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Thread: no play peg in hole that locks but can be removed and replaced easily

  1. #1
    Associate Engineer
    Join Date
    Feb 2012
    Posts
    1

    no play peg in hole that locks but can be removed and replaced easily

    ipt>
    Hi, This is my first post on the forum. Hopefully someone will be able to help me out.

    The problem I have is getting a no-play fit between a tube and a hole. The part in question is around 33mm OD (and min 20mm ID), around 800mm long. The requirement is for this part to fit into a hole and lock into place providing virtually no play in all directions and lock in place BUT is required to be easily inserted and removed (with some kind of catch?). With a standard peg in hole fit with plastic parts and moulding tolerances even low CPK values will mean that a worst case fit will translate to a large amount of play at the end of the 800mm tube.

    Ideas I have been experimenting with so far are non-locking taper fits (7 degrees or more). This works well however im struggling to work out how to keep the tube held down. The variation in tube/taper size diametrically means that the parts can vary vertically by a few mm and a catch would be required to work over this distance. The taper works well as long as the parts are held tightly face/face against each other. Any lift of the tube will result in the parts breaking away from each other when load is applied.

    This seems like quite a universal engineering problem however im still finding it difficult to find an application where it may be used already. Any ideas would be much appreciated.

    Just to add, the inside of the tube on both male and female parts (min 20mm) has air-flow and needs to be free of any restrictions.

    Kind regards

  2. #2
    Technical Fellow
    Join Date
    Feb 2011
    Posts
    1,043
    Hi and welcome to the forum.

    While this project is obviously all very clear in your mind, I have no idea what you are trying to do. A sketch, drawing or photo of the section in question will go an enormous way towards me offering any suggestions. Maybe others here will not be so dense as I, but I am struggling to understand what you are trying to pin to what, where, why and how.

  3. #3
    Lead Engineer RWOLFEJR's Avatar
    Join Date
    Mar 2011
    Location
    Rochester Pennsylvania
    Posts
    396
    What you seem to be looking for is gonna be very hard to acheive. Tight but still able to slip... hmmmm...

    Maybe just put clearance for about 90% of the fit distance and only "size" about an inch at each end. Much easier to hold diameter or taper tolerances for an inch each end than through the entire 30"-ish length?

    Maybe shallow tapers with small rounded bump ring on male and small groove ring in female to snap together when home? Not a ratchet tooth catch cause it'd be hard to get apart but a round or V so it'll come apart relatively easy depending on amount of engagement. (You were talking plastic right?)

    If that idea doesn't grab you I have another method but I'd need to know more of the particulars.

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