How to construct the top for a corner unit seamlessly...

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Forum topic by 404 - Not Found posted 01-05-2013 08:38 PM 1298 views 0 times favorited 8 replies Add to Favorites Watch
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404 - Not Found

2544 posts in 3170 days

01-05-2013 08:38 PM

No matter how I look at this job, all I can see is pitfalls.

It is going to be beech, the diagram above shows board orientation only.

There’s a profile to be routed on the ends and front edges.

Option one:

If I make it from solid beech, the pieces will contract and expand at different rates and eventually it won’t be right. There’s also the end grain to end grain joints which more than likely won’t be perfect. It will inevitably be weak at the joints too.

The only redeeming quality of doing it this way is it wouldn’t take long to make or be terribly complicated to do either.

Option two:

I could veneer the whole thing on a sheet of mdf. The downside being this will take an enormous amount of time, taking in to account the edges will have to be lipped with solid, then veneer over the top of the lippings, then there’s the curved centre piece to do as well. And to stop it puckering up, it will have to be done both sides. With my primitive veneering set up and the reach that is required for clamping where the boards turn the dogleg, it’s going to be a pain, a test of ultimate will, a heartbreak climb uphill…_

Option three:

Veneer sections f&b on mdf, join them together. This is still going to be time consuming but easier than option 2, simply for gluing up. On the downside to doing this, we return to the weak joints mentioned in option 1.

Option four:

This is where you guys come in. What have I missed? What would you do?

I’d appreciate any suggestions or insights you may have. Option 2 is my preferred method, but I’m really not looking forward to doing it. As a postscript, the primitive veneering method mentioned includes making the 1/16 veneers myself. There is a very good chance that my saw won’t be able to handle that much beech.

8 replies so far

View jdmaher's profile


439 posts in 2781 days

#1 posted 01-05-2013 09:19 PM

What is the function of the corner unit? Kitchen cabinets? Workbench?

Is this job for yourself, or a paying customer?

It is unclear what the priority of your concerns are? Stability? Cosmetics? Ease of construction? If all, what’s most/least important?

My guess is that you may be worrying too much about wood movement, but I don’t really know what you’re trying to achieve.

Form follows function, so let us know the intent of the piece and suggestions might be more useful.

-- Jim Maher, Illinois

View Dan Krager's profile

Dan Krager

4202 posts in 2435 days

#2 posted 01-05-2013 09:31 PM

This is interesting.
I don’t share all of your concerns about the solid wood option. First,granted that beech is a relatively active hardwood. Comparing beech to cherry, the movement might be about twice cherry. In 26” the movement would be close to 1/2” for a 9% moisture content change according to the charts. That would be like bringing this into a dry oven from the Florida boathouse. In a temperature and humidity controlled house, not even a 1% change. However, if the 26” radius were built with a T&G in the middle, (fourth board from front) to allow the back to move independent from the front section, then the movement between the center and end panels is minimized. I think a French (sliding) dovetail between the end and center panels is very workable. I might even go so far as to introduce breadboards at the ends of the panels, too, just to break up the visual attraction to the joint itself.

With loose battens underneath or breadboard ends and the same finish on both sides, your panels will stay flat. If you secure the French dovetail at the front only, then any movement that does occur will be noticeable only at the back where there might be a backsplash or molding to cover it if it is objectionable.

No matter how you look at it, it’s a challenge, but that’s the fun right? I’d definitely opt for the hardwood.

-- Dan Krager, Olney IL Now there's a face that would stop a clock! And seriously mess with small watches.

View madts's profile


1873 posts in 2541 days

#3 posted 01-05-2013 09:41 PM

Have all the wood run in the same direction. Yes you will some end grain, but cover that with tape.

-- Thor and Odin are still the greatest of Gods.

View Loren's profile


10477 posts in 3849 days

#4 posted 01-05-2013 09:48 PM

To fix the wood movement problem, change the angle so
each joined end grain edge is 22.5 degrees. If I’m
not mistaken the boards will move equally and you
can confidently dowel the end grain joints to minimize
creeping. Wait till the glue inside is plenty dry before
flushing the joints. Just as with biscuits, moisture in
freshly glued dowel joints can cause the surface
to temporarily bulge while the glue dries.

I’m not convinced you couldn’t just get away with
doweling those joints as you have it drawn, I don’t
think the differences in wood movement would be
enough to split your boards. As you’ve drawn it the
joint is a bit risky, but not frighteningly so.

View 404 - Not Found's profile

404 - Not Found

2544 posts in 3170 days

#5 posted 01-05-2013 11:19 PM

JD, This will be the top for a corner entertainment unit. There won’t be huge amount of weight on it, but as it’s supposed to be a flat surface, and because it’s on the large side and low down, any misalignment or opening up of gaps will scream “LOOK AT ME” to anyone passing. I don’t want that to happen. In terms of priorities, my number 1 concern is that it is stable, 2, strong, 3, not hugely time consuming to construct. It is a commission of sorts (I’m making this for a cabinet maker friend who designed it but is not well enough to make it at the moment).

I considered the 22.5° approach, I can’t help but think that’s a little too unconventional, I considered a frame and panel construction using breadboard ends, but I can’t get the joints looking right with the curved front piece.

I had another thought… well two actually…

opt 2 – If I veneer onto one solid piece of mdf, start with the diagonal section slightly oversize, then clean up the ends with a router using a zero clearance guide, clean any glue off the substrate with a No. 92., then just butt the straight pieces up to it…

opt 3 – Veneer over mdf and join together, but I could rout for long splines on the underside to keep it all together.
this is looking like a winner at the moment.

or… another thought, I could try that 22.5° on a piece of scrap to see how well it will glue up…

View RonInOhio's profile


721 posts in 3065 days

#6 posted 01-06-2013 01:00 AM

The last three boards or so going into the corner seem to be redundant. Unless there are other reasons for that I’m not seeing ,seems like a waste of wood and time there.

I suppose it may simplify things just having it go all the way back into the corner.

View 404 - Not Found's profile

404 - Not Found

2544 posts in 3170 days

#7 posted 03-27-2013 09:58 AM

This is how I did it in the end, photo shows top from underneath. 22.5º Joints cut with router with a mitre at the edge where the curve went into the inside corner. Bicuit jointed, tacked in place with pocket screws, removed pocket screws when dry, routed out for 1/2” fingers. It came out really strong.

Thanks everyone for your help.

View woodbutcherbynight's profile


5702 posts in 2610 days

#8 posted 03-27-2013 03:32 PM

Interesting how this developed and the suggestions made. I like how your final solution came out though. Nice work.

-- Live to tell the stories, they sound better that way.

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