# Screws - Coarse vs Fine Threads



## rance (Sep 30, 2009)

I ran across two boxes of 1-1/4" screws the other day. One is coarse and one is fine thread. I realize that *coarse are intended more for soft woods* and *fine are intended for harder woods*. I don't really like stocking both though so I figured that the coarse ones would win out. *With hardwoods I pre-drill *anyways so I might just have to drill an ever so slightly larger holes for the coarse thread screws. Any reason I might not want to do this? Just a ponderance.


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## kizerpea (Dec 2, 2011)

yeah….if the wood is to hard POP goes the head!


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## Jim Jakosh (Nov 24, 2009)

They both have a purpose- especially when using a Kreg fixture where you cannot pre-drill. The fine ones are needed for the hardwoods. When I pre-drill, I use the same drill size for what every wood, the coarser thread cuts the soft wood easier so no bigger hole is needed. The thing is that the OD is the same for both in the same size - say a #8- so the hole should be the same.
My 2 cents worth…...............Jim


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## dhazelton (Feb 11, 2012)

Drywall screws? Fine thread is meant for steel studs.


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## rance (Sep 30, 2009)

Yeah, I think they are drywall screws. I just don't like stocking both. I'm thinking that I can use coarse for both.


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## tyskkvinna (Mar 23, 2010)

Honestly I use coarse across the board. If the wood is particularly hard I just go really gentle and sometimes back up and go back down.


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## waho6o9 (May 6, 2011)

GRKs totally rock, move up a notch and rock on.


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## andy_P (Aug 13, 2009)

I think what you have to consider is that the threads are taking a good enough bite in the wood surrounding the hole you drill so that it holds. If you are using glue along with the screws, I think this becomes less of a factor. Send me the ones you decide not to use…...LOL.

that's my cent and a half, rance.


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## fussy (Jan 18, 2010)

Rance,

I wood use whatever I had. Seems that is usually coarse thread. If I'm leery of using coarse in hardwood, I wax the threads with beeswax and go slowly; back out and go again if it seems to bind.

Steve


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## HamS (Nov 10, 2011)

I was just going to say wax the screws first in hardwood but Fussy beat me to it. I have a cake of beeswak the size of a tuna can on my bench and one in my tool box just for that. I use the wax a lot on hardwood. It usually is not needed in softwood and sheetgoods.


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## oluf (Jan 29, 2010)

I find beeswax a little hard for using on screws so I buy a wax toilet boal gasket. They are good for about 1000 screws or until you step on it. But than you don't have to sweep the shop any more. The sawdust will all be on your shoe.


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## rance (Sep 30, 2009)

Good input from all. I think I'll just use these fine threads where I can until they are all gone. Those are the ones I didn't buy myself. Any new ones I buy will be coarse(like Lis uses).


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## Kentuk55 (Sep 21, 2010)

I use a wax ring from a toilet…. A new one of coarse. I keep a wax ring in an old cookie can, and when I do any screwin, I'll dip me screw in the wax ring, and go to town


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## gfadvm (Jan 13, 2011)

Rance, It ruins my whole day when I twist the head off of a screw and it happened too often with those black screws in hardwood so I took the cure. Now they are used only in pine or plywood. Just sayin.


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## rockindavan (Mar 8, 2011)

Fine threads are nice particularly when using pocket holes (however rare the occasion is), especially when you have to take the joint apart a couple of times. I recently screwed a face frame on to a cabinet and had to take it on and off 2-3 times. Coarse threads have a better chance of stripping out.


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## rance (Sep 30, 2009)

Good point Andy. rockin, I'v had just the opposite, the fine seem to strip out more often. Several factors could affect this.


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## MrRon (Jul 9, 2009)

Fine thread drywall screws have a tendency to shear the heads off when driven into hard woods. I wouldn't use them. In softwood, the coarse thread drywall screws are ok. When driving regular wood screws into hardwood, always use a lubricant, like wax and drive without stopping. When you stop, it takes a lot of torque to start the screw again. The increased torque can exceed the tensile strength of the screw and it will snap.


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## Dusty56 (Apr 20, 2008)

Drywall / sheetrock screws aren't intended to be used for woodworking. 
They're not made to take the torque required for fastening , and often lose their heads : (
Fine thread woodworking screws are meant for Hardwoods because the grain is tighter and you can actually form threads in the hardwoods without stripping and or pull out, versus softwoods , where they need to have the coarse threads to take a bigger bite of the wood for better holding power and less chance of stripping : )


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## BertFlores58 (May 26, 2010)

Technically speaking in relation to bolts, the finer the teeth (high thread per inch)-the stronger it will be in terms of diameter of the bolt and the nuimber of teeth. Similarly, the wood either soft and hard, can be joined together using finer screw in cases where there is a limited wood thickness. Use longer coarse thread if there is enough wood thickness and finer ones for limited wood thickness. For example, a 3/4 inch wood will need 1/2" penetration (at least) ... it will be stronger if you use a fine thread than course thread of the same length of screw.


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## parkerdude (Dec 13, 2008)

I have gravitated as far from screws as I can. I try to glue as much of my work as possible, reserving their use to times that clamps are difficult. I think glue generally makes stronger joints than screws.

I do use screws when making shop aids, jigs, fixtures etc., that I think might be temporary, or projects that are for outdoor use. I'll take my hardware back out of those items after I finish using them.

I almost never drive screws home with power tools, unless I have set the clutch on my drill/driver to prevent breakage.

YMMV


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