[mlabruyere]

OK....maybe I am overreacting here but these marks drive me crazy.

I've got the Z-Axis as perpendicular to the table as I can with my bubble level (USA made high end)

The material is .75” birch plywood.

Tool is a 1.25” Carbide Hinge Mortising Router Bit

I was running at 100IPM at .005” cut depth

They propagate along the X axis the image is rotated 90 degrees

Any ideas what I should do?

[Dorsal]

A bubble level will NEVER give you the angular resolution you need to get your Z-axis perpendicular enough.
You need a 12 X 12 sheet of glass, a deck of cards and a dial indicator with a beam-mount.

1) Lay the sheet of glass in the middle of your work-bed and mount your dial indicator into the router chuck, so that you have at least 3 inches of radius of rotation.
UNPLUG YOUR ROUTER!
2) Rotate the router by hand until the indicator is aligned along the X-axis, then move your entire gantry along the same axis as you "read" the surface of the glass. Do not rotate the indicator at all, this is a straight-line sweep.
3) Add shims under the glass until your indicator stays at ZERO from the front to the back of the glass sheet.
4) Rotate the router by hand to align the indicator on the Y-axis, then swep along THAT axis to read the surface. Do not rotate the indicator at all, this is another straight-line sweep.
5) Add shims under the glass until your indicator stays at ZERO from the left to the right of the glass sheet.
Your glass sheet is now parallel to your ACTUAL X-Y plane!

6) NOW, slowly rotate the router (sweep it in the 3 inches of rotational radius) and read the dial indicator. Adjust your router head by whatever means your machine has available until an entire rotation of the indicator produces less than 0.001" of deflection.
Your router head is NOW perpendicular to your true X-Y plane within 0.001"!

You may need to resurface your spoil board when you've completed this, especially if it took more than ONE playing card to level that piece of glass. One angular degree equals 0.017 per inch per degree, so if you needed 2 cards (approx. 0.019") in 12 inches, your bed-surface is approx. 1/12 of a degree (6 arc-minutes) out of square.

[Drools]

A video of this procedure would be very appreciated.

[brtech]

I don't need no stinkin video, once I figured out what a "beam mount" was. I've seen one, but didn't know what it was called.

Thank you so much for describing this. It's great. I assume this is a standard machinist setup for this kind of problem. I'm an EE who has worked with machinists and always admired the results of decades of experience passed down from one machinist to another to be able to get this kind of precision.

I'm betting there is some similar setup for checking X perpendicular to Y. Could you describe that? I appreciate that this mechanism checks for both Z perpendicular to X and Z perpendicular to Y without really depending much on X perpendicular to Y.

Couple of questions:

It would seem that "runout" is an issue, and in fact it's more complex, because the beam fit into the chuck is also important.

Where do I find an inexpensive beam mount that will work in a typical router chuck?

It seems to me that you need to lock the shaft of the router to sweep X and Y to set the glass plate shims. How do you do that?

How do you interpret the results? I was guessing that you at least start by looking at, say 12 o'clock and 6 o'clock and adjusting one axis, then look at 3 and 9 and adjust the other, then look for some possible interactions, but is there a better technique?

[TSJ]

Here is a relatively inexpensive set up tool or a mill.

Pro Tram System

I found the web suite because they advertise on the forum.

[jsheerin]

Runout is the issue you're trying to solve.

The glass plate thing seems overly complex. Just surface your spoilboard with a small diameter cutter. Then use something flat and parallel like a 123 block that will bridge over any scallops left by the small bit to take readings on at +/- x and +/- y. Then adjust your spindle alignment to get all the readings the same. I had to loosen bolts, tilt my spindle to the side, and shim under the bottom with some aluminum foil to get it lined up.

I built a bar to hold my dial test indicator. Just take a piece of aluminum, drill holes in either end, one to mount a 1/4" dowel pin and maybe a set screw to hold it in place, and the other one to mount your dti or dial indicator. Nothing has to be precision made on it as long as the pin that mounts in your spindle's collet is the right size so it mounts like a bit would.

[mlabruyere]

A bubble level will NEVER give you the angular resolution you need to get your Z-axis perpendicular enough.
You need a 12 X 12 sheet of glass, a deck of cards and a dial indicator with a beam-mount.

1) Lay the sheet of glass in the middle of your work-bed and mount your dial indicator into the router chuck, so that you have at least 3 inches of radius of rotation.
UNPLUG YOUR ROUTER!
2) Rotate the router by hand until the indicator is aligned along the X-axis, then move your entire gantry along the same axis as you "read" the surface of the glass. Do not rotate the indicator at all, this is a straight-line sweep.
3) Add shims under the glass until your indicator stays at ZERO from the front to the back of the glass sheet.
4) Rotate the router by hand to align the indicator on the Y-axis, then swep along THAT axis to read the surface. Do not rotate the indicator at all, this is another straight-line sweep.
5) Add shims under the glass until your indicator stays at ZERO from the left to the right of the glass sheet.
Your glass sheet is now parallel to your ACTUAL X-Y plane!

6) NOW, slowly rotate the router (sweep it in the 3 inches of rotational radius) and read the dial indicator. Adjust your router head by whatever means your machine has available until an entire rotation of the indicator produces less than 0.001" of deflection.
Your router head is NOW perpendicular to your true X-Y plane within 0.001"!

You may need to resurface your spoil board when you've completed this, especially if it took more than ONE playing card to level that piece of glass. One angular degree equals 0.017 per inch per degree, so if you needed 2 cards (approx. 0.019") in 12 inches, your bed-surface is approx. 1/12 of a degree (6 arc-minutes) out of square.

Thanks Dorsal! I'm going to give this a go....after I locate a dial on a beam mount.....

[mlabruyere]

Here is a relatively inexpensive set up tool or a mill.

Pro Tram System

I found the web suite because they advertise on the forum.

I've seen this tool before....nice find.

[rowbare]

Here is a good video on tramming a mill. The same principles apply:

[nomedia="http://www.youtube.com/watch?v=JfANyiS8Hs4"]YouTube - BRIDGEPORT MILL Tramming or Indicating the Head to Zero[/nomedia]

bob

[brtech]

I built a bar to hold my dial test indicator. Just take a piece of aluminum, drill holes in either end, one to mount a 1/4" dowel pin and maybe a set screw to hold it in place, and the other one to mount your dti or dial indicator. Nothing has to be precision made on it as long as the pin that mounts in your spindle's collet is the right size so it mounts like a bit would.

Ah, so the angle the bar has with the dowel pin and the angle the bar has with the DTI don't matter, because no matter what they are, the DTI tip sweeps a circle perpendicular to the axis of rotation, the angles just displace the circle in Z. And any X or Y offset don't matter either, they just move it or change the radius. What matters is the rotation is around the axis of the spindle. Gotcha.

Still looking for some similar way to verify X is perpendicular to Y.

[jsheerin]

Cut a square. Measure across the corners. The measurements should be the same. If not, your x and y are not square. Making a bigger square will reduce the error from your measurements.

[M250cnc]

Ah, so the angle the bar has with the dowel pin and the angle the bar has with the DTI don't matter, because no matter what they are, the DTI tip sweeps a circle perpendicular to the axis of rotation, the angles just displace the circle in Z. And any X or Y offset don't matter either, they just move it or change the radius. What matters is the rotation is around the axis of the spindle. Gotcha.

The right way.

Still looking for some similar way to verify X is perpendicular to Y.

This can be accomplished using a rectangular piece of a nice machinable plastic and a DTI affixed to the Z axis

Machine the two long edges and one end

Flip the piece 180 degrees so it is upside down in the same position

Set one long edge parallel with the DTI

Then measure the reading on the end

If the machine was cutting dead square the reading would be Zero all along.

But if there is a taper the the error is half the reading obtained

After adjusting, recut the end and flip and recheck