Round Table question - An Update.

[Phil Pascoe]

I've never seen two identical wheelchairs (and being in one I look ) but don't forget they are designed as far as possible to use in a domestic environment - it wouldn't be a good idea to give someone their chair and say - by the way, you need new furniture. I think mountains are being made out of molehills by people who absolutely no experience of a wheelchair, but Steve's comment made a lot of sense - make dummy first and check it out with the actual chair, not just any chair.

 

[SteveF]

not too clever about counter balance calculations myself
but
could the centre post be offset to allow more room?

Steve

 

[Phil Pascoe]

The centre post isn't really the problem - even if it were too close, it would be between your legs.

 

[Jacob]

......- make dummy first and check it out with the actual chair, not just any chair.

You don't even need to do that - just run the actual chair up to an existing table and see how much room you have or have not, and plan accordingly.

 

[Zeddedhed]

Thanks for all the replies.
It does seem that a few assumptions are being made that are leading to some 'interesting' comments.

To clarify a few points:

I would always make up a mock up of a piece such as this - almost a given I would have thought.

The clients wheelchair DOES need to go underneath the table a significant distance. This will not hamper him from using the table - rather it will help. As someone pointed out not all wheelchairs (or users) are created equal.

The central pillar design is NOT inherently unsuitable for a wheelchair user for the reason given in the second half of the above point.


I should point out that I genuinely have found it helpful to read the discussion my original question prompted, but (and I say this with some trepidation and genuine humility) the original question was simply to ask if anyone was aware of a set of design guidelines for circular tables specifically relating to stability.

Some of the replies could be seen to imply that I haven't given this enough thought. If I'd asked how to design a circular table for a wheelchair user I would have expected the replies I got, but I didn't (and I didn't, if you follow).

Anyway, I really am grateful that you all bothered to reply. This is probably not the right place to have a little semi hissy fit but I do sometimes see this on threads where an OP has asked a question and is deluged with replies that are not answers (which is not always bad) but sometimes seem a tad derogatory.

If this all sounds like bollocks then sorry. Maybe it's the heat.....

 

[Jacob]

....
The central pillar design is NOT inherently unsuitable for a wheelchair user for the reason given in the second half of the above point.
.............

If you say so, but I had a prob with a table for my old mum - circular table with central pedestal with 3 splayed legs base. This got in the way because the chair footrests were low and projected well forwards, i.e. inherently unsuitable design.
The solution was a normal rectangular table but with the legs well in from the ends (about 18") so that the top projected out over empty space. This meant she could use the end of the table easily - get her feet under (between the legs) but also swing the chair out sideways as there was nothing in the way, neither legs nor structure on the floor.

Some round tables have a very small footprint. Stability is up to the user I guess. This one might be a hazard at a drunken party!

Hope that helps!

 

[Zeddedhed]

If you say so, but I had a prob with a table for my old mum - circular table with central pedestal with 3 splayed legs base. This got in the way because the chair footrests were low and projected well forwards, i.e. inherently unsuitable design.

Unsuitable for your old mum I agree. Not all wheelchairs and their users though.

Having said that I do wish the client would simply let me build a square/rectangular table with either large overhangs as you suggested or widely spaced legs so that his w/chair can easily fit between them.

I guess thats one of the challenges of building something bespoke especially when the brief is very specific.

Obviously there will come a point where if the brief is simply not viable given the other constraints (cost, space etc) then the brief may well need to be amended.

But I do like a challenge.... :roll:

 

[Jacob]

....
But I do like a challenge.... :roll:

Sounds like the challenge is to make your client change his/her mind!
Oddly enough my old mum was really keen on round tables as she thought you could get more people around them, which is not really true at all. I had to show her the error of her ways.

 

[Zeddedhed]

So now the design has been finalised, mock up's have been mocked up and we're all set to go but.........

I need some advice on a couple of the elements if you would all be so kind.

Firstly, here's a (very quick and dirty) sketch up view of the design:

The central column supporting the table is going to be approx 65mm diameter from American Black Walnut.

The plan is to make it from 4 bits of 35 x 35 glued up and then turn it down. I chose this approach for reasons of stability although I accept that this might not be required with properly Kiln dried wood. I also reckon it'll be cheaper.

Can anyone see any problems with this?

Next the feet. They will be made from a Walnut/Maple?walnut sandwich and then shaped on the bandsaw/rasps/sanding/biting - whatever to get them to a kind of 'slipper profile' Although the drawing shows them ending at a point almost, they'll actually be about 8mm thick at the end. At the middle they'll be 25mm thick.

The joinery (?) to join them all together will be as straightforward as I can get it.

One foot will end in a point, the other two will be square. The whole lot will be dominoed together. Then I was planning to drill three holes and insert some 10mm threaded bar that will extend about 200mm up into the column, all held in by some kind of epoxy resin.

A similar arrangement of 'feet on the top' fixed to the column with long screws and to the underside of the table top with shorter screws.

As for the top, the client wants solid wood but is prepared to budge on this if it causes the table to become unstable.

Therefore the alternative is to veneer either ply or MDF.

There are two potential problems with this:

1. I've never done ANY veneering and have no idea how to do it, other than: make round top - stick on veneer - cut off excess.

2. Definitely need a solid edging so that it can have a profile. I have no experience of steam bending so would have to machine up a curved 'band' of Walnut approx 30mm thick by 40mm wide.

Any thoughts people....

 

[Jacob]

..
Any thoughts people....

Mainly that you should look closely at some existing round tables (and or designs) or you risk attempting to reinvent the wheel.
e.g.
Small round tables with solid tops (12 to 18mm?) are common and don't usually have any sort of edge except a thumbnail moulding or similar. May have two battens under.
Larger ones may have a constructed ring apron - built up with small lengths of softwood laminated, lapped , glued and nailed, then veneered. Easier than it sounds - you build it like a model aircraft i.e. lightly pin the first layer to a board with the pattern on and build up from that.

 

[Zeddedhed]

..
Any thoughts people....

Mainly that you should look closely at some existing round tables (and or designs) or you risk attempting to reinvent the wheel.

Maybe I should have said 'Any useful thoughts people'

 

[Zeddedhed]

Any takers?

Are my table making suggestions that strange?

 

[Jacob]

Any takers?

Are my table making suggestions that strange?

Joining a 65mm dia column to a flat base, without the usual triangulation of brackets etc, looks like the biggest prob. That's why I said to look at other tables.
None of them do what you are trying to do - because it won't work, at least not without some hidden steelwork. Why not just go for steel?

PS the nearest I could see to your design is this one, which looks like wood but has a massive cast iron base and column.

 

[Sheffield Tony]

Firstly, here's a (very quick and dirty) sketch up view of the design:

View attachment 1259

The central column supporting the table is going to be approx 65mm diameter from American Black Walnut.

The plan is to make it from 4 bits of 35 x 35 glued up and then turn it down. I chose this approach for reasons of stability although I accept that this might not be required with properly Kiln dried wood. I also reckon it'll be cheaper.

Can anyone see any problems with this?

Next the feet. They will be made from a Walnut/Maple?walnut sandwich and then shaped on the bandsaw/rasps/sanding/biting - whatever to get them to a kind of 'slipper profile' Although the drawing shows them ending at a point almost, they'll actually be about 8mm thick at the end. At the middle they'll be 25mm thick.
[snip]
Any thoughts people....

Looks fairly likely to tip. I mentioned earlier that I wouldn't go for 3 feet. Look at your drawing; when one foot is lifted off the ground, the remaining two provide the fulcrum. A line through the tips of those two feet - about which the table is hinging as it tips - is not a long way out from the centre. It is half the length of the foot, to be precise (legs length L, 120 degrees between them, L * cos (60) = 1/2 L). When the C of G passes that line it tips. Added that, the centre of gravity looks high with the thin feet and thick top, though that could be just an illusion depending how you make it.

 

[Jacob]

I was thinking more of the join from column to base. A bit of weight on the edge of the table would pull out the bolts from the base, or loosen them so it'd wobble about. A lot of leverage there, in a small area.

 

[Zeddedhed]

So to update on this one.....

After a few mock ups and more discussion and some design refinement the table finally got made.

Here's some 'photos of what we've ended up with.

This is how it went together

Detail of the feet

And another

Anyway, not wanting to gloat or anything......BUT, it's very stable and the client is extremely happy. He can sit comfortably at it in his wheelchair which tucks under nicely. The footrests miss the table feet by about 15 - 20mm so he can get as far under as he wants to.

The mockup was tested to destruction which involved me standing on it (about 18 stone) and gyrating and jerking like some kind of teddy-boy on drugs. It actually withstood enough of this treatment for me to get all sweaty, before it eventually gave way leaving me in an undignified heap in the workshop whilst the apprentice laughed so much he was sick.

It's basically just screwed together - no glue. I decided that if running repairs were needed for any reason then best not to glue it up. We'll see.

Thanks for looking and thanks for the advice back in July everyone.

 

[Zeddedhed]

One final question on this for you all.....Does anyone have any ideas about what I could put on as a final finish coat that would offer weapons -grade protection without to much faff. It's currently been subjected to 3 coats of Osmo Polyx Clear Matt (as is nearly all of my work these days..

 

[flying haggis]

After reading the entire thread, I rather like the final outcome, simple elegant and obviously turned out to be very functional =D>

 

[Phil Pascoe]

I'd have thought the only thing that would really go on top of Osmo would be a wax - so microcrystalline.

 

[custard]

One final question on this for you all.....Does anyone have any ideas about what I could put on as a final finish coat that would offer weapons -grade protection without to much faff. It's currently been subjected to 3 coats of Osmo Polyx Clear Matt (as is nearly all of my work these days..

Nice job, in fact very nice job as you've succeeded in giving a boring old table design a contemporary spin and that takes some doing. I'd have loved to see the Sycamore repeated somewhere else on the table to re-inforce the motif but I guess there comes a time when the price can't justify any more work.

Regarding finishes, if you've applied Polyx then there's nothing further to be done without stripping it all off as nothing, not even shellac, sticks to Polyx. But that's okay, Polyx gives superb protection against spills and stains (although not much mechanical protection against scratches) and is dead easy to freshen up with additional coats in the future in case it does get scratched. Actually, that's a big plus as a number of finishes aren't that easy to freshen up, many versions of Danish Oil won't actually adhere to themselves (if the instructions talk about recoating not less than Y hours and not more than X hours then it's one of these), pu varnishes rarely adhere well to themselves once fully cured, and a couple of dustings with a silicon spray like Mr Sheen would also cause problems for many finishes...but not Polyx. Your choice of the Matt finish Polyx is ideal IMO as too much of a shine wouldn't sit well with the contemporary design.

But for future reference a wiping varnish would give a harder finish, although even adding extra flatteners to a matt varnish would still result in too much shine for my liking.