DownWest
Well-Known Member
Iroko does move. Two cases were rainwater got under terrasse doors and the new iroko t&g floors looked like a rough sea.
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Iroko expansion?
- Thread starter dgadee
- Start date
Keith 66
Well-Known Member
A lot depends on where in the tree it came from, if its just rift sawn or quarter sawn. But Iroko is variable & can warp quite violently at times. One board i had had for about ten years so it was well seasoned, very dark hard timber. I needed a keel for an 18 ft rowing boat so thought cut it out of that. Marked it on the board with its 2" of rocker & started cutting with the skil saw, as i cut it started curving away the wrong way & ended up 4" out at one end. But i was able to flip it upside down & it fitted the molds just fine!
Graham_Wright
Well-Known Member
Mine is double hinged and, because it doubles as a passerelle, heavy. The bungee would need to be long enough to allow full deployment. However, I think if it were taken from the deck, over the pushpit and down to the end of the ladder, it would work. I have yet to try it.A piece of bungee of suitable length might slow its descent.
Catalina36
N/A
Try two bungees, one at the hinge and one at the end.Mine is double hinged and, because it doubles as a passerelle, heavy. The bungee would need to be long enough to allow full deployment. However, I think if it were taken from the deck, over the pushpit and down to the end of the ladder, it would work. I have yet to try it.
Babylon
Well-Known Member
All wood moves (shrinks or expands) across its width depending on changes in moisture content.
Iroko, like all oily timbers, will have greater resistance to rot, but this has nothing to do with with its "movement in service" which will remain the same.
Quarter-sawn boards (i.e. those cut from the very centre of the tree straight out along the radius) will exhibit least cupping across the width, whereas plain-sawn boards (i.e. those cut through-and-through above and below the quarter-sawn boards will have the least stability in terms of cupping across the width as environmental moisture levels change. This is why fit-critical moving parts like traditional drawer-sides are usually made from quarter-sawn wood, and even then an extra shaving or two is taken off the height (width across the components) of the whole drawer-box to prevent jamming in the most humid of conditions. Bowing and springing along the length depends on many factors (including the section of the tree any given board is from) but is usually only encountered when first getting components out from a well-seasoned board - when the tensions in the board are finally, fairly immediately released! Once this has settled down and the component re-milled to final section, environmental moisture changes will continue to have some effect but this is usually negligible in practice relative to movement across width.
A circular hole bored into the face of a board will become an ellipse as the board reacts to moisture changes: while the radius parallel to the grain direction will remain the same, the radius across the grain will shorten as the board dries and shrinks, and lengthen as it swells, etc.
If movement across the grain is estimated to be a max of say +/- 5% then a 25mm diameter hole will become a variable ellipse with the dimension of the 'moving' axis varying from 23.75mm to 26.25mm.
Iroko, like all oily timbers, will have greater resistance to rot, but this has nothing to do with with its "movement in service" which will remain the same.
Quarter-sawn boards (i.e. those cut from the very centre of the tree straight out along the radius) will exhibit least cupping across the width, whereas plain-sawn boards (i.e. those cut through-and-through above and below the quarter-sawn boards will have the least stability in terms of cupping across the width as environmental moisture levels change. This is why fit-critical moving parts like traditional drawer-sides are usually made from quarter-sawn wood, and even then an extra shaving or two is taken off the height (width across the components) of the whole drawer-box to prevent jamming in the most humid of conditions. Bowing and springing along the length depends on many factors (including the section of the tree any given board is from) but is usually only encountered when first getting components out from a well-seasoned board - when the tensions in the board are finally, fairly immediately released! Once this has settled down and the component re-milled to final section, environmental moisture changes will continue to have some effect but this is usually negligible in practice relative to movement across width.
A circular hole bored into the face of a board will become an ellipse as the board reacts to moisture changes: while the radius parallel to the grain direction will remain the same, the radius across the grain will shorten as the board dries and shrinks, and lengthen as it swells, etc.
If movement across the grain is estimated to be a max of say +/- 5% then a 25mm diameter hole will become a variable ellipse with the dimension of the 'moving' axis varying from 23.75mm to 26.25mm.
