Drilling with a spindle?? Halp!

[johnm]

Folks -

Okay - I've got to drill several holes about 1.5" deep in the end of some music stand legs. I am building a vertical clamping jig which will sit in the lathe/indexer well (we have a 5x8)so that I can drill three leg-ends at a time. The work piece will sit at a 15 degree angle so that the holes in the head end are vertical.

The legs are hard maple - I need to drill both 1/4" and 3/8" holes (the 3/8" is a pocket hole from the underside edge - concentric with a 1/4" hole in the end of the leg)

So, I don't think that brad point bits should spin at 15k - based on the feedback from my post about forstner bits earlier, I am wondering if I can get away with this at all. I was thinking if I slowed the spindle down to 10k, combined with slow z moves and small "peck" steps to clear the chips it might work. On the other hand, I don't want to have music stand leg flambe or FUBAR the spindle.

I guess I could come up with a carrier for a hand held drill mounted on the Z column, but was hoping not to have to add that additional level of complexity and fabrication.

I haven't yet quite figured how to do the pocket holes from underneath yet, so I'd appreciate any input there as well...

I have a set of long brad point bits, but am concerned about spindle arbor clearance to the work and also "whipping" of the long drill bits. I will cut the bits down in length if need be.

Thanks in advance!

John
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[richards]

John,
Have you thought about building a jig to do the drilling on a drill press or even with a hand drill? I've drilled lots of simple holes at 5,000 RPM with my spindle, but never deep holes or slanted holes. Sometimes it seems that trying to have one tool do everything complicates the process.

[johnm]

Mike -

Yes, I built a jig for the drill press, version 1.0 as it were.... The chuck of the drill press inteferes with the head end of the leg. Additionally, I was not able to repeat the locational accuracy of the holes over a group of parts - and my quill travel is also a limiting factor.

I guess I should have mentioned these in my OP.

I am thinking of a drill guide block or some such to keep the bit from wandering as it enters at an oblique angle.

John

[beacon14]

John,

I think it should be pretty straighforward. When you clamp the leg to the end of the table it should look something like this:


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Make sure the drill is entering the workpiece at 90 degrees. 10K rpm should be OK, you'll have to experiment with pecking strategies but I'd enter as fast as you can without stressing the bearings and pull back up at full jog speed. The total depth of cut according to my drawing is under 2.75" so you should be able to use a 4" twist bit (I like the "bullet" style tips myself).

For the 3/8" pocket holes, while the collet might clear the edge of the leg the gantry will get in the way. I'd clamp a few pieces of scrap to your table end like this:


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Then clamp the middle piece to your leg like so:


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and drill the pocket hole by hand using a 6" twist or brad point bit.

Hope this helps,
David B.