Engineer's square

Nov 24, 2009 111 Replies

For testing drill press runout you can, with the power cord unplugged, use a coat hanger chucked in the drill press such that it lightly touches the drill press table top. When it is even all the way around, the spindle is perpendicular to the table top. No special tools needed!

Phisherman wrote: ...

??? I've never seen a precision-enough coat hanger that any part of it would be straight/level enough in reference to any other that it would be of any use as a measuring tool...

How does this work, exactly, again?????

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The hanger is crooked enough that it touches the table at least several inches from the center point or the point that straight rod in the chuck would be. As you rotate the chuck by hand, the tip of he hanger should just touch the table (in a circle) if the table is level. It's kind of like the process of leveling a RAS table by removing the blade and setting the bevel with the arbor straight own, then checking that the arbor just touches the table as he arm is swung and the motor pulled along the arm.

It's the same procedure as leveling the table on an RAS to the blade. You can use a coat hanger, a dowel, anything that gives you a reference height.

He's assuming you have a radial drill press or a table that moves laterally and in and out I think.

If the idea was/is the single-point, simply a chunk of 10ga wire bent would be simpler. Maybe that's what phish was suggesting just use the hanger for the wire, I'm still not sure...

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Now that's clever--bending the hanger.

A single point doesn't give you levelling.

No, he's not. Bend the wire like a Z. Put one end in the chuck. Bring the table up (or the quill down) until the free end of the wire comes close to touching the table and turn the spindle by hand. Keep creeping down until the end of the wire touches the table all the way around as you turn the spindle. The further the end of the wire is from the spindle centerline, the more accurate it will be.

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Clever.

Lew

J. Clarke wrote: ...

Rotating it does (or can assuming a fair amount which was the reason for the ??? to try to ken what was the way the suggester thought this works...)

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Again what I said -- it that's the intent, simpler to take the wire and bend it w/o the hanger itself. Of course, it assumes it's mounted in the chuck and up to the point at which the bend occurs is straight and perpendicular, otherwise it rotates around a non-vertical axis...

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Still relies on the center portion in the chuck to be perpendicular and straight else't the whole thing rotates around an inclined axis.

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'Scuse? It's going to rotate around the axis of the quill, or it isn't going to rotate at all. :-D

The point won't perfectly unless the vertical portion extended from the chuck is also aligned in that same axis. If there's any bend in it it will simply amplify that and you'd adjust the table to match.

The objective is to have the table perpendicular to the quill, not to have either of them exactly vertical.

If the quill is bent, it needs to be straightened and until that is done there is no point in trying to align the table.

The distance from the chuck to the tip of the rod will remain constant, allowing to square the table.

The point isn't the quill itself bent, it's finding a piece of hanger wire that isn't... :)

Whatever error there is in it is amplified by the radius or rotation...

The idea is ok, it's the implementation that has to be good to get it to work in practice....

The whole IDEA is to bend the frigging wire so that when you spin the chuck is traces out a circle in space that is perpendicular to the quill--you then align the table to that circle.

Machinists have been doing it this way for at least 150 years. I, myself, have done it hundreds of times (yes, I am a machinist). It doesn't even matter if the chuck or spindle is bent, this method will get the table perpendicular to the spindles axis of rotation.

No need for it to be strait. No matter what shape it is, it is not going to change the spindle axis. The wire will rotate around that axis.

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