Centering Over Round Piece

[EdK]

I need to bore some 1" holes through the middle of a piece of aluminum/aluminium tubing. What's the best way to get the spindle of the mill over the highest point on the tubing? I've have one of these and have used it but I don't think it's accurate enough for this application.

Center Finder

Attached is a picture of the part I'm making.

Thanks,
Ed

   

[EdK]

Answering my own question but after I posted the question I realized I could likely do it with one of these edge finders.

Ed


  edge finder.jpg (Size: 4.92 KB / Downloads: 105)

[PixMan]

I find it's more accurate to use a dial test indicator on a long arm. You might not be able to reach the tangent point of a 1/5" radius with one of those.

[EdK]

(09-04-2013, 12:43 PM)PixMan Wrote: I find it's more accurate to use a dial test indicator on a long arm. You might not be able to reach the tangent point of a 1/5" radius with one of those.

Ken,

That's my concern also.

My first thought was to use a dial indicator but how do you keep the contact point in line with the axis of the mill spindle?

Ed

[dallen]

finding center is easy once you get it lined up on the mill table so that its straight. I take that the holes have to be in alignment to the center of the tube right

DA

[EdK]

(09-04-2013, 03:45 PM)dallen Wrote: finding center is easy once you get it lined up on the mill table so that its straight. I take that the holes have to be in alignment to the center of the tube right

DA

Correct.

Ed

[Highpower]

I do this:





But I use a full diameter 1/2" center finder and leave the .200" tip for small diameters.

[TomG]

Ed,

You can also use an dial test indicator to center a part. Just swing the indicator on each side of the part and adjust the table until it reads the same on each side. If you do it on a piece of tubing, set your quill stop so you can set the indicator to the same level in Z on both sides of the tube (preferably at the center).

Tom

[PixMan]

I run the indicator up & down to find the high point of the radius and side-to-side to find the low point of the straight at centerline, then adjust the Y axis until the readings are equal.

[Sunset Machine]

If the work is too large for an edge finder, lean a square against it and reference from that. In a similar fashion you can reference from a vice jaw. You can also kiss the top of the work with a small endmill and eyeball it, the middle of the narrow line it produces will be center.