I'm going to make a all-wood floor to ceiling cat tree,which looks like this or so

enter image description here

And here comes the problem

The commercial ones use pine to make the base and pads, but the pillar is often made of paper or a pvc tube

And they use a single threaded insert to connect them together like this

enter image description here

When i use a wood pillar (maybe birch, or pine, its cheap and easy to get here) this method may not work well because the end grain dont hold threaded insert well and wood is much heavier than a pvc tube so a single threaded insert might have problems in strength

And I come up with some ideas

Firstly, use dovetail to turn the endgrain into long grain

enter image description here

(sorry i just made a mistake and the dovetail is drawn upsidedown)

or Secondly, dont cut the pillar into short parts, keep it long and solid and use dados to hold the pads

enter image description here

So is there any better joints for this work? Thanks a lot

(Notice, its important to make it detachable. )

Any suggestion or comment is welcomed

  • Making multiple vertical segments as in your first option will add more work and challenge your skills at maintaining absolutely vertical connections for a straight line column appearance. Option two will work well with fewer parts. LeeG's answer proposing epoxy should be plenty strong enough for a connection in this project.
    – Ashlar
    Jun 26 '20 at 14:34
  • Larger thread inserts epoxied in place will probably be fine.
    – jdv
    Jun 26 '20 at 14:57
  • Also, you can research a little on how small watercraft have masts that can be broken down into shorter sections. Lots of clever ideas there that could be borrowed, most of which you know are strong enough for this solution. The fact that your pole is supported at either end means you don't have to worry about deflect all that much.
    – jdv
    Jun 26 '20 at 15:29
  • If you go with the dovetails (a nice touch that the kittehs won't notice), make sure you cut them in the opposite way it seems that you drew them. The narrow opening should be at the end of the segment with the wide part into the column segment. It appears that you've got them drawn wide at the end, narrow inside - it's too easy to pull out this way. (Not that there should be a lot of longitudinal force, but if you're going to the effort...)
    – FreeMan
    Jun 26 '20 at 18:26
  • Also, if you go with the dadoed option, don't mess with threaded inserts at all, just put a bolt through one side and a nut on the other. Bore a hole big enough for the bolt head/nut and a socket and they can be recessed to make them harder to see.
    – FreeMan
    Jun 26 '20 at 18:31

Use a 3/8" or a M10 or so threaded insert. Epoxy it into the ends (don't rely on the threads of the insert). For the top piece, bore a hole down the center for some threaded rod, and then epoxy a nut in the end. This will allow you to tighten it against the ceiling.

While it is true that inserts set into end grain aren't as strong as they are into cross grain, if they are epoxied in, and the pieces are screwed together firmly so there is no lateral play, they will be plenty strong enough for your application.


The ones you may have been looking at with the threaded rod and insert must have small threaded rods for connecting the pieces together. A threaded rod and inserts can be quite strong. Use at 1/4" or greater diameter rod and it should be strong enough. There is nothing wrong with having the end grain for the inserts for this projects. See my markup of your design. Just cut the rod into 3-4" long rod and hand screw the parts together.

enter image description here

  • 2
    Make sure you provide a source for this image.
    – jdv
    Jun 26 '20 at 15:31
  • @jdv I'm guessing the drawing is homemade ("See my markup of your design), but I may be wrong. Either way it should be noted.
    – FreeMan
    Jun 26 '20 at 18:29
  • It uses images from the same web site we all looked at for "large threaded inserts" :)
    – jdv
    Jun 26 '20 at 18:42

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