OK, just how large is to lare, I went through the steps just like Bruce said to but did not resize it, so how small does it need to be?
SmokeboxRob Wright said:
OK, just how large is to lare, I went through the steps just like Bruce said to but did not resize it, so how small does it need to be?Smokebox</blockquote>Rob,
Size: 650 pixels wide by x high
Resolution: 96 dpi
File size: <100K i.e somwhere between 50K and 100K
OK, the scaned image is at 100 dpi when I get off work in the morning I will redo it. Thanks
SmokeboxRob,
To get good quality you scan at 300dpi, afterwards you start adjusting for usage on the internet.
If you are planning to build a large bridge, it is amazing just how much structural steel tubing/channel/angles/etc. are required. I once looked at building a large scale version of the Devil’s Gorge bridge in 1:32 - needed something like 1200’ of various profiles for the 12’ span! I decided I’d rather have a new car.
Anyway, there was a thread on the “other” large scale site last year about the structural strength of brass shapes when used for bridge construction. It inspired me to look into the possibility of forming my own shapes from galvanized sheet steel. I’m fortunate to have a fairly complete sheet metal shop and shearing/bending up to 16 gauge steel is not that difficult for me. Anyway, I made up some 48" long “C” channel from some scrap 20 gauge sheet lying around in my garage. The results were some channels that were 3/4" high with 1/4" deep flanges.
I then did some testing on them. Simply supported (placing the ends only on a couple of bricks) I used a dial indicator to measure deflection at the center of the span for a standardized weight. For this testing I used a single, center located weight of 10# - simulating the loading of a moving large scale train gets a bit more complicated, but could be approximated by developing a distributed load test - i.e., place a 2# weight every 6", etc.
Anyway, the results showed some fairly predictable patterns, but also showed promise for large scale bridge building. For those of you that care, I performed the testing on a Grade A 36 x 48" granite surface plate utilizing a Brown and Sharp dial indicator - suffice to say that this gives an accuracy far exceeding anything that would even be remotely required for LS bridge building. The results are the averages of three separate determinations - after set up, the weight would be gently laid/balanced at the center point, the result recorded, the weight removed and the process repeated. All the testing was done within a two hour period when the temperature was between 75-78^o F.
Placing a single channel flat (the two short legs facing down) resulted in a deflection of 0.486". Flipping the channel over improved the results - 0.425". This makes sense - the latter configuration exploits the compressive strength of the steel within the short legs.
Placing a single channel vertically was relatively simple, but balancing a 10# weight on the 1/4" wide flange was impossible, so I stacked some bricks to about 18" high and suspended the weight using some fishing line. Given the larger vertical cross section, the deflection was considerably less at 0.356".
Placing two channels vertically back to back to form an “H” column on its side resulted in a deflection of 0.226"
I then clamped the two channels together, drilled holes every 6" and pop riveted them together. As expected, deflection again decreased - now it was 0.208". I would suspect that tack welding would produce an even stiffer column.
At that point, I became convinced that it would be viable to build a bridge using home made structural shapes, though I had yet to fabricate angles, T’s or tubing sections.
I also have not tested any such shapes made from aluminum (you could get rolls of 0.032" aluminum that gutter installers use - could even get them precolored in a dark brown to represent rust). While aluminum would resist weather much better, welding it is much more problematic though possible. I suppose the structure could be designed to make pop rivets less visible if one objected to them.
Brian
OK, let’s see if I did it right this time…
IT said it was copied to the clipboard but where is it at, as I do not see it here.Well, Rob, you need to load it to a server. (ie: My Files here on LSC or something similar like trainweb, geocities, etc) then you place the URL on the page to where it’s located (http//:www. somethingorother.com) example: http://www.lscdata.com/users/kenbrunt/ _forumfiles/lumbermill06.jpg
BOB WRIGHT: I would look into useing steel (as in mild) or aluminum shapes. Steel you could weld or braze but aluminum you would need to bolt (unless you learn to weld aluminum which is tricky). Also, you might want shorten up the bridge a bit! Remember you bridge something you can not fill as the CP did in the 1860s. They would build a trestle and come back later and fill in the gap!
Paul
After reading this thread a few times, and doing a few minor calculations; I’ve come to a conclusion.
You could probably go out and purchase an inexpensive “Mig-welder”, along with all the light steel you would need, and a metal cutting blade for your chop saw; for the price you would have to pay to purchase the brass for this planned bridge.
A good steel bridge will last as long as you will ever need it in any outdoor situation, and be less likely to be stolen for scrap value…
Does anyone sell steel angles, channels, etc comparable to K&S brass angles?
E. Paul Austin said:
BOB WRIGHT: I would look into useing steel (as in mild) or aluminum shapes. Steel you could weld or braze but aluminum you would need to bolt (unless you learn to weld aluminum which is tricky). Also, you might want shorten up the bridge a bit! Remember you bridge something you can not fill as the CP did in the 1860s. They would build a trestle and come back later and fill in the gap!Paul
SmokeboxI think all of you are making sense, I just wanted the bragging rights of being able to say I had an 8 foot long brass bridge.
You know how some folks in the smaller scales will snuff their nose at ya if you didn't have something brass. I call it poor manners. But I'm sure you all know what I mean.
Plus I thought that by spending 20-30 bucks on brass each payday would soften the pain in the wallet of making a monster like that.
SmokeboxRob,
You thought the money was gonna hurt? What about all the blooming work with all the unexpected little glitches - unless you live in a “Murphy free zone”. 
I just ordered 220’ of 1/2" square steel tubing for a welded bridge. It was .65 cents a foot. Will borrow a chop saw from a buddy to cut up the pieces and got a welder to weld it up for $60. So not bad…Jerry