To drawbore or not to drawbore that is the question.

[Fitzroy]

Evening all, I’ve been working on a new garden arch and I’m about there. I’ll update my WIP at somepoint but for now have a question I need to answer before I potentially stuff it all up.

I’ve bracketed the corner joints for extra strength. I’d planned to drawbore all the joints as this is going to be out in the rain for a while. The grain direction on the brackets is I’m worrying not ideal for drawboring.

My options in my opinion are:
- proceed as planned and drawbore the joints with 8mm pegs, tenons are 12mm thick
- clamp, drill and peg with no offset
- drill, screw, and plug through the bracket into the upright/headers.

All thoughts, ideas and comments welcome.

Thanks

Fitz.

PS yes I learnt you can’t slide tenons in two directions at once, took me a bit to figure out how to resolve that one, at least I spotted it before I chopped the mortices!

 

[MattRoberts]

I would have thought draw boring required through tenons in order to be effective, and unless I'm viewing the photos wrong, they're not through tenons?

I'd vote for pegging with no offset

 

[Phil Pascoe]

Why? You only need space at the bottom of the mortice for the tenon to drawn into.

 

[Doug71]

Use some PU adhesive and drill, screw, plug, not proper joinery I know but will be fine.

 

[MattRoberts]

Why? You only need space at the bottom of the mortice for the tenon to drawn into.

Indeed, and having that gap in a mortise is surely not as effective a joint as not having a gap.

 

[Phil Pascoe]

How much are you pulling it up? A couple of mil? Show me M&T that's got a smaller gap in it than that anyway.

 

[Fitzroy]

I don’t think the peg in a drawbore joint moves the tenon more than a fraction of a millimetre, the shoulders are tight up to the workpiece without the peg. The peg just puts tension into the joint and ensures it stays in place.

I’m worried the tension will split off the top of the tenon as the grain direction is not aligned with the tenon. Need I be?

Fitz

 

[ColeyS1]

I’m worried the tension will split off the top of the tenon as the grain direction is not aligned with the tenon. Need I be?

Fitz

That would be my concern as well. Probably safer to just clamp tight and peg.



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[geraldmartin]

Allways found on all the oak gates that I have restored, the rot has entered along the end grain of the dowel into the joint.

 

[Jacob]

Very elaborate constructional details for an out door structure - or indoor even!
Those tenons on the brackets would be very weak, due to cross grain. Be a lot better and easier just flush, glued and screwed.
No need for draw boring anywhere either - even more complication!
Draw boring doesn't make a stronger joint it's just a crafty technique for things difficult to clamp.
Is this thing having a roof? If not, all the joints are vulnerable as water traps.
What's it for BTW?

 

[Fitzroy]

Thanks all for the comments, very helpful.

@Jacob. What’s it for? Two things, to replace a knackered arch that supports a honeysuckle in my garden, and as a fun way to learn/practice woodwork/joinery.

No roof, just some lattice to add. Appreciate lots of the joints are water traps, ho hum.

F.

 

[Sgian Dubh]

As others have said, I too think drawboring the tenons of the bracket into the other members wouldn't be a good idea primarily because of the weakness in the tenons' grain. However, you mention in your last post the exercise was in part to improve your joinery skills. In that vein, if I'd been really determined to give drawboring a go I would have used a loose tenon: create a mortice in both the bracket and the straight members it joins to. Fashion slip tenons with the long grain perpendicular to the shoulder lines of the bracket and glue those into the bracket mortices. After the glue has set you could then glue the other end of the tenons into the straight members and incorporate drawboring.

Would I go to all that trouble? No, but as a learning exercise it could be useful. Slainte.