Modified Floor Block for 4x4 CNC

Hey Everyone!

I’m planning on manufacturing and building my own small office out of the skylark 200 system; the problem is I only have a 4’x4’ CNC router, so I have to modify all the blocks. I started with the floor block as a test and would love to hear some feedback.


  • Too many joints - Less strength in floor
  • Joints are at odd spots - I tried to shift the locking features to get a better location, but this is the best I could find


Hi @CSpurge, great to see that Skylark 200 might be useful to you! I also share your concerns about the number of joints, and more importantly their location. When testing (see figure below), we found out that the side dovetail join is the weakest point. On the contrary the structural demand is highest in the midspan, and minimum at the support location. So it might not be good to have the weakest point of the beam where the highest structural demand occurs. It might be better to swap the location of the joints in the top flange with the location of the joints on the side panels (see sketch).

Having said that ,at the end of the day it depends if the beam has “enough” capacity to take the load (whatever configuration you end up choosing). This last mainly depends on the span, expected snow, etc. Do you perhaps know any structural engineers around your area? S/he should be able to quickly tell you the amount of expected load and compare against the capacity of the beams (find the values here ).
Should you not be able to move the joints, you could eventually nail/screw a plate to locally reinforce the joint (maybe from the inside part of the cassette).

Hope it helps!


@Gabriele, That’s a great point. I’m going to modify my design like you show and I think I can still have it fit in a 4’ area.

Thanks for the input and explanation!

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@Gabriele, So I changed it as suggested, but my joints (top to sides) are now very close together. Should I cut the top and bottom into 4 pieces to spread the joints more evenly or is it better to have fewer pieces even though the joints are close?

Here is the small wall modification… if anyone wants access to these files, just let me know.

Hi @CSpurge, it’s a tricky one isn’t it? Sorry I don’t have a comprehensive answer, but my hunch is to have fewer joints. To my understanding, the lower number of joints, the stiffer. And stiffness governs the design of the beams. I have tried sketching other configurations, but none wasn’t more convincing than yours.