Pilot hole vs clearance hole

[wrmnfzy]

I'm getting ready to start assembling my platform bed, for strength is it better to drill pilot or clearance holes for the screws?

[Hobbyman2]

A little wax on the screw never hurt.

[newportcycle]

Which screw's? Clearance holes speak for themselves, clear area around the screw, no holding power there, just slip through. Pilot hole is drilled to prevent splitting, and yes little wax on screws in pilot holes makes for happy driving.

[JPG]

Pilot holes are for the part that the screw threads 'screw' into.

Clearance holes are for the part that the screw is fastening to the part the screw 'screws' into and/or the part of the screw that does not have threads(shank).

[dusty]

Not really about pilot holes and clearance holes but it is somewhat applicable:

https://www.albanycountyfasteners.com/b ... e-a-shank/

Deck screws are normally threaded all the way leading to the possibility that the screw may not pull the decking material down tight onto whatever it is being attached to.

[wrmnfzy]

What I'm trying to determine is which way would hold the best. I kinda had an inkling as to what the difference was but was trying to determine the above.

[ChrisNeilan]

Clearance holes allow the piece to de drawn tight against the opposing surface. Sometimes with just a pilot hole, the threads in the first piece don't allow the two pieces to be tight against each other. Does that even make sense?

[wrmnfzy]

Yes it does and that was my initial thought process but having never done it that way I was looking for validation and if it presented any other problems. Thanks.

[garys]

I decide if I'm drilling pilot holes by the type of wood I'm using. Soft woods don't require it in most situations. Hardwoods are likely to split if not pre-drilled. Also, in extremely hard woods, the screws often twist off before finding their way into the wood without a pilot hole.

[Ed in Tampa]

In days of old you drilled pilot holes, clearance holes and countersunk them.

The idea is the counter gives the ability to the screw to pull the two parts together. The pilot prevented splitting and gave the screw the most hold. The countersink flushed or hide the head. The screw used had a head, shoulder and threaded portion.

Most of today's “craftsman” use drywall screws and cram things together with impact or powerful drvers. Most screw manufactures accommodate them by making very sharp fairly long taper screws that will some how accomplish the desired task.

The picture/diagram that Dusty posted is the correct way to do it. The correct screw would then
Have a head that sits flush with the surface, a shoulder the length of the thickness of the first piece of wood minus the taper depth and threaded section about 3/4's the thickness of the second piece of wood.

Screws like this are made but few of today's craftsman use them or are aware of them.

My rule of thumb is if I just want to hold things together I use “high quality” dry wall screws and a impact or power driver. If I want to build qaulity i use counter sinks, clearance holes and pilot holes usually hand driven lubed with bees wax. I have some drills that drill a tapered pilot, a correct length pilot and a counter sink in one operation.