Help me fix my drill press, please...

[radhak]

I have the Delta 11-990, a 12" Drill press. Works fine in general, but I have not really checked it for straightness. But now that I am using it to drill my pen blanks, I find that it has a definite drift away from the center : huge in percentage terms.

I cross the top of my blank in pencil to identify the center, and make sure the tip of the drill-bit hits that mark. But after drilling, I find the hole comes out almost 50% to the left. The speed is the lowest (650rpm), and the bit is very sharp, and the wood is rather soft (even pine or mahogany).

When I did it very slowly, I can see a definite flex in the bit when it starts drilling, towards the left, even after I made sure the chuck was holding it really tight.

Yesterday I tried to drill a rather big hole for a perfume atomizer (15mm), and the drift was so much that I had to discard a perfectly nice piece of Carob wood because of it.

Any ideas on how to fix this, or if this is even fixable?

[Whaler]

This may or may not help but worth a try. I step drill all of my blanks that use any tube over 3/8" by drilling a hole about 1/2 the size of the final hole and then drill with the full size bit.

[Stytooner]

Thats quite a bit of drift.
Have you tried tramming the table? Make sure that it is true first, then insure the blank is true in the vise. Bits of this size don't generally wander that far. Especially true with brad point bits.
You can check runout by hand if it's alot. Grab it while unplugged and try to wiggle the chuck.
If there is noticeable play, you can try removing and cleaning the chuck and taper. Reseating the chuck in different spots on cheaper machines can have a varied effect as well.

[radhak]

Dick, I tried that method, and the final result was a bigger hole ! the bit drifted even more - that was what told me the DP was to blame and needed fixing.

Lee, that is good direction - what I plan to do now. Lemme give it a try.

[BobSch]

Are you sure your table is perpendicular? From the picture I saw, the table can be adjusted is the left or right side is too low or high.

Sounds like the right side is high.

[Richard in Smithville]

Take a length of stiff wire-coat hanger will do. Put a 90 bend in the wire and chuck in your press so that the bend is just a hair above the table. Rotate the drill by hand. That will tell you where it's out and if you know if it's just the table.

Also, I clear the hole often when drilling a blank. It helps to keep the heat down when drilling.

[LCHIEN]

are you saying that the hole is centered in the top of the blank but when it exits the bottom, it's off center?

You don't mention the diameter, I assume its like 3/8"?

My first suggestion swould be to increase the drill speed. It may be counter intuitive but faster speeds will cut the wood, slower speeds plow thru the wood and will tend to follow grain which could force it off. The recommended speeds for soft and hard woods with a 3/8" bit are 3000 and 1500 RPM for twist bits and 1800 and 750 RPM for brad point, respectively. It will also give a smoother cleaner hole. 650 RPM might be too slow.

A brad point bit will be better than a 118 degree twist bit because if the starting tp and the circumferential cutters.

Another suggestion would be to use a drilling jig basically like a three sided box as tall as the blank to be drilled, clamped to the table. make sure all sides are very square and this will prevent tilting in any direction if the table its mounted to is square to the bit. Clamp to both vertical sides. An oversize bottom that can be clamped on opposint sides will help keep it square to the table. The extra height of a pen blank exaggerates any angle errors off perpendicular.

Finally, it might also help if you have this jig, to drill halfway to 2/3 thru from one side then flip the piece and drill the other side. The holes will be perfectly centered in each end and maybe a bit bigger in the middle but for a pen this will be hidden.

I sometimes find it helpful to do the method whaler suggested - stepping up the holes when I can't seem to get the bit started right and centered in the entrance end. The smaller bit (brad point) is easier to start in the grain and step up with a step drill bit to get the entracne hole right, or use a twist bit whihc will sort of self-center if its a bit floppy.

[leehljp]

I fully agree with Loren. Faster speeds cut better than slower speeds and tend to be straighter.

You haven't mentioned clamping. It the blank well clamped?

As a last case scenario on good blanks, drilling on the lathe can guarantee the entry and exit points. On lesser expensive pens and for high quality blanks, one of a kind blanks or blanks that were barely large enough to make a pen - I drilled on the lathe. Lathe drilling can be made guarantees entry and exit points.

Below are two links that deal with the need for controlled entry and exit points on narrow antlers. Ordinary blanks can easily be done the same way. I have done this too and it works for me.

(On the lathe)
http://www.youtube.com/watch?v=SAEEaF8z2jM

(On the DP)
http://sarkon.net/poppopshop/