Leveling the Drill Press Table

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Stan Pope
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Leveling the Drill Press Table

Postby Stan Pope » Mon Feb 16, 2009 1:07 am

For years I have used a try-square or machinist's square to check that the drill bit and the drill press table were perpendicular. That has worked pretty well.

A couple nights ago, I stumbled upon an alternative method that cuts the error in half and led to a quick adjustment of my drill press table. At the same time, it proves (or disproves) the orientation quality of the drilled holes. Here are the steps:
1. set the fence across the drill press table (approx perpendicular to the table's axis of rotation.)
2. Drill left-side holes in two separate "car bodies", carefully assuring that the opposite side was firmly against the drill press table and the bottom of the car body was firmly against the fence.
3. Insert spare #44 bits in the drilled holes, leaving 2/3 to 3/4 of the drill bits' lengths exposed.
4. Slide the car bodies against each other with the right side against a good plane surface (e.g. drill press table) so that the exposed drill bits appear side-by-side as viewed from the top of the car bodies.
5. Observe whether the space between the drill bits disappears "all at once" or "gradually moving up or down." Holes from quality drilling technique will exhibit the "disappear all at once" behavior. If not, Stop the Test NOW.
6. Turn one of the car bodies end-for-end (car bodies top-to-top or bottom-to-bottom) and again slide them until the exposed drill bits appear nearly side-by-side.
7. Observe whether the space between the drill bits disappears "all at once" or "gradually moving up or down." Holes from quality drilling technique when the table is perpendicular to the drill bit will exhibit the "disappears all at once" behavior.

Why? Because the drill bits' deviation from perpendicular happens on both sides of perpendicular, and the angle between the two drill bits is twice the deviation from perpendicular.


Stan
"If it's not for the boys, it's for the birds!"
St_Louis_Racer
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Re: Leveling the Drill Press Table

Postby St_Louis_Racer » Mon Feb 16, 2009 9:11 am

Great timing Stan. A guy at work 5 minutes ago just asked me to bring in my #44 so he can test drill some holes.


Kenny
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Re: Leveling the Drill Press Table

Postby Kenny » Thu Feb 19, 2009 5:38 pm

Nice post Stan.

I would like to add, however, that one must be using two blocks with identical dimensions and that they should be verified flat and square on relevant sides.

In my opinion, ensuring one has a flat, square block is an often overlooked early step that may result in headaches later. Headaches that any amount of alignment cannot resolve.

Another thing is to keep all surfaces clean! It's amazing how one little shaving between block and fence or table can cause so much deviation.


Unsolicited bonus tip:
I flatten and square my blocks with a hand plane (block plane). This seems to be a lost art. People marvel at the speed and precision a sharp well-tuned block plane can remove material. At .001 in thick, no power tool can touch it, and the finish is ready for primer. No sanding. No noise. Three keys: Scary sharp blade, steady vise or support for the block, and practice on another piece of pine first. When you take a 2 in wide strip thin enough to see through you'll smile from ear to ear and wonder what took you so long to figure this out. I should post a video on this...


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Randy and Son
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Re: Leveling the Drill Press Table

Postby Randy and Son » Thu Feb 19, 2009 6:09 pm

Another property that the blocks would exhibit, if the drill and table are perfectly square to one another is that .....

.....with both blocks sitting on a flat surface, a pair of bits inserted in one block would line up perfectly with the holes in the other block. Then when simultaneously inserted into both blocks, they would both still sit flat on the surface. Neither one would tip an edge and sit at an angle.

This would also "double" any error that may be present.

FWIW;

Randy


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Stan Pope
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Re: Leveling the Drill Press Table

Postby Stan Pope » Thu Feb 19, 2009 6:32 pm

Kenny wrote:Nice post Stan.

I would like to add, however, that one must be using two blocks with identical dimensions and that they should be verified flat and square on relevant sides.

Thank you. Note that the "bodies" were not "turned over". The same side was down in all cases. So we have some leeway on "flat". There must be no irregularities which would slip into the voids on the table.

And folks couldn't understand the value of Sophomore Geometry class! Hah!

I got the page with pix posted at http://www.stanpope.net/drlpress.htm


Stan

"If it's not for the boys, it's for the birds!"

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