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Thread: Joinery Advice Please!
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2nd June 2020, 10:47 AM #1Novice
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Joinery Advice Please!
Hi All,
I'm a newbie to woodworking and this forum and I find myself in need of some advice from those more experienced.
I am making a very basic cushion bench for my wife and I got a little over zealous and joined up the mitred face frame of the bench base before I though about how I'd fix the cross members which will support the legs and cushion base.
Now I know I should have thought of this before and probably used some sort of tenon or dowel joint and glued it up all at once, but it's done now and it's not coming undone, so I need a new method.
I have the obvious choice of using some brackets to fix internally, as it will be on the under/inside of the bench and no-one will ever see it, but I will know and I won't be happy with that. I was considering pocket holes, however I'm using old recycled hardwood and it is VERY hard. Even when pre-drilling pilot holes the screws are going in really tight, so I'm worried about splitting the face timber or snapping screws trying to drill them in without a pilot hole.
Any advice on a method to retro-fit these pieces would be greatly appreciated. I have attached some pictures/drawings below to illustrate what I am trying to achieve.
Thanks
Toby
Bench 2.png20200531_181700.jpgBench 4.png
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2nd June 2020 10:47 AM # ADSGoogle Adsense Advertisement
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2nd June 2020, 11:31 AM #2Senior Member
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Toby. Just use the pocket hole system but put some bees wax or candle wax on the screws.
Makes a big difference and it works.
What I often do is drive the screw in until it gets a bit tight, undo it and it will be warm or hot.
Lay the thread on the wax and it will melt onto the screw.
It has never failed for me.
Hooroo.
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2nd June 2020, 11:44 AM #3Novice
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Hi Johh,
Thanks for the advice. Do you think I'd need to use specialised pocket hole screws for this - such as Kreg? Or can I use a generic self drilling pan-head screw? From my reading on this forum, there is a fair bit of debate on this subject.
Thanks
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2nd June 2020, 11:55 AM #4GOLD MEMBER
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Is your cushion top planned to be smaller than the frame, like shown? If so, this will be a bit visible, that may or may not be a good thing...
if you really don't want to do pocket holes (and many people, here and elsewhere, will say they're ok), and your cross members aren't yet cut, what about half-laps ? That will allow them to sit on the top face and be even with the top of the frame.
My concern would be the first inset set of though, given they are technically bearing all the weight because they are the leg mounts. So if it were me, I'd carefully cut through the mitres and shorten all my dimensions by a few saw kerfs and do it how I wanted it done in the first place....
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2nd June 2020, 12:16 PM #5
You could secure a rail around the perimeter on the inside which your rails then sit on. Think of how the slats on a slat bed are secured. The problem however is that all the leg force is pushing against a couple of fasteners.
Originally Posted by poundy
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2nd June 2020, 12:18 PM #6Novice
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Thanks Poundy.
The cushion top will be inset inside the frame. I will use 12mm ply as the bast of the cushion top, so these supports need to sit 12mm (plus allowance for the upholstery wrap) below the top edge of the frame - so a half-lap isn't an option. I'm hoping to get a nice snug fit to the inside edge of the frame so it won't be visible.
I'm happy to use pocket screws if they're a suitable option, I just wasn't confident based on my experience screwing into this timber in the past.
I hear you about cutting and starting again, but I'd be more worried about making a bigger mess of it by trying to cut and re-do.
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2nd June 2020, 12:32 PM #7
John's spot on.
But any sort of oil or grease will work in a pinch. I usually use lanolin, or occasionally cooking oil.
Another option would be to dowel straight through the rails, use a contrasting wood colour and make the dowells a design feature. Or recess the dowels a little and insert matching/contrasting wood plugs.
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2nd June 2020, 12:37 PM #8Novice
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The force is not too much of a concern. Because of the design, the cushion top is not actually fixed to the frame at all. The top is screw from the underside to the cross members and the the legs will be fixed to the underside of the cross members, so all the force is sandwiching the cross member between the cushion top and the legs. The frame itself just needs to be held in position and also need to help assist to stop twisting caused by the legs being on an angle, so not a massive force but still needs a reasonable amount of securing.
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2nd June 2020, 01:30 PM #9GOLD MEMBER
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Those Kreg screws are self-drilling mushroom head screws. Self-drilling makes the joining much simpler and more accurate. I would recommend you stick with proper Kreg screws at least until you are familiar with the pocket hole joinery. Another option is to use through dowels. They can be effective as well.
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2nd June 2020, 02:39 PM #10
Sorry, but if you are expecting the whole thing plus the weight of two people to be supported on legs only fitted to two of the cross members you need to either house or mortise them in. Plus your sketch shows the legs splayed out so there will also be twisting forces on them. As much I really like pocket hole joinery the forces being applied to them in this application isn’t what they are designed for.
Poundy’s suggestion of cutting through the mitres and restarting would be the ideal method; alternatively research loose tenons. If you have a router you can cut the mortices in the rails and in the ends of the cross members and insert some hardwood tenons, although it will still involve having to cut through one set of mitres. Unless you cut them from the front and make them a feature...Nothing succeeds like a budgie without a beak.
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2nd June 2020, 04:21 PM #11Senior Member
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Use proper pocket hole screws.
They are self drilling and the square drive is positive.
Regards.
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2nd June 2020, 04:54 PM #12Originally Posted by justonethingOriginally Posted by Wimmera Jack
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2nd June 2020, 05:03 PM #13Originally Posted by Chief Tiff
May I suggest that you stop work immediately untill you solve this problem. Unless fixed, it will destroy your project. Strong words, but unfortunately true.
But do not worry. We have all made horrendous errors in the past. The trick is in how well you recover from them. My interests are increasingly on the design side of design and make, and when I design something now, I simultanoeusly design how to make it - the two are tightly interelated.
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2nd June 2020, 05:05 PM #14Novice
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What about a "floating tenon" / "tongue & groove" type joint?
So, seems like a lot of doubt in the pocket holes, and I do tend to agree that it's not the application they're designed for. A lot of pressure would be placed on a couple of screws - especially the twisting force from the legs.
What about a "floating tenon" / "tongue & groove" / "bridle join"?
I can use a router to cut the "mortice" in the frame and cut some pieces of hardwood to size to use for the "floating tenon" / "tongue". Then cut the groove across the end of the cross member so it can slide over the tenon. See my rough sketch below of what I have in mind.
Bench 5.png
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2nd June 2020, 06:14 PM #15
Might work...
Can you please tell us the dimensions of the cross members and how thick the rails are? And if you’ll be using the same timber that the other components are made from?Nothing succeeds like a budgie without a beak.
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