Edge finder

Someone posted these irresistible old Belgian toolmaker apprentice prints for an edge finder to the “Machinist Museum” group on Facebook. They also showed a boring head, a hand drill, vernier calipers and depth gauge, and a surface gauge.

Based on those, mine’s only lightly modified and it’s 60% the size. I don’t know how that would affect my grade, but it seems to work alright and it’s a good size for my Unimat and other small machines.

Attachment 25414Attachment 25415

Attachment 25416Attachment 25417

Parts

Attachment 25418Attachment 25419

Some operations

Attachment 25420Attachment 25421

In a Unimat drill chuck, and next to a 3/8” shank Brown & Sharpe edge finder for scale

threesixesinarow,

That is a great little edge finder and well executed. I have been trying to find a tiny commercial version but no luck so far. The Unimat has a very short amount of travel in the Z axis making something like this almost invaluable. Thank you for posting this! I am going to make one for myself.

Thanks, Dick,

This should take you to the Facebook post where I found the drawings: https://www.facebook.com/groups/1687...5396386379373/


Did you check out the pair of little edge finders from Proxxon?


On the Unimat I usually leave the key screw disengaged so I can pull the quill out when there isn’t clearance in front of the chuck. I guess you could make the shank and the probe shorter, though - I’m not sure how useful it is having two smaller diameters on the working end.


I imagine it was a good apprentice project because of the different processes and tools involved, but didn’t take so long so what it teaches stays clear.

threesixesinarow,

Thanks for the tip on leaving the key screw disengaged. I never gave that any thought before, but it does allow one to retract the quill to change bits with no loss of location. That was my biggest frustration. I need to think more outside the box. I did go to the Proxxon website and saw the little edge finders. Well worth the asking price of $35, but I would like to build my own. There is satisfaction in doing.

threesixesinarow,

I forgot to ask if you wound your own spring.

Quote:

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Originally Posted by old_toolmaker

threesixesinarow,

I forgot to ask if you wound your own spring.

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Yeah, just with the lathe slow and in reverse and feeding and supporting the music wire mandrel by hand.

I guessed at the diameters and made the ends where the tension matched the B&S.

threesixesinarow,

I have some 4140 pre-hard steel. I am thinking of using that. What steel did you end up using for your edge finders? Did you harden them?

Quote:

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Originally Posted by old_toolmaker

threesixesinarow,

I have some 4140 pre-hard steel. I am thinking of using that. What steel did you end up using for your edge finders? Did you harden them?

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I think it’s about the same but I hardened it.

- Clark

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Thanks threesixesinarow! We've added your Edge Finder to our Measuring and Marking category,
as well as to your builder page: threesixesinarow's Homemade Tools. Your receipt:

<div id="blocks"> <div class="block b1 pngfix"> <div class="bimg"> <div> <a href="http://www.homemadetools.net/homemade-edge-finder-4"> <img src="/uploads/217702/homemade-edge-finder-4.jpeg"/> </a> </div> </div> <div class="head pngfix"></div> <div class="left pngfix"></div> <div class="right pngfix"></div> <div class="blockover b1 pngfix"> <div class="title"> <a href="http://www.homemadetools.net/homemade-edge-finder-4">Edge Finder</a> <span> by <a href="http://www.homemadetools.net/builder/threesixesinarow_2">threesixesinarow</a></span> </div> <div class="tags">tags: <a href='http://www.homemadetools.net/tag/edge-finder'>edge finder</a> </div> </div> </div> </div>
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threesixesinarow,

Maybe I will use O-1

Quote:

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Originally Posted by old_toolmaker

threesixesinarow,

Maybe I will use O-1

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I would have preferred that but I used what I had and it seems to harden enough.

I used one of my little ER-11 spindles to grind it - the big Unimat pulley makes it hard to do anything between centers.

I'm a big fan of 0-1, unbelievably fine material. Sure some are more modern, but never been a substitute for Oil hardening grades. As far as a spring goes, a couple weeks back needing one for my edgefinder [and inappropriate to spin one on shop time] I had one scrounged from a oil seal.
No such thing as scrap, until you can't hold it.

Toolmaker51,

I can't agree more. For me saving junk to recycle into something else is almost a disease.:hattip:

Yes. No end to what use 'material' can be put to. Present situation stifles originality like whats due tool posts and Quorn Grinders. But I see all kinds of worthwhile remnants. Right now I'm mulling 30°-ish ramps to perch machinist jacks at different increments; similar to planer gauge or adjustable parallels. Anytime I clamp long bars [key-waying etc.], level stock on blocks without touching vise bed, even with two vises in alignment, especially when there are stepped diameters. Machinist jacks are fine, at lower amounts of extension. Each seem to have their own individual harmonic limit that fail to dampen vibrations and consequent chatter.

Recycling
Attachment 25552

threesixesinarow,

A super nice tool chest made with recycled material! WOW

Quote:

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Originally Posted by old_toolmaker

threesixesinarow,

A super nice tool chest made with recycled material! WOW

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Thanks, Dick,

Reusing wood often doesn’t need the same kind of creative thinking as metal, though. The drawer pulls were a small exception, and I thought a nice tie-in to the ongoing Studley thread.

The spring in the edge finder shares a similar source.

Quote:

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Originally Posted by threesixesinarow

Thanks, Dick,
Reusing wood..........often doesn’t need the same kind of creative thinking as metal, though. The drawer pulls were a small exception, and I thought a nice tie-in to the ongoing Studley thread.
The spring in the edge finder shares a similar source.

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There is a statement in one [which I don't recall] of my older books on genuine gunsmithing; not just the screwing things on variety. The quote, which comes to mind whenever I select remnant or other passed over wood, is in section about stockmaking and the nature of it. "Wood is alive until it burns".

In many ways, real Gunsmiths are ultimate toolmakers, not just by combining form and function; but all manner of cross discipline work to complete things like double rifles, side x side shotguns, handwork developed by Frank Pachmayr accurizing 1911's, and countless others.
https://www.google.com/search?q=fran...nt=firefox-b-1

Toolmaker51,

I have an interest in and appreciate all types of hand work. I also like to watch skilled people work. My dad was one those rare types who had mastered many skills and passed them on to his children. He is gone now but I still have all the memories.

Edge Finders have always fascinated me. Ive been a machinist / tool & die maker since the early 70's and even in retirement use one frequently in my home shop on the ol' DoAll mill. But, i never understood how they work. What is it that makes them go off-center so accurately?
And, who was the lucky guy that first encountered the principle?

Quote:

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Originally Posted by gatz

Edge Finders have always fascinated me. Ive been a machinist / tool & die maker since the early 70's and even in retirement use one frequently in my home shop on the ol' DoAll mill. But, i never understood how they work. What is it that makes them go off-center so accurately?
And, who was the lucky guy that first encountered the principle?

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Let me take a shot at it. A little gedankenexperiment may help.

Imagine spinning up a tire and then dropping it on the ground while it's still spinning. As soon as it gets purchase (an olde time word for friction) on the ground it will begin to roll away in a direction determined by the direction of its spin vector.

A similar thing is happening with the edge finder (EF). As soon as it touches down on the part, it gets friction and begins to roll away. It's rolling is quickly stopped by the spring by which it is attached to its shaft but it is displaced far enough that we see the offset. Of course, it won't see any friction until its center is one probe radius from the edge of the part.

Try an experiment. Edge find on an edge parallel to the Y axis on the mill. Approach from the right towards the left with an EF spinning CW as seen from above. If what I wrote above makes any sense, then the probe should deflect in the -Y direction, i.e., towards the operator.

I haven't actually tried this so please report your results.

Makes sense. I was going to pose in my post "what happens if one oils the EF small end?"

I think your assumption re the offset movement is correct.
I might see if that's the case tomorrow.

In circumstances where logistics make it difficult to use an edge finder the old dodge of using a cigarette paper stuck to the edge if the part with a drop of oil works well. You can use the rotating cutter or drill to just flick off the paper and you will be .001 inch or .02mm from the edge. Near enough for most applications. Will not mark the part either.

^ I've done that many times.