Tapered Drill Bit Depth

[Paul Fitzgerald]

I used a straight bit with a built in countersink on the last project requiring wood screws. I had some trouble with the unthreaded shank of the screw splitting the cedar, so I started using two drill bits (one for the pilot hole and the other for the shank hole) and manually countersinking. That was time consuming but worked just fine.

I'm working on another project requiring wood screws. This time it's pine. I decided to give the tapered bits with a built in countersink a shot. They're definitely quicker than having to use two drill bits and manually countersinking, but I've found that setting the depth is critical and problematic.

I've searched the Internet as well as this forum. All I've been able to find is confirmation that the issues I'm having are common. Unfortunately, I've been unable to find any helpful tips or a guide to help properly set the depth on the bit set for the length of screw to be used.

Pardon the upcoming pun... I'd rather not waste my time screwing around with scraps all afternoon trying to figure out the proper depth to drill for each length screw I'll be using.

Do any of ya'll use tapered bits for wood screws? Do you have a system for setting the depth properly for each length screw you'll be using?

Thanks in advance,

Paul

[Lawrence Smith]

Hi Paul

I built a boat where I used tapered drill bits in conjunction with silicon bronze wood screws. The way that I set the depth was to hold the screw next to the tapered bit and set the counter sink on the bit so it was almost even with the head of the screw. I naturally checked it in some scrap to verify it had the proper holding power by just running a screw in the scrap. After you do it for a while, you will know where to set the countersink. I always used soap as a lubricant to run the screw in. I did not use a power screw driver, always a HIGH QUALITY hand held screw driver and straight slot screws. This is the way I was taught how to properly utilize taper drills and wood screws at the Wooden Boat School.

Bear in mind that taper drills come in several different sizes. They are numbered as to the size screw that you want to use. It is imperative that you use the proper size. There are many different makes of taper drills on the market. The best ones are made by Fuller, but even they can burn out quickly if you don't keep the bit clean. You can generally get the Fuller bits at most marine supply stores or Jamestown Distributors which is an online supplier of marine products.

Hope this helps. My $.02

[Tom Veatch]

Do you have a system for setting the depth properly for each length screw you'll be using?

Like Lawrence indicated, just setting the total length of the drill bit to be equal to the length of the screw has worked well for me.