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Edge finding or 2" diameter

Froneck

Titanium
Joined
Dec 4, 2010
Location
McClure, PA 17059
I need to locate the edge of 2" diameter "washer" 17/32" thick. Actually it starts as a machined "washer" 1-3/8" ID X 2" OD X 17/32" thick. Then cut int 4 sections. Ends are milled so they are parallel and perpendicular to cord dimension .915" I then have to put a 4.2mm hole parallel with the cord so that the side .040 away from the ID. ID and OD are machined to within .001" so I can locate ID using the OD. I have Starrett 828 "wiggler" and 827A edge finder. (actually all the Starrett 827 series) Problem is locating the exact center of the OD. I have a B&S 1/2 X 1/2" but don't want to use 1/2" chuck plus being the width of the part is 17/32" and is between the jaws of a Kurt vise. I did find a 10mm X 10mm B&S on ebay but it's taking forever to be delivered, I paid for it 11/8, delivery is supposed to be 11/17 but tracking states it hasn't been picked-up yet!
I measured the diameter of the 828 .100 edge finder rod and it also is .100" Can I use the rod to edge find rather than the small .100" end until the B&S 10mm edge finder arrives?
 
Boy you lost me with that description. How about a picture to show us exactly what you're trying to do.

What's a B & S 1/2 x 1/2"?
 
What's a B & S 1/2 x 1/2"?
I think he's talking about an edge finder with 1/2" shank and 1/2" endcap.

I am also having a hard time visualizing how this annulus ("washer") was cut into segments. I am guessing that the thing was cut along 4 non-intersecting .915" chords, and the ends of each segment were made square to the cutlines. But my CAD scratchpad tells me that a .915" chord won't intersect the ID, so I'm still scratching my head what shape(s) this thing was turned into.

Froneck, if I understand the thrust of your question, you can use any edgefinder you like that will fit in the space you have to work. All you need to know is the diameter of the endcap, and you can obviously measure that.
 
I suppose I can make a photo but being home now I'll have to do it tomorrow. Simply think of a washer with 1-3/8" ID and 2" OD and 17/32" thick. I cut it like a pie into 4 equal pieces that will have 45° ends. I mill the 45° so top and bottom are Parallel .915" apart.
Think of a locking collar and I want to put the hole for the lock screw. It's somewhat like a washer so I place it in a vise, edge find the OD, move over the required distance for the locking screw. I can't use the Starrett 827A that has 3/8" shank and .200" tip, the radius will hit the 3/8" diameter first. The 828 with the ball will have to be at exact center and the .100 has a short length so it too has to been dam near center. The 1/2 X 1/2" type edge finder will work but requires a 1/2" chuck, I purchased a 10MM X 10mm edge finder on ebay but it's taking forever to get here!
Photo is completed item, set screw is into the 4.2mm hole that can't be seen in the photo to hold the item on a 4.2mm rod. The OD is milled flat and is parallel with the 4.2mm hole.

CIMG2044.jpg
 
Make a fixture perhaps in a piece of scrap aluminium which you clamp in the vice
And clamp the object with some clamps

Mill a corner on the aluminium with some known distances from the hole location and you can reclamp the ficture for reuse

Peter
 
If I am understanding you correctly, can you find the edge of the vise jaws for your "Y" dimension? I think some people prefer a DTI over an edge finder for more accurate results on jobs like this.
 
Yes I have been using the Starret .200 Diameter edge finder to locate the edge of the fixed jaw on a Kurt vise. I've been using the wiggler .100 tip edge finder but not the tip, about 1/2 way up the rod. Seen to work OK. Location need not be super accurate, .005" is enough. My 10mm B&S edge find has financially been shipped, I'm hoping to get it in 2 days though I ordered and paid for in at ebay Nov. 8th!
 
up-date

The B&S edge finder came. I didn't know what 10mm X 3/8" X 10mm meant. When it arrived I found that it has 3/8" shank for about 1/2 the length 10mm until the moveable end that is 10mm Dia. about 12mm long. I guess the 3/8" end is so it can be used in a 3/8" collet or end mill holder.
Solved the problem, works great, thanks for the suggestions!
 
For an edge finder,
just use any diameter dowel pin or the like
that you can find, chuck it up, ink it up,
bump your part, when the ink starts to rub
away, stop and subtract 1/2 the diameter of
your pin. You don't need an edge finder.

-Doozer
 
Doozer:

Thank you for validating my own thinking. I was wondering why what is sometimes called a 'touch off' would not work for the OP. Years ago, we used a slip of paper against the work and moved the work until the cutting tool just grabbed the paper. One trick I learned ages ago was to use cigarette rolling papers, which are an even 0.001", and sometimes, a drop of oil on the paper to hold it in place. For larger cutting tools and larger work, we used to cut a slip of regular paper from anything handy such as a notebook or similar. Mike the paper, hold it lightly between thumb and index finger on one hand while feeding things so the tool eventually just grabbed the paper. Done right, the paper will be pulled between the tool and the work. Mike the paper, take half the diameter of the tool and add the two numbers. Use that number as the 'offset' from the edge to centerline of spindle. I am of an old enough generation to have done this many times on horizontal milling machines where an edge finder would not work. I know there are people who will set up a howl that getting one's fingers near a moving cutter and holding onto a slip of paper is an unsafe practice. Suffice it to say, we were taught to do that at Brooklyn Technical HS in machine shop classes. "Sharpies" and similar had not come on the scene in those days, so the touch-off using paper was standard. We were also taught to put a thin coat of layout dye (which we universally called 'Dykem Blue') on work setup for precision grinding operations. When the grinding wheel just began to scuff through the blue, we called it 'zero' and started from there. We never thought that a coat of dye (or ink) was something to use on a milling machine for a touch off.

I've done touch offs using drill rod or dowel pins as you describe, sometimes using feeler gauges between them and the work, sometimes using paper. There are jobs where an 'off the shelf" edge finder just is not long enough, such as coming tangent to the side of a large diameter. It is on those jobs that I fall back on your method, albeit using a feeler gauge or paper rather than ink.

Something I always enjoy is the fact that most machine shop work, like so much else in our lives, is mainly 'head work'- figuring out how to do a job and making the setups, etc. It also confirms something I realized at age 6: 'There is usually no single right way to do any job'. We all see things through different eyes, and I know from experience that I sometimes miss the obvious and do things in ways that are a bit harder than the next guy's methods.
 
Joe- Many times when I need to touch off
a feature that is below the top surface,
I use a ground drill blank, like 6" long.
Chuck it up, ink it up, and what I like to do,
is this... The rod is going to have some small
amount of run out. With the rod spinning,
move the table until the inked up spinning rod
just contacts the workpiece. You will see the
ink on the rod start to rub on one side only,
just because of the run out. Continue to move
the table until you get a continuous band of ink
that is scratched away. That means you have
pressured the spinning rod perfectly straight,
and you can now assume the exact diameter of the
rod is the exact offset you need to subtract out.
That is the key to the most accurate use of this
method. Look for the full circle, continuous rub
ring on the inked up section of the spinning rod.
Things like this, I find so simple. If anyone
doubts this method, tell them to compare results
from using an edge finder or an indicator and a
toolmaker's chair. I think people have been so
engrained in convention that they do not or can not
think outside the box that they have been programmed
to think within. It is a societal problem. I find it
interesting when I do things different than everybody
else. Their reaction sometimes borders on violent rebuke.
People hold on to things done the same way because they
are afraid of things that do not meet approval of their
peer group. To these people, group acceptance and
approval is paramount to their sense of security and
happiness. It is a follower mentality that assures they
will not bound for greatness. Only servitude.
I get it that it takes all kinds to make the world to
go around. I hope maybe someone will read my posts and
they will see the forest AND the trees, and maybe they
will start thinking and acting to lead their own destiny
and not just hope that it happens. Doozer out.
 
Yes I have done edge finding with dowel pins and drill rod. When I'm being lazy I'll run the spindle backwards with an end mill and piece of paper. Sometimes with a dial indicator with long stem and a few other ways I've forgotten.
However what I'm doing with the 2" diameter ring is cutting into 4 pieces, ends are milled parallel .915". It's then put in the vise at 10° off vertical. Most of the item is between the vise jaws so it don't move. Being only .531" wide not easy to put paper or see magic marker/Dykem rub-off. Edge finder makes it easy to see when it kicks off. Plus a lot less time on a part that cost must be kept as low as possible. So I'm looking for the fastest way to find the edge of the OD so I can compute the edge of the ID.
Plus being a tool nut I now have a 10mm edge finder in my tool box! Being B&S it's in with other B&S and Starrett tools and not made by Flung Dung in China!:D
 
No one is trying to convince you to edge find another way.
We get it, you have a solution to your problem.
This forum is a knowledge base to benefit other people as well.

-D
 
No one is trying to convince you to edge find another way.
We get it, you have a solution to your problem.
This forum is a knowledge base to benefit other people as well.

-D

This is very real and important, many times I end up using the second or third recommended method in a post simply because it works better for the capabilities of my shop and myself.
 
As ways there is a lot of ways to skin a cat. The best way is the one that works at the time it was needed. Nice thing with the Forum is that others can add to methods so that when the time comes there are a number of solutions to choose from to "getter" done.
 
I use masking tape for touch-off. it stays where you put it and can be marked with a color marker it in poor light.
Important to consider the mill tram and the length of your touch-off device compared to the length of your tooling (cutters), a dowel the same diameter as a mill cutter can be used for touch-off (taped or just sharpie marked) and can sometimes save time.
What are you using to cut the washer?
How do you index for the next cut of the washer?
Vise jaws are often a poor way to make a high-volume part...if it is a high-volume part.
Simple fixtures are often better. The likes of an angle plate with half of a parallel clamp set at locations for each operation and dowel pins set in the angle plate for each operation for part location. One such clamp zone would be the 10* angle. One advantage of the angle plate fixture is that you can use both sides to hold various part operations. Good to make such an angle plate if heavy stock so as to avoid vibration and chatter. For your part, a 3/4 or 1" x 4" x 12" long, just bolted together might be a good angle plate fixture. long sides and edges might be surface ground so making a very accurate fixture, mild steel would hold close for a very long time with careful using/

OT : Back in the day old fasioned grease pencils were common and one could touch the grease to know you were .002 off, smear the grease to know you were .001 off, and then spot see the part surface to know you were zero...Then ceramic marker replaced the old grease pencils and they are crap for the task.
Mostly for grinding but they were also good for mill and lathe work.

On the Blanchard, I would double tape and then put a couple of grease pencil marks on my spotter to see about + .005 and witness to near zero with not measuring the part
 
up-date

I did get the Brown & Sharpe 10mm X .375 X 10mm edge finder. It's a 100m edge finder with the "chucking' side ground .375" but short about 1/2" and tapered to 10mm. It works and gets the job done but I don't care for it. I chuck it in a 3/8" Albrecht chuck mounted on Moore taper and used in #3 Moore jig borer. Seems to wobble a bit probably due to short chucking area. If I put my 3/8" X .200 Starrett in the chuck no noticeable wobble is detected. Being I don't need high accuracy for the edge location it works but I'm disappointed in it! So I checked the company that listed it since no B&S 10mm edge finder was listed on ebay and have a 10 X 10mm B&S edge finder on the way since the other 10mm edge finder did work as needed but with issues. One of the reasons I didn't use the dowel pin and feeler method is that the edge located is below the vice jaws. Part is not quit in the middle of Kurt 6" vice the part edge located is about 1" in from the end of the vice jaws. Paper would work but again being lazy the edge finder worked great. I got the other one just in case I need better accuracy though I guess I can put the stepped down version in a Moore tool holder. But being a tool nut I had an excuse to by another tool:D
 








 
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