Best edge finder for oldie

No, the angle doesn't matter for the ones in the last photo. The 2 parts are held together by an internal spring.

Murray

Same for the electronic types, work at any angle,

Emgee

edit typo

Edited By Emgee on 09/03/2018 21:22:23

The wiggler (which I favour) and the simple edge finder liked by Murray and others work on the same principle. For all practical purposes a wiggler is the inherently amplified version.

Having the bitch job from hell sitting in the Bridgeport needing some in process edge finding ('cos someone drew it up to be done on his CNC'd Taig) I thought I'd take the opportunity to revisit the simple edge finder after 30 or so years. Half an hour of playing confirmed my view that a good, Huffam, wiggler is at least as accurate and generally much easier to use.

Although once you get your eye in its not that hard to see when the simple edge finder snaps true the wiggler is that much more obvious. I reckon to stop feeding just as the stem starts to move. Usually things settle at about half a ball ends width out of vertical which is easily under a thou error on both my Huffams. Long stem is an advantage when working off the back side of job as required if using the 1/2 function on a DRO for very fast and error free centre-line location. The only real disadvantage of the wiggler is its length. Easy to run out of headroom on small machines.

Huffam leaflet shows both vertical and horizontal use.

I have a Hamier 3D Taster if I want to get serious about things but it pretty much never sees daylight. I seriously doubt if its any more accurate than a wiggler used on both sides with the centre-line calculated via the 1/2 function of a DRO. Probably a little better than a wiggler in single side mode.

However you have to get a good wiggler. As mentioned in my earlier post the common, relatively cheap, sets in a plastic wallet with snap-in collet type carrier for the probes are an unreliable waste of time. You can pin them down, I got mine to a reliable 3-4 thou kick off error, but life is too short when better things can be found!

Clive

Edited By Clive Foster on 09/03/2018 21:49:33

You can use a pointed one to line up with a centre pop in the mill, in the same way as the old sticky pin. My set came with a ball end, a pointed end and a cylindrical end, any of which fit into a ball socket on the part that goes in the chuck. To pick up a centre pop, you put the pointed end one in, then carefully!! set it to run true with your fingers with the machine turning at a modest speed. When it is running true, you can move the table until the pin is exactly over the centre pop. The old sticky pin idea was the same, except you attach an ordinary sewing pin to whatever is in the chuck using blutak or putty. Again, set it to run true with your fingers, then pick up the centre pop, or an edge for that matter. That is how our forefathers used to do it.

John

Cigarette paper stuck in place with spit for edge finding and sticky pin for centre finding.

Russell

One of the best tools in the box, I have about 20 different types, for some reason I keep acquiring more of em, I was watching a toolmaker mate ages ago, he was setting up a job for an injection mould tool, I asked why he didn't use a wiggler to find edges and centres etc, he said cos there crap once you eyes get older, he is in his late 50's now and a very good mate who makes very good but expensive tools.

I proceeded to demonstrate it pop to one side as it passed centre at which point its one tenth, the look on his face when it dawned on him he had been doing it wrong was priceless, he now uses one all the time.

I run mine at about 700 rpm, you can usually here it as it pops and or feel it if the lights bad or in shadow, the pointy end I use with the spindle stopped, I locate the point in a hole or pop mark and feel for an edge where the pointed section meets the shaft whilst moving the part.

Shaun

What hasn't been stated is exactly why the cheap wigglers aren't worth using and why the better ones cost what they do. How repeatable and accurate they are is a function of how well the wigglers working faces have been heat treated, ground and then precision lapped. The best ones will have a dead flat mirror lapped finish on both faces so they kick off at a constant and repeatable point every time. They do need a gentle cleaning and a single drop of light machine oil applied from time to time. Russell's mention of cigarrette rolling papers is a very old machinist's trick and one I use quite often. If your careful that paper can do edge finding that no other tool can do. The Zig Zag brand I use are almost exactly .001" thick. Held with a pair of needle nose pliers to protect your fingers edges can be found with the cutting tool rotating in the exact tool holder your going to be using so even tool runout can be compensated for. X,Y and Z can also be found with that simple piece of paper. They can also be used to locate a tool tip on the part face or it's O.D. on the lathe, locating a drill point at a known location for tailstock drilling and do it all to less than 1/2 a thou if you take a bit of time and your careful. Thicker paper can't be as accurate since you have no idea how much the cutting tool is compressing the paper with a stationary tool or exactly at what position it tears the paper with a rotating tool or part. I've also got and use a Haimer 3D and there's no doubt it's far more accurate than any wiggler type I've used. They do need to be properly zeroed to the machines spindle C/L and kept in a dedicated end mill holder to get the very best from them.