Let's suppose an acrylic sheet with a hole on it

I want to insert something into that hole, let's say an acrylic rod

The hole has a diameter of x and the rod has a diameter of x-y. If I increase y, the cylinder is not going to enter, if I decrease y, is not going to embed, so, How do I know what are the limit values of y so that the cylinder stays in the hole?

I am not quire sure about how to address this problem, but I find it many times in my life

Should I use a probability distribution where y is the probability of the cylinder being embedded correctly?, How much does the material of the cylinder and the sheet with the hole matter? How much the values of y change if the value of X is increased (A hole with a bigger diameter)?, Could you give suggestions of how to solve this problem

Edit. I am asking because I want to make an acrylic case for an electronic project, like this: enter image description here

The acrylic sheets I am using have a diameter of 2.5 mm and 1.75 mm .. So I would like to know what should be the size of the holes .. And a way to apply the same method for any other thickness .. The holes are not exactly circles, they are rectangles, but I think it is easy to analyse it with circles and rods ..


Machinists call this a "press fit" when you need a pin or cylinder to remain tight in a hole. Specifications for press fits vary as to uses, or materials. A .002 inch press fit would mean that the cylinder diameter is .002 inch larger than the hole. Freezing the cylinder as cold as possible will make it contract somewhat to make installation easier. It will usually need to be installed with a hydraulic press, or tapped in with a hammer or mallet. Since acrylics can crack, you should look up material specs for materials and thicknesses involved. It may be easier to make a looser fit and "glue" it in with a resin compound. Hope this helps.

  • $\begingroup$ I am doing an acrylic case .. the sheet has a thinness of 2.5 mm .. What shoud be the size of the hole then? $\endgroup$ – DieDauphin Dec 9 '19 at 3:31
  • $\begingroup$ If you have some drops or scraps to test with you might try a few tests to see what would be tight enough without cracking the acrylic. $\endgroup$ – Adrian Howard Dec 9 '19 at 3:36
  • $\begingroup$ what are drops, what are scraps? When I search in google for drops I get water .. My native language is not English .. The method of trial and error is what I am doing, but I would like a theoretical way to explain that $\endgroup$ – DieDauphin Dec 9 '19 at 3:45
  • $\begingroup$ Sorry, drops and scraps are leftover or extra pieces that are not needed, so you can use them for tests. $\endgroup$ – Adrian Howard Dec 9 '19 at 3:46
  • $\begingroup$ Oh, I don't have that because I am going to do the cuts with CNC machines, I only send the files in vectorial format and they give me the acrylic with the cuts .. that's why I would like to have a theoretical way to think about that .. $\endgroup$ – DieDauphin Dec 9 '19 at 3:49

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