Edge Finder Question

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tornitore45
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Edge Finder Question

Postby tornitore45 » Fri Sep 11, 2009 3:49 pm

If you have a 0.5" and a 0.2" edge finder available and the part/vise has room for both is there a reason to use one rather then the other?

Does the larger snaps crispier?
Common wisdom is to run them around 1000 RPM
Does the diameter make a difference, the 0.5" rubs at 2.5 times the SFM than the 0.2". Should keep same RPM or same SFM?

I read somewhere that oil is bad makes them slogghish.
Any true to it?
Oil where? On the edge to be found or between the edge finder parts?
Mauro Gaetano
in Austin TX

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seal killer
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Postby seal killer » Fri Sep 11, 2009 8:29 pm

Mauro--

I can't answer most of your questions, but maybe I can help a bit.

I usually use the "paper method" because it is quicker and serves me well. But, when I really need to get it right on the money, I use one of my 0.200" edge finders. I love'em.

I have run mine at 1000 RPM and slower. No oil is necessary and (I have read) is harmful. Of course, if the mechanism is stiff, then oil probably will not hurt it because I imagine it is already trash.

Good luck!

--Bill
You are what you write.

Jay, Idaho
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Postby Jay, Idaho » Fri Sep 11, 2009 8:43 pm

I have several but like the .200 models best. My spindle speed is 1400 rpm. I go a lot slower when using a .500 diameter contact tip.
These are fast and neat but not as accurate as one of the types that require you to indicate inside a "box" that is twice as wide as the edge below that rests against the edge of the part. Some of those have magnets in them but mine was a project when I was in my apprenticeship.

Opinion of one,

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GlennW
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Postby GlennW » Fri Sep 11, 2009 9:18 pm

Jay, Idaho wrote:These are fast and neat but not as accurate as one of the types that require you to indicate inside a "box" that is twice as wide as the edge below that rests against the edge of the part.


Like this one Jay?

http://mooretool.thomasnet.com/item/all ... d&filter=0

Dunno how they can make them so cheap :shock:

It is the only thing I've seen from Moore without their logo stamped on it. They turn up on eBay occasionally for around $350.00, but I'm not sure how to tell a counterfeit one from the genuine article since to logo is not on them.

There was one for $250 a while back with no identifying marks and the seller claimed that he had ground the name off of it. :roll:
Glenn

Operating machines is perfectly safe......until you forget how dangerous it really is!

toastydeath
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Postby toastydeath » Fri Sep 11, 2009 10:50 pm

I generally use the .2. There isn't a huge amount of difference, sometimes a situation calls for a finder the same size as the shank it's on, sometimes you need to get in a small spot. Pick one.

The one thing I'll say is don't skimp. Get one expensive, mechanical edgefinder with a .2 or .5 tip (i go with the .2) on one end, and a cone tip on the other.

My Starret is expensive (50 bucks) but is quite accurate - it's about .0002-.0003 off true location.

The cheap ones and the ones people have tried to lubricate in a misguided attempt at maitnence off as much as .003".

Harold_V
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Postby Harold_V » Fri Sep 11, 2009 10:54 pm

Contrary to some reports here, I find edge finders to be rather speed sensitive. My ½" functions very best @ roughly 2,000 RPM. The motion is distinct and crisp, and reliable. I've done .001" tolerance work with confidence and had no problems.

I strongly recommend you experiment with your edge finders. Try them at various speeds, up to the point where those that have a spring start pulling away from the main body. That, of course, is too fast. Anything under that to slow speeds should be explored. I believe you'll find your particular type(s) have a sweet spot at which each will operate best.

Harold

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Pennsy fan
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3D Sensor

Postby Pennsy fan » Sat Sep 12, 2009 12:44 am

This what I use, not cheep but real nice to just 0 out the pointers and your done.

http://www.haimer-usa.com/usa/taster-universal.php

David.
Attachments
TasterUSA%203D-Sen%2BFond.jpg

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GlennW
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Postby GlennW » Sat Sep 12, 2009 6:24 am

I use a Starrett .375" shank .2 edge finder and got curious about it's accuracy (once again) so I secured a 1-2-3 block to the table and indicated it dead square to the table movement. I then set up a DTI and set it to a .250 ring gauge, zeroed the dial and verified it numerous times, found the edge and checked it numerous times for accuracy. I then used the Starrett and it was right at .0001" off the mark on six tries at 1000 rpm. I was pretty impressed. Then sprayed it with WD-40 and it made no difference.

All of this under better than average conditions.
Ray Charles could hit a tenth with the vernier dials on the machine.

Image

Surface finish of the part will also have an effect on cylindrical edge finder accuracy.
Last edited by GlennW on Sat Sep 12, 2009 8:21 am, edited 1 time in total.
Glenn



Operating machines is perfectly safe......until you forget how dangerous it really is!

CarlD
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Postby CarlD » Sat Sep 12, 2009 8:05 am

There is one thing no one has mentioned. You have to sneak up on the edge. If you move to fast you won't get a true reading of the break off center. You have to stop exactly when the tip goes off center.

They are very accurate and I use the .5" more than the .2" end. It depends on the clearance in the work. I have noticed the .5" snaps off center crisper than the .2" does, at least it seems so to me.
It's only ink and paper.

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Frank Ford
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Postby Frank Ford » Sat Sep 12, 2009 9:23 am

A couple of years ago I was reading a thread (here or HSM) about edge finders and somebody recommended the Hermann Schmidt. I've learned to check out and seriously consider product recommendations I see on these forums, so I got one and was amazed at how much smoother it was than my Starrett. Also, the lapped bearing surfaces are larger, so it really snaps:

Image


Next day I donated the Starrett to TechShop. . .
Cheers,

Frank Ford
HomeShopTech

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GlennW
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Postby GlennW » Sat Sep 12, 2009 5:38 pm

Just in case someone with a new surface grinder that enjoys making tools would like to make one :)

Image
Glenn



Operating machines is perfectly safe......until you forget how dangerous it really is!

John Evans
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Re: 3D Sensor

Postby John Evans » Sat Sep 12, 2009 7:35 pm

Pennsy fan wrote:This what I use, not cheep but real nice to just 0 out the pointers and your done.

http://www.haimer-usa.com/usa/taster-universal.php

David.


OK ya got me hooked how much and who sells?
Tks John


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