Gater Foam isn't that strong

I would Suggest using 1/4 inch Plywood with a 1 by 2 Frame work for both strength & stability at a minimum and at that laying the the 1x2 on edge you would end up with a minimum 2 in thick platform.

At 6 Feet a single engine would break or fold the Gater foam in half and collapse the whole duck under not to mention anybody that just barely hits it with their head or shoulder the whole 2 foot by 6 food section would fly across the room and send trains crashing to the floor.

Wow! That wasn't what I heard

Wow! That wasn't what I heard from others.  I was told it was way stronger than insulation foam board.  I just never asked when it was discussed if it could span 6' without support. 

Ken L.

Well, I guess i will need to

Well, I guess i will need to do more research on my own on this.  This was a conversation last year during a train show, so I don't even know the people who were in the conversation.  But they suggested the materials came in thicknesses as much as 2".  I was hoping someone who belongs to this forum would have used such product for subroadbed to give information in a model railroad use context.   I'm not even sure where I could find the stuff.

Ken L.

I have never seen thick gator foam

But that doesn't mean it doesn't exist but if you look at the price of the 1/4" thick at $9.00 for a 18"X24" a 6 foot By 24" sheet would be aroung $50.00 Thats a guess as I've never found any over 3/8" thick.

Wait another 8 hours and the rest of America will wake up and give you a more imformed answer.

Dan

Gator Board

I think I'd shy away from Gator Board, not due to it's strength but it's cost.

take a look at some of the prices online for a 2" thick piece.

Engineering thinner sections to make a 6" foot span would certainly be possible, there was recent article in another magazine about using it for show modules, and from all accounts it held up well.

Another option would be to use a mix of materials, such as aluminum bar (say 1" wide strips, along the edges) or even 2 x 4 steel studs to provide strength.

Either way, I'll be interested to see what you come up with.

Dear Ken, Are we talking

Dear Ken,

Are we talking _GatorFoam_ or _Foamcore_?

Correctly laminated, a Foamcore roadbed can support significant weights,
(anyone wanna try supporting a 4-kilo O scale SG Sunset brass 2-6-6-2 loco?
I've done it "without a net" for a Foamcore Module clinic, Inc live laser deflection measurement!),

and tag-teamed with qubelok/aluminium framing,
can create a 1" thick benchwork which can suspend 10 kilos accross a 4'/1200mm span without deflection...

http://carendt.us/scrapbook/page97a/index.html#chicago

http://www.carendt.us/scrapbook/page87/index.html

Happy Modelling,
Aim to Improve,
Prof Klyzlr

Holy Sheep Dip they do make

Holy Sheep Dip they do make 2" gator foam and it would cost you $1000.00 in order to get the size you want.

so I change my answer you can use Gator Foam if your NUTS .

Dan

OK back to Blue Foam you can also get a 4'X8'X1" blue foam and buy two sheets of 4'X8'X1/8" luan plywood and a 1 quart can of foam glue all for about $24.00 to $30.00 total cost for everything.

Then glue 1 sheet of the 1/8" luan to each side of the blue foam and allow to dry fro 24 hours. If you can find a 2'X8'X1" thick piece of blue foam then you will only need a single sheet of 1/8" Luan plywood. 

Any way you look at it you end up with a 1-1/4 to 1-1/2 inch Thick 2'X6' sheet that will make a pretty good base for your duck under. I would suggest placing a 6'X1"X2" CVG (clear vertical grain) Douglas Fir strip on each edge for a little extra strength or better yet a piece of 1"X1-1/2"X6' steel "U" Channel along the two long edges for a really strong and durable 2 ft X6 ft and only 1-1/2" thick  Bridge that will hold a considerable amount of weight and give you the thinnest and strongest duck under possible for the required area without spending $1000.00 on gator foam.

Dan

steel studs or aluminum angle?

Seems to me for this situation you need to balance thinness and strength.  Not only should you be worried about the "bridge loading", but also about the potential for this to get accidentally knocked around.  That's why I'd seriously consider some metal in the design.  What about 1/2" or 3/4" aluminum angle screwed to 1/4" (I'd go for oak) plywood?   Don't forget the "abutments" where this will attach to the rest of the layout, too.

The other consideration will be sound transmission.  You'll probably want something between the structural members and the track to keep the sound down.  

dave

Protection

Even if Gator Foam can span the chasm without bending etc, it still needs to protect the track/scenery which crosses it from accidental bumps and jars caused by people "nodding under" your nod under. In this case, the light weight of the material actually becomes a liablity, rather than an asset.

-George

I'd stay away from Gatorfoam

Personally I'd stay away from Gatorboard for use as a roadbed. While it is strong it is expensive and would bow spanning large distances. It's excellent for use in other areas such as cores for modeling structures. I've even used it for things like raising areas of a layout for structures and under highway surfaces, and my backdrops are hung on gatorfoam.

And as others have mentioned, a huge difference in gatorfoam vs. foamcore. In durability, strength and especially price. I use both in my line of work for building displays and mounting posters, etc. A 4x8 sheet of 3/16" black extruded Gatorboard will run about $50 a sheet at bulk prices. Foamcore is about $12 a sheet.

Operating on Assumptions...

Dear Ken L,

Well, you've recieved a number of answers,
but I fear we (the collective "brains trust") may alll be responding based on assumptions, rather than hard facts.

Can I get you to answer/state the following "problem criteria":

- What scale/gauge are we considering here?

- How much do the _actual_ trains you intend to operate weigh?
(Don't guess, actually break out the kitchen scales and measure them).

- How many tracks are you intending to cross this 6'/1800mm span?
(do I have the 6'/1800mm span dimension correct?)

- Are you intending to use pre-fab track, handlaid, or some mix inbetween on the "bridging piece"?

- Apart from basic track and ballast, is the bridging section going to have to support any other scenery/structures/"stuff"???
(track, throttle, and layout power buss wiring is a given)

- Are you intending for this to be

* swing up at one end (one end free + other end hinged vertically)
* fully removable (both ends free)
* swing aside (one end free + other end hinged horizontally)
* permanently mounted (both ends _Solidly_ anchored in place)
???

- will this duckunder be used constantly during "normal operations", or only for initial Entry/Exit to the layout?
(speaks to the ammount of care being taken by operators while negotiating the duckunder,
and whether trains will or will not be on the "bridging piece" during human movements...)

Happy Modelling,
Aim to Improve,
Prof Klyzlr

- What scale/gauge are we

- What scale/gauge are we considering here?

HO

- How much do the _actual_ trains you intend to operate weigh?
(Don't guess, actually break out the kitchen scales and measure them).

Can't at the moment, becuase they are in storage for the moment, and mostly unassmebled. 

- How many tracks are you intending to cross this 6'/1800mm span?
(do I have the 6'/1800mm span dimension correct?)

yes. the span is 6' across.  about 9' of track or so.  it is one tail of a wye that is a junction between the mainlines that head to Erie, Pittsburgh, and Harrisburg.  All three lines are modeled and will be operated on.  This is why there is a walk/nod under.  one of the branches off the wye has to cross the aisle. 

- Are you intending to use pre-fab track, handlaid, or some mix inbetween on the "bridging piece"?

Atlas, ME, and Walthers (depending on what is on hand) Code 83 Flex track,> - Apart from basic track and ballast, is the bridging section going to have to support any other scenery/structures/"stuff"???
(track, throttle, and layout power buss wiring is a given)

Maybe track feaders and 12 AWG bus wire for the track power because I don't like relying on rail joiners, though I may try to bond the few track pieces together so there is nothing underneath the board.

this is because I don't want to have to worry about aligning the trackage for the wye
 

(speaks to the ammount of care being taken by operators while negotiating the duckunder,
and whether trains will or will not be on the "bridging piece" during human movements...)

Constantly during normal operations.  Most peopel will be able to walk right under it (77" clearance) because I have some operators in the area that are fairly tall.  I'm more concerned of the board sagging.

Ken L.

Dear Ken, Thanks for the

Dear Ken,

Thanks for the info. That helps narrow things down some

FWIW,
- a B'mann HO 8-40CW weighs in at 575grams
- a new Atlas HO GP40 weighs in at 450grams
- a current DCC-compatible Athearn SW1500 weighs 250grams
- a stock latest-gen centre-motor B'mann HO 44 tonner weighs 140grams
- and a stock Athearn current-gen 40' hicube boxcars with metal wheelsets weighs 105grams
(these are from my kitchen scales, and my personal "stock out-of-box" models, YMMV).

Given the scale/gauge you're using,
and the lack of other scenery stuff that could contribute to the load on the "bridge section",
I personally (if in your position) would feel very comfy deploying

- a 25mm square aluminium tube frame
(using the lipped tube intended to provide tabletops and shelve supports)

- with the "deck" being 3 X 5mm foamcore laminated sheets

This combination will be very light weight, will give a 1" thick benchwork ready for roadbed and track,

and is rated to handle a 10+ kilo (22+ pound) load over a 6' span without visible deflection.

Given a B'mann 8-40CW is 10" long, and a 40' car is around 6' long

3 x 8-40CW @ 10" long/575grams ea = 30"/1725grams

+

7 x 40' car @ 6" long/105grams = 42"/735grams

= 2460grams over 72" (that's a "typical load" over your nominated 6' span length),

or just under 2.5 kilos (5.4 pounds) in total.

With a 4:1 rating against the load, Sounds do-able to me,
(you're not looking to build a bridge section you can chin-up your own weight on),
 
and still cheap enough that if you're somehow not happy with it,
you're still in a position to replace it with a lump of 1" thick plywood...

Hope this Helps,

Happy Modelling,
Aim to Improve,
Prof Klyzlr

Gatorfoam Benchwork

 I just noticed the thread on Gatorfoam benchwork and I thought I would give my 2 cents worth on its use. On My Allegheny Terminal HO layout (Great Model Railroads 2010), utilized gatorfoam for all the large steel mill structures. I also used it (1'2" thick) as the subroadbed/non-traditional benchwork for one of the towns. I spanned 16" without any deflection in a three year period. If you want to make Gatorfoam sections extremely rigid; hot glue a three inch strip down each edge at a 90-degree angle to the large flat area and you will be hard pressed to ever bend a 12" - 16" section of it. If I were spanning the 72" section, I would use 1/2" Gatorfoam at a minimum width of say 6" - 12", with the 3" - 4" strips down the side. The whole thing would probably only weigh a pound or so, and it would not flex under the weight of an HO train.

Due to a recent move, the HO Allegheny Terminal layout has been dismantled (anyone need any really large structures?) and in the new smaller space I have, I will be building an N scale Pacific Northwest layout utilizing Gatorfoam for all the subroadbed/"non-traditional benchwork". The actual layout pieces will be modified box sections of Gatorfoam about 12" deep, 6" - 12" high and 48" - 72" long. The Gatorfoam boxes will sit on shelf brackets around the perimeter of the room. On the central peninsula's, they will sit on a modified L girder wooden benchwork for added strength and weight. I don't want to attach legs to my Gatorfoam sections. I would not recommend building all the benchwork out of Gatorfoam, unless it is a shelf type railroad. It is amazingly stong material and I am looking forward to starting construction with it this weekend.

Gatorfoam is not for everyone

This is an old thread I came across doing a Google search for Gatorfoam and model Railroading.

For any one just coming across this thread I would say that to keep in mind Gatorfoam is it is NOT foamcore. Foamcore is the most common sheet material sold at places like Michaels. The surfaces of Gatorfoam are a manufactured hard, wood composite. Gatorfoam is warp free and takes paint well. I use unbraced 3/16" Gatorfoam for my backdrops and 1/2" for my bench tops and even cut 3 1/2" strips for perimeter and cross bracing. For that I had my supplier cut the 8 foot long pieces for me.

I then built 24" x five foot and 22" x eight foot long extensions to my N Scale Mooers Junction Railroad. Both of these are supported only at the ends, leaving room underneath for rolling storage racks.

A Google search for Gatorfoam and Model Railroading will turn up some of my blog posts here at MRH along with info on the award winning models that Dave Myers, my supplier, has done using Gatorfoam.

Yes it can be pricey but for my money, living in an apartment, I can use only hand tools and work late into the night keeping the noise and dust down. Nothing goes to waste and a couple strokes with a knife and you are ready to go. Coarse drywall screws are firmly gripped by  the foam core and virtually anything you can shape with wood or foam insulation you can do with Gatorfoam.

John

blog on using gatorboard

there was a whole topic on using gator board as a module. it was very light and reenofrced.   I don't quite know how to search past topics..it was within the last few months

Suggest you go here and browse for info

http://www.graphicdisplayusa.com/

Check local sign making outfits, commercial photo service providers, etc. for possible sources of supply.

To search MRH

Try a hollow core door

For a panel of this size, try a hollow core door you can get one 2 feet by 6 - 8" (other widths too), 1-3/8" or 1-3/4" thick. Cut it to length, plug the end and add some 1-1/4" aluminum angle along the long edges and you are good to go. Less than a $100 and an hour tops!

Gatorboard is good

I just came back from the Fine Scale RR EXPO and Dave Myers gave an excellent presentation on this subject with a demo of the 1/2" being used to span a 16" gap.

I would use it as it is fast and if you add the glued stiffeners mentioned above, more than strong enough.   Gatorboard is more than just foam.   The hard surface is ideal for mounting your track and it cuts easier than Homasote.   Use Phenoseal adhesive caulk to mount the board and the track.

Dear Bloodhound, Any PDF or

Dear Bloodhound,

Any PDF or notes available from that clinic, for those who weren't in attendence?

Happy Modelling,
Aim to Improve,
Prof Klyzlr

PS a bit over 1/2" (3x 5mm thicknesses laminated together) of Foamcore will support a Sunset Brass O scale 2R UP 2-6-6-2 Challenger over a 400mm (16") span with no deflection, with no additional "L" or "T" girder gussetting/support...

I'd also note that a 60" x 40" sheet of 5mm foamcore is < AUD$20 if purchased in singles, or < AUD$10/sheet when purchased by the carton. 2x 60"x40" sheets will give enough material to build a complete 5' x 1' x 2' full-proscenium module (integrated roof/lighting pelment/backdrop-coved-to-ceiling), or a pair of 5' x 1' x 4" "domino" modules. That's far cheaper than the GatorFoam prices noted here http://www.gatorfoam.net/GF-Order-Form.html