question about a tooling ball for part zero location

Hello,

I have a question about tooling balls that I'm hoping that someone can help me with. Basically, my question is: What's the best way to indicate them in?

To be a little more specific, I'm using it on a 3 axis CNC mill. The tooling ball is pretty straightforward to use in a hole that's in the same axis as the spindle, because you can use an indicator to set the X and Y axis, then the Z can be set from the face of the part. But I have an operation where the part is tilted over to about 37 degrees. in this case, locating the X and Y is still straightforward with an indicator in the spindle. But how would you set a Z height in a situation like this? I wouldn't have confidence that setting XY zero and then trying to drop a Haimer on top of the tooling ball would work

the setup looks like this:




And there's a picutre of the balls in question here: Octodyne on Instagram: “Hey #instamachinist does anyone know what these are called? I was told that these spheres fit into a reamed hole so that you can locate a…”


It feels like there must be a solution to this that's obvious, but I have't uncovered it yet... would love some ideas.

The tooling ball should have a shoulder and is usually a nominal distance from the center. Knowing that distance it's a fairly straightforward set of trig calculations to determine the distance to the center of the hole on the angled face. There are several sources for how to use these that are videos and text. Do a search and something will come up, report your findings after. If you still have questions just ask, they're not difficult to use it's just new to you.

oh, maybe I understand... that would be trig based on the angle and known distance? So in this case it's a .500" ball, and .500 from the center of the ball to the shoulder. Knowing the angle, then it would just be trig to calculate out the distance. I'll have to brush up on the math, but I think I understand the concept.

My high school math teacher would LOVE this situation, I should have paid more attention 25 years ago!

You'll need to get an ACCURATE dimension for the height of the ball to the shoulder to get a starting point. Other than that I think you've got the concept of how they're used. Making sure the shoulder is flat on the surface, no burrs and stoned flat, is important too for accuracy. Like you, I also had trig in high school and wondered "What am I ever going to do with this so why bother?" Little did I know back then that I would use it on the job almost every day for over 35 years. Shocking isn't it?

O/H = Sin
A/H = Cos
O/A = Tan

Where O = Opposite
H = Hypotenuse
A = Adjacent

Mnemonic for remembering solutions of right triangles: Oscar/Has A/Hairy Old/Arse for Sin, Cos, Tangent in right triangles (only).

craqus said:

oh, maybe I understand... that would be trig based on the angle and known distance? So in this case it's a .500" ball, and .500 from the center of the ball to the shoulder. Knowing the angle, then it would just be trig to calculate out the distance. I'll have to brush up on the math, but I think I understand the concept.

My high school math teacher would LOVE this situation, I should have paid more attention 25 years ago!

Click to expand...

Lot more than "25".. but that Trigonometry Tribe Indian Chief was already famous:

SOHCAHTOA

The numbers thereafter usta bee in books, but are now in phones and wrist watches and .. wot the Hell.. for-sure the Canon AE1 and at least one family of Microwave ovens... prolly also battery-powered dildos, "technology" as it has become.

Why don't you just set your work coordinate at the center of the ball? That's what I do. Indicate the ball in X & Y, then touch off Z (by your preferred method). Don't do trig. Let your CAM system do it.

rainman said:

Why don't you just set your work coordinate at the center of the ball? That's what I do. Indicate the ball in X & Y, then touch off Z (by your preferred method). Don't do trig. Let your CAM system do it.

Click to expand...

That is how I have always done it... assuming you have some cad/cam package. For example, you can download a solid model and plug it into your part.

McMaster-Carr

Then it is just a matter of setting your work coordinates to the center of the ball...

edit: Should add depending on your accuracy needed the model is a "reference" (but pretty damn close from what I have seen), but you can measure center to shoulder and make it *perfect* if needed...

Make sure you work to the centerline of the ball, not the top. X/Y, centerline is easy. Z, top of ball is easy, centerline takes more thought. Physically, we would hold a drop indicator in a tool holder and bring it down to the top of the ball. We would then take the tool holder with the indicator into the presetter and measure the tool length with the indicator plunger physically held to the setting where we touched off the ball. Then we would add the ball radius. If you touch off your tools in the machine, do that as you always do, and use the drop indicator to measure from the top of the ball to your touch off location and add (or subtract) your ball radius.

Thanks for the responses. I was having a brain freeze on this, but have now figured it out.

1. I'll use a Dial Test Indicator on an Indicol to locate the X-Y position of the tooling ball. It takes a couple of minutes to do this with a indicator that reads in .0005" graduations, but I have a high degree of confidence that it's accurately located. Once the spindle is dead center over the tooling ball, I'll move onto the Z dimension.
2. I'll then switch tools to a Dial Drop indicator. This will have a broad "foot" on it, and held in a collet in the mill. I'll then zero the drop indicator foot to the top of the .500" ball. The Z height becomes the tool length of the Dial Drop indicator to zero, plus .2500" which brings it to the center or the ball.

That should allow me to do each setup in under 5 minutes, with only 2 tool changes. My CAD will do the math for me. I can visualize chief SoCaToa weeping a single tear over this.



Sorry Chief.

I worked in a shop that had 8 fadal 4080 mills 7 of them had fatal 2 axis rotary tables. Most of the programs used the centerhight of the "B" axis as the Z work offset. The tables also had the hight stamped into the base.