More lamination

[EASLOOP]

To build my sister frames I am intending to use 5mm thick by 30mm wide by 300mm long strips of timber. They will need to be cold bent through a radius of 150mm. I planned to use oak but white ash may bend easier. Does anyone have any experience with cold bending with either of these timbers.

 

[kds]

I have cold-bent 4mm ash with no trouble at all and steam (or hot water) bent oak up to 9mm for frames. It dries and takes a curve quite quickly - but why dont you try a bit of each by making up a short laminate and bonding it on a simple former. Then let it go !
Ken

 

[Spuddy]

I like ash, many good properties - used it for my tiller. But oak a much better choice for down in the bilges cos ash not durable in those conditions.

 

[johnlilley]

Ash bends a bit more easily than as oak, but it would not be advisable to use ash because it is not durable in contact with fresh water. When choosing the timber, you'll find that if you cut the frame with the growth ring pattern on the end grain parallel with the wide side of the frame (plain sawn or slash sawn and running fore & aft along the hull)) it will bend easier than timber with the rings parallel to the short sides (quarter sawn or rift sawn and at 90 degrees to the planking), it does make a difference.
John Lilley

 

[EASLOOP]

Well, looks like ash is a no-no, so its back to oak. Not a bad thing really. If I steam bend can I bend a 25mm thick by 30mm wide by 300mm long length of oak through a radius of 150mm?

 

[johnlilley]

Sounds a bit steep to bend anything of that thickness over such a tight radius if it is only 300mm (1 foot?) long. Far better to take the shape of the hull at that point and attach blocks of timber to a section of 18mm plywood at points on the curve then laminate a section of frame on the board, much easier than working on the boat and cleaner and more reliable.
Cut a cardboard template using the hull exterior at that point and just fair up any knuckling, also easier than working inside.

John Lilley

 

[EASLOOP]

Thanks for that. I meant 3 feet, not 300 mm. Does that change anything?

 

[johnlilley]

You might be lucky if the timber is straight grained, slightly green and very hot having steamed for a good time and you are very quick, no guarantees either way, probably worth a try, if no good you'll probably have to laminate.
John Lilley

 

[EASLOOP]

Thank you again for your help. So it is now full 'steam' ahead, as it were and if that doesn't work I will laminate.