[mandalayurts.com]

Hi all,

I'm quite intermediate in my wood working skill.

I'm making traditional door frames for yurts which incorporate large mortises for the four sides of the door frame to simply slot together. I'm making it from pine and spruce wood, with shou sugi ban / yaki sugi treatment. .

As you can see on the photo, this soft wood can easily begin to split out at the ends when making the mortises.

What would be the best way of preventing this from happening? One idea would be to join a small piece of oak with dowels, square on, next to the mortise to prevent further splitting out.

I know however that oak will move much less than the softwood and in humid conditions, I'm not sure how the join would effect the softwood, struggling to move against the solid piece of oak...

Any suggestions or advice are welcomed, with much appreciation

Thanks!

Charlie

 

[Steve Neul]

When you are planning the wood for glue up dowel the joint each side of the mortise. Still it shouldn't split until it is under a lot of stress if it is a good joint. Generally a glue joint is stronger than a solid board, the wood should split elsewhere than the joint. When you prepare the wood for the glue joint you should be able to dry fit the wood and have no gaps laying on the table without clamps. If you have to use clamps to force the wood together the pressure used to force the wood together is how much pressure there is pulling at the joint trying to pull it apart.

 

[Tony B]

.......... If you have to use clamps to force the wood together the pressure used to force the wood together is how much pressure there is pulling at the joint trying to pull it apart.

Well said.

 

[DrRobert]

It is a split, not a glue line failure.

My first thought was two crossgrain dowel pins on either end of the through mortise, but I think your idea is a good one.

Four inlaid strips - top/bottom & both sides 1/2” thick x 1” wide + thru pins either side will add a huge amount of strength!

 

[mandalayurts.com]

Well thank you all for your input, very helpful to get confirmation of my idea with some useful hints how to make it a good job.

I think what Steve is saying is that I should plane my board perfectly flat to contact the oak reinforcement perfectly, otherwise there will already be stress upon the joint right from the outset. Is that right?

There is a pretty massive cup in the board, I wonder whether I'd be wise to search for a better one that trying to plane it out actually...

 

[DrRobert]

If I‘m reading yiu right, you want to glue the oak to the surface id the pine? IMO thats not a good way to go about it.

If you just glue it to the surface you‘ll have a chunk of wood stuck on cross grain and no pins or dowels? - you really want to do that? Your choice - you have to evaluate how much stress will be on the mortise, and how durable you want it to be & if you want any craftsmanship in it.

If that doesnt matter or it won‘t show, then just screw and glue the batton on, it will take most if not all odf the cup out, too.

If you want to do it right, do what I said. 😆😆

 

[mandalayurts.com]

Thanks Robert. No, I do really like your idea with the inlaid strips. I was thinking about it more - I have to consider where my skills are up to the task, maybe I need to watch some tutorials on that.

My idea with the oak might seem a bit crude, but the block would actually also help support the door uprights. My idea was to fix the baton with dowels as I said, although I'm wondering if perhaps some wide screws would hold in even better, reducing cupping problems.

Dowels or screws with glue - which would give more strength?

Thanks for helping me to learn.

Charlie

 

[DrRobert]

So these boards with the mortises are vertical? A pic of a drawing woukd really help.

But yes, if the battons would also function as a support, they can be attached to the surface rather than inlaid. Screws would pull some or all of the cup out and be plenty strong enough is they’re big enough #10 or 1/4”

How are the boards with the tenons held in place?

 

[mandalayurts.com]

On a yurt, the doorframe is simply 4 pieces of wood, slotted together. The uprights or 'tenons' are pulled outwards due to their attachment to the tension band that runs around the wall.

Here was my solution today - but very much a solution in progress - I will be making more of them! So please comment if you have any better ideas...

I planed across the grain to make a flat, shallow groove where I join the oak block with dowels.

Planing across the grain was a bit rough, and sanding wasn't so quick as I'm without a belt sander. I sanded it down by hand until there was no gaps more than 1mm, then used polyurethane glue to fill gaps (of 1-2mm should be acceptable and still strong as far as I understand).