Project update: the Petrolia & Erie

Folks:
Two 2 x 4 grid sections have been completed. The 2 x 4 L-girders made earlier were joined by short L-girders into a
grid. After finding that the first, which had yellow glue and wood screws at all joints, made distressing cracking noises when 'tested', I switched to Liquid Nails for the small-area joints, and started using drywall screws at all joints, having run out of wood screws. Both units seem extremely rigid against bending and racking stresses; twisting is decent but not perfect. There has to be a way to make a light model RR frame that won't twist! Maybe I could try some 1 x 2 cross-bridging...
Having put aside the question of legs, I am now pondering my options for topping these units. I want a flat top, lightweight yet rigid, cheap to build, with all fasteners from below, and of course /quiet/. What does everybody think about:
-1/4" plywood or masonite glue-laminated to 2" foam- the board holds the screws; the foam provides rigidity, and can be sculpted. Track would be laid on cork roadbed. Cost, probably .75 per square foot. I could also use just foam, at .50 per square foot, but would have to glue this, which I'm trying to avoid.
-3/8" or 1/2" plywood or waferboard with 1/2" Homasote glue-laminated to it. Track would be directly laid on the Homasote. Not so easy to sculpt, perhaps, and a bit more expensive, at $1 per square foot, but perhaps quieter and stronger? Certainly it would hold nails better.
For this section of board, since it's going to be a flattish industrial area with a number of spurs, I'm not going to bother with open-grid work. If I use the Homasote-plywood method I may well space the board out 1" or so, though.
Has anybody some suggestions or favored methods I might try here?
Cordially yours: Gerard P. President, a box of track and some grids.
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snipped-for-privacy@gannon.edu wrote in

Have you considered building triangles into your structure? They're the best geometric shape for keeping things in place.

Get good plywood if you're going as thin as 1/4". If you're thinking of moving the module (for shows or moving every couple years) stop no shorter than 1/2" cabinet grade. "I need your help to move this" is a lot easier than "I've got to fix this huge crack down the middle of the road."

I haven't used homasote, but one complaint I heard often about it is its responsiveness to humidity.

Build slow, and take the time to reevaluate your work if you're not sure about it. That way, you've only got a module or two to fix, rather than a whole layout.
I made the decision to finish (but not superdetail) each module of mine before I went on to the next module. As a result, I've always got something different to do and space to try something new.

Puckdropper
--
Wise is the man who attempts to answer his question before asking it.

To email me directly, send a message to puckdropper (at) fastmail.fm
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Puckdropper wrote:

Use deeper but thinner sections of timber - even use plywood in place of timber.
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snipped-for-privacy@gannon.edu wrote in
In the below, I suggest using baltic birch rather than regular wood or other plywood because it is much stronger, has twice or more number of plys, and its outer layer won't shred like soft plywood (bitter experience here with Home Depot plywood). You will need to find baltic birch at a hardwood supplier. 1/2" is stronger than 3/4" regular plywood or dimensional wood.

Next time consider using 1/2" baltic birch plywood for the frame, fastening it with Tite-bond yellow glue and airgun brads. Incredibly strong and true.

You do not need the plywood if you do below. 1) Make sure that you get flat 2" foam. I got some that wasn't. 2) Nest the foam inside the frame, either all 2" or less and glue it with Tite-bond also. Knife cut, foam cutter, or sand the foam so it just fits inside and doens't distort the frame. 3) A 2" triangle or square of 1/2" baltic birch in the corners will strengthen the corners and provide a ledge so the foam is all at the same depth.
You could nest it only 1" deep if you wanted a stream to wander through. If the module is just flat, consider gluing and bradding 1/4" baltic birch to the top and adding a 1" brace every 18" or so to prevent any sagging.

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On 26 Mar 2007 12:53:12 -0700, snipped-for-privacy@gannon.edu wrote:
You might try (if you have access to a table saw or radial saw) using I-beams made from 1x2s on their sides, with a 3/8 deep groove centered in one facing side of each, and a 3" piece of 3/8 MDO or plywood glued into the grooves as the web of the beam. Lighter and cheaper than the usual 1x2 plus 1x3 L-girder combination, but reputed to be quite stiff.
And triangulated bracing can help resist racking.
--
Steve

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Steve Caple wrote:

Racking or twisting resistance is a function of the depth of the framework. It pays to use the lightest possible beams, so the above is a good suggestion. The same method is used in so-called engineered floor joist systems.
Trevor Marshall (IIRC) published an article in RMC in which he described building 4" deep frames made of 1/4" or 3/8" plywood. He used hot glue, screws and 1x1 blocks in the corners, adding diagonals to triangulate the whole frame. He first cut large holes (ca. 2" diameter) in the beams. The holes lightened the framework, and also provided passages for the wiring. The frames were 4ft to 6ft in length an up to 2ft wide. IIRC the lumberyard ripped the plywood sheets for him. He wrote that the net cost about the same as for the usual frame made of 1" dimensional lumber, and a good deal lighter, despite the extra bracing.
A lot of work IMO, but probably justified for portable module sections, or in preparation for the moves that seem inevitable in one's career-building years.
A bricklayer friend has given me cutoffs of black extruded styrofoam insulation panels 15-5/8" wide by 3" or 3-1/2" thick. Very light, very rigid, won't rack, period. I will be gluing two of these side by side to make a "frame" 31-1/4" wide by about 48" long, as base for a portable N scale exhibition layout. Two pieces of 1/4" ply glued to the bottom will help hold the pieces together, reducing strain on the center joint. (Just an oval of track with passing siding and a couple of spurs, looping round a bay, tunneling through a headland, and crossing the harbour mouth on a bascule bridge. I want an excuse to build a lighthouse.)
HTH
--


Wolf

"Don't believe everything you think." (Maxine)
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Wolf:
Hmm. I read Marshall's article a while back. It seemed like a good system for a solid top (I can't recall if such was his layout). I do wonder how well it would work out with open-grid framing. Probably the 3/8" ply would flex too much.
Seems like his holes should have been about 1-5/16". ISTR that a beam isn't greatly weakened by crosswise holes that take up no more than the central third. Of course any horizontal drilling would make it less rigid in the horizontal direction...a 2" hole through a 4" beam would cut strength in this direction in half (in the vertical direction the effect would be much less).
I've seen this thick styrofoam, and it is indeed rigid stuff. What's it used for, walk-in coolers?
Cordially yours: Gerard P. President, a box of track and some grids.
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snipped-for-privacy@gannon.edu wrote: [...]

Well, no, it wouldn't actually. The resistance to flexing is in the geometry of the frame, not the size of the members. Marshall's frame is a full 4" deep. Every cell is a triangle, none a rectangle. That's what makes it rigid. Compared to a 1x3" beam, the 4" beam is about 2-1/2 times more resistant to vertical bending. The triangular braces increase resistance to sideways tipping, which would result in twisting of the whole frame. The result is a very rigid frame, much more rigid than a 1x3 frame even though the beams are much thinner.
However, you're right that a skin on the top and bottom would increase rigidity even more. It would prevent almost all sideways tipping of the beams. IIRC, Marshall did put a 1/8" or 1/4" skin on the bottom of his frames. As for open grid framing: the risers and roadbed of an open grid system would actually add to the stiffness of the frame.

You can remove a good deal more than 1/3rd of the material. The plywood spars used in WW2 fighters had holes about 2/3rds the depth of the spars. And consider a truss: it's a beam with triangular holes in it. Most of the beam has been removed. Or consider an I beam: that's a solid beam with most of its material removed, too.

Most of the resistance to bending/flexing is near the edges of a beam. The further apart those edges are, the stronger the beam is. I forget the formulas, but IIRC a beam that's twice as deep has four times the bending resistance. **

No, regular wall insulation, installed between the studs. Or glued to the concrete block walls. Easier and much more pleasant to install than fiber glass batts, and a higher R value, too. Up here, we believe in keeping the heat inside in winter and outside in summer. :-)
--


Wolf

"Don't believe everything you think." (Maxine)
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GP (and others),
What I did was the following... I went to the lumber yard and bought some good one side 3/4" plywood. I had them cut it into strips that were three and four inches wide by the length of the material. I estimated how many of each I would need.
I had a pretty detailed plan that I worked off of for the frame. I carefully used thin long nails and wood glue to build the framework; I used the three inch strips on their edge. I tried to consider section joints and having some longer strips for added strength & rigidity. I made smaller sections in the garage then assembled them in my train room due to doorway considerations.
Once I had the entire frame completed on the floor in my train room, I added the four inch strips on the outside so that the bottoms were even with the framework. This made the framework recessed an inch inside of the outside framing. I also added some simple metal 90 angles in strategic corners for extra strength & rigidity. Now comes the hard part... I raised the entire grid up on some boxes that looked like milk crates to attach the legs. I was careful to keep the tops of the legs level with the tops of the framework. I attached the 2x4 legs with wood screws & bracing.
Next, I laid sheets of 1/4" luan plywood on the framework. Where necessary, I simply marked them from below to fit then cut them out. I used wood glue and an electric brad gun to secure the plywood to the framework. When the framework was completely covered, I did the same ting with 3/4" blue foam insulation board. I tried to stagger the joints for extra strength. After the parts were cut to fit, I glued them in place with Liquid Nails that was compatible with foam. The 3/4" foam and 1/4" plywood made up the extra inch so that when I was done, the deck of the layout was even with the boards I used on the outside of the layout.
My layout kind of looks like a big capital "E" and it is strong enough that a relatively light tap on the one end can be felt all the way around to the other end. The layout is in a climate-controlled area (heat & A/C) but I have not seen any issues with moisture causing warping or anything along those lines. The boards on edge give you plenty of space to run wiring in such a way that it doesn't hang down in the way. All in all, I'm pretty satisfied with the way it turned out.
What I would do differently would probably only be to use 1/2" plywood instead of the 3/4" There isn't a whole lot of difference in price, but it would be lighter and probably about as strong. But the 3/4" foam glued to the 1/4" plywood seems to be plenty strong.
By the way, cork roadbed is glued to the foam; track is glued to the cork roadbed. That makes it pretty quiet. If you use any kine of nails that run into the plywood, that will allow the sound to resonate from the bottom of the layout like one large speaker. The only problem with this track-laying technique is that you need to be pretty sure where you want your track to be laid; the glue isn't easy to remove from the track and nearly impossible to remove from the foam & cork roadbed.
If anyone wants a more detailed description, please contact me outside of the group & I'll try to explain in more detail what I did.
dlm ------------- Dan Merkel
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Dan Merkel wrote:

I would go with the 1/2" plywood sides to the frame rather than 3/4" or even lighter. (we've been metric in NZ for the last 30 years) I've used 9mm ply. For the top surface I use 9mm Chipboard (coarse MDF) plus 12mm Pinex (compressed soft fiber) and on the outside faces I use 3mm or 5mm brown Hardboard. 3mm where the edge stops at baseboard level and 5mm where it forms the backscene and boxes in the structure'
My reasoning is that the trackbed needs mass to dampen train noise. Where the track rises or falls within the baseboard I make sure the corners in particular are gussetted with the 9mm chipboard and also areas between tracks that aren't required to be open for access are filled. I think the depth of the sideframes is important for rigidity but the thickness needs only be sufficient to stop them buckling from weight (people leaning on layout) so possibly a single 1/4" thickness might do the job. I keep meaning to try making the backscene the rear frame structure, but baseboard construction always seems to be hurried as I always seem to be focussed on the layout to come. ;-)
The other two factors I now try to keep to are total weight (moveable by two people, one being my wife) and baseboard (module) size small enough to fit through a standard doorway.
One I built was so precise that it jammed going through the doorway because I hadn't taken account of the vinyl to carpet floor covering transition.
Regards, Greg.P.
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Hadn't really noticed, but I guess we have more than one "GP" on the group.
dlm
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There can only be one!
Let the duel begin *8^}
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Paul Newhouse wrote:

I've missed something here - is Dan suggesting I've contradicted myself and are you suggesting I'm likely to face myself with pistols or swords at daybreak???
I merely posted my prefered method of building baseboards based on 43 years experience - everyone is free to build how they like IMHO.
Regards, Greg.P.
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Greg Procter wrote:

GP:
Actually, Greg, I think he just noticed that you and I happen to have the same initials, and pointed it out for general amusement.
Cordially yours: GP (The one with the box of track and some grids.)
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snipped-for-privacy@gannon.edu wrote:

Wolf gets a bit stroppy at times for no apparent reason. I thought he was at it again. I normally sign as follows:
Regards, Greg.P.
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Hi Greg:
This is off topic, but
I was sitting in a medical lab with my 86 year old Aunt this week, waiting for our turn to get her tested, reading an article in last week's U. S. News and World Report on Iceland (one place I've fantasized emigrating to), and the article said that in a survey of 168 countries, Iceland, New Zealand, and I think Finland were tied for the three countries with the least corrupt governments.
On the other hand, does New Zealand still prohibit U.S. Navy ships carrying any atomics from making ports of call there?
Wayne
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Wayne L wrote:

Well, we really don't understand why the rest of you accept corruption in politics!

Absolutely - why would we run the risk involved in allowing _any_ nation's nuclear powered or armed ships in our waters???
Regards, Greg.P.
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Greg Procter wrote:

If you're allowing any US combat ships into your ports the chances are that they're bringing nukes in with them any, to hell with treaties. Let me give you some details. I was in the US Navy in the early 1970s. I was on the nuclear weapons handling team for my ship. Japan also prohibited any nuclear-powered ships or nuclear weapons to be brought into any port. When my ship went to Yokosuka we did *not* offload our nukes first. Instead, extra lead shielding was placed around each warhead to prevent any stray radiation from being picked up by Japanese inspectors on the pier with highly sensitive radiation detection equipment. (They were prohibited from coming on board for a visual inspection.) The shields weren't something that we rigged up out of spare parts. They were standard issue to any ship carrying these warheads made just for this purpose. The US Navy intentionally and repeatedly violated our treaty with Japan, just as we have violated treaties with the Indians and other nations through the decades.
--

Rick Jones
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Rick Jones wrote:

So far the USa has "refused to confirm or deny ..." the existance so they have not come to our ports. The problem is the USA's.

Obviously there has to be a degree of trust for obvious reasons - you are telling us that the US doesn't deserve any trust - I can't say I find that in any way surprising.
Meanwhile, this is a model railway ng so perhaps we should stay with that topic.
Regards, Greg.P.
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I don't see much risk. Doesn't New Zealand have any nuclear generating plants? As Al Gore says; they're carbon neutral :-) The answer to the "why" is.........we industrialized 1st world nations need to stick together, like we did in WWII, Korea, Vietnam, Kuwait, Iraq and Afganistan, for mutual protection, and to spread democracy, freeedom and a better standard of living for everyone. I think there is a good chance that a day will come in the not too distant future when we, western civilization, will suffer such a devastating attack from the muslims and/or communists that only nukes, and lots of them, will beat them back into submission to the ground rules of the civilized cultures. Will New Zealand stand up and do it's part, as Australia and so many other counties have in the past?

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