Fully threaded screws

It seems to me that fully threaded screws are commonly used to join wood, but I cannot see how any clamping force can be attained. Surely screws with some plain shank should be used so that the thread is only effective in one of the pieces. Am I just old-fashioned?

Woodworking Asked by Mike Kenefeck on January 7, 2021

3 Answers

3 Answers

You can do two things to workaround the issue that comes up using fully threaded screws (that it is difficult to fully clamp the pieces together and they can potentially be pushed apart):

  1. Clamp the pieces before screwing - this will ensure they are held tightly together.

  2. Drill a larger pilot hole in the top piece. This prevents the screw from threading in the top piece and ends up working the same way that screws with a plain shank near the top work.

Correct answer by Steven on January 7, 2021

I find that when bridging happens, pushing the boards apart instead of drawing them together, I'll back the screw out, pull them together (by hand or with a clamp, as appropriate), then drive the screw home again. In almost every situation I've come across, this is sufficient to get the boards tight together.

I would agree, however, that an unthreaded portion of the screw or a clearance hole would eliminate the problem from the get go.

Answered by FreeMan on January 7, 2021

You're right to be concerned about the proliferation of modern "wood screws" that are fully-threaded as the design of traditional wood screws was quite deliberate to provide holding power into the piece of wood beneath without gripping the piece of wood on top (leading to a problem called bridging, where the screw's grip on both pieces doesn't allow any gap to close up).

However, you can still make use of them in the normal manner by drilling appropriate holes in each piece just as was done traditionally.

See previous Answer that covers clearance holes and pilot holes: Are there specific types of screws I should use for woodworking?

Answered by Graphus on January 7, 2021

Add your own answers!

Related Questions

How to Attach Sides to Rabbit Pen

0  Asked on May 12, 2021 by dizzy49


Looking for the LEAST fragrant wood for storing tea

1  Asked on April 27, 2021 by doogan


Laminating a long beam for strength

2  Asked on April 22, 2021


Blotchy pine doors

0  Asked on April 18, 2021 by janice-smith


How can I fix smears after wipe on gel finish?

1  Asked on April 8, 2021 by joanna


What is the name of this way of Joining?

2  Asked on March 31, 2021 by fditz


Ask a Question

Get help from others!

© 2021 All rights reserved.