Woodworking Questions - How to get the screws flush!

[Metro Red Line]

I've put my benchwork together with 1x4s and 1 5/8" drywall screws. Things hold together fine but when I drive the screws in the heads stick out a bit. I'm using a power drill with a Phillips bit and there comes a point where the screw just spins in place and doesn't go in any further.
I can't explain it since about 20% of the screws were able to go in with the head flush with the surface of the wood. I am pre-drilling the screws about halfway with a bit that's narrower than the screw. On the basic benchwork frames it tolerable though I'd want them flush so I can place the fascia over it. Also I'm screwing in a plywood surface at the top. and I have a 1" foam going over that, so any screw heads sticking out is a no-no. What am I doing wrong?

[Vail and Southwestern RR]

I've put my benchwork together with 1x4s and 1 5/8" drywall screws. Things hold together fine but when I drive the screws in the heads stick out a bit. I'm using a power drill with a Phillips bit and there comes a point where the screw just spins in place and doesn't go in any further.
I can't explain it since about 20% of the screws were able to go in with the head flush with the surface of the wood. I am pre-drilling the screws about halfway with a bit that's narrower than the screw. On the basic benchwork frames it tolerable though I'd want them flush so I can place the fascia over it. Also I'm screwing in a plywood surface at the top. and I have a 1" foam going over that, so any screw heads sticking out is a no-no. What am I doing wrong?

If the screws are spinning they have pretty much drilled a hole, and are not doing anything good.  Try to back off on your speed a bit.  If you are using a cordless drill with a clutch, back it off a bit.

To get the head flush you want a contersink bit.  It has a bit down the middle which will drill the pilot hole, and a larger wedge shape that drills out a place for the head to nest.  Look for a #6 for those screws.

[Train Master]

jeff uses a countersink bit on his dremel. it works real good

[RonP]

If you are predrilling already then get a wing bit and counter sink a whole the width of your screw head just a weee bit. 1/2 wing bit should be sufficiant.

[Metro Red Line]

Thanks folks! Learn something new everyday!

Actually I used the largest bit I could find - a 1/4" bit and pre-drilled about 1/4" in and was able to get the screw in flush. I also did this with the screws that stuck out and now they're flush as well.

[jim22]

Your screws must be stripping their threads before sinking their own heads.  In hard wood like oak, screws may even break off before sinking themselves.  You should get a set of counter-sinking drill bits as mentioned above.  They have a straight part which drills a good size pilot hole and a wider part which cuts a v-shaped hole into the wood to receive the screw head so that it is flush with or even below the surface.  I have a black-and-decker set of about 5 different sizes.

Jim

[reklein]

Metro red line, Drill a clearance hole through the peice you are attaching. A clearance hole is a hole that will just pass the screw. Kind of a pain but it will allow the screw to draw  itself all the way in without stripping. If your screw is spinning without drawing itself in ,you've either broken the screw head off or have stripped out he wood. In which case you need to go to a larger diameter screw or a longer one.

[tgindy]

For stripped-out wood threads I have used the old, "adding a toothpick(s) in the stripped screw hole trick," to get more wood for the metal screw threads to bite upon.

[bjdukert]

As stated above a countersink will put the head flush and be careful you don't go too deep with the countersink. I also use an 1/8" drill bit for the pilot hole and the drill bit fits into the countersink and I haven't had a screw turn free or loose it's grip.

Re-read your second post and a 1/4" drill bit is much too big for the drywall screw. The hole is so big it isn't letting the threads bite into the wood like they should. 

Duke  

[Vail and Southwestern RR]

He's using the 1/4" as a countersink bit, a bit clumsy, but it should work.  I use 3/32" for the pilot holes for the drywall screws.

 

[bjdukert]

Ok,read a little more carefully.

Duke

[bogp40]

I notice that the countersink/ driver sets were not mentioned. I would suggest the Dewalt, Stanley or Makita countersink/driver sets. They come in a few different styles but basically are a reversing pilot countersink on one end and the #2 phillips on the other. Most common sets found at Home Depot, Sears etc, have a #6, 8 and 10 pilot/ countersinks. The pilot drill is replaceable and adjustable for depth. The allen wrench is actually built into the tools shank just for this purpose. These sets are very reasonable ($15-20) and for light use in benchwork should last years. I use these daily in cabinet installation and find that a bit can last me 3-4 months of drilling maple, oak, poplar , hickory and ash.

A clearance hole should not be nec for working w/ pine. The spinout trouble is probably due to too large a pilot bit or too deep a hole. Also when the screw is being driven, start to back off on the trigger and feel the screw start to torque then stop. You may be ramming the screws at full RPM and just spinning them out. The drill you are using could also be too powerful and lack the control need for this work. A decent VSR drill or cordless screw screw gun works best for this. I swear by Bosch, but don't forget, I use these tools everyday, any good name brand will do for light duty.

[reklein]

I think model railroaders should also subsribe to a woodworking magazine.

[larak]

Great suggestions above.

Clearance hole in outer piece, countersink. It's OK to use a large bit for a countersink but it's easy to go too deep. Better to buy the correct tool. You won't regret it.

I used three cordless drills for my benchwork. 1) Clearance 2) Countersink 3) Driver. It saved swapping bits but it's dumb to buy three cordless drills for a one time job. (I have them for my business). Don't forget that that old style corded drill will work just fine for drilling. Better than the cordless actually. Use the cordless for driving though, and set the clutch. Screw length should be about three times the thichness of the face piece of wood. A bit longer is better in soft pine.

Finally, drywall screws have little shear strength. Deck screws are stronger AND some brands will countersink themselves.

Karl

[Anonymous]

try using a dewalt countersink tool that goes on the end of your drill and this tool can flip ovet to a screw bit also try switcking to deckmate screws

[bsteel4065]

The pupose of a pilot hole is to prevent the wood from splitting and also to guide the screw into position. A screw must have a sufficient amout of wood around it and beneath it to take hold and work properly. The pilot hole should therefore be of minimum diameter (possibly one third of the final hole diameter) and should not be drilled to the full depth of the length of the screw.
A countersink bit will allow the head of a countersunk screw to sit flush with the surface. If a countersunk isn't used, then you run the risk of not only a screw head sitting 'proud' but also the wood splitting around the top of the screw.
If a screw spins around and around it is securing nothing. It is best to drill another pilot in a different place and go again or use the hole as a pilot and put in an even larger and longer screw.

Hope this helps.
Cheers
Barry