"Coarse" vs "Deep" threads

Ok - Potentially silly question. McFeeleys sells screws that are either Deep thread or Coarse or Fine. What is the difference between a "deep" vs "coarse" thread? Applications differences? All of the ones I have bought are "deep" threads and I have been very happy with them. I have some "deep" thread and "fine" thread Kreg pocket screws and both work well in hardwoods that I have used to date with no noticeable difference.
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On 8/16/2012 10:26 AM, GarageWoodworks wrote:

Ok. It looks like "deep" and "coarse" are the same thread type.
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On 8/16/12 10:14 AM, GarageWoodworks wrote:

I thought "deep" had a reduced shank diameter. Overall diameter the the threads are the same, but because the shank is narrower, the threads are deeper. Make sense?
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On 8/16/2012 11:23 AM, -MIKE- wrote:

Makes sense. How does 'deep' differ from 'coarse'? It's funny, I have around four FWW articles on screws and they all gloss over thread types.

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On 8/16/2012 11:40 AM, GarageWoodworks wrote:

(duh) Scratch that. I'm still half asleep. I got it.

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I do know that for certain applications like screwing in the sides of say particle board you need a certain kind of screw.
My own definition
Coarse vs fine is the threads per inch. Deep threads are the differnce between the the outer diameter and the root of the screw.
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Screws made specifically for termite barf are usually deeper in thread, Brian.
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Not sure what distinction McFeeley's is trying to make, but generally, "coarse" and "fine" in relation to screw or bolt threads has to do with thread count per inch (or put another way, thread pitch.). "Deep" of course would refer to the depth of the threads, peak to root or valley. So it would be very possible for instance to have a coarse thread that is shallow, or a fine thread that is deep.
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On 8/16/2012 10:26 AM, GarageWoodworks wrote:

I think Larry got it right, but I also think coarse threads are generally both coarse and deep, and fine threads generally fine and shallow, but I guess it doesn't have to be that way.
I like coarse/deep threads all the time. Fine/shallow threads are shaky in soft woods like pine, but coarse works in both, so I buy only coarse/deep.
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