Author Topic: Mitre joint gaps solution  (Read 3147 times)

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Offline Zebt

  • Posts: 49
Mitre joint gaps solution
« on: January 07, 2017, 10:42 PM »
Hi,

In the process of making a sideboard and entertainment unit.
I'm using 35mm thick camphor laurel wood, well seasoned. It is slightly cupped.
Dimensions are 450mm deep front to back so the mitre joints are quite long, when offering up the edges they of course don't meet well due to the cupping. The sideboard is 2.5metres long.
I am considering routing the edges but I'm guessing this will open the gap more in some of the areas.

One end of the sideboard is a waterfall so I am hoping to get at least this one as accurate as possible.

All suggestions welcome!

Thanks
Zeb


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Offline Chris Wong

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  • Posts: 838
  • I make sculptural furniture.
    • Flair Woodworks
Re: Mitre joint gaps solution
« Reply #1 on: January 07, 2017, 11:46 PM »
Can you flatten the material first before joining it? If not, if you are reinforcing the joint with Dominos or splines, you might be able to clamp the material flat until the joint is glued.
Chris Wong, http://FlairWoodworks.com

The thoughts and ideas expressed here are my own and do not necessarily represent those of http://UltimateTools.ca.  But Dan does say "hello".

Offline mrFinpgh

  • Posts: 203
Re: Mitre joint gaps solution
« Reply #2 on: January 08, 2017, 12:42 PM »
Is there a reason to keep the cupping in?

I can't see a scenario where the cost of flattening out out the cupping is going to be greater than the cost of trying to fine tune a long miter. Especially if you want continuous grain.   

Maybe someone with more experience knows some tricks, though.   I have a hard enough time getting a sharp miter with flat wood!

-Adam




Offline Michael Kellough

  • Posts: 2856
Re: Mitre joint gaps solution
« Reply #3 on: January 08, 2017, 12:46 PM »
As the other guys said, you have to flatten the stock first if you don't want to need bolts across the joint.

Offline Zebt

  • Posts: 49
Re: Mitre joint gaps solution
« Reply #4 on: January 08, 2017, 04:46 PM »
Thanks guys, the reason for not flattening first is both finding a place to do it and the cupping on a few pieces is up to 10mm so it would reduce the thickness too much.
I'll see how I go with the domino's and clamping!

Zeb

Offline mrFinpgh

  • Posts: 203
Re: Mitre joint gaps solution
« Reply #5 on: January 08, 2017, 10:49 PM »
I would consider ripping it down the middle, then.  Not sure if its already been dimensioned to width, but getting rid of that cup will help everything.

-Adam

Offline Chris Wong

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  • I make sculptural furniture.
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Re: Mitre joint gaps solution
« Reply #6 on: January 08, 2017, 11:12 PM »
As long as the cut surfaces are flat, you can join them without a gap. Doesn't matter if they're cupped or anything. The surfaces just may not line up.
Chris Wong, http://FlairWoodworks.com

The thoughts and ideas expressed here are my own and do not necessarily represent those of http://UltimateTools.ca.  But Dan does say "hello".

Offline Linbro

  • Posts: 195
Re: Mitre joint gaps solution
« Reply #7 on: January 08, 2017, 11:14 PM »
Yes, you will definitely need to flatten it. No way a mitre will stay tight, no matter how many dominos you put in, or how hard you clamp it.
10mm is a lot of cup.

Offline Discap

  • Posts: 74
Re: Mitre joint gaps solution
« Reply #8 on: January 08, 2017, 11:50 PM »
Flatten it either with a jointer (hand or power) or cut it and reverse the panels. Even with the cut you will need to flatten. Believe me I have tried it. You will waste the wood and your time.

Bill

Offline Michael Kellough

  • Posts: 2856
Re: Mitre joint gaps solution
« Reply #9 on: January 09, 2017, 12:56 AM »
At 35mm thick how will you cut the miter? Do you have the TS-75?

You need the outer surfaces to be flat at the joint and the flat area needs to be at least wide enough to support the saw track.

You can use a router sled to do the flattening.

The trouble with the simple furniture designs is there is no way to hide mistakes. Everything has to be perfect. Starting with the stock.

Offline Zebt

  • Posts: 49
Re: Mitre joint gaps solution
« Reply #10 on: January 09, 2017, 06:51 PM »
At 35mm thick how will you cut the miter? Do you have the TS-75?

You need the outer surfaces to be flat at the joint and the flat area needs to be at least wide enough to support the saw track.

You can use a router sled to do the flattening.

The trouble with the simple furniture designs is there is no way to hide mistakes. Everything has to be perfect. Starting with the stock.

I have cut all the pieces with the TS55, mitre surface is less than 55mm. I have been experimenting with clamping the worst piece flat, it moves relatively easily to flat, so I'm hoping that once the Domino's are in and I glue up it should hold, i've also done a bit of 40 grit sanding to reduce the worst of the cupping so getting closer.
Now trying to decide what finish to use, ie. oil or go for a glossy finish, the wood has fantastic features.