Coarse or fine - pocket hole screw question

Rennie Heuer

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I'm building a frame for a display booth (7.5' tall and three sections 9' long made up of 3 - 3' x 7.7' sections hinged together - think really big face frames). I'm milling poplar into 3/4 x 2 1/2 for the frames and everything will be joined with pocket screws.

Question - Poplar, although technically a hard wood, is relatively soft. Should I use the fine thread screws intended for hardwoods, or go with the coarse thread screws normally used on pine, etc.?:huh:
 
Wow, Tough Question

My gut reaction is to go with the fine thread and set your driver torque setting really low so you don't strip out. This coming from someone with limited pocket screw use, so take for what it's worth. Maybe do a test "drive".
 
My expeirence is 'when in doubt, use coarse'. The fine threads strip out too easily in softer hardwoods, like alder, poplar, etc. On the other hand, we ran out of fine thread at the shop a while back and have been using coarse for oak assemblies and it works just fine. So well, in fact, that we stopped bothering to keep the fine thread on hand.
 
I've put together a few dozen large picture frames made of poplar where I used the 1" coarse thread Kreg screw to hold them together. Works great. In fact, the one I did with red oak, I used the coarse screws on it as well. While it may not be what Kreg calls for they worked, didn't split the wood, and are still holding it together today.
 
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