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Edge finding that does not mare the work.

rons

Diamond
Joined
Mar 5, 2009
Location
California, USA
Finding the center of a .752 square bar.

Using a Fisher edge finder the position to the furthest vise edge is cranked.
The table is locked and the crank is turned the opposite way to move the position from the vise end and out to the center position.
Center point drill, drill tap hole, tap.
Result is not centered so good.

Edge finding on the work piece was not done because the edge finder leaves a indentation.

Some new way I am ready to try...

The bar happens to have a center bored .375 hole.
I set the bar vertical with the hole facing up.
Insert a .375 bar into a collet, blue the bar, then draw the var into the hole below. Adjust/re-blue until bluing is evenly wiped away.
Then rotate the bar 90 degrees and drill/tap hole.

Question is: edging on a vise edge and reversing direction any good?
 
Haimer 3d, Not even worth messing with a edge finder. About 300 dollars but you will not look back after you try it
 
Optical (microscope) center and edge finders work well and obviously leave no mark.

Starrett and similar edge finders work well. I have never left a mark on the work when using one.

Mind the feed screw direction when finding an edge. Reversing the feed after locating the edge can introduce lots of backlash error.

Larry
 
My Starrett edge finder barely leaves any mark on a machined aluminum surface. Maybe yours is diamond coated? How fast you spinning it?

Are you finding the vise jaw location without vising a part in it at the same torque?
 
My Starrett edge finder barely leaves any mark on a machined aluminum surface. Maybe yours is diamond coated? How fast you spinning it?
You're supposed to spin them ?

j/k, j/k but did have a "machinist" guy in once who didn't know that ... was kind of a shock :eek:

I've used them on teflon without getting an indentation, so not sure where that comes from. King Kong Edge Finders, with the Jumbo Centering Spring ?
 
Optical (microscope) center and edge finders work well and obviously leave no mark.

Starrett and similar edge finders work well. I have never left a mark on the work when using one.

Mind the feed screw direction when finding an edge. Reversing the feed after locating the edge can introduce lots of backlash error.

Larry

If it wasn't obvious about the backlash, I am taking that into account. Thing is that this project requires an exact center location for a center pin
that will locate a .375 round bar. The bar will move in/out by 1 inch. The long adjustment screw on the end clear shows if the center location of the
adjustment pin is off by a little.

In this pic the .375 bar slides in/out from the square bar. At the end of the .375 bar is supposed to be a vertical screw used as a clamp hold-down.
If the center screw is no tracking the hole down the center the error is seen when the long hold-down screw is skewed to one side.
DSC_1047.jpg

DSC_1049.jpg
 
The bluing on the rod then inserted in the hole method appears to be working. The original fit was for 2 inch long.
When held vertical the rod would slowly hit bottom, going slow as the air pocket collapses. So now I am tapping my BP
dials by 1/4 increments between each .001 division.

(The sliding table on my 10" grinder is sure making my tool bit grinding come out perfect. Tired of doing it by hand).
 
Haimer 3d, Not even worth messing with a edge finder. About 300 dollars but you will not look back after you try it

Ten bucks - or used-to-be - for an 8X "watchmakers" eye-loupe with an already attached spring-steel headband to park out of the way.

And any average craftsman's existing collection of metrology and layout goods wudda SOLVED Rons leetle Earth-Shaking problem with nary a wasted minute nor even a second thought.

OR any dead-average "center finder", but only if properly utilized.

Some folks just have to make "grand and important problems" out of the commonest of solutions, mis-applied?

:(
 
Haimer 3d, Not even worth messing with a edge finder. About 300 dollars but you will not look back after you try it

Uh, you might ...

I've used extensively the Fisher style off-axis edge finder and a Haff & Schneider 3D taster (and now a proper spindle probe in the CNC).The problem with the 3D taster is the large shank, and the long length. You can't hold the 3D taster with a drill chuck, so you have to change tools. Maybe you have to anyway if you are milling, but for just drilling, it's an added tool change. And the long length means you probably will need to drive the knee down and then back up, and maybe in the process lose your place if your knee is not snug.

I gave up on the 3D taster in the manual machine. It still finds time in the CNC for special cases like I want to profile a flat surface or tram a vise.

Regards.

Mike
 
Uh, you might ...

I've used extensively the Fisher style off-axis edge finder and a Haff & Schneider 3D taster (and now a proper spindle probe in the CNC).The problem with the 3D taster is the large shank, and the long length. You can't hold the 3D taster with a drill chuck, so you have to change tools. Maybe you have to anyway if you are milling, but for just drilling, it's an added tool change. And the long length means you probably will need to drive the knee down and then back up, and maybe in the process lose your place if your knee is not snug.

The Haimer Zero Master model is 10mm shank and <4" long, so if you're running a 1/2" drill chuck it should fit.
 
I think I am missing the issue. It looks like you are working on stainless. If your center finder is marring the stainless you may not be using it properly. I have never had a mar on any material, as the spinning tip is polished and applies less than an ounce of pressure.
 
I'm using a 5x eye piece. The finder is spinning at 600 rpm. On aluminium the mark is more noticeable.

Say I have located a hole at x/y on a milling machine.

The easiest would be to drill a hole in the exact center of a square bar 1" wide.
Then lock a tap into the drill chuck and start the tap into the hole.
Unlock tap from chuck and attach tap wrench. Use a point center in drill chuck and turn the thread by hand with the wrench.
Turn down the head of a Allen bolt the same thread size as the hole.
Screw bolt into hole.
Measure distance from Allen bolt head on each side. The distances should be the same.

What should one expect? Does running a tap through a hole throw off the location accuracy?
 
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We may be talking apples and oranges. Do you have a picture of the finder you are using? The spinning one I use does not require any magnification to use, as do some of the once mentioned above.
 
Edge and Center Finder, 3/8" Shank, Fisher 1959 - LittleMachineShop.com

I use a 5x eye piece and watch for the spinning edges to line up straight. It is not audible. When I bought it another guy was asked if he needed one.
This guy looked at it in his hands and said I didn't like the spring action. What do I know, I bought it anyway.

Pretty sure that style edgefinder is designed to jump when you touch the edge-using a magnifier to line up the edges defeats the design of the tool. My experience is that generally this style edgefinder (with one notable exception) is only consistently accurate to approximately +/-.0005". If you need better locational accuracy than that, would suggest you use a high quality tenths indicator and a Toolmaker Chair or a Centering scope, or a gage block wrung to the edge you are locating.
 
Pretty sure that style edgefinder is designed to jump when you touch the edge-using a magnifier to line up the edges defeats the design of the tool. My experience is that generally this style edgefinder (with one notable exception) is only consistently accurate to approximately +/-.0005". If you need better locational accuracy than that, would suggest you use a high quality tenths indicator and a Toolmaker Chair or a Centering scope, or a gage block wrung to the edge you are locating.

Exactly, line up slowly against the work while it's wobbling. It will slowly get perfectly concentric to the body of the edgefinder, at that point move very slowly until it kicks out (one way or another) mark your spot. Don't forget to subtract .100 to get the center of your spindle on the edge of the material. Takes just a little practice but you should be able to get within the above stated */-.0005". I usually spin around around 500rpm, lowest setting for high range on the Bridgeport. Your mileage may vary.. Good luck!
 
+1. When used properly that finder will leave no marring whatsoever. It is not meant to stick the point into your work. The point would be used to insert in a hole...and then touch off each side and use math to find the center.
 








 
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