding wood surfaces.

Start by weaving the vertical portion. This is the part that is a secrete and I can't reveal. Just kidding! The bottom rail of the back is wrapped first while leaving spaces for the vertical cord to fall in when the top is being wrapped. The top rail is then wrapped with a single cord and then drops down to form the vertical lengths at the appropriate spacing. The hole in the top of the rail allows you to form a wide band of cord on the back of the seat while maintaining the pattern on the front. Why you ask? Ok, lots of speculation on this but the answer is simple. You need a place to hide your knots when doing the left to right weave.

Here are some photos of everything all done up. 

Now all you need to do is install the arms and legs without getting glue on any of that cord. Yikes! Don't fret just use some blue painters tape around that area. Oh and make sure and do the finish before the weave, of course.

Now I have on the chopping block a set of four "Round" chairs (aka "The Chair") to do. Can't wait to get to them!

Solid Wood!

As you might guess, I love solid wood. I will use solid wood down to the most minor components of a piece. "Solid wood" furniture that is sold on the market today often does not have solid wood drawer bottoms or drawer sides. Generally they are made of plywood.

I thought I would show a bit of construction of my drawers. Each piece for the drawer bottom is resawn from larger stock and tongue and groove routed to fit together. They are held in place by a dado cut within the drawer sides, completely housing the drawer bottom with the exception of the back that is left open to allow for wood movement. Here are a few photos of the drawers parts and their construction.

Why don't I use plywood? There are some advantages to plywood such as very little wood movement which means it is quite stable. A good thing for mass production. However, I have deep concerns over the glues that are used in plywood. Most have formaldehyde to some degree or another in them. These create serious contaminates for indoor air quality. I feel that if you are buying quality custom pieces that are meant to last generations then they should serve those who use them to their benefit including their health. Maybe you agree.

That Cracks Me Up

I am always pleased to hear when someone receives a piece of furniture from me and they are amazed at how well built it is. (Sorry, I know it sounds like I am patting myself on the back but, please read on). However what this tells me is that most people have never really seen properly built furniture. This is not really our fault. Most of us have experienced furniture the Ikea way, screws for joints and particle board for the structure. It reminds me of how there was a time when the average person could buy a used vehicle, look it over, and actually know what to look for to see if it where in good shape. There has alway seemed to be a lose of knowledge as society "advances".

So let me get to the point of this entry.  I just recently had a customers who had previously bought a table  from a "craftsman" and it was cracking down the center of the table very badly. I was unfortunately unable to give her a simple fix. It was constructed inproperly from the beginning. Let me show one way you should expect a solid wood table top to look from the under side when it is properly constructed. This photo is the bottom of a typical table top I build in my shop.

Notice the little blocks attached to the bottom of the top that are then slotted into the rails. Notice that the rails create a frame work. Why go to all this effort, can't I just screw the top to the base and legs? Its true, I could, and some have tried (as in the case of the "craftsman" I perviously spoke of).

Now here is why you shouldn't... First you need to understand that wood moves with moisture change from summer to winter. It moves a lot, as much a 1/8" per foot, depending on wood type. Thats 3/8" for a three foot wide table. Now look closely and you can see that the slot that the block is slotted into is oversized. This allows the top to "float"on the framework under the table top while staying in place and flat. If you where to screw the top on in a fixed position (which might seem the obvious thing to do) then the top will start to split down the length of the table as it expands and contract through out the year. I know, scary.

So bottom line. Buy well made furniture from a craftsman that not only has the tools to "work wood" but also understands wood and how to properly build with it. Century's of tried and true construction methods can't be ignored when using this ancient building material.