Carpentry DIY, why do the furniture I make shake

The points you yourself said are the causes of the shaking, so what else do you want to ask? Generally, the furniture made of three-in-one connectors will not shake as long as there is a back panel, and it will not shake if it still shakes, indicating that your cabinet feet are uneven and inconsistent.

Generally, such problems can only occur if the structure is not reasonable or the connection is wrong.

Obviously, the size of the timber saws is different. Or the hole you hit is not standard. Or your nails are too small or too few nails. There is nothing unreasonable about the ever-changing structure of furniture.

Oh, there are many reasons for this, the most likely is that the boreholes in the joints between the timbers are not of the same size or the nails at the joints are not completely filled with boreholes. Actually, I don't understand this in words, but if you try it, you'll know how to fix it. The most common failure of novices is when making chairs, and the wood feels straight.

However, the size and length of the hole drilled are all factors that determine whether it can be done well. A few small errors eventually led to the chair being deformed, and the legs were not in the same line. I can't see the picture, only LZ checks it by itself.

What kind of shaking, is the furniture uneven? Or the furniture structure itself is relatively loose and shaking.

If you see the real thing, it's easy to say.