Is there a way to make an oval thumb hole with the jayhalk drill press that says you can't?  Is there a way around it, possibly by using a dremel or other creative way?
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Shane Soule

No offense Paul but the flat bits are not required they only make it a bit easier.
On a standard jig the x axis table movement doesn't have a fine enough movement to make them accurately with out a mod, mills that most ovals are done on either have digital readouts or a micrometer style movement.
What I suggest if trying to make an oval on a standard jig is to get a magnetic based dial indicator that can be placed next to the table so you can make accurate table movements. This will require that you convert your f/r and l/r pitches to a single pitch based on the angle of the oval and place the ball in the jig using the converted pitch. This is not something you would want to do for others though due to the length of the conversion equation.
I can convert your pitches for you if you would like to give it a shot.
Something else you could do if you have the resources would be to add a reduction gear setup on the threaded shaft that is on the lateral table movement this would allow slower/smaller table movements. The reduction gear could be made easily from a torque multiplier torque wrench or adapter they are a bit pricy though and only available from a few companies.
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I personally don't care for this type of setup they do work well though.
The people I work for have 2 centers one with a fullsize mill that works the same way as the mini-mill in that you set pitches with the X & Y table movements and the other is an ovalmatic where pitches are set with the jig and then the jig can be rotated to make the oval. I find that I can replicate ovals more accurately on the ovalmatic even though it is on an older mill.

To make an oval you don't have to have both X & Y table movements you only need one or the other and can just place the ball in the jig at the appropriate angle and make the table movements. This same thing could be done with a Jayhawk Pro Jig with it's single table movement and the setup I mentioned before. When doing it this way you aren't really milling the oval you are drilling the oval. That may sound stupid so I will clarify. Milling by definition is done where you drill to the depth and then make the appropriate table movements while the bit is still at full depth this is where the special bits come in since you are cutting with the side of the bit. When drilling an oval you drill your round hole and then withdraw the bit and make the table movement and drill again, no special bit is required because you are still cutting with the face of the bit and not the side. Drill presses are not made heavy enough for the "milling" process due to their smaller shaft diameter possibly allowing bit deflection which will distort the oval and could damage the press if the movements are made with too much force. When "drilling" an oval use caution in that you should drill slow to reduce vibration and deflection also large table movements with this method will cause the oval to have ridges in it for this reason I don't make movements that are larger than .025".
For instance my oval is 55/64" ovaled by .050 each direction so if using the "drilling" method I drill the 55/64 round then move the table .025 drill again and so on.

PS: To my knowledge most proshops accually "drill" ovals not "mill" them even though they are doing the process on a mill. At least not by the definition that a machinist would give for "milling".
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Edited on 12/27/2005 11:24 PM