Great way of doing this. I hadn't thought of using the indicator this way. I like the fact that you did this in the real world. It looks like a good way to check concentricity.

Nice to see someone actually testing equipment like this Mike and what the real world accuracy levels are against the dti method. About the only thing I could suggest would be checking that electronic indicators body and it's probe run out by first spinning it on a V block and indicating both the body and tip. Then indicate the same areas with it mounted in the machine. While I've never bought one of these yet, I have read a few posts that at least some of the off shore one's have very poor run out numbers. My Haimer 3D uses a dedicated end mill holder with the indicator permanently mounted and zeroed exactly to that holder. It wouldn't be impossible to do the same with that edge finder using multiple set screws to zero it to the holder and spindle. Battery replacement might make that impractical though.

Great comparison Mike! We have a dealer in Australia who sells a similar electronic edge finder with a spring loaded ball bearing in the bottom, but it needs a 3/4 (or maybe 20mm?) collet, and it sticks a long way down, so I haven't given them a look, but seeing a much more compact one like yours is making re-think this, and it looks good enough :) Have a good one!

Nicely done Mike! I don't think I have seen any comparison like this.. Good info! Thanks and stay safe... Fred

I went through that same exercise and found about the same. If I want a dead nuts edge find I use the same process as you have shown. By the way excellent explanation I liked it. When and if I get back in the shop next time I use it I will mention you comparison. Catch ya later.

electronic edge finder work in low rpm for more precision round-out.

I've wondered for ages about these electronic finders... and like you always felt the indicator was the ultimate method. I did feel the electronic could be slowly rotated... but for me to be honest and seeing as I rarely bother about odd tenths that could be a useful device to have as another option. It's certainly plenty sensitive. Good the beaver damn is gone. $600 seems pretty pricey for trap but reckon it'd be quite a challenge to make one too. Hope all well Mike.

Interesting Mike. Next video can you please turn off your camera autofocus, drove me nuts with it keep popping in and out, Thanks. Question please, I have never used an electronic edge finder, but surely you need it to rotate as usual to compensate for runout. Is that not why there are 4 portholes to show the light. Were there any instructions when you bought it. Good job with the JCB. Surely the forks on the tractor will lift the concrete, it lifted up your bandsaw when it fell over. Regards from Australia.

Inaccuracies of both methods come from TIR of the spindle/collet/indicator holder. This is nicely explained in this video: kzfaq.info/get/bejne/mM2RatxlztTKeaM.html The “lighthouse “ edge finder is to be used with the spindle slowly turning. If the TIR of the spindle is “substantial”, your center is near a point where the light blinks on/off as the indicator that is off center by half of the runout, spins. When the “ lighthouse” that was blinking stays on, you went too far. If it goes from off to on without blinking, either your spindle and the edge finder are near perfect, you approached the edge too fast to notice the blinking or the error of the spindle and the indicator compensated canceling each other. This would be rare and more of a fluke but it could happen. Repeating the measurement after rotating the indicator in the collet 180 deg can verify that. That video I linked also nicely explains why TIR of the spindle does not have any effect on edge finder with floating tip or a wiggler. Those types of edge finders are concentric with the center of rotation of the spindle regardless of TIR. Because of that they are more accurate. But the “lighthouse “ is way faster and if you know what is the TIR error you can compensate for it .

Could hear the rattling and had a good giggle to myself.

What was the name of the brand of the electronic edge finder and the model number?

You sound like Bane from Batman movie, except you need to put a mask on and lower it just a little bit.