## Floating fastener formula

## Floating fastener formula

(OP)

Guys,

The floating fastener formula from Appendix B of ASME Y14.5-2009 gives only:

The floating fastener formula from Appendix B of ASME Y14.5-2009 gives only:

H=F+T

This is the simplest case where one part has the same hole size and feature-relating positional tolerance as the other. But what is the **general**case where the hole sizes and feature-relating positional tolerances are NOT the same?H. Bruce Jackson

ElectroMechanical Product Development

UMD 1984

UCF 1993

## RE: Floating fastener formula

I suppose it's H1= F + T1 and H2 = F + T2, but then that assumes the fastener is the same diameter for each portion instead of having a step, so H1 = F1 + T1 and H2 = F2 + T2.

Other than that there's an infinite range of ways to shift tolerance for location from one hole to the other with the projected fixed fastener formula being the limiting case.

## RE: Floating fastener formula

## RE: Floating fastener formula

If H1=F+T1 and H2=F+T2 then does it follow that:

H1-T1=H2-T2?

H. Bruce Jackson

ElectroMechanical Product Development

UMD 1984

UCF 1993

## RE: Floating fastener formula

## RE: Floating fastener formula

I do not bother with the formulae. This can easily be modelled from first principals.

In the floating fastener case, you have a fastener with a maximum diameter, positioned exactly at nominal. Your holes must not intrude into that diameter. There are multiple solutions to this problem.

In the fixed fastener case. your keep-out is the maximum diameter of your fastener, plus its positional tolerance. Again, there are multiple ways to not intrude into the space.

--

JHG

## RE: Floating fastener formula

Regards,

Jason C. Wells