I've been looking online to buy some screws for a wood box I'm building and I want to have some thumb screws to close the lid down which will screw into something like the following:

http://www.rtlfasteners.com/RC/q.html

and I have no idea what all those numbers mean. The box is about 2'x2'x1'. I want something with a thread size that will be easy to screw off and on and will stand up to repeated screwings (for lack of a less vulgar word =)) and to be somewhere more than 3/4" but less than 1" length (thread length) Any idea of which to go with?


Thanks
Bill

 

The numbers mean diameter-threads per inch.These are all in common machine screw sizes.1/4 = quarter inch,10 = 3/16,8 = 5/32 and so forth.Except for the #2 and possibly the #4,thumb screws will be easily found in these sizes.You'll have to take a look and decide on the size that best fits your needs.Go to a real hardware store.If they stock Midwest Fasteners or Hillman they should have what you are looking for or be able to get it.Big box stores may or may not stock the thumb screws I'm not sure but the help there will only find a blank stare if you ask them to find it for you.The pictured inserts are a bit harder to find.Ask the help for assistance.

 

So, as far as difficulty in unscrewing them and the ability to stand up to repeated ins and outs they all stack up about the same?

 

the torque needed to rotate the screw would be similar size for size. The quality of fit (closer tolerances are a "snugger" fit as there is less slop in the fit) will tend to change the torque required to an extent.

The bigger thought, in my mind, is that the more threads per inch, the more rotations it will take to unscrew the screw the same distance.

 

You should be able to find the threaded inserts in Rockler.com

 

Larger thumb screws have larger wings and are therefore easier to turn by hand.

Because much of the fasteners today are imported you will find a wide variance in quality even within the same brand or company.For instance Midwest and Hillman both use items from all over the world.

 

The threads per inch determine how fast the screw moves in or out.

A 1/4-20 is 1/4 inch diameter, has 20 threads per inch, and requires 20 turns to move one inch.

A 10-32 screw has 32 threads per inch and requires 32 turns to move one inch. Hope this helps.