Making a semi circular table

[morpheus83uk]

Hello,

I am looking at making a semi circular table which I have started cutting out the semi circles however I am trying to work out if my idea will work. I am using 27mm thick pine and the semi circles will be 280mm radius. I am thinking of putting a 22mm thick piece of pine (or maybe two) which is around 300mm wide using a mortise and tennon joint towards the back so the top (which will have some circles grooved out for some cups etc) will be on there. so effectively its sitting on a semi circle and also the weight is on the hanging part of the top. And example of what I am trying is attached (just pretend the ovals are semi circles).

Also I am going to finish with some Danish oil to give it some protection and also a bit of color.

Would this work or would it just simply not take the weight? If not could anyone point me in the direction I would need to go?

Thanks

James

 

[MikeG.]

You might be better with a pencil & paper sketch. It's almost impossible to decipher what you're attempting from your description and a misleading drawing.

Why are you cutting it out if you aren't sure if it will work?

 

[morpheus83uk]

Hi Mike,

I will get that sorted ASAP. I can cut the semi circles as they will be the main design however its how I make them stand is what I am unsure about so I can cut the semi circles just nothing further until I know where I am going.

Thanks

James

 

[ScottGoddard]

Hi - I believe i have done something similar...

the bottom piece needs to extend past the top to provide some stability, IMHO.

 

[morpheus83uk]

Happy New Year!

Yes Scott that's is very similar!

I haven't got very far with the cutting yet at the router killed by bit when I was using it as the variable speed just ramped up to max and wont do anything else so it needs to go back tomorrow for repair. So I have only partially cut out the top semi circle.

So how much bigger would I need to make the base? Maybe a 20mm bigger radius would that be enough?

I also notice that you have a bar for stability on your top I was hoping to do it without and just a mortise and tennon so it doesn't protrude like yours as it will be sitting next to the sofa as a side table and can be moved out into the room if needed. Would this work or would the weight cause issues?

Thanks

James

 

[MikeG.]

Happy New Year!

Yes Scott that's is very similar!

I haven't got very far with the cutting yet at the router killed by bit when I was using it as the variable speed just ramped up to max and wont do anything else so it needs to go back tomorrow for repair. So I have only partially cut out the top semi circle. ..........

Well take that as an opportunity to develop your hand-tool skills, James. It will be quicker and easier with a few basic tools than it would be with a router, and you'll be finished well before your router is repaired.

 

[sunnybob]

If I'm guessing correctly, you want to make a semi circular side table to hold drinks while in your chair, and also to be able to move it into the room to serve other chairs?

There are a couple issues if so;
If the semi circle is 28 cm, then the front to back is going to be only 14 cm at best.
You'll barely fit two small coffee cups with saucers on that, and even then the saucers will be overhanging the edges.
If you have carpet its going to be extremely unsafe.

I strongly advise changing the shape to more round or square to give you more surface area, and you would need to add considerable weight to the base to stop tipping over.

 

[morpheus83uk]

MikeG How would I go about doing this with hand tools?

SunnyBob Yes that's pretty much it.

The radius of the semi circle is 28cm so the diameter is 56cm and front to back will be 28cm.

It will be going on a wooden floor not carpet as we don't have any carpet downstairs.

How would I increase the weight to the bottom? Would increasing the bottom semi circle to 30cm radius giving a diameter of 60cm be enough weight to stop the tipping? Or would it need to be bigger? Maybe have an oval for the base and mount the stand in the middle with the semi circle on top so there is some wood at the front back and sides but a slight overhang from the semi circle?

Thanks

James

 

[sunnybob]

Thats a better size than I first thought.
basic physics says you have to more weight at the bottom than the top to make things safe. Either increase the bottom diameter, or double up on the wood, or screw a metal plate into the underside, options are many, but you must take into account to total loading on the top, not just the empty weight.

But would those sharp corners be a nuisance when the table is in the middle of the room? Accidental knocking over is also something to be considered before you invest a lot of time building. (Theres a good reason why most coffee tables have 4 legs).

 

[ScottGoddard]

so the vertical piece is one piece that is screwed into the bottom that provides extra stability. However, there is still some flex (not alot to worry about though). The top piece slides over the vertical piece, with a 2-3 inch hangover on the back end, also acts to balance (although not a great deal).

I assuming you aren't going to have any hangover and mortise the top and bottom from the vertical piece. I think you would need a 30mm bottom and 20-25mm top. To me anything smaller wouldn't give you material to create a joint strong enough.

Looking at your design you also my suffer from lateral movement, rather than back - front as you would only have 20-30mm of glueing surface.

 

[morpheus83uk]

Ok thanks for all that.

If I were to mortise and tenon just the top but more in the center to distribute the weight over the stand more and increase the base radius to 30cm / diameter of 60cm and screw the base into the stand do you think that would be enough to prevent the lateral movement / balance issues with the weight of say 3 pints of beer being the most on it?

As it stands I will have just the top cut out so everything below is open for discussion.

Thanks

James

 

[morpheus83uk]

Just having a think about this and I am thinking of making the base 400mm radius giving an 800mm diameter in the 27mm pine I have currently. I am going to bring in the mortise and tenon by an inch or two for balance and stability which should hopefully then hold anything placed upon it given the weight on the floor with a near double size base as the top.

Would this be more adequate for what I am planning?

Thanks

James

 

[Racers]

Do you have enough wood to make a mock-up with screws instead of joints?
I would be the best way of testing your design.

Pete

 

[morpheus83uk]

Unfortunately I don't which is the problem but I do see what your saying.

 

[Racers]

Bodge together some pallet wood, old shelves, chipboard etc

Pete

 

[morpheus83uk]

I was thinking that but I wasn't sure about how the weight would be distributed and if it would be a proper test.

 

[Racers]

It would go a long way to proving the design.

Even a charity shop wardrobe should produce enough for a couple of mock ups.

I made a softwood mock up of my dining room chairs before making them, I had to change quite a lot, but as it was a mock up a couple bits screw on didn't matter.

Xmas Chair maquette and finished one by Racers, on Flickr

Pete