Tool New Measuring Tool Idea?

[whydontu]

Ok, so I often need to lay out pipe sections, many times to locate diametrically-opposed outlet connections. Also have to check out-of-round and establish whether out-of round is within fairly sloppy tolerances. Size ranges from 0.405” o.d. to 12.75” o.d.

So my idea is to fabricate a very simple center finder with a direct-reading scale that compensates for the offset from the vee-angle. On my photo, the distance in black changes with each workpiece diameter, so either a bunch of trig to work out a non-linear scale to compensate for the offset. Or a sliding scale with a fixed zero point (blue dot) that adjusts for the offset.

Thoughts? Or does anyone know if such a beast already exists?

 

[PeterT]

Could you not just flip the ruler around so its zero edge is on the edge of disc diameter (where your 2.5 is) & read result where your blue dot is?

 

[whydontu]

Could you not just flip the ruler around so its zero edge is on the edge of disc diameter (where your 2.5 is) & read result where your blue dot is?
View attachment 62281

Well that’s too obvious, which is why I didn’t think of it.

 

[PeterT]

And then of course there's cheapo digital calipers that can measure internal & external or zero set to compare... all on one handy device. Maybe not for banging around in tough conditions though.
Or maybe they are already occupied to perform other duties LOL.

 

[Susquatch]

Thoughts? Or does anyone know if such a beast already exists?

Could you not just flip the ruler around so its zero edge is on the edge of disc diameter (where your 2.5 is) & read result where your blue dot is?

Or, slide the ruler down until the 10 is at your zero and measure up to the disk. You could even sacrifice a ruler and cut the end off.

This approach would preserve your ability to use the fixture to find the center of the disk and also do your measurements on various sizes without sliding the ruler around each time you use it.

 

[Chip Maker]

Wouldn't a combination square work?