Doghole Retrofit: Auger or Forstner?

[Danny Thompson]

Bought some holdfasts. Need some holes in my workbench. Using the drill press is not really an option.

Will a 3.5" deep hole drilled with a forstner bit be straight enough? Or do I need an auger bit?

[glenn bradley]

You don't mention the material you will be drilling. My top is 3" of MDF so a 3/4" spiral bit in a plunge router gave me the cleanest holes. The first few holes I made with a large brad point bit as shown in post #11 of this thread (http://www.sawmillcreek.org/showthread.php?t=57879). Others here have used a variety of drills including plain old spade bits. Your material will give varying results with each method.

[Danny Thompson]

It's Southern Yellow Pine.

[Casey Gooding]

In the last bench I built (3.5" cherry top) I started with a 3/4" router bit in a plunge router, then finished off with an auger bit.

[Mike Henderson]

The problem I have with Forstners is that once they get deep, you have to keep pulling the bit out on a regular basis or the chips get packed in hard above the bit. But I think Forstners give the cleanest entry hole.

You could start the hole with a Forstner (maybe an inch) and then drill the rest with a regular twist bit.

All of them blow out quite a bit on exit so if you can clamp a backer board it will help. I know people can't see the exit area but I know it's there and I don't like blow out.

Mike

[Once you start with a twist drill, you can help align it if you take a piece of 8/4 and drill it on the drill press. Then clamp it above your starter hole. It will force you to hold the drill in the right position.]