What is the best way to get a measurement center of two holes?

[GubNi]

What is the best way to get center to center distance between two holes? For example I have two 1/2" holes are about 4.5" apart center to center. I need to know if it's 4 7/16, 4 1/2, or 4 9/16. I have a good caliper, but it's still a guessing game.

 

[Infamous1]

I go inside one hole to outside other hole, always worked for me but im not the sharpest lightbulb in the box.

 

[GubNi]

I go inside one hole to outside other hole, always worked for me but im not the sharpest lightbulb in the box.

That's what I have been doing, but I was wonder if that's the best way. It leaves some margine for error.

 

[rockcity]

Edge to edge is the same as center to center.


Ok well, disclaimer for some that may be too dense to pick up on the logic... (not you Shawn...)

Assume it's the same edge on each hole. Not near edge and far edge, obviously.

 

[a_kelley]

Measure outside-outside & inside-inside and average. Then compare or average with inside-outside.

 

[a_kelley]

It also depends on configuration of said holes. If it's on a bolt circle, it will not be the same as center center.

 

[GubNi]

Edge to edge is the same as center to center.

Sometimes I am guessing within .05 of where that edge is.

 

[rockcity]

Sometimes I am guessing within .05 of where that edge is.

Are you measuring holes in concrete?
Were they burned in A36 with a torch with your eyes closed???

 

[rockcity]

Stick a dowel in there, make sure they are parallel, then measure edge to edge?

 

[Jeff B]

I need to know if it's 4 7/16, 4 1/2, or 4 9/16.

I think glasses will help you more than anything.

 

[Fabrik8]

Measure outside-outside & inside-inside and average. Then compare or average with inside-outside.

This.

But, forget about the inside/outside measurement. Just average the inside/inside and outside/outside.
The problem with inside/outside is that it takes some eyeballing with a normal set of calipers. You can use the inside measurement caliper end for outside/outside measurement, and the outside measurement caliper end for inside/inside measurement, so there's less eyeballing of the calipers to line up on mixed inside/outside hole edges where you don't have something to positively locate the caliper edges with.

Lots of methods will work if all you need is 1/16 inch accuracy though.

If you want to get fancy, you measure the hole diameter, then zero the calipers at that diameter.. Then measure the outside/outside edge distance, which will be the center to center distance because you've already zeroed out the half of the hole diameter in each hole. Tricky if the holes are very small, because the calipers may not get an accurate diameter measurement.

Some of this only works if the holes are the same size.

 

[GubNi]

Thanks for all the info guys. That really helped out. My problem was worn out holes. When I measured several and took the average it made sense.