Widget for the Edge Finder

[ddickey]

Made one of these today as I thought it would be convenient to use without having to change collets every time I want to find an edge.
I got the idea from Mr Pete.
For an arbor I used a 3/8" endmill. The fit for my edge finder was very nice with no play but when I tried it out there is significant run-out.
So I have two questions.
Is it worthless now as the edge finder is not running true?
Any idea where I went wrong?
I believe my mistake was using an arbor. I should of just drilled and reamed the hole then flipped around and made my steps. I was using an ER collet.

 

[grantj]

I'm not sure I understand completely, but the best way to make this would be to drill and ream the stock material first, then cut the steps by turning the stock mounted on an arbor between centers.

 

[Bob Korves]

Chuck it up on one of the steps in a collet on a lathe and then first bore, then ream the hole to the next nominal size. That should take away the runout. An end mill is not a great arbor...

 

[rgray]

I think you have the right idea. Might want to check the runout on the end mill when in the collet and be sure it is very close to zero. Otherwise do it with the 4 jaw so you can get it right at zero.
I'm assuming there is no through hole.

 

[ddickey]

To late now.
Okay I think I understand why.

 

[ddickey]

That's correct.
Steps are .250-.750 in .125 increments.

 

[RJSakowski]

If you're talking about one of these, runout isn't an issue, assuming it's not huge. The beauty of this type is that before it jumps, it centers itself on the spindle axis. The wiggler type of edge finder is self centering as well.

 

[ddickey]

Yes one of those.
I made another one quick this time not using an arbor.
Turning the steps then taking out the piece, turning around using one of the steps to hold like what Bob suggested..
Two odd things happened.
The reamed hole is tighter and the run-out is greater.
First method I have .01"
Second method .012"
Holding the edge finder in an R8 collet, trying for the same length, .001"

 

[RJSakowski]

Yes one of those.
I made another one quick this time not using an arbor.
Turning the steps then taking out the piece, turning around using one of the steps to hold like what Bob suggested..
Two odd things happened.
The reamed hole is tighter and the run-out is greater.
First method I have .01"
Second method .012"
Holding the edge finder in an R8 collet, trying for the same length, .001"

If I were making your piece, I would do the following. First drill and ream a hole in the stock to fit your indicator shaft. Rough turn the outer profile.leaving some material for cleanup and drill and tap for the set screw. Then I would mount an oversized bar in the chuck and turn to the diameter of the indicator. Do not remove the shaft from the chuck. Install the workpiece on the shaft and turn the O.D. of your part. Since the shaft has not been removed from the lathe subsequent to tuning, it should be true to the spindle axis and the part, using the shaft as a mandrel should also be true to the spindle axis and you should have concentricity.

edit: There's no harm and a lot of benefit to using a center in the tailstock.

 

[woodchucker]

Made one of these today as I thought it would be convenient to use without having to change collets every time I want to find an edge.
I got the idea from Mr Pete.
For an arbor I used a 3/8" endmill. The fit for my edge finder was very nice with no play but when I tried it out there is significant run-out.
So I have two questions.
Is it worthless now as the edge finder is not running true?
Any idea where I went wrong?
I believe my mistake was using an arbor. I should of just drilled and reamed the hole then flipped around and made my steps. I was using an ER collet.View attachment 232771

I would have drilled and reamed, or drilled and bored the hole. Then I would have mounted it on a tapered mandrel, and cut the steps.

When you say arbor, what type? and if you mounted it in an ER, was the ER holding the arbor? What about the other end? Was it in a center?
Edit: OK, I missed the part about the endmill... to me that's not an arbor.