I enjoy creating mechanical designs but I am not a trained mechanical engineer.

I have a technical issue with a joint design that needs to be permanently retained using a press (snap) fit. Any idea on the size and tolerances for these two 304 SS parts to be pressed together using an arbour press without permanent deformation of either part? I will use a little lithium grease to help with the press fitting which will also serve as general lubrication for the shock absorber joint.

press fit size mm sample with rubber surround timing station

  • $\begingroup$ Welcome on the Engineering SE! Some pro tips: :-) Your first post is visible also from your reputation (which is 1 on start). I suggest to make your question title to a round, clear question, it is much more important as it seems! The answerers see a list of (typically) 50 questions, and it depends on them, where do they click. And you want an useful answer. :-) $\endgroup$
    – peterh
    Aug 1, 2018 at 0:08
  • $\begingroup$ Material? As heating may help iethermal expansion or softening... $\endgroup$
    – Solar Mike
    Aug 1, 2018 at 5:16
  • $\begingroup$ @PeterStoneham Out of curiosity, are you planning to press these parts together, and then overmold them? $\endgroup$ Aug 1, 2018 at 19:33
  • $\begingroup$ Material is 304 Stainless. The parts should be pressed together at room temp without heating. I plan to press the SS parts together then fit a pre-moulded silicon part over the two parts. Over-moulding is not an option as the design needs to be pre-tensioned. My gut feeling is 6.2mm into 6mm diameter hole. $\endgroup$ Aug 2, 2018 at 2:23
  • $\begingroup$ Just to clarify the photos show prototypes I have already made. I am now just refining the design of the two metal internal parts before I get the next set of samples turned. $\endgroup$ Aug 2, 2018 at 2:29

1 Answer 1


During mounting of the coupling, the parts will have to deform. This is not easy in your design. If you make slots in the female part, this will be easier.

See as an example this feston plug that I designed. https://cults3d.com/en/3d-model/tool/festool-plug-20mm


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