Helo to decide tolerance

[Max44]

Hi all,

I need a little help to determine a tolerance.

I have to design a bracket to fit to a vehicle using two pins. The two holes on the vehicle are at 1000+/-5mm centres. The holes are each 50+/-1mm diameter.

If I make the holes in my bracket the same diameter, what tolerance should I use on the holes centres to ensure the bracket always fits? It is not possible to use slots or adjust the centre distance on site. If I use 1000+/-5mm then their could be a nominal 10mm error.

Thanks

 

[desertfox]

hi Max44

What size are your pins and what tolerance, not sure that with such a wide tolerance of +/- 5mm you can get what you want.

desertfox

 

[Max44]

Hi Desertfox,

Pin dimensions not yet determined but need to be a nice running fit. I also think that I cannot get a perfect solution but thought I would see if I can get some 'best practise' replies.

Thanks

 

[desertfox]

Hi Max44

Not sure how your going to get a nice running fit with +/- 1mm on hole diameters.
To get a useful answer we need all the information (if a useful answer is possible in your case.
With the tolerances your quoting the pins would have to be a large clearence fit at present.

desertfox

 

[KENAT]

The spreadsheet in my 4 Sep 08 3:26 post on thread1103-221602 may help a little. Make sure and look at the examples and ideally look at ASME Y14.5M-1994 where it shows the basic form of the calculation you need to do.

KENAT,

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