Perpendicularity of B Datum Hole to A Datum

Hello everyone,

I am looking for some guidance on the best way to check perpendicularity of a B datum hole back to A datum. The material is 1.6mm thick and the only thing I can think of would be to measure the B datum at 2 or 3 different depths then construct a cylinder. Am I wrong in thinking this callout is a little silly? I'm grateful for any advice you guys can throw my way.

Thanks

vpt.se 10 months ago

The perp tolerance seem to indicate that the toleranced feature isn't a line (no Ø symbol) or the tolerance only applies in one direction. Additionally, there is no Ø preceding the dimension 12.
This makes me wonder if the toleranced feature really is a hole/centerline. It "looks" more like perhaps a surface that is toleranced?

Could you show us more of the drawing? Like showing the hole and datum B?
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Smasherofprobes 10 months ago

Here ya go!
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ArkansasBeeper 10 months ago

The likelihood of getting good data from a 1.6mm surface is fairly slim. Maybe if they are cutting it with an endmill, and you have a half mil probe.
You can dimension it to make them feel good though!
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Matthew D. Hoedeman 10 months ago

if this is sheet metal, and a pierced hole, it is a 'foolish' callout. What it boils down to is that they want the hole pierced perp to A. I see this a lot, and yes, all-but impossible to measure a cylinder in that pierced hole.
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bfire85 10 months ago

I see this a lot too. Bogues callout to be honest, as Matt stated. Your perpendicularity will just be really good.
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Kai Kendall 10 months ago

If it's a really shallow cylinder, you're well within tolerance, in all probability.

VERIFY PC-DMIS OUTPUT WITH MANUAL CALCULATIONS
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Cris_C 10 months ago

I see this a lot too. Bogues callout to be honest, as Matt stated. Your perpendicularity will just be really good.

Same here. Luckily this sort of silly callout always measures in tolerance. A shallow hole would have to be seriously crooked not to.

However, I only work with machined parts. This callout on a pierced part would be a headache.
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Smasherofprobes 10 months ago

Thanks everyone I appreciate your feedback.

Is my approach to measuring it correct? 2-3 measurements at different depths then constructing a cylinder? I'm also assuming a 0.5mm or 1mm ruby would be best for this situation?

New customer, new headaches, I guess.
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ArkansasBeeper 10 months ago in reply to Smasherofprobes

Make sure to use sample hits or else there isn't much hope on something that thin, and two levels is fine.
It should always be good due to how short it is.
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bfire85 10 months ago in reply to Smasherofprobes

Yeah, use sample hits. 2 levels should be fine...doesn't hurt to do three, but honestly, the measurements won't vary much. You can always test it out.
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