Why is the unthreaded portion of the 80mm and 90mm screws 30-35mm? It works rather poorly for 45-lumber. I've looked in nearby stores like Jula, XL bygg, K-Rauta, etc. The closest I found is Biltema's outdoor screw 5x90mm, which has about 40mm unthreaded, which works if you drive the screw in 5mm or so.
Why is the unthreaded part on 80mm and 90mm screws 30-35mm? It works rather poorly for 45-timber. I've looked at nearby stores like Jula, XL bygg, K-Rauta, etc. The closest I've found is Biltema's outdoor screw 5x90mm which has about 40mm unthreaded, which works fine if you drive the screw in 5 mm or so.
I was probably not clear. I mean for example when you screw a 45x45 regel to another. The threads should grip on the regel behind and not in the top one. As it is now, the last threads will remain in the top regel when the screw is fully screwed in.
I usually assume that those last thread turns are torn apart when the studs are pulled together. So the screw will work as intended even if the unthreaded part is too short.
It is very difficult to join wood with a fully threaded screw and get it tight. The wooden pieces tend to separate, unless you pre-drill something larger than the thread in the piece where the screw head sits. The Biltema screw you show is perfect; it has a section (thread) with a higher pitch, pulling the pieces together more. The perfect screw for 45 mm timber would have had the fine thread at 45 mm from the head
I usually assume that the last few threads will break when the studs are tightened together.
Exactly, and it works quite well with Biltema's screws. But when there are 10-15 mm of threads left like on most other screws, it feels quite wrong. Do professionals not use screws? I can't imagine they pre-drill everywhere.
Exactly, and it works quite well with Biltema's screw. But when there are 10-15 mm threads left like on most other screws, it feels quite wrong. Don't the professionals use screws? I can't imagine they pre-drill everywhere.
Looks absolutely brilliant for a 45 rule! Usually, you don't drive the screw a little deeper than to be flush with the wood. And those few mm that might be in the 45 won't have any significance, they'll just tear the thread.
Probably better that the part without thread is actually a bit smaller than 45 in this case, ensuring you always have 100% thread all the way in the wood behind!
If you want to join two 45x45 pieces, you need a 45mm thread on a 90mm screw. Not all manufacturers provide this because many purchase screws "off the shelf" from Asian manufacturers.
Some manufacturers have had this for a long time, while others have just realized it.
It's a hassle with too long a thread. You have to screw in, screw out, and screw in again.
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