Author Topic: "L" girder question  (Read 1998 times)

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Chris333

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"L" girder question
« on: December 23, 2010, 06:07:16 PM »
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Got my wall up and all the L girders are now installed. Here you see one of the 1x2's that will lay across the L's:


On top of the 1x2's will be 2" foamular 250 (higher PSI) So how far apart should I put the 1x2's to support the foam? Every 12" sounds a little too much.

Ideas?

Basic plan for reference:
http://picasaweb.google.com/ErieChris333/NewLayoutSpace#5548911296893943538

davefoxx

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Re: "L" girder question
« Reply #1 on: December 23, 2010, 07:12:34 PM »
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Chris,

Ed's spacing his shelf brackets at 12" with no other support.  That seems to be sturdy enough, but 16" may be pushing the limit.  It would be so disappointing later if the foam develops a sag.  I don't know if the higher PSI foam will be stronger, but one idea would be to place a 1"x2" along the back (against the wall) and a 1"x2" stringer across the face (parallel to the L girders).  Think of building a ladder.  That way, you would have built a framework (not just a joist every 12" to 16" or so) to support the foam at the front, the back, and at every joist.  Then, joists spaced 16" apart may be enough.  But, admittedly, I'm speculating.

The framing is looking good so far.  Keep those pics coming.

Hope this helps,
Dave Foxx
« Last Edit: December 23, 2010, 07:14:55 PM by davefoxx »

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DKS

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Re: "L" girder question
« Reply #2 on: December 23, 2010, 08:14:39 PM »
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I made a similar arrangement for one layout, but to support the foam reliably, I ran 1x2s lengthwise as well as across. I just attached the longwise parts to the ends of the crosswise parts to make a box. With this arrangement, I only had a crosswise piece every 24 inches, and it was more than adequate.
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Sokramiketes

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Re: "L" girder question
« Reply #3 on: December 23, 2010, 09:44:04 PM »
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Any aversion to just putting plywood on top of your L girders and layering foam on top of that?  Seems like it would be less work.  The L girder with 1x2 method is more for cookie-cutter plywood roadbed, so you can vary the height of the supports.  I don't think you need it in this instance.  And besides, those L girders must not be that far apart, if you want to be like Ed you might just be able to put foam down directly on top? 
Mike

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Chris333

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Re: "L" girder question
« Reply #4 on: December 23, 2010, 10:48:35 PM »
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The L's are close here. On the other side they are about 2' apart. In the past I have just used a grid of 1x2's with foam on top, but it is never perfectly level that way. I figured the L's would keep things level since I worked them with a 6' level for 2 hours. Plywood means I have rent a truck again...

Guess I can box the 1x2's in, but still use the L's to keep them level.

wm3798

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Re: "L" girder question
« Reply #5 on: December 25, 2010, 12:27:26 PM »
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Maybe I'm old school, but I like to use a plywood sub roadbed, then use the foam to fill in the blanks with scenery.



It makes it easier to manage grades (which may not be an issue for you) and just generally provides a more stable base for the track in my opinion.  Plus, I don't have to be nearly as finicky about cutting and filling the foam, since none of it needs to be adjusted for trackwork.

Lee
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93cram

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Re: "L" girder question
« Reply #6 on: December 25, 2010, 02:15:30 PM »
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Guess I can box the 1x2's in, but still use the L's to keep them level.

Chris, you can always have a try with some piece of 2" foam (you'll have to buy it anyway) and cross girders located either at 16 or even 24" to test the resistance of the whole.

I'd agree that L girder would be enough particularly if you double the foam breadth (which would give you some 3 to 4" of under track
level terrain to represent ravines etc...).
If you decide to go with foam only upper benchwork, I'd advise to lay your track on a strip of some harder material (hardboard, thin plywood,
etc...) than foam, or even cork.
I've settled on 2mm PVC flooring material for ease of cutting as well as sound deadening properties.

This PVC sub-base will represent my track under bed layer (some 4" for a double-tracked line), while I don't want add a cork trackbed because it would make my track profile too high for a 1950's prototype IMHO.
I can always go with some thinner material (1mm) to locate under sidings.

FWIW, I guess the kind of track profile you're looking after (modern mainline or otherwise) may have some influence on your choice of benchwork and track bed material.

Marc

Chris333

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Re: "L" girder question
« Reply #7 on: December 25, 2010, 02:21:21 PM »
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I don't really have a problem with plywood, but then I would have to know exactly what every scenery element will be before I cut the plywood. I just love foam.  As for grades, if there is even one slight little dip anywhere my steam engines will find it. If I had a table layout I could level that easy, but an around the room/walls layout is harder to level. This house is 85 years old so the rafters aren't perfect, can't measure down from them. The floor is newer and slopes to a drain in the center. The part of the layout closest to that drain is 1" further to the floor than the rest.

Guess I just overbuilt it with the L's. At least it isn't shelf brackets   :P

After I lay the 1x2's and they are level I will add a few long end 1x2's.



Chris333

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Re: "L" girder question
« Reply #8 on: December 25, 2010, 02:59:57 PM »
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Pics of the test:

14" apart.



Seems to be OK.