Ratio!?

[treeturner123]

I'm sure that someone on this forum will have some good ideas even if there is no absolute answer!

I'm looking to make some small Sofa height round tables with a single stem. Base and top will be turned from re-used solid oak strip kitchen work tops so fairly heavy.

Is there a ratio of diameter of the base to the top?

I'm guessing that there may be two answers, an aesthetic one and an engineering one; so the best answer may be somewhere between over cautious and 'That looks ready to tip!'

Ideas please!

Thanks

 

[ChaiLatte]

There are a couple of semi-fixed dimensions in your plan already - the 'sofa height', the thickness of the worktop and the width of the worktop (which imposes a maximum diameter).

Start with a 1:1 ratio at the height you need, using the maximum diameter and adjust to suit.

If you eant to push the envelope on 'that looks ready to tip' consider hollowing out the underside of the top just leaving a full depth rim and hollowing out the underside of the base and filling with lead.

 

[TheTiddles]

Depends where the centre of mass is

 

[Fitzroy]

Tip on its own, with some weight not central (magazines, books, coffee cups), with lots of weight ie a person sitting where they should not? Copy someone else's homework is another option, a google search for 'stem coffee table' returns lots of images. Most to my eye look like the base diameter is 2/3 to 1/1 with the top diameter where the top is relatively small ie 60-70cm, with the ratio of top to bottom increasing with larger diameter tops.

 

[Steliz]

If you have the top and base the same then that will be fine. That's what I did and I've had no problem in several years.

 

[recipio]

The base should be not less than 2/3 of the top. Any more will be unstable.

 

[rafezetter]

Not what you asked for but a possible idea to reduce it being top heavy might be to have the top made in 3 parts - 2 halves with a thin central middle ring (ring not disk) - reason being you could then hollow out a lot of the weight from the two halves interior and use the ring as a disguise for the join.

It would also give an opportunity to have a threaded bolt or rod attached (epoxied?) in the bottom half, that then screws into the stem and adds some tensile strength back into it.

If you have or bought one of those long central boring cutters you could probably do it from both ends and have a threaded rod going right through the middle from top to bottom, with fixings at either end.