# Wiggler or edge finder?



## DavidR8 (Apr 27, 2020)

In yesterday's drawer cleaning I came across a complete Starrett S828HZ wiggler set in perfect condition.
I see people using the type of centre finder that spins until on the edge and then goes off to indicate the edge. Are these type more useful than the Starrett set?


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## RJSakowski (Apr 27, 2020)

I have both and use the edge finder exclusively.  I am able to repeat a edge found to +/- .0001" consistently.


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## Lo-Fi (Apr 27, 2020)

I also find the edge finder totally reliable, repeatable and accurate. I got a 10mm wide finder, which works perfectly with my mill having 5mm leadscrews. Makes it super easy - one turn to get to the edge from where I picked up with the edge finder. I find less thinking on simple ops like that is a definite advantage. I don't think I'd get anywhere near the same accuracy with a wiggler, but I'm sure very useful in some situations where edges aren't easily picked up with an edge finder.


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## benmychree (Apr 27, 2020)

I have been told that if you grind a small flat on an edge finder that it increases it's sensitivity, I did it to mine; I have always thought that if you advance until the edge finder goes off, that you went a bit too far, I go until no light gap can be seen with a strong back lighting.  I use both an edge finder and wiggler, mostly the sharp point for picking up prick punch marks or center lines, they are both useful., also the wiggler set can be used to mount a Last Word style indicator.


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## Winegrower (Apr 27, 2020)

Could someone please explain exactly why (not how) an edge finder works?


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## bakrch (Apr 27, 2020)

The only thing I use my wiggler set for is picking up a hole that I want to drill with the head kicked on an angle. 

I will spot the hole/ holes with the mill squared up,  then set the head angle. Use edge finder to find Y zero. Then,  pointy wiggler tip finds spot center for X.  

I use my edge finder every day, to pick up edges or find center of a round part,  wiggler set maybe use it once a month.


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## Mitch Alsup (Apr 27, 2020)

An edge finder works because the tip is fictionally bound to the shaft, and it takes just enough pressure on the tip to overcome this friction for the tip to walk/move off center. This side "pressure" versus the tiny amounts of friction eliminates tiny particles, liquid films, and the like from giving false readings.

I use edge finders for finding edges, I use wigglers for finding centers. They both have <different> purposes.


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## derfatdutchman (Apr 27, 2020)

They both have their uses. The majority of the time I use the edge finder. But there are times the wiggler is very useful. The disc is useful when you have to pick up the edge in a confined area. The point for picking up lines and center punch marks. It’s worth having both in your tool box.


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## RJSakowski (Apr 27, 2020)

The way I use the edge finder is to approach the edge relatively quickly to get an idea as to the location. Then I back it off ad nudge the tip wihn my finger nail to run true and approach the edge at around .0002"/sec. as determined by my DRO.  what this does is it allows the tip to become perfectly centered on the spindle axis.  As you continue the approach at some point the perfectly centered tip will contact the edge and the tip will deflect to the side at which  point the edge is offset by the radius of the tip.

Approaching too quickly can cause one of two errors. Too fast an approach can cause an overshoot because of a delayed personal reaction. On the other hand if approached too quickly, the top may not center and it can deflect prematurely.  Slowing the approach prevents both of these issues. If you have a DRO you can easily check your positioning ability by finding the opposite sides of a known block. A 1-2-3 block is a good candidate.  Find two opposite sides and compare the DRO readings to a miked value. 

Different materials react slightly differently as do ifferent surface textures.  Hard, smooth surfaces provide the best accuracy while softer materials or those with rougher surfaces can cause slight errors.  Surfaces should be clean and dry.  A liquid film can cause viscous drag which will deflect the tip prematurely.  I apply a light oil between the tip and shank and wipe it dry with a clean cloth.  This leaves a very light film on the surface which enhances the deflection.


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## ErichKeane (Apr 27, 2020)

I definitely get more use out of my edge finder, but a few times I've used the wiggler. The wiggler is useful for finding a punched point, a scribed line, or centering on a small hole (where the coax indicator isn't going to work).

I'm glad I have both, and for a few bucks they are worth having in a drawer for when you need it.


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## projectnut (Apr 28, 2020)

Another vote for the edge finder.  As many others I have both in the shop, but the edge finder is used far more often than the wiggler.  In fact for most hole locations the wiggler has been replaced by a co-axial indicator similar to this:






						Co-Axial Center Indicator Set
					

Shars Tool




					www.shars.com


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## ErichKeane (Apr 28, 2020)

projectnut said:


> Another vote for the edge finder.  As many others I have both in the shop, but the edge finder is used far more often than the wiggler.  In fact for most hole locations the wiggler has been replaced by a co-axial indicator similar to this:
> 
> 
> 
> ...


 I  have two problems using the coax indicator on small holes:  1- If they are threaded, the hard tip can ruin my threads.  2- It is particularly finnicky on smaller holes.  

That said, its about 30x the amount of work as a wiggler


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## kb58 (Apr 28, 2020)

Since this thread popped up, I've always wondered: is there a too-fast or too-slow speed for an edge finder? I use mine all the time and never have a problem because the mill's always running at a speed appropriate for a given cutter, but I'm still curious.


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## projectnut (Apr 28, 2020)

There are different speeds recommended by different manufacturers.  Starrett recommends using their 827A edge finder between 800 and 1,500 rpm's.  Brown & Sharpe recommends "up to 1,000 rpm's.  I have a couple from the MSC "value collection" that have a recommended "minimum speed of 300 rpm".  I find using any of them at about 800 rpm gives repeatability of .0002".

The key to repeatability is keeping them clean.  My oldest are the ones from MSC.  They started to get sticky and lazy a while ago.  I found soaking them overnight in diesel fuel removed years of gunk and made them respond as good as new.


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## macardoso (Apr 28, 2020)

I'm a big fan of electronic edge finders. Tormach made a really nice one some years ago with a 0.4000" tip that was spring loaded to prevent overtravel. I trust it within .0005-.001". The spherical ball also allows you to do some centering on rounded surfaces if they are symmetrical about the centerline. Something like finding the center of a beer can laid on its side. I don't think they make this anymore, but I don't know why.




If I need really good precision, I will use my tenths DTI to pick up the edge. That is more accurate than the machine is able to move.

I don't know why, but I don't trust myself with a normal mechanical edge finder. Maybe the ones I have are junk, but they don't seem to crisply snap from running true to "broken". Takes maybe 2-3 seconds for them to roll off to the side. For this reason I switched to electronic devices a few years ago and haven't looked back.

EDIT: another big plus for me is that this edge finder has a repeatable length, so I use it as a master tool for setting up my CNC. I can probe in X, Y, & Z all in one go.


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## RJSakowski (Apr 28, 2020)

When I use the edge finder, I usuaqlly put the spindle in manuaql mode and dial the speed until it seems right.  Yesterday, U raqnit in auto mode so I could actually read ths speed.  750 rpm was about where I normally run.  In my experience, running faster gives a more crisp "snap" when the edge is touched.  Too high a speed can throw the tip out once it is displaced.  

I failed to mention previously that I try to engage just an 1/8" of the tip.  When using the edge finder for finding the center of a boss or a hole, I use the same tip engagement for bothe side.


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## BGHansen (Apr 28, 2020)

I use an edge finder 90% of the time.  I've used a wiggler to find the center of a hole, but not an edge.

I use the wiggler with the sharp point to locate a punched hole on center when doing 4-jaw work on the lathe.  Put the wiggler in a chuck in the tail stock and bring the point into the pricked hole.  Then put an indicator on the shaft of the point and dial in the 4-jaw.

Bruce


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## Suzuki4evr (Apr 28, 2020)

projectnut said:


> The key to repeatability is keeping them clean. My oldest are the ones from MSC. They started to get sticky and lazy a while ago. I found soaking them overnight in diesel fuel removed years of gunk and made them respond as good as new.


And I just wanted to ask on how can a edge finder be serviced, thanks projectnut. O my vote is also for an edge finder by the way.


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## Suzuki4evr (Apr 28, 2020)

projectnut said:


> There are different speeds recommended by different manufacturers.  Starrett recommends using their 827A edge finder between 800 and 1,500 rpm's.  Brown & Sharpe recommends "up to 1,000 rpm's.  I have a couple from the MSC "value collection" that have a recommended "minimum speed of 300 rpm".  I find using any of them at about 800 rpm gives repeatability of .0002".
> 
> The key to repeatability is keeping them clean.  My oldest are the ones from MSC.  They started to get sticky and lazy a while ago.  I found soaking them overnight in diesel fuel removed years of gunk and made them respond as good as new.


Can you give it a light oil like a penetrating oil or will that make it easier for grime to collect?


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## projectnut (Apr 28, 2020)

Suzuki4evr said:


> Can you give it a light oil like a penetrating oil or will that make it easier for grime to collect?



I've heard of people using everything from sewing machine oil, to WD40, and even ATF.  Personally I haven't used anything on any of mine (2 Starrett, 2 MSC, and 1 B&S) in over 20 years.  The MSC ones were cleaned for the first time last week.


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## Mitch Alsup (Apr 28, 2020)

Suzuki4evr said:


> Can you give it a light oil like a penetrating oil or will that make it easier for grime to collect?



I use ISO 32 to lube the tip/sliding-plate of the edge finder.


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## Lo-Fi (Apr 28, 2020)

Giving the sliding surfaces a light stoning improved mine considerably. I keep it dry, any kind of oil doesn't seem to do it any favours.


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## mikey (Apr 28, 2020)

My Starrett 827A was sticking one time so I contacted Starrett and was told to gently lift/separate the tip from the body (without stretching the spring) and clean it with some contact cleaner, then use a drop of light oil to lube it, then gently blow out any excess oil. This was over 20 years ago and that edge finder is still working fine. 

They also told me to use it between 800-900 rpm for best accuracy, so I listen to them.


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## ericc (Apr 28, 2020)

Hmmm. Very interesting. I have always had bad luck with edge finders. I don't own one, but the one at the local makerspace was not reliable. I should have tried to clean it. Too late now. I had much better results by using the "catch and drag" method with paper.


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## BGHansen (Apr 29, 2020)

Hi David,

Thanks for opening up another "rabbit hole"!  Many ways to spend money on finding center or an edge.  Here are some from my shop; there are probably more.  I guess before I share my "arsenal", one handy tool you already have is your DRO.  Yours likely has a "1/2" function.  You can find the center of a block, boss, or hole using an edge finder and your DRO.  Move in X to find the LH edge and Zero X.  Then shoot to the RH side and edge find it.  Leave the table at the RH edge and type "1/2 X"; your DRO X is now at the half-way point between the two.  No need to enter anything in the DRO to compensate for the diameter of the edge finder.  Repeat if needed to find the Y.

The same technique can be used to find the center of a hole or boss.  Eyeball center on the Y and repeat the X procedure above.  That'll give you an approximate center in X.  Move X to that location and repeat the process on the Y axis.  Move to the center in Y and repeat the process for X.  

Here are a few other methods, I'm sure others with a bigger tool box than mine and more experience will add to the list.

Bruce


You've got edge finders and wigglers down.  I'm lazy and edge finders are cheap, so I have them in 3/8" and 1/2" diameters.  That way I can grab either one depending on the collet in my mill, quite often saves a collet change.






I'll use the electronic edge finders also.  Catch is the material has to be conductive, so won't work on wood or plastic.  Good idea to confirm the battery by touching off to some steel for starters.  The larger one is an import that has a 20 mm shank and a 10 mm ball.  I typically work in English units, so punch the E/M button on the DRO when using this one.  Also have a dedicated 20 mm R8 collet for it since all of my tooling is English.  This one has a super bright light and tone when it touches off.  These are under $20 on eBay.
The other one is a Borite electric; has a 1/2" shank.  This one lights up only, no tone like the import above.  I'll grab this one if the spindle happens to have a 1/2" collet in it.  I have two of them from eBay, under $20 for each one.
Condition on these is the spindle run-out is not accounted for as they are typically used without the mill running.  Probably not a big deal if your spindle/collet have very little run-out.  The import is pretty tall, so maybe better suited to a knee or square column mill than a Rong Fu.




Real sophisticated method used for 100's of years is a piece of paper.  My dad was a high school shop teacher and taught this method.  He originally used cigarette papers which were something like 0.001" thick, but kids kept stealing them to roll their own.  Super cheap and pretty accurate, just compensate for the thickness of the paper.  He'd run the mill with the cutter in place and stick the paper between the cutter and the work.  Creep up on the edge until the paper starts to catch.  My old Dilbert day-calendar pages are 0.003" thick.




Another possibility is a centering scope.  Probably more useful for finding a scribed line in the middle of the work or a pricked hole, but you could find an edge.  It's a microscope that goes in the spindle, peek through the eyepiece on the side.  The scope has a cross-hair or line for alignment.  Mine has a pretty tight focal range and needs to be about 1" above the work +/- practically nothing.  Personally, it's a paperweight in my tool box.  I've used it twice, didn't learn my lesson after the first time bumping my head into the mill; you're practically kissing the work to use these.  Naturally, no power on the spindle when using these.  A popular make off eBay is Skoal, run around $175.  Mine is a Center-Scope brand, got it for probably under $40 on eBay.




One "essential" is an Indicol type dial test indicator holder.  You can't use them to find an edge, more for getting on center of a hole or boss.  These attach to the spindle and you manually sweep them with the indicator in contact with the work.  I usually do X then Y.  Touch off on the LH side and zero the indicator.  Swing to the RH side and note the number.  Adjust the table for half the distance and re-zero.  Then swing back to the LH side and repeat the adjustment if necessary.  Swing to Y close to me and move the table in Y to zero.  Then repeat the process in Y swinging between front and back.  Pain in the butt with this method can be the visibility of the DTI.  Some guys use a mirror to see the back side, most probably stand at the side of the mill and/or crane their neck to see.  This one is done without power to the spindle also.  They can be used to tram or square up work to an axis.  My holder is a $15 import.  I leave a decent 0.0005" Mitutoyo on mine, so variable price on the DTI.




A co-axial indicator does the same thing as the Indicol, but is done under power.  These let you find center of a boss or hole pretty quickly.  Plus side is the indicator face is stationary, so no gymnastics required to read the display.  Down side is they are a bit tall, so not the best option for a Rong Fu mill, better suited to a knee mill or square column mill.  There's a reaction bar that rests on a surface (I usually throw an angle plate on the table), adjust the probe to make contact with the work.  Turn on the mill and see the indicator needle wildly wobble.  Adjust the table in X and Y to minimize the wobble.  You can tell if you've gone too far as the needle wobble will increase.  
I have a center-finding attachment for pricked holes which I don't believe is standard with the Blake co-ax's.  They are around $40.  Process is the same to find center on a hole; tip of the probe is spring-loaded so you jam it into the hole and fire up the mill.  Move the table to minimize the needle wobble.  Tubalcain has a good video on using these.  I started with a Shars which would NEVER get below about 0.020 indicated on center.  My Blake will dial in to 0.001 with no issues.  A decent Blake can be had for around $100 off eBay (around $350 new). 
By the way, the indicated numbers on the dial SHOULD NOT be taken as an absolute measurement.  If the needle reads a variation of 0.005 (for example), that doesn't necessarily mean 0.005".  Lots of geometry involved like angle from center, length of probe, etc.  I've not checked my Blake against the Indicol method above, but if it was super critical, I'd go with the Indicol over the co-ax.  They both account for spindle run-out.




Yet another is a laser center/edge finder.  There are videos of guys using them to find the edge of their vise or work, but these are not as accurate as an edge finder or piece of paper.  I primarily use mine to find the center of a hole or a boss, works quicker than a co-ax or Indicol, but not as accurate.  I can typically hit within 0.005" of center (or better).  Mine are from SDA, there are a couple of other makes out there.  SDA sells ones that project a dot, cross-hair or concentric circles.  The circles one is nice for finding a hole or boss, you adjust the spindle/table up/down and dial a circle right on the edge of the work.  There's a polarizing filter on the end so you can adjust the thickness of the lines, but doing so means the line is harder to see.  I turn off my shop lights when using these.  These are >$150 new though I bought mine off eBay for under $50 each.
There are some videos out there where guys have taken a laser pointer and mounted it at an angle in their spindle.  Turn the spindle on and project a spinning circle, diameter is varied by raising/lowering the table/spindle.  Might be a nice project though without the polarizing filter, I wonder about the thickness of the projected line.  Probably not bad if you were setting up to knock a hole in wood for a corn-hole game, but I wouldn't use it to find the center of an engine block cylinder.  








Another one for the CNC mill is a probe.  I have a Tormach and use the heck out of my probe.  The length and diameter of the probe ball are programmed into the machine.  I move to a corner (vise or work), hit a button and the controller touches off in X and Y and zero's the machine on the corner.  Same thing for a boss/pocket or hole.  Move the probe over the work, hit a button and Z is set.




I think that's about it in my tool boxes.  And to your original question, even with all of these options in my tool box, I use an edge finder 90% of the time on a manual mill.


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