Below is a link to pictures of a king bed frame and mattress I am assebling with the knowledge gained from this site. I am waiting for the cover but everything else is ready to test. Living in Connecticut, I was able to meet the friendly people at KTT.
goldfreaz.weebly.com
Hi goldfreaz,
Thanks for the pictures and the description of your new sleeping system … I appreciate it!
Your bedframe looks very strong and very suitable for a latex mattress. I’m curious … how did you measure the deflection so accurately?
Your mattress components also sound great and I’m looking forward to your feedback when everything is put together.
Thanks again for sharing all the parts of your design … and congratulations on your new sleeping system 
Phoenix
I can help answer one of your questions Phoenix as to how he came up with the deflection data. By the looks of his #'s and the screenshot of Ansys it appears this guy may be an engineer(like myself). Ansys is a Finite Element Analysis program that is used to analyze the stress/strain of a particular component or a system of components. To put it simply you enter in some properties of the material and apply a load/loads to a component or assembly and it will tell you what the deflection is and what the resulting stress and strain is among other things.
0.015" deflection @ 400 lbs seems a bit flimsy to me… Maybe it needs some ceramics or carbon fiber? 
(…seriously, it looks amazing!)
Hi Pist0lpete,
That’s very interesting … thanks
So as long as you know the properties of different species of wood … I’m guessing primarily the modulus of elasticity (such as here) and you enter them into the application along with the dimensions of the assembly and slats and the span lengths then you can just input the stress and it will provide the expected deflection? That’s very cool!
Phoenix
Pheonix,
The model uses a modulus of 1.5e6 psi and a poisson ratio 0f .42 for all the various woods. The value for soft woods like spuce is 40% lower and for hard woods like oak ~30% higher. The deflections would be porportional to the modulus for the same geometry. All contacts between pieces of wood are assumed to be perfectly bonded. This is not true for the slats which are not screwed down. All other joints were screwed and glued. In fact the frame was so rigid that I could not pull the diagonals to be equal with large clamps. One diagonal is about 0.5" longer than the other.
I thought this was over kill (even for a life time engineer) but the weight and rigidity of the frame is noticeable better than the standard steel bed frame with wheels and box springs.
The software is Autodesk Inventor, though I use Ansys Mechanical at work.
goldfreaz
All good info to know… It appears you created a very solid bed and foundation that will last for many many years. I am anxious to hear on how your DIY mattress works out comfort wise. Keep us posted.
Hi goldfreaz,
Thanks for the additional info. This is really interesting stuff to me
While I’m certainly not an engineer so this would be at the edge of my understanding … I’m not clear on how poisson’s ratio would apply to a foundation (although I understand how it would apply to a mattress that was subject to compression forces). Is this because a lower poissons ratio would mean the wood was more elastic which in turn would allow for more bending under stress across the same span?
Of course this isn’t something that I “need to know” and my knowledge of all of this is limited but I’m curious about how it factors in.
Phoenix
Phoenix,
It is interesting that the Poisson ratio is high for wood. Another thing you can study in Wikepedia is orthotropic. I did not model it but the elastic properties of wood are different with the grain compared to perpendicular to the grain. In general, the deflection of the frame is relatively insignificant compared to the body and the foam.
The Poisson ratio of foam is close to zero. If you compress it in the vertical direction, it expanse very little in the lateral directions. It would be interesting to model the contour of the human body and spine alignment laying on layers of foam. Develop models for women with bigger hips and men with bigger shoulders laying on foam in different positions and quantify spine alignment and pressure points. This must be already done, but I could not find anything on the web after looking 30 minutes.
The spine alignment would depend on the muscular structure, mass distribution, and the body contours along the spine.
goldfreaz
Hi goldfrreaz,
There are some interesting books I’ve read that go into all of this in much more detail (including mathematical models and specifically designed testing systems that take into account the different response of each of the body tissue layers). Back and Bed … Ergonomic Aspects of Sleeping is one of them (which has a fair bit of higher level math but is still generally inside my range of understanding) and another one is Preventative Biomechanics … Optimizing Support Systems for the Human Body in the Lying and Sitting Position which is also very interesting reading but is much more difficult to read and includes some math that I have some difficulty with.
Phoenix
Hi Goldfreaz,
I am planning on building a platform bed frame for my new latex queen sized mattress. I have never done something like this before. I was wondering if you had any more pictures and if you could go into more details on your plans or some resources you used for your plans.
Thanks!
Pheonix,
Thanks for the book references. I read some of the first one on Amazon preview. It was packed with information.
Sleepy,
The wood was free and I own many power tools. Even with all these resources, this bed frame took 60-80 hours of work. The most important design features are (1) a split frame so it can be move, and (2) 1" thick slats that are supported well in the center as while as both sides of the bed. Gluing the frame together requires a thickness planar and table saw. You may be better off looking at other designs on this board that use 2x4, 2x6, 4x4, deck brackets, and deck screws.
Thanks for the reply goldfreaz. Would you mind posting any resources/threads you found useful. I only found the “king size deck” thread regarding DIY frames. I have plenty of tools at my disposal just need a good set of plans and a list of materials/wood I’ll need. I haven’t built much before and certainly no project like this, so I would need plans that are fairly detailed. Thanks for your help.
Hi sleepypeepy,
I’m not goldfreaz of course but the foundation post here has some DIY foundations and platform bed designs contributed by some of the members here that include instructions, pictures, and material lists. There are links to two of them at the end of the KD foundation section and one at the beginning of the slatted platform bed section.
Phoenix
Thanks for those links Phoenix.
I definitely like the idea of a split frame since I am in an apartment and will likely be moving in a year.
Goldfreaz, how are the two sides held together and how easy to take them apart? It looks like there only 2 legs in the middle. Do these detach when you take apart the two sides? Any additional pictures of the frame?
That .015" is going to look pretty small once you see your latex “oozing” out between the slats.
Very I formative stuff , I am a structures specialist who works in collapse zones and the study of the elasticity of wood and running grains are very fascinating . I thought it in our studies to look at the time of yr a piece of wood is harvested contributes to these measures. Sometimes I don’t think engineers have anything better to do! Except build cool beds! Nice work!
Interesting to know about the timing the wood is harvested. I was of course aware of how important grain orientation was but had never heard about harvesting and its affects.
I have added more detail to my bed frame illustrations. Also, the stiffness of two mattresses are compared. I much prefer the King size mattress, although the queen size mattress from Spindle is still very good. More importantly, my wife likes them both.
Details:
Hi goldfreaz,
ILD is a little less precise than you seem to have documented it, although you have basically the correct info. One example of this is that Ild is usually measured with a 4" layer for polyfoam, and a 6" layer with latex foam. Each is measured to 25% compression, however that means that there is 1" deflection with a 4" layer and 1.25" with a 6" layer - the impact this has is that it’s easier to compress a material by 1" than 1.25" and therefore if ild is compared between the two is such that the polyfoam ild would be higher were it tested in the same way as latex.