Rails –a camel built by bureaucrats and engineer

Instinct...

mark hennebury

I am not an engineer, or anything else really, I have no training or certificates at all, consequently I go on instinct. That said, the fastening system that you have used just doesn't feel right to me. I understand that it has been designed by an engineer. tested and verified to far exceed code. I have no doubt that it does what you say it does. I don't like the concept. You have a long lever acting against screws. I also have doubts on the longevity of this design. I certainly wouldn't pay an engineering firm for coming up with it. The joint that I suggested, I have no such doubts or concerns. It is simple, incredibly strong, and will last as long as the bridge. I have no data to back that up, just a belief. You are more that welcome to make one a stress test it. As for construction, there are ways to do production efficiently. Could you get the post cut and drilled prior to arrival at the site? There are many portable power tools designed for timber notching. There are ways. I would choose the best joinery then figure out the most efficient way to do it. I of course work for myself so code is of no concern to me. I have been told that engineer's design jobs to just meet specs, and no more, yet you were able to reduce the fasteners and reduce the size while improving performance. If the engineers did their job, would that have been possible? I just don't like the concept.

Re: Committee of two

Tom Gattiker

This was probably built by very well meaning volunteers, perhaps those who know a lot about trailbuilding, which (like woodworking) is often a lot more complicated than it seems

Re: Hiden screws

TomD

I am not sure of the actual design referred to, but when the head of a screw is countersunk, it is less likely to shear off, and one would hope the design in question is loaded in shear for the most part. Those bolts in Mark's post above your question are just out of the way, I don't see and load transfer from the counter-sink. In wood it may help a little, but for the most part the head failure mode will not be offset by side pressure from softwood.

Of course there is snagging.

One problem with the current practice of running screws in till they often bury out of sight is that without a counter sink and a properly drilled and set screw head, the screws is splitting the wood, and actually destroying the seat. So if the options where; guy with countersink bits and a driver that sets to a prescribed depth; vs, guy with hammer drill letting it rip, it would make a huge difference in execution. And obviously the engineer has data on one procedure and horror when faced with quantifying the other.

Did you guys get Mike Holmes, and his build it right crew? He was a talented contractor who made his TV name pointing out how bad a lot of work was in the Toronto area, where almost anyone can hang out a shingle and do home renovation work. He was very proud of his hammer drill and putting screws into everything, and whenever I saw him smiling at a well installed piece of framing he had screwed into place with his drill and some deck screws, it would mutter under my breath "of course you do realize that nails are a rated framing fastener, and deck screws are not". Low an behold he did a job in the LA earthquake zone and someone who knew the code there, put him straight on screws. Of course there are rated screws but they are incredibly expensive, and they are a lot less likely to be set properly by most folks than that trusty nail. It is a bit like the gluing endgrain issue where people mistake the fact that endgrain joints are strong, because they are not the full strength of the underlying material. But in this case people mistake poor nail resistance to extraction, for bad engineering in structures where the fasteners are all set to mostly resist shear.

Re: Committee of two

Bill Tindall, E.Tn.

What is the "this" you are referring to?

Re: Committee of two

Tom Gattiker

Oh. I was just referring to a picture of a bench that was being discussed. As one who does trail work (and uses a lot of trails) and who is a wood worker, I've observed that the two skill sets rarely overlap! That said, good trail builder do some amazing stuff with dirt, rocks, and such.