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Thread: How To Use An Edge Finder??
06-27-2005, 11:03 PM #1
Bought a milling attachment for my 13" Southbend. At the same time I bought a set of endmills and a set of "edge finders". They were only $15 bucks and I've never seen them used before, I guess I thought they might come in handy. There is several different types. one is pointed, the others are strait and vary in diameter. They all seem to wind up some how and the release when you let the tip go. Anybody have any idea what I'm talking about?? If so could you help me out and explain how to use these. Id like to be able to acurately locate a drill bit in a punch mark, I guess I figured the pointed one would work for this, was I wrong??
06-27-2005, 11:25 PM #2jfsmith Guest
There are many article concerning using an edge finder, there is a thread on using edge finders:
Or from Sherline:
Hope this helps
06-28-2005, 05:37 AM #3
Looking at the two links, they don't really help a beginner using edge finders.
An edge finder consists of two cylindrical parts held together with a spring internally. Don't twist them! You'll only loosen the spring.
Put the edge finder into your collet/chuck on your machine. It does not matter if the lower part is off centre.
Start your machine and move the workpiece towards the edge finder. At some point, it will start touching the edge finder, and the edge finder will begin to run "smoothly" against the piece. Move the workpiece a little further, and the edge finder will suddenly "jerk" to one side. You have now found the edge.
Add the half diameter of the edge finder to the reading on your dial, and you should be right above the edge of your workpiece.
06-28-2005, 07:03 AM #4
Benta is right on but let me add.
i think that its best to kick off the contact cylinder as it gives you a visual approach to the part.
once contact is made zero the DRO and back off and recontact to verify your number.
then move the radius of the edge finder and rezero the DRO.
one other thing i do is make a datum absolute then if necassary you can use the incremental function for bolt circles, distance between holes for keyways etc.
and you still have your origion...jim
06-28-2005, 07:37 AM #5
I understand the edge finder procedure, but i think what he wanted to know was how to use the center finder portion...i am also interested in knowing the same..
06-28-2005, 08:00 AM #6
well i use the V end to locate the center of slots and grooves that are too small for the .200" section to fit into.
i have seen people use that for picking up transfer or center punch dimples and ive seen the edgefinder shatter when the user gets a little heavy handed, even have one myself to remind me what not to do .
in my opinion if you wish to pick up punched locations your better off buying a co-ax indicator with the center punch attachment.
its much easier and more accurate.
if you have multiple locations you can chart them as you indicate them, provided you have a DRO, then go to the numbers for subsequent operations...jim
06-28-2005, 03:35 PM #7
I've always start with the edge finder nonconcentric and approach edge until its concentric. This is with the spindle not running. Do you see any problem with this approach? It really doesn't seem that difficult to verify the cylinders are lined up by eyeball.
06-28-2005, 03:40 PM #8
why do you not have the spindle turning?
the recommended speed is 1000 RPM not stopped.
Starret claims the accuracy of edge finders is .0002" i doubt very seriously that your eye is that good...jim
06-28-2005, 03:44 PM #9Do you see any problem with this approach? It really doesn't seem that difficult to verify the cylinders are lined up by eyeball.
06-28-2005, 03:53 PM #10
you know that reminds me of when i was a leadman in West By God Virginia one time.
we had hired a guy i worked with at National Mines Service Co. and he asked me how to setup a job. he was a pretty good machinist too.
so i say get a 3/8" edge finder and hit the datum corner and set zero.
simple enough right?
i look over and he has a 3/8" drill and a piece of notebook paper feeling for drag on the paper, fortunately he didnt have the spindle running.
he was amazed when i showed him a edgefinder, he would edgefind just for the hell of it.
so much for assuming what experience people have...jim
06-28-2005, 05:38 PM #11
I'm self tought so thanks for correcting my proceedure. I'll try running the spindle.
06-28-2005, 06:23 PM #12
For the pointy end, I make the point run true with a pencil or similar (while the spindle is running), then eyeball the point to the scribe lines, center punch mark, or whatever it is I'm aiming for.
06-28-2005, 06:27 PM #13
ive always found that a wiggler is better for picking up layout lines.
its smaller and the point is finer...jim
06-28-2005, 06:32 PM #14
I'm with you on that one, but cathead asked...
I even put my wiggler point in the tool & cutter grinder and sharpened up the point. Starrett disappointed me with the somewhat blunt and eccentric tip when I got it.
06-28-2005, 06:43 PM #15
nutsrusted (Boy, what a handle! ), I hope you don't take offense. Sometimes us old farts are surprised that 'everybody doesn't know', what we learned many years ago. And, even new edgefinders don't come with instructions; I guess the manufacturer thinks, if you buy one, you know how to use it.
Ok, here's the training speil: mount your edgefinder in a collet in the spindle (NEVER in a drill chuck! ONLY drill bits are used in drill chucks! [img]tongue.gif[/img] ). Turn on the spindle, in the 1000-1200 RPM range. Make sure the .200" dia. end is off center, if it's not wobbling, flick it with your finger. Now, slowly bring it up to the edge of the part that is against the back (fixed) jaw in the vise. As the end contacts the part, the wobbling will diminish. Very slowly advance the table, until you can discern no wobble. Now, tap the 'Y' axis handle with your finger, until the edgefinder 'jumps'. Now, the OD of the edgefinder is at the very edge of your part. Retract the quill, 0 out your DRO 'Y' axis , and dial off 1/2 the dia. of the edgefinder (usually .100"). Repeat for the 'X' axis (usually done on the left side of the part, as you are facing the mill). Now, the far left corner of your part is your datum; all holes, slots, pockets, etc. will be accurately positioned, from that corner.
Using the centerfinding point involves a slightly different technique. Here's mine: Mount the point in a collet, keeping it as concentric with the edgefinder body as you can, by eye. Move your punch mark under the point, again, as close as you can by eye. Bring the quill down into the punch mark (spindle stopped!), then raise it about .010", so it's not bottomed in the dimple (if you can't 'feel' .010" with the quill handle, dial it off on the knee). Start the spindle, then slowly move the 'Y' axis, until you see the least wobble. Do the same with the 'X' axis. Repeat.
Hope this long-winded reply helps. (sometimes the 'instructor' in me comes out )
06-28-2005, 06:49 PM #16
yeah i did the same thing even relieved it back .3" or so.
thats one thing thats never a loaner did that one time got back a dull point and a lame excuse ...jim
06-28-2005, 07:55 PM #17
Thanks RAS. My handle is meant to describe my state of mental being but I guess it comes across a little different
No offense taken to positive feedback in technique. I have allot to learn.
Recently I've been trying to get into a small job shop so I can get a formal edjucation
It's so hard to land that first job.
06-28-2005, 08:12 PM #18
Why is it not OK to use an edgefinder in a drill chuck, so long as I am aware of the lack of precision of a drill chuck compared to a collet? I confess I do it all the time on a Bridgeport when locating drilled holes, and have never had an issue. The edgefinder doesn't seem to know the difference. Inquiring minds....
06-28-2005, 08:29 PM #19
From the Starrett web site:Edge finders are easy to use. They are placed in a collet or chuck. The worktable is then traversed to obtain contact between the rotating edge finder and the work. Contact will shift to concentric position relative to the body and with very slight additional table adjustment, will move off center with a decided wobble. At this point, the center of the finder is exactly one-half the diameter of the contact from the work edge, permitting accurate location for other machining operations relative to the edge.
I do prefer the Herman Schmidt edge finder - the body is .375, the tip .200 and the interface between them is .500 - really gives a positive snap to the edge finding. About the only Schmidt product I can afford. Here's a link: http://www.hschmidt.com/edgefinders.html
06-28-2005, 08:49 PM #20RAS,
Why is it not OK to use an edgefinder in a drill chuck, so long as I am aware of the lack of precision of a drill chuck compared to a collet?