Concentricity gauge build

[Jmorrismetal]

There have been a few times I have wished I had a simple little concentricity gauge dedicated to the reloading room for measuring runout in cases and to see how well bullets are being seated, so I built this one today.

There is a slot machined into the base plate that the bearing holders ride in with an extra wide slot under that so the nut plate has clearance. This makes it so I just need one Allen wrench from the top to set it up.

The bearings are .375 and set into the aluminum carriers with Devon, I used a 1/4" stainless rod to mount one of my indicators to and a 1/4" dowel to locate the back of the case.

Tested it out on a precision ground dowel and it works but I think I am going to add a spring loaded wheel with and o-ring on the OD to act as a "tire" that holds the case down and back against the dowel and give my fingers something a little larger to turn.

 

[Welder84]

Wow! Impressive

 

[StickShaker]

Nice job....the spring loaded wheel is a nice bonus.

 

[Jmorrismetal]

Yes, the wheel helps out quite a bit, this is what it looks like.

 

[Jmorrismetal]

I had a little time today and built an H&H style gauge too.

 

[StickShaker]

I had a little time today and built an H&H style gauge too.

I wonder if it would be worth the trouble for increased accuracy to make a holder stout enough so you could add a hand operated lever opposite of the indicator to bump the "off" rounds closer to perfect?

BTW, I really like that old indicator in post #4. Are the limits set for +- .0005? Very impressive if I'm reading that right.

 

[Jmorrismetal]

I wonder if it would be worth the trouble for increased accuracy to make a holder stout enough so you could add a hand operated lever opposite of the indicator to bump the "off" rounds closer to perfect?

BTW, I really like that old indicator in post #4. Are the limits set for +- .0005? Very impressive if I'm reading that right.

I have that in mind but didn't have time to implement it.

The goal is to pick the dies that do it right from the beginning though vs "fix" them.

This is a better view of the "test" indicator. A regular 1" dial is good enough to see what's going on though.