Drilling into 1/2" plywood

[groucho]

I work a lot with 1/2" latvian birch plywood and I often need to make a hole that is a 1/4" diameter. I'm often making several pocket and contour cuts with a 1/4" down spiral endmill at the same time and I would like to avoid changing out bits when I might otherwise do all my milling operations with one bit.

My question is this: How should I accomplish these 1/4" diameter holes? I run into this same challenge sometimes with my 1/8" bits too. It is tempting to just peck drill my way through with the endmill. It seems to be up to the challenge when I use it to mark my initial work holding locations on the sheet face.

More daringly, I could just drill straight through with these endmills as long as the sheet thickness isn't to many multiples of the endmill diameter.


The plywood seems to do okay with this sort of behaviour but I've read several posts maligning the use of endmills for any kind of drilling. On the other hand, using smaller bits and doing helical ramping to the bottom of the hole seems a little involved, silly and takes time. Any help in addressing this common need to drill holes is greatly appreciated.

Thanks in advance. Mike

[EricSchimel]

You could probably get away with doing some drilling with a compression spiral. Typically the first .2" of the cutting portion are upspiral, and the rest are down. You could peck two times at around .25" each and probably be fine.

[groucho]

I have compression spirals too but my present project doesn't require them. Hoping I can get away with the down spiral. i might try shorting the peck since the down spiral probably increases the heat in the hole.

[coryatjohn]

In my experience, a downcut and drilling do not make for anything but smoke and excitement.

[brian.owen]

Plus--leaving the chips nowhere to go will ensure that your hole diameter wont be accurate. Does the hole have to be exactly 1/4" or could it be oversized?

[dlcw]

Boring bit. Use the correct tool for the job. It might require a tool change but your end result will be much better and, as mentioned before, your chance of starting a fire are virtually nill with the boring bit. Only if it went in the wood and kept spinning without being retracted. I.E. Shopbot comms error...

I run my boring bits at 6400 RPM with a .5IPM plunge rate. I drill a LOT of holes when cutting cabinet parts. On the order of thousands. Works great.