Drilling holes in plywood

[Silverwind]

I have a piece of scrap plywood laying around and was practicing different layouts on it...

however sometimes when I drill the holes through the wood (about 50% of the time) the exit wound.. well cracks/splinters..

i'm not sure if this is just cause it's cheaper plywood or what.. but i would like to avoid this when I build my real CP if possible

[Silverwind]

I don't think it matters, but i'm using a 19.2v drill with a 1 & 1/8" wood boring bit. (or is that 1 & 1/4")

either way i've already put buttons in there and it fits perfect, except the breakage isn't nice

[slug54]

Clamp a piece of old 2x4 or other scrap lumber to the back of the the area where you are drilling. If you do this it should minimize the blowout on the back of the plywood.

                                   Slug54

[mcleanjoel]

Don't drill all the way through - stop when the point of the bit makes it through then finish from the opposite side.

[Brax]

Yes, either drill on top of a scrap piece of wood as a "backer"

Or the other alternative is to reduce your pressure to almost nothing and slow down just before you cut through. This will GREATLY reduce blowout, but the foolproof way is to have a backing board.

[rampy]

Slugs right.. clamp a scrap piece underneath the piece you're cutting...

Here's another trick, but I don't think it works with a spade bit (it works with the hole saw bit)... drill far enough on one side so that the guide part of the bit (mandrel?) pops out the other side... Then flip it over and do the last 1/4" or so  from the other side....

*Shrug*

rampy

[mcleanjoel]

Yes it works great with a spade bit.

[toyguy]

Get access to a good drill press with a nice table and a good, sharp Forstner bit.  You can then drill them fast, clean and straight and since the piece is on the table flat, the bottom will not splinter.  Did mine that way and it came out perfectly.

[Frostillicus]

Get access to a good drill press with a nice table and a good, sharp Forstner bit.  

Yes get a good Forsnter bit - and drill press and you get holes that look like they were machined out with a CNC machine...