One tool - two uses

[mklotz]

A recent article in American Machinist reminded me of something I made twenty years ago for a friend. The body of the tool is a through-drilled cylinder with one quarter of its body accurately milled away.



Insert the punch, made from hardened drill rod, into the hole, align the edges of the cutaway portion with your scribe lines and voila (not viola - that's a musical instrument), the punch mark is on the intersection of the lines.



But wait, there's more! (He shouts, madly waving his Ginsu steak knife.) Ever had the problem of having to align to the edge of a piece of stock angled in the milling machine vise? Drop the body of the punch over the edge and use the edge finder to locate on its circumference. Since the diameter of the punch is known (or can be easily measured), it's a simple matter to locate the spindle axis directly over the edge.



The one shown is massive enough to not move under the friction of the edge finder but, if you have problems, apply a dab of oil or grease to hold it in place with the capillary action. (I have a miniature version that requires this action to remain in place.)

[Doc]

Marv I like especially the second use I have ran across where I wanted to pick up the exact edge and had to dig out a couple magnifying glasses and a lot of squinting to get there.

Thanks Marv!

[JohnC]

Hi Marv,
Very nice tool thank you.  One question.  You say the quarter section is 'accurately' milled away.  Now I can see that for the vertical cut you would use an edge finder and move in by the radius of the ring.  For the horizontal cut do you touch off on the top and move down by the radius, or is there a slicker way?
Thanks,
John

[mklotz]

It's been a long time but I think that's how I did it.  Now that I know a bit more I might be able to puzzle out a more clever approach.

[JohnC]

 

Crikey Marv - that was a quick response!!  I shall await with interest -I intend to make one of these tomorrow.

Thanks again,
John

[Ian S C]

You could proberbly use it as a key seat rule, it might be more accurate than the bit of brass angle that I use.  Ian S C

[kevin45]

I know this is an old thread, but looking at the part made, I would have not thought of doing something like that. I usually put construction holes as a reference point. But seeing and reading this about using grease to hold it in place, instead of doing that, one could put a small neodymium magnet in each of the flat surfaces. I can see many uses for something like this as far as using it for a reference point. 

[m_kilde]

Hello Marv

I too like the edge locating function of this tool.

Thanks for sharing.

[Mosey]

  Outstanding

[Lew Hartswick]

That would have been handy to accurately locate the "corner" of the part in this operation. The part had
been pretty roughly "deburred".  To locate the place to make the V the top of the part was about the
only datum available.
   ...lew...