I wish to build some seating of a half round circular nature which is quite straightforwa5 - 6 cmsd in itself but I would like to angle the back-rest part of the seat and angle the knee to heel part of the seating backwards...the actual seat part will be mdf, the verticals I'm wanting to do in 90mm x 12mm redwood cladding ( later to be painted ).
The diameter of the seat inside edge to outer edge is 138/ 228cm ( so seat width 45cm )
Any tips..
Oooh! This sounds interesting and quite possibly could get overly complicated too!!
Not knowing your thought process Tymbian, I may well be treading familiar ground for you, however, particularly as your request is so open, so here are my initial thoughts. I'll more than likely think of some more or refined approaches, especially with a few of us having a conflab here 🙂
Loft it out full size and plan view. This would give you the arc's for the seat and the boarded backrest. I was thinking of a horizontal rail 80mm or so down from the top of your vertical backboards and for added boing, it could be laminated... Use the full size plan to create the jig kinda thing. I wont elaborate cos I have a feeling you've done this before?
Could introduce another near the feet of the boards, which of course will be a slightly different radius. These could be joined to the seat by a number of thicker section and shaped uprights perhaps?
I'll stop there...
@ Slackalice...I was thinking along those lines. Thing is it has to fit in an octagonal space. I'm thinking to work it out so...a semi-circle with a radiusof 114cms has an arc length of 358cms. The backrest slopes back 10deg to a height of 46cms increasing the radius of the larger semi-circle by 81mm giving the arc a length of 383cms. 383cms devided by 9cms ( cladding width ) is 42.5 pieces. 358cms devided by 42.5 = 8.42cms.
Therefore I would need 42 pieces of cladding 46 cms long ( ends cut at 10 deg ) top remains 9cms wide shamfering down to 8.4cms ( 3mm - 0 off of both edges )
Sounds like you're butting the back boards? Or in other words, no gap between them, if I'm correct understanding that bit? In which case, if you're chamfering down the back boards to suit the difference in top and bottom arc lengths, you'll need to also bevel the edges, so that the boards close up front and back - bit like planking a boat. Quite a lot of work there, or if a gap between the boards at the back is not an issue, then a 90deg cut edge works fine!!
If your back rest is at 10deg from the plumb, then your back boards will need to be longer than 46cm to gain a plumb height of 46cm - but I reckon you knew that! the dim wont be much more than 46cm, possibly 5-8mm at a guess?
I'll take your word on arc lengths C=2 x pi x r an all that. Sounds like you've got that bit thought out.
How are you planning on sticking/joining it together?
This sounds like the kind of thing I'd model in 3d in my lunch hour. 🙂
Hmmm...
Off you go then Taki. Can't wait to see the result..
Quite pleased with this so far first time and all that....
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