# Screw Sizes Types, et cetera



## Phlogis (Feb 4, 2013)

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.


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## DIYaholic (Jan 28, 2011)

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.


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## kizerpea (Dec 2, 2011)

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..


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## 33706 (Mar 5, 2008)

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


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## JoeinGa (Nov 26, 2012)

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

http://www.wlfuller.com/html/wood_screw_chart.html

http://images.meredith.com/wood/images/pdf/screwchart.pdf

Oh, and *WELCOME TO LJs*


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## DIYaholic (Jan 28, 2011)

poopiekat,
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.


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## TedW (May 6, 2012)

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


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## JesseTutt (Aug 15, 2012)

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.


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## BillWhite (Jul 23, 2007)

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


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## Cosmicsniper (Oct 2, 2009)

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.


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## waho6o9 (May 6, 2011)

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!


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## MrRon (Jul 9, 2009)

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.
www.woodweb.com/knowledgebase/ Wood Handbook.html


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## Phlogis (Feb 4, 2013)

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.


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## huff (May 28, 2009)

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.


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## oldnovice (Mar 7, 2009)

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.


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## MrRon (Jul 9, 2009)

"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.


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## runswithscissors (Nov 8, 2012)

True wood screws are becoming somewhat rare. They are the ones with a smooth shank below the head, and threads the rest of the way. The point of the smooth part is so the screw can pull the 2 parts together. With an all-thread screw, your pieces have to be in tight contact from the start. If, for example, you fasten 2 boards together with an all-thread, and start with a 1/8" gap between them, you cannot close up that gap with screws. The top piece hangs up on the threads, and can't be pulled up tight no matter how hard you drive the screw. (Guess how I know this?)
Trouble is, not all boards that are going to be fastened to another board are going to be the same thickness as the length of the smooth shank, so sometimes they work fine, sometimes not.

As for McFeely screws, I haven't used theirs, but I have used the so-called "combination" screws, for either phillips or square drive drivers. They're supposed to be the best of both worlds. To me, they are the worst of both worlds. What does a phillips bit look like when the driver cams out? Like a combo screw, of course. And if you use square drive, well, the corners already have been conveniently rounded for you. I have had very poor luck using them, as you can probably surmise.

I'm with Ted when it comes to sizing screws: hold the screw up to your work (both pieces), and eyeball it. If it looks okay, it should be okay. By the way, I like the tapered pilot drills, such as Fuller's. I have used them for years with good results. Some people think they don't leave enough wood for the threads to bite into, but I have not had this problem, either in softwood or hard. They come with a combination countersink/counterbore which is handy, too.


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## oldnovice (Mar 7, 2009)

I use Fastap whenever possible as IMO they are the best carpentry screws available today! These screws may not look as the traditional zinc wood screws as they are Black Oxide coated (that's what my supplier carries) but they are also available Silver Unichrome.

*I like them because the really pull two pieces together and I have yet to have one break or the head strip out!*

I buy these at my local lumber yard and always buy a couple of boxes … just in case I may run out!

I only used McFeely's screws once and was dissaponted in there strength, combo head, and the square drive head.

*Take a close look at these and you will see why I like these screws!*


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