Screw Sizes Types, et cetera

  • Advertise with us

« back to Designing Woodworking Projects forum

Forum topic by Phlogis posted 02-05-2013 08:53 AM 2993 views 0 times favorited 17 replies Add to Favorites Watch
View Phlogis's profile


6 posts in 2115 days

02-05-2013 08:53 AM

Topic tags/keywords: screw type gauge wood root shank

Hi, I’m austin and I’m new to this forum and to woodworking. I’ve recently been trying to get into the specifics about “screw sizes” for my project. Yes I admited I am fairly paranoid and OCD, but I think it matters.

Onto the question. I do have a specific size for a specific project that I need to know, but I’m looking more for knowledge so that I can apply it in later applications.

So I know that there are screw gauges, commonly 6, 8, 10 and so on. I’m screwing red oak 2×4s together and have yet to find an information or chart on what screw guauge for what application.

I have found information on length, I’m going with 2 1/2 inch long wood screws and I think that 2/3 of the recieving material should be threaded.

I also think I’m going to go with coarse rather than fine thread because its a hardwood?

Also I’m going to go with standard threads per inch. I also need a slightly bigger pilot hole for the shank than the root, but I have found a pilot hole chart.

The only thing I can’t find is when to use what screw gauge.

I appricaite any indepth screw knowledge and advice you have.

-- Newbie

17 replies so far

View DIYaholic's profile


19670 posts in 2853 days

#1 posted 02-05-2013 01:25 PM

From what I remember reading, as far as thread pitch (fine Vs. coarse) goes, hardwoods should recieve fine threads & softwoods should recieve coarse threads. Sorry, I can’t offer or recommend any screw gauge advice.

-- Randy-- I may not be good...but I am slow! If good things come to those who wait.... Why is procrastination a bad thing?

View kizerpea's profile


775 posts in 2545 days

#2 posted 02-05-2013 01:26 PM

Wrong ….fine thread for hard wood …coarse thread for soft wood…coarse will ring off in hard wood…or find out the hard way…or buy a kreg jig…lots of us have them..


View poopiekat's profile


4384 posts in 3912 days

#3 posted 02-05-2013 01:48 PM

I’m not aware of pitch choices in wood screws. Drywall screws, maybe, but not wood screws.

-- Einstein: "The intuitive mind is a sacred gift, and the rational mind is a faithful servant. We have created a society that honors the servant and has forgotten the gift." I'm Poopiekat!!

View JoeinGa's profile


7739 posts in 2185 days

#4 posted 02-05-2013 01:58 PM

I Googled and found a simple cart for pilot hole sizes. Printed one out and hung it near my workbench. I refered to it fairly often till I started remembering which size drill bit for which size screw.

Here’s a couple to choose from


-- Perform A Random Act Of Kindness Today ... Pay It Forward

View DIYaholic's profile


19670 posts in 2853 days

#5 posted 02-05-2013 02:11 PM

Good point. I was refering to pocket hole screws.
From the posted chart links (refering to standard wood screws), Hardwoods get a larger diameter pilot hole than those for softwoods.

-- Randy-- I may not be good...but I am slow! If good things come to those who wait.... Why is procrastination a bad thing?

View Ted's profile


2873 posts in 2389 days

#6 posted 02-05-2013 02:24 PM

I generally use what screws I have on hand at the time, or whatever the store stocks. Then I use the appropriate size drill bits to make pilot holes as needed. For wood screws, I would drill an initial pilot hole for the upper shank portion of the screw, then drill deeper with a smaller diameter bit for the threaded portion. With hardwoods I would make the threaded portion of the pilot hole just a little smaller than the diameter of the threads, or just enough to give them some bite. For softwoods I make the threaded portion smaller to give the screw a little more bite.

For all of this, I generally don’t measure anything.. just hold drill bit against the screw and eye it for the right size. I often put just a touch of wax on the screw for hardwoods, to help them drive in easier.

Welcome to LJ’s

-- You can collect dust or you can make dust. I choose to make it.

View JesseTutt's profile


854 posts in 2288 days

#7 posted 02-05-2013 02:47 PM

I don’t have a McFeelys catalog handy but they have a lot of useful information in it. I know they have a drill size chart for different types of screws and discuss different screw (metal) made from. I don’t recall if they have a chart for screw diameter use.

For structural joints I tend to use the largest screw I can. For non-structural whatever size I have a lot of.

-- Jesse, Saint Louis, Missouri

View Bill White's profile

Bill White

5108 posts in 4138 days

#8 posted 02-05-2013 03:37 PM

+1 on gettin’ a McFeely’s catalog. More than you’ll ever want to know, and they have quality products.


View Cosmicsniper's profile


2202 posts in 3336 days

#9 posted 02-05-2013 03:47 PM

When using the pocket hole screws, I always use coarse threads on hardwood simply because I always strip out the fine thread ones. Then again, I’ll often break off the coarse ones by over torquing. Either way, I’m too reckless with pocket hole screws…because i’m an impatient idiot. You likely won’t over -torque your screws like I do, so it’s probably not an issue and you can use fine threaded screws in hardwood with good effect.

-- jay,

View waho6o9's profile (online now)


8490 posts in 2754 days

#10 posted 02-05-2013 04:31 PM

GRKs are an option and available at Home Depot as well.

Welcome to LJ’s Austin and enjoy your journey, it’s going to
be a good one!

View MrRon's profile


5150 posts in 3421 days

#11 posted 02-05-2013 08:14 PM

A lot depends on your application. if it is a structural joint where failure is not an option, you need to use glue. Screws will then act as “clamps” until the glue has set. Glue joints can fail if moisture is allowed to penetrate the joint. Screws can be the secondary joint strength and a larger screw may be needed. Not knowing what the sizes of wood you are joining together, it is difficult to tell you what size of screw to use. There is only one screw pitch per size of screw used for either soft or hard wood; no fine or coarse pitch. The pilot hole is what will vary depending on the hardness of the wood. Go to this link, chapter 7 will tell you everything you need to know about screws or anything else for that matter.​Wood​Handbook.html

View Phlogis's profile


6 posts in 2115 days

#12 posted 02-05-2013 11:53 PM

Thank you all for your great responses!! It’s much appreciated. I’m now positive of how I’m going to implement my fine threaded screws using the pilot hole charts based on my screw type.

But honestly I’m still not sure if I’m to use, #6, #8 or #10 sized – and why

For clarification purposes, I’m attaching a 21 inch red oak 2×4 flat against some 5/4 red oak with glue between the joint. And it needs to be very sturdy, as I’d like the quality of this piece to be high and lasting.

Thank you for the warm welcome.

-- Newbie

View huff's profile


2828 posts in 3463 days

#13 posted 02-06-2013 12:59 AM

A #8×2 1/2” fine thread screw would give you all the strength you need; as long as you don’t twist it off in the red oak. If you pr-drill a pilot hole, you should not have a problem.

A little trick you can do when running long screws into hardwood is to put a little soap on the threads of the screw for lubrication. I keep an old bar of hand soap in the shop for that purpose.

-- John @

View oldnovice's profile


7274 posts in 3545 days

#14 posted 02-07-2013 01:40 AM

Without any detail about the loads on the pieces it is difficult to to suggest what size of screw should be used. If the assembled pieces are just by themselves; not supporting anything else then the glue would suffice but if these pieces are part of something else and/or have a load on them then screws may be needed.

-- "I never met a board I didn't like!"

View MrRon's profile


5150 posts in 3421 days

#15 posted 02-07-2013 06:31 PM

“For clarification purposes, I’m attaching a 21 inch red oak 2×4 flat against some 5/4 red oak with glue between the joint. And it needs to be very sturdy, as I’d like the quality of this piece to be high and lasting.”

Are both sides exposed to view? Best to fasten through the 5/4 into the 2×4 and if exposed, counterbore and plug.

showing 1 through 15 of 17 replies

Have your say...

You must be signed in to reply.

DISCLAIMER: Any posts on LJ are posted by individuals acting in their own right and do not necessarily reflect the views of LJ. LJ will not be held liable for the actions of any user.

Latest Projects | Latest Blog Entries | Latest Forum Topics