Press fit clearance?

  1. dobbslc

    dobbslc Forum Supporter

    Messages:
    5,737
    Location:
    Hertfordshire UK
    I have a turning job for a mate that involves a press fit of a sleeve onto a suspension ball joint with nurling on it. Is there any kind of dimension to work to per millimetre of diameter for a good tight fit?
    Here's a picture of the parts.
    20200507_190826.jpg
    It's going to be made into a wishbone for a car.
     
  2. daleyd

    daleyd Member

    Messages:
    7,101
    Location:
    Wrexham, North Wales
    Zeuss tables have a chart for differing fits. If you haven’t got a copy I’ll get a pic next time I’m in garage - there is a pdf online.
     
  3. mtt.tr

    mtt.tr Member

    Messages:
    4,033
    Essex England
    + a thou is no heat pressfit, 0.0254
     
    Morrisman likes this.
  4. Matchless

    Matchless I started with nothing, still have most of it left

    Messages:
    1,626
    Location:
    Essex UK
    they are not easy to press in on E30 BMW's I would try to get someone to measure the internal on a factory wishbone if possible,
     
    Wallace likes this.
  5. addjunkie

    addjunkie Member

    Messages:
    6,469
    Location:
    Northumberland. Reet oot in the sticks
    I would also suggest putting the joint in the freezer and ring in the oven before pressing together. So you can pick a tightish fit.

    Right hand side of the chart
    https://en.m.wikipedia.org/wiki/IT_Grade
     
    Shox Dr, Arc Tourist and daleyd like this.
  6. mtt.tr

    mtt.tr Member

    Messages:
    4,033
    Essex England
  7. Brad93

    Brad93 M J B Engineering

    Messages:
    10,386
    Location:
    Essex
    Thou per inch
     
    doubleboost, dobbslc and RobCox like this.
  8. dobbslc

    dobbslc Forum Supporter

    Messages:
    5,737
    Location:
    Hertfordshire UK
    Thou per pinch sounds good Brad.
    Those charts are a bit over my head......
     
    Other Daniel likes this.
  9. addjunkie

    addjunkie Member

    Messages:
    6,469
    Location:
    Northumberland. Reet oot in the sticks
    IMG_0613.JPG

    Easy enough to follow your looking for something like an H7n6. The H shaded section on the diagram is the hole
    The n the shaft diameter

    The numbers in the middle corresponding is how much extra to make your interference.

    I prefer the imperial version in the old zeus books
     
    dobbslc and daleyd like this.
  10. Agroshield Member

    Messages:
    1,366
    Everybody is repeating the thou' per inch parrot fashion as if it is a mantra or something.

    Do any of you actually look at the photo he has posted and consider if this is the standard situation covered by the books?

    Has anyone ever installed wheel nut studs? Do the two things not have some small degree of commonality?

    The item to be pressed in is serrated, so consideration of the minor diameter is probably of some importance. A quick file test of the item might tell you if it has any hardness to it, and hence will be designed to deform the item it is pressed into.

    Second, the tube into which it is to be pressed is relatively thin wall, so it will deform.

    Patrick Gill's advice is correct: find a factory part and copy what they have done.
     
    nickk, slim_boy_fat, Wallace and 5 others like this.
  11. 8ob

    8ob Forum Supporter

    Messages:
    6,692
    Location:
    moscow on thames
    Also worth considering is the bore of the sleeve will distort when its welded in which may tighten things up a bit, I have pressed a few of these things in/out over the years and they either fall out or they are a pig, OEM tin wishbones are probably not the best thing to try and obtain an accurate bore size from.

    Bob
     
    slim_boy_fat, Matchless and dobbslc like this.
  12. Other Daniel

    Other Daniel Member

    Messages:
    92
    Location:
    France, Charente
    Me too :laughing:
    I wonder if there is a simpler chart for those of us not building electron microscope beds.
    Will now get sidetracked into Google searching ...:vsad:
    ATB,
    Daniel
     
    dobbslc likes this.
  13. dobbslc

    dobbslc Forum Supporter

    Messages:
    5,737
    Location:
    Hertfordshire UK
    I don't have an original one but my mate does have the hand built one that we're copying, He's dropping it off along with more steel for the inboard sleeves at some point. I don't think it needs to be very tight as the serrations are only about 6mm high. :thumbup:
     
  14. dobbslc

    dobbslc Forum Supporter

    Messages:
    5,737
    Location:
    Hertfordshire UK
    Here's a picture of it.
    IMG-20200507-WA0003.jpg
    It's off an Alfa GTV / 75 race car.
    @Dcal I think it was you that asked what it's for. ;)
     
    Dcal likes this.
  15. rory1

    rory1 Member

    Messages:
    1,183
    Location:
    Macclesfield
    Personally I’d make it a little bigger than the minor diameter of the knurl. (Without knowing the depth of the knurl or the diameter I can’t say what “a little bigger” is
     
  16. pressbrake1

    pressbrake1 Forum Supporter

    Messages:
    2,882
    essex england
    That’s diameter and thickness and material dependant. On a bit of good stuff a thou oversize could mean a 50ton press!
     
    Shox Dr and Morrisman like this.
  17. Dcal

    Dcal Forum Supporter

    Messages:
    2,351
    Location:
    Antrim Northern Ireland
    Thanks @dobbslc thought it looked familiar.
    Is he doing away with the torsion bars?
     
    dobbslc likes this.
  18. Matchless

    Matchless I started with nothing, still have most of it left

    Messages:
    1,626
    Location:
    Essex UK
    the BMW arms are malleable steel forgings I assume, they do bent if stopping very quickly i.e. a tree.
     
    8ob and dobbslc like this.
  19. dobbslc

    dobbslc Forum Supporter

    Messages:
    5,737
    Location:
    Hertfordshire UK
    Coil springs all round I think! Same as the 75 he has.
     
  20. 8ob

    8ob Forum Supporter

    Messages:
    6,692
    Location:
    moscow on thames
    Luxury Patrick:laughing:, The only vehicles I have had the misfortune of working on with these splined joints have had pressed tin wishbones on yanks and Vauxhalls, normally been in since god was a boy and dont like coming out. :vsad:

    Bob
     
Advertisements