Advice for this part please and a couple of other niggling questions - ISO/BS8888

[ska7ch]

Hi there guys,

Just looking for some feedback/advice on the drawing attached. It's the spider component for a custom universal joint. The intent of the part is for the position of the 2 opposing spigots to be tied up nicely WRT each other and the level of perpendicularity of the 2 other opposing also tied up nicely so as the part assembles correctly into the housings and operates as intended. Feel free to comment on the way in which I've detailed, i'm still fairly new so I'm sure there's some things to pick on but i'm curious to hear the thoughts on other and more robust ways of detailing.

So to the other couple of questions I have...

Q1) What's the best way to tie up 2 opposing holes/features. From a bit of research i see the ASME standard has a CF callout for a thru hole which creates 2 opposing holes but I don't see anything similar for ISO. I often use a ommon datum where there's 2 opposing bearing housings is this a good practice?

Q2) Circlip groove....or similar internal/external feature. Should i treat this as a FOS and locate it with a TED to the mid plane, or should i opt for Profile?

Appreciate any responses,

Jack

 

[Belanger]

Well, I will offer a couple of general comments, if it helps.
Since everything seems symmetric and equally disposed, you could just use a single position callout for all four spigots, rather than picking 2 of them as being concentric and then the other 2 being positioned. (Maybe still leave the datum symbols for the subsequent profile tolerance?)

But whether you do that or keep the current method, the geometric tolerances for the for spigots will require a diameter symbol in front of the 0.05.

As for a circlip grove, here's a general rule of thumb: if you want to control the size or form of the groove to the same accuracy as the location, then use profile. But if you want size/form and location held to different tolerances, use position. Both of those symbols will rely on a TED to the datum(s) since some sort of location would be controlled.

Other folks have any ideas?...

John-Paul Belanger
Certified Sr. GD&T Professional
Geometric Learning Systems

 

[Sparweb]

I can't read the dimension tolerance of the spigot diameters. +?/-? Something is wrong with your text styles/sizes. What are the standard dimension tolerances on your drawing?

STF

 

[fsincox]

Ref Q1:
The ISO has used the term CZ (common zone) for a long time instead of CF. I never really understood why ASME did not just adopt the same terminology.
Frank

 

[CoryPad]

A1) Not to say this is best, but current high-volume automotive applications use position and symmetry callouts for the opposing bearing journals on crosses (aka spiders).
A2) I do not see any groove on your drawing for a retaining ring (aka circlip) - is your question for another part, perhaps the mating yoke that the cross fits into? If so, the same high-volume automotive applications only use old-school linear dimensions for the retaining ring grooves.