Checking axis fit...

[LostL]

Hello!

Looking for a good way to evaluate whether a pin will be able to pass through two holes. The holes are some distance apart, and the holes are short. Doing a regular coaxialty evaluation is prone to being unstable with the short reference and the distance in between. Any good ideas?

/L

[JEFMAN]

Construct a max inscribed cylinder through all the hits, and look at its diameter...

[LostL]

Forgot to mention, there are cases where the holes have different sizes. That was my initial idea as well, but I would like a single methodology for all cases if possible.

The current idea I have is something along the line of doing a straighness evaluation, deduct the result from the max inscribed diameters and check so that the values are above minimum sizes. It´s a little more complex than I would prefer though.

[JacobCheverie]

Will Jefmans solution not still work? If you are just interested in passing a pin then it shouldn’t matter if the holes are different sizes, only that while aligned to a particular DRF, the net clearance will allow the pin diameter.

imagine they are perfectly coaxial and one hole is much larger. All that matters, if trying to pass a pin, is the smallest hole diameter. A max inscribed cylinder should give you just that. Same if they are not coaxial. Any interference should be picked up in the evaluation as max inscribed...

[LostL]

Different nominal sizes. One could be 8mm, the other 10mm. The pin will then have a step.

[AndersI]

What about the following?

- measure a circle at each hole (CIR1, CIR2), many points, spread over as much surface you can touch.
- construct a 3D line circle to circle (LIN1)
- level to this line, set as workplane
- construct PCIR1 from the hits of CIR1 and PCIR2 from the hits of CIR2 (max inscribed); these should tell you what can pass each hole in the direction hole-hole

(Please correct me if I'm wrong - this was just an idea I had)

[LostL]

Interesting! If I cant think of any issue I'll see if I can get some test setup to verify.

[JEFMAN]

Will Jefmans solution not still work? If you are just interested in passing a pin then it shouldn’t matter if the holes are different sizes, only that while aligned to a particular DRF, the net clearance will allow the pin diameter.

imagine they are perfectly coaxial and one hole is much larger. All that matters, if trying to pass a pin, is the smallest hole diameter. A max inscribed cylinder should give you just that. Same if they are not coaxial. Any interference should be picked up in the evaluation as max inscribed...

I think in this case the pin has different steps (diameters), but I'm not sure.
If it's not the case, you're right !

What about the following?

- measure a circle at each hole (CIR1, CIR2), many points, spread over as much surface you can touch.
- construct a 3D line circle to circle (LIN1)
- level to this line, set as workplane
- construct PCIR1 from the hits of CIR1 and PCIR2 from the hits of CIR2 (max inscribed); these should tell you what can pass each hole in the direction hole-hole

(Please correct me if I'm wrong - this was just an idea I had)

I think your solution could work fine only if the holes are short, otherwise the "angle" between 3D line and each cylinder axis could give a bad result...
But you proove that a retired still have good ideas !

[AndersI]

I think your solution could work fine only if the holes are short, otherwise the "angle" between 3D line and each cylinder axis could give a bad result...

That's why I wrote "spread over as much surface you can touch", just like when you measure a cylinder as secondary datum (measure as circle, but collect hits on the full cylinder).

But you proove that a retired still have good ideas !

I'm not retired until Tuesday...

[LostL]

Will Johan have an emergency hotline or are you retiring completely?