Drilling pilot holes and clearance holes

[Al Launier]

Paul

WL Fuller, in Warwick RI. makes any type of drill bit you can think of.
All they make are drill bits and milling machine cutters. If what you're looking of is not in their online catalog, it's an odds on bet that they can make it for, if you can provide them a drawing.
I think page 32, of their current catalog, is close to what you're looking for. You might have to special order a longer pilot.
Give them a call.

http://wlfuller.com/html/catalog.html

Mike is right on. This is what is commonly used in manufacturing by Machinists and Tool & Die Makers. You could also check out McMaster-Carr at https://www.mcmaster.com/#step-drill-bits/=1cxrncu

[Ruperto Mendiones]

Since MDF is mentioned, step drills for confirmat screws might partially fulfill the op's search. Hafele and Rockler have their own versions--at opposite extremes of the budget.

[Derek Meyer]

I would look at Confirmat screws as well. Search Amazon for "confirmat" to see the screws and links to the bits, which drill the pilot hole with a clearance hole for the smooth portion of the screw and a countersink for the head so the screwhole can be plugged. I've used them on MDF and particle board and they work extremely well.

[Mark Bolton]

Does anyone make a two diameter drill bit that drills the pilot hole and clearance hole at the same time?

Paul, I mis-read your post in my last reply thinking you were talking 3/4" diameter not depth. This may be a low-ish cost for something that is adjustable and is made for thousands and thousands of holes with a 3/8" bore but has much greater depth capacity and adjustable pilot depth.

https://www.amanatool.com/424000-fac...9mm-shank.html

[Greg Hines, MD]

I use a lot of Kreg Pocket Hole screws for what you are describing, with or without a pilot hole. If you are trying to use screws to pull two parts together, I would use a pocket hole screw first, to pull them together, then screw your finish screws in place, then replace that pocket hole screw with whatever you were using on the remainder of the project.

Doc

[Rick Potter]

+1 on the type screws Glen Bradley recommends, but I do want to address your comment on the dulling of the countersink.

I had the same problem, using a lot of PB and MDF. You can sharpen the countersink with a diamond file, but I found a set of countersinks by (I think) Snappy that had carbide edges, and also take replaceable brad point drill bits. They last a really long time.