# Shopmade Edge Finders



## Hexbasher (Jan 16, 2008)

Got this idea from over on PM aboot a month or two ago(From Tdkkart's Post in a the 'Electronic Edge Finders' thread), and I finally had 3 hours free last weekend (14 hours weekdays machining between work and school, and weekends doing well, the busman's holiday routine between overtime, harleys and toyotas)






2" OAL 0.750 bearing, 0.500 chucking dia
3" OAL 0.750 bearing, 0.375/0.500 chucking dia
4" OAL 0.750 bearing, 0.375/0.500 chucking dia
6" OAL 22mm bearing, reduced neck, 0.375/0.500 chucking dia

the 6 inch one is the one i really wanted to make for _bastard*_ CNC setups where i have raw stock over hang and only 0.25 of machined material sticking out of the vise to sweep a dial on, it has a 50 buck 22mm bearing on the end of it, i peeled the seals off, flushed the grease out with methl-hydrate so it spins (and stops) more freely

simple to use, chuck, run, slowly bring to edge, when the outer race stops spinning, you've found it. the bearings with the plastic seals on it (with brands and whatnot on it) are easier to see vs. ones with metal seals

making em:

my ER collet chuck for my Okuma LS had too much run out for my liking (0.0005 on the taper)...so i bored some softjaws and chucked a 5c collet chuck, still not good enough (0.0002 was the best i could get after hitting with a brass hammer for a bit)

i ended up using the collet chuck to rough, and i finished between centers, practically zero runout, which was my biggest concern with the 6 inch one. I used DNMG - 221 S/S grade inserts, but i've have no prob in the past with general purpose inserts, i wanted the s/s inserts because i took a light skim cut (0.0005) to 'true' up the 0.500 diameter for chucking (@ 2000 RPM 0.002 feed) I'd run it faster if i could but thats the fastest my manual lathe runs and it would take too long to program and set up on one of the CNC lathes. the 1 rad (1/64) TNR is great for undercutting fillets (which i always do on tooling)

these four were made from 1/2 inch O-1 drill rod, my favorite/most common side project material..bearings were pressed on. all of them (except for the 2inch stub) have turned 0.500 and 0.375 dia for chucking (my two most commonly used collets)














on a 5 month old Haas VF-1 the 6 inch had 0.0001 repeatability or better (after touching off the 1-2-3 block, i zeroed the operator page, backed off and found the edge again, the next ten or so times i found that edge the op page read +0.0001)...done at 1000 RPM

the three others have shitty bearings and i'll prob be replacing them in the future, but good enough for a manual mill with 0.0005 repeatability on a POS Dahlih mill

with the short ones on a manual mill, theres nothing to break, and if you go too far the table will go no where further (hand feed talkin here)

its a great design thats highly customizable and modifiable for whatever your needs are.

_*Bastard - aka oddball aka awkward Op. 2 setups, awkward castings, SNAFU jobber type stuff_


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## Spin Doctor (Jan 19, 2008)

I've seen the trick before but had forgotten it. My favorite one when setting up is to simply put a 1/2 dowel pin in the spindle, position the spindle, set the read-out in X at -.2500" and bump the stock up against it. Close the vise and set my work stop. Close enough for most work as most stuff is +/- .005" anyway. It normally would be with in about .0005". The back of the vise/s I would check on a regular basis and keep that zeroed in Y. But my favorite edge finder is one of these


[url]http://www.emachinetool.com/tooling/temp_right_images.cfm?FamilyID=S984054&Source=PTC
[/url]

Simply bring the contact ball up to the work and when the needle reaches zero the centerline of the spindle is on the edge of the part. You can even pick up holes with them.


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## greenie (Jan 19, 2008)

What ever happened to the simplest idea of all, the off-cut of 1/2 inch ground, painted up with a black Sharpie?


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## BobWarfield (Jan 19, 2008)

There's also the second simplest: the ole cigarette paper trick.

BTW, I did a study of a bunch of these one time for z-axis touch offs. Not exactly like what we're doing here, but go to my mill tips page:

http://www.cnccookbook.com/CCMillTipsTechniques.htm

Search for "Accurate Z-Axis Adjustment on the Mill".

The cigarette paper thing works well. 

One thing for those on this board to keep in mind is machine rigidity and play will vary considerably. The Haas pictured or Rake's Mazak will be hugely rigid compared to most home shop machines. Choosing a technique that doesn't require too much force will be helpful.

I quite like that SPI gizmo. I'm wondering if it does everything a Blake coaxial indicator would do in a more modern package? 

Best,

BW


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## tattoomike68 (Jan 19, 2008)

I use a peice of paper here at home. Thats all I have.


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## Powder keg (Jan 19, 2008)

What do you need an edge finder for? Can't you see it?
	

	
	
		
		

		
		
	


	




Wes


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## Spin Doctor (Jan 20, 2008)

BobWarfield  said:
			
		

> I quite like that SPI gizmo. I'm wondering if it does everything a Blake coaxial indicator would do in a more modern package?



In a lot of ways they beat the Blakes alll to blazes. But hey can not be used with the spindle running to dial in on th efly. They are most useful on CNC machines where the guy spinning the MDI might be 5 or 6 feet, OK two meters, away from the indicator or edge finder. Try hearing an edge finder (I like the audible ones) with all the noise in a typical shop. Plus there is always the venerable "Tool Makers Chair" /".400 Block" and its close cousin the "Corner Finder"


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## Lew Hartswick (Jan 20, 2008)

"Tool Makers Chair" /".400 Block" and its close cousin the "Corner Finder"

Those terms ring a bell but no picture comes to mind. Got a ref to photo?
Thanks.
  ...lew...


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## BobWarfield (Jan 20, 2008)

Lew Hartswick  said:
			
		

> "Tool Makers Chair" /".400 Block" and its close cousin the "Corner Finder"
> 
> Those terms ring a bell but no picture comes to mind. Got a ref to photo?
> Thanks.
> ...lew...



From the list of edge finding gizmos:






...you will find the tool maker's chair and the corner finder are the 3rd and 4th items respectively on the top row from the left.

Marv Klotz has published a relative: his round stock with the cutout edge finder and center puncher.

Cheers,

BW


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