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23rd September 2019, 11:52 AM #1Senior Member
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Help- accidentally sawed through pocket screws
I was ripping a lovely rosewood tabletop for recycling. Imagine my infinite shock when I heard a buzz and saw some sparks fly.
Now, I'm left with this (pictures attached). I have to remove them so I can joint the boards and glue them up again.
The problem is though, I have no idea how the screws got there. The underside of the boards are rough and covered in some gunk. I cannot see where screws went in. I assume they have to be pocket screws. It would be terrible if pocket holes were drilled and then filled.
The challenge is that one half of the screw is the head and the other side is the tip, and I don't know which. I am thinking of planing the underside of the board to reveal where the screws went in.
Firstly, can anyone shed some light on how this tabletop was likely to be constructed? Is pocket screwing glueups standard practice in commercial furniture?
Further, how can I remove the screws? I have a screw extractor kit, but I can't punch a hole to get the drill started. Also, the screws may be at an angle.
20190922_221814.jpg20190922_221714.jpg
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23rd September 2019 11:52 AM # ADSGoogle Adsense Advertisement
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23rd September 2019, 12:22 PM #2GOLD MEMBER
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My guess would be that it's a home made job and the screws have been used for alignment of the boards. You drive the screw into the side of one board, cut the head off and then drive/clamp the boards together. The side that the head has been cut off is likely to be an unthreaded shank and much easier to remove. The screws should be at 90 degrees to the timber in both planes. If they are pocket hole screws (driven at an angle from one board into the next) then you should be able to find the screw heads or a plug/filler where they have been covered, but from your description that doesn't sound likely. Are the screws at relatively regular intervals?
The easiest way to remove the threaded end will be to carefully excavate around the screw with a chisel until you can get a pair of vice grips on it to unscrew it. A couple of small flats filed on the screw can help the vice grips get a good hold. Yes it's a PITA, but it does work.
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23rd September 2019, 01:28 PM #3Senior Member
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Thanks, that's a great diagnosis! I didn't consider screws work their heads cut off but I suppose that could be used for alignment. Is this is the case it would be much easier, although still tedious to excavate. I'll excavate it further to see if it is straight.
I'm not sure if it home made or commercial. I suppose commercial furniture would have biscuits or dominoes. That said, I've seen some boneheaded stuff done as shortcuts in commercial. Homemade stuff usually exhibits more care, especially if they are able to achieve a good looking result. I can't see any case where someone capable of doing a tight glue up would resort to this
Yes, there are about 6 along the 1.8m length
Edit: Come to think of it, if you are correct, then the screw threads should only be on one side of the board. This I'll have to check, but I don't recall seeing any circular (non-threaded) screw cross sections
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23rd September 2019, 01:43 PM #4GOLD MEMBER
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Just leaving this here.....
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23rd September 2019, 02:08 PM #5SENIOR MEMBER
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My stud finder has a metal setting and I always run it over used timber. It has picked up some reasonable small broken nails and hasn't missed anything yet.
You can't use up creativity. The more you use, the more you have. ~Oscar Wilde
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23rd September 2019, 02:39 PM #6
One way to remove those is to drill a hole alongside the screw then with a nail punch or old screwdriver or the like knock the screw shank over into the hole you just drilled and extract.
I think most of know the feeling when you see sparks fly off the saw blade. Get a metal detector and always suspect things may be lurking in old wood.
Regards
John
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23rd September 2019, 07:32 PM #7GOLD MEMBER
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Most times i’ve seen screws used in tabletop glue-ups it has been of Asian origin - village level stuff. Typical source is Bali, though I did have a bed head made of old-growth teak from India which was ruined for recycling cos of screws.
The timber looks to me like rubberwood (not rosewood, sorry) which would support Asian origin.Apologies for unnoticed autocomplete errors.
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23rd September 2019, 08:09 PM #8Senior Member
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really? It has a nice contrasting grain, aalthough I do think it has been stained
20190923_190521.jpg
edit: I just calculated the density of 2 pieces. They came out to 770 and 810 kg/m^3
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23rd September 2019, 08:48 PM #9GOLD MEMBER
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I was going off photo 2 in your original post - which looks hard boney white, like rubberwood.
Rubberwood is very really figured though, so maybe not.
It will be interesting to see after it’s been through the planer.
Where did the identification as rosewood come from ?Apologies for unnoticed autocomplete errors.
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23rd September 2019, 08:55 PM #10Senior Member
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Going along the edge grain, it actually changes colour from really white to reddish brown in patches
It was second hand furniture sold as rosewood. The price was more like rubberwood, so I could've gotten stooged. I'll never ever be good at identifying timber, but I did all I can to make sure that what I saw was the real wood, and it looked pretty good to my eyes.
See at the bottom of the pic I posted, I chipped away at a knot to make sure it's a real knot? it's a real knot
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23rd September 2019, 10:48 PM #11
One possible avenue to get the pieces of screw out is to try and drill down their centreline with a small left handed drill bit. As the cutting edge of the drill bites into the metal, it is applying a torque to it that is trying to unscrew it from the timber. Haven't seen it applied to a screw in timber, but it has a fair degree of success in removing broken bolts, studs etc threaded into metal. Biggest issue in your case would be that you need to be close to the centreline and inline with the screw, as if you drill through the side of the screw, you defeat what you are trying to do because because the bit effectively pins the screw into the timber preventing rotation and winding it out.
I used to be an engineer, I'm not an engineer any more, but on the really good days I can remember when I was.
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23rd September 2019, 11:56 PM #12GOLD MEMBER
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24th September 2019, 12:52 AM #13Senior Member
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24th September 2019, 09:27 PM #14
A center punch
I am learning, slowley.
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24th September 2019, 09:52 PM #15
The issues with a screw extractor are that you need to drill a hole to insert it in, then when you insert it and wind on it, they tend to expand the screw as you wind the taper in to get it to catch. A left hand drill will generally catch and wind the screw out during the drilling stage, and certainly should not expand the screw as a screw extractor might.
I would suggest a file to get a flat surface followed by an automatic centre punch to create a starting point.I used to be an engineer, I'm not an engineer any more, but on the really good days I can remember when I was.
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