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Screw Sizes Types, et cetera

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Forum topic by Phlogis posted 532 days ago 1183 views 0 times favorited 17 replies Add to Favorites Watch
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Phlogis

6 posts in 532 days


532 days ago

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

DIYaholic

12846 posts in 1270 days


#1 posted 532 days ago

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 procratination a bad thing?

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kizerpea

746 posts in 962 days


#2 posted 532 days ago

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..

-- IF YOUR NOT MAKING DUST...YOU ARE COLLECTING IT! SOUTH CAROLINA.

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poopiekat

3549 posts in 2329 days


#3 posted 531 days ago

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!!

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JoeinGa

3086 posts in 602 days


#4 posted 531 days ago

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

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

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DIYaholic

12846 posts in 1270 days


#5 posted 531 days ago

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.

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

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Tedster

2245 posts in 806 days


#6 posted 531 days ago

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

-- I support the 28th Amendment. http://www.wolf-pac.com/28th

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JesseTutt

793 posts in 705 days


#7 posted 531 days ago

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

3339 posts in 2555 days


#8 posted 531 days ago

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

-- bill@magraphics.us

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Cosmicsniper

2199 posts in 1753 days


#9 posted 531 days ago

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, www.allaboutastro.com

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waho6o9

4744 posts in 1172 days


#10 posted 531 days ago

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

2715 posts in 1838 days


#11 posted 531 days ago

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

6 posts in 532 days


#12 posted 531 days ago

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

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huff

2779 posts in 1880 days


#13 posted 531 days ago

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 @ http://www.thehuffordfurnituregroup.com

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oldnovice

3573 posts in 1963 days


#14 posted 530 days ago

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

MrRon

2715 posts in 1838 days


#15 posted 529 days ago

“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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