Wiggler or edge finder?

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 In fact for most hole locations the wiggler has been replaced by a co-axial indicator similar to this: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 www.shars.com
 
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 In fact for most hole locations the wiggler has been replaced by a co-axial indicator similar to this:

Co-Axial Center Indicator Set

Shars Tool
www.shars.com www.shars.com
Click to expand...
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 :)
 
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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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.
 
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.

1588080021934.png

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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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.
 
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
 
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.
Click to expand...
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.
 
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.
Click to expand...
Can you give it a light oil like a penetrating oil or will that make it easier for grime to collect?
 
Suzuki4evr said:
Can you give it a light oil like a penetrating oil or will that make it easier for grime to collect?
Click to expand...

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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