ross
Junior Member
Posts: 52 
|
Post by ross on Jul 11, 2015 15:06:19 GMT -5
Hiya, a relative newbie here. I've been chopping up some oak over here in the UK and hope it might be interesting. First a 12"x12" lump of English oak, with beetle and rotten knot;  Draw a circle on the end and cut the corners with a combo square;  rip down with a KSS80  and you have an octagonal post  Next get a 6"x6" and bash it with a drill and chisel:   whizz up and down with a chamfer cutter on a router;  ...and you have a beam;  cut another beam and rasher the end with the KSS80, bash with a "Birmingham Screwdriver" and whittle with a chisel;    and there's a tenon. I think there's a bit of difference between oak framing over here and "square rule" in the US, not the least being that our oak is a bit rough and tough. I think we use brute force and ignorance a lot more! |
|
ross
Junior Member
Posts: 52
|
Post by ross on Jul 11, 2015 16:39:57 GMT -5
|
|
|
|
Post by wrightwoodwork on Jul 11, 2015 16:47:54 GMT -5
Typical engineer then. I have a theory if the method Has worked and lasted for few hundred years what more scientific tests and reports does one need that a technique is suitable
|
|
ross
Junior Member
Posts: 52
|
Post by ross on Jul 11, 2015 17:25:56 GMT -5
Typical engineer then. I have a theory if the method Has worked and lasted for few hundred years what more scientific tests and reports does one need that a technique is suitable Unfortunately the oldest oak peg structures still standing here are only 800 years old, it can't possibly be as well researched as stainless steel which has been around since........1912!! (1820 if you're French or 1890 if you're German). I was at a timber framing conference a few years back where a "famous" engineer said that dove-tail sockets shouldn't be used on jowl-post top-joints either  , having only been used for at least 1000 years (admittedly they do all split!). |
|
|
|
Post by Red on Jul 12, 2015 1:38:22 GMT -5
The engineer has said we need steel pins for the king posts as "oak pegs are not strong enough for tension joints". I'll need to pop over to Winchester Cathedral and down to Portsmouth and HMS Victory to tell everyone what danger they're in   |
|
|
|
Post by wrightwoodwork on Jul 12, 2015 2:15:39 GMT -5
I think we as joiners are passionate about the use of timber and believe in timber and it's structural properties when used in the right way. Where most engineers seem to not be trained in its properties and can't give numbers. Where with steel it's a lot easier for them.
|
|
|
|
Post by mick on Jul 12, 2015 3:55:23 GMT -5
Looks great I like your style keep it coming
As for engineers
|
|
|
|
Post by Red on Jul 12, 2015 13:25:02 GMT -5
...whizz up and down with a chamfer cutter on a router.... |
|
ross
Junior Member
Posts: 52
|
Post by ross on Jul 12, 2015 13:54:29 GMT -5
...whizz up and down with a chamfer cutter on a router.... Thanks Red, I hadn't thought of that, yet another reason for chamfers  |
|
|
|
Post by Red on Jul 12, 2015 14:23:16 GMT -5
Yeah, Ross, I've seen some testing results between square and chamfered edges -- and it's not even close.
Jargon's not my thing any more, but, put simply, it takes a LOT more time/heat to get a chamfered timber to burn and, obviously, this goes a long way toward dispelling the old fear that timber frames are highly vulnerable to open flame.
|
|
ross
Junior Member
Posts: 52
|
Post by ross on Jul 12, 2015 16:13:46 GMT -5
Yeah, Ross, I've seen some testing results between square and chamfered edges -- and it's not even close.
Jargon's not my thing any more, but, put simply, it takes a LOT more time/heat to get a chamfered timber to burn and, obviously, this goes a long way toward dispelling the old fear that timber frames are highly vulnerable to open flame. It's quite well known that oak is resistant to burning down. I also read a claim from the Japanese that fewer people died due to fires in timber houses than more modern structures, though I'm not sure of the basis for the claim. |
|
|
|
Post by wrightwoodwork on Jul 12, 2015 16:36:39 GMT -5
I was at a talk on glulam beams a couple of years back. One of them architects asked what needed to be done for fire safety. The engineer told him nothing needs to be done has timber has its own fire protection by charing which then cuts out the oxygen to the fire which it needs to burn also they know as engineers that timber is very predictable in a fire and chars at a rate of 40mm an hour. Where with a steel building they cannot predict how the steel will react to the severe tempeture it is put under and bends on anywhere all over the place. With timber as they know the charing rate they cam easily add more timber to increase fire resistance where needed
|
|
|
|
Post by Red on Jul 13, 2015 13:47:07 GMT -5
I was at a talk on glulam beams a couple of years back. One of them architects asked what needed to be done for fire safety. The engineer told him nothing needs to be done has timber has its own fire protection by charing which then cuts out the oxygen to the fire which it needs to burn also they know as engineers that timber is very predictable in a fire and chars at a rate of 40mm an hour. Where with a steel building they cannot predict how the steel will react to the severe tempeture it is put under and bends on anywhere all over the place. With timber as they know the charing rate they cam easily add more timber to increase fire resistance where needed
Although the exact wood species would factor into the discussion, natural timbers will certainly burn. I've seen several barn fires in my time and, in my opinion, this is why a lot of folks assume that timber frames are susceptible. Chamfering the edges of the timbers, as was previously discussed, is one way to decrease the burn rate of a natural timber -- because rounded edges take longer to ignite.
Don't get me wrong, I don't think that a timber frame is any more susceptible to flame than many other forms of construction materials, but fire is a common [perceived] concern, nevertheless. |
|
|
|
Post by wrightwoodwork on Jul 13, 2015 15:38:07 GMT -5
They where referring mainly to glulam beams also mainly pines etc obviously all timber will burn when a fire rating is given on anything it doesn't mean it isn't going to resist fire it's the length of time it take the fire to burn through it. Generally when designing a building they are looking at how long it takes the human element to escape or the fire brigade to get there and make safe be it 30 minutes 1 hour, 2 hours or whatever is deemed suitable for the building and it's use and how it's used. I'm sure that somewhere there will be tables on the burning rates of different timber species.
|
|
|
|
Post by Red on Jul 13, 2015 16:24:33 GMT -5
They where referring mainly to glulam beams also mainly pines etc obviously all timber will burn when a fire rating is given on anything it doesn't mean it isn't going to resist fire it's the length of time it take the fire to burn through it. Generally when designing a building they are looking at how long it takes the human element to escape or the fire brigade to get there and make safe be it 30 minutes 1 hour, 2 hours or whatever is deemed suitable for the building and it's use and how it's used. I'm sure that somewhere there will be tables on the burning rates of different timber species.
I was simply complimenting the original poster, Ross, for taking that extra step and chamfering his beams. If taking the time to finish his beams in this manner helps improve potential escape time, so much the better.
I think we can all agree that any added safety measures are a good thing. |
|
, having only been used for at least 1000 years (admittedly they do all split!).
