Benchwork Decking

[PRR1]

As I get closer to entering the stage where I put on the decking for the benchwork frame, i have found that I do not want to use what I originally planned. I was going to use the extruded pink foam, but after the recent posting about it, I decided to go a different way. I am now leaning to plywood or OBS board. What do you members recommend? Also 1/4" or 1/2" thickness?

Thanks

[selector]

If it is to be your main nether surface above the joists, I wouldn't go less than 1/2".  In fact, I use medium grade 1/2" ply, the kind used for sheeting under a roof.  However, many will insist that 5/8 and 3/4" are their prefered thickness.  What matters is that it doesn't delaminate easily, isn't badly warped, and that you support the 1/2" stuff with joists of some kind on 12-14" centers.

Crandell

[aflyer]

PRR1,

It sounds like we are both about at the same stage in our build.  I am no expert but based on what I have read here and on other train forums, I will be using 1/2 plywood.

I stopped by Lowes tonight, and can buy 4X8X.5 "hardwood" plywood for $36.00 a sheet.  I think I counted 7 ply and found no voids, at least on the edges of half a dozen sheets I looked at.

Good luck with your decision,

Aflyer

[matthewd5]

The way I look at it, your gonna put a whole lot of time and labor into everything that goes on top of this surface and through it...

I went with a 3/4" sheet of oak plywood, but its hard to come by, my next best choice is Baltic birch plywood, it is often used by cabinet makers for its fine finished quality and high quality construction

look for a specialty wood place, the sort of place that might cater to woodworkers

I think it's worth it in the long run and its not that much more than AC Plywood

matthew

[HObbyguy]

It sounds like several of us are around the same point- just posted essentially the same question a week or so ago.

General (average) consensus is 1/2 to 3/4 inch ply, the better the grade then the less that thickness is critical.  And spacing 12-14" or so.  Based on this I picked up a sheet of the 1/2" hardwood ply from Home Depot and should be ready to lay it out and begin cutting sections this coming weekend.  But I only bought one sheet to try out, and mentally prepared to go buy something better if I am not satisfied.

[jrbernier]

  I used 1/2" plywood - Sanded on both sides.  It is supported by joists on 16: center.  I have had no problems with warping for sagging - 26 years.

  I would not use OSB, it is just too unstable.  I have seen folks use it, but it is just not smooth and I have seen it come apart after lots of water based scenery work.  If you can afford it, common birch plywood is really nice to work with, but about twice the price!   Baltic Birch - Don't even ask about the price!

Jim

[aflyer]

If I was going with a flat table top I might opt for the 3/4 inch, but I am doing a cookie cutter top with grade changes.

I wonder how the 3/4 inch plywood would bend to accomodate 2 and 3% grades?

Thank you in advance,

Aflyer

[selector]

All plywood will bend, some more easily than others.  As I said earlier, I used 1/2" exterior ply for my several bench tops and for the sub-roadbed of my one-coil helix.  Some of it coming off the high side of the helix is cookie-cutter, all the same stuff.  Depending on the quality, if you get down to 3/8" and thinner, it might not take a steeper vertical curve into a severe grade without delaminating somewhat...or catastrophically.  Decent 3/4" won't bend very easily for sharp rises; it'll need more room to get to a given grade. 

You'll find that anchoring cookie-cutter strips of 1/2 -5/8" plywood for about 6-8" along the bottom and then bending it into a 3% or 4% grade over the next 18" is quite doable.  Just do support it every 10-14", including under the vertical curve, to keep it all put over the long term.  Reverse it all at the top.

Crandell

[matthewd5]

i really think for the huge time/labor investment its worth the extra effort and expense to get better plywood than regular lumber yard stuff

i've built a bunch of other plywood based work tables and with decent 3/4 plywood i've never needed any cross braces, just the 2x4's used around the border

i'll definitely keep an eye on it to see if there is any warping but i'd be really surprised

matthew

[woodman]

Being a cabinet maker, using baltic birch or oak plywood is complete over kill. The amount of money you would spend on those two products would be better spent above your layout and not under it. I have never heard of anyone using oak plywood on a layout. I would go with 1/2' plywood, exterior is fine, just check for voids and knots. I am assuming your framework is 12" to 16"on center, if the joist are  any further apart then I would go with 3/4" plywood.

[matthewd5]

I just had the oak plywood hanging around from a cabinet project

I still think Baltic birch is a viable choice

Matthew

[HObbyguy]

selector

You'll find that anchoring cookie-cutter strips of 1/2 -5/8" plywood for about 6-8" along the bottom and then bending it into a 3% or 4% grade over the next 18" is quite doable.  Just do support it every 10-14", including under the vertical curve, to keep it all put over the long term.  Reverse it all at the top.

I've been wondering about that.  By "anchor" do you mean run a support lengthwise underneath the ply right before the grade change starts and ends?  That's what I did last time (many years ago.)  But my vertical easements were too short and grades too steep for good operation.  This time my max planned grade is 2% and I've been figuring on about 12" easements at bottom and top by bending the 1/2" ply.  Does this sound reasonable or should I figure on longer easements?  Obviously the longer the easements, the steeper the grade in between so there has to be a bit of a balance.

[doctorwayne]

aflyer

If I was going with a flat table top I might opt for the 3/4 inch, but I am doing a cookie cutter top with grade changes.

I wonder how the 3/4 inch plywood would bend to accomodate 2 and 3% grades?

Thank you in advance,

Aflyer

I used 3/4" firply, and it worked just fine for my grades, most of which are 2.5% or less.  My layout isn't cookie-cutter style, although the roadbed is pre-cut from plywood curves, which are then spliced together to get the necessary length of run.  It forms its own vertical easements if you install the grade properly.

To do so, I attach risers to the bottom of the roadbed which coincide with the joist-spacing of the layout's framework.  Because most of my grades are on curves, I next install the cork roadbed and, when the glue has dried, the track.  (This isn't necessary, but it makes a later step much easier.)

At the bottom of the grade, pick a riser at least 1' before the point where you want the grade to start, and fasten it to its joist.  Repeat this at the top of the grade, using a riser about the same distance beyond where you want the grade to end.
Next, find the mid-point of the run between those two points:  if your track is straight, a tape measure works fine.  If it's curved, a much easier-to-use measuring device is a train of known length.  It doesn't have to be pulled by a locomotive - hand-power works fine.  Once you've located that point (remove the train if you used one  ), manually elevate the nearest riser until the the mid-point is at one half the total elevation, and fasten that riser to its joist.  With a short grade, and using 3/4" plywood, you should be able then to simply attach the remaining risers to their respective joists, as there should be no sagging.
If your grade is a longer one (the one shown below is about 45' long), repeat the measuring exercise to find the 1/4 and 3/4 points, and continue to subdivide the run as necessary, elevating the risers to the calculated proper height and fastening them until no sag is detected where the risers are not attached.  They can then be attached, without raising or lowering, where they sit.

It's also possible to add superelevation (with built-in easements in and out of it) if your grade, like mine, is curved.  For this, having track in place allows you to place a train on the curve to see how much superelevation "looks right".

First, make a pencil line across all risers at the point where they intersect with the top of the joist, then remove all of the screws holding the risers to the joists.  (You don't want the train in place quite just yet ).   Next, raise the mid-point riser, as you did before, but when the pencil line becomes visible, push the bottom of the riser towards the outside of the curve.  This will twist the roadbed all along its length, to a diminishing degree as it gets farther away from that point.  Align the inside end of the pencil line with the top of its joist and clamp it in place (the remainder of the line will be above the joist top, and rising towards its outer end).  I like to place a short train (5 or 6 cars) atop this mid-point of the track to see if the superelevation needs to be increased or decreased - adjust accordingly, then fasten that riser to its joist.
Next, working in both directions from the mid-point, elevate the risers until the pencil line is just visible, taking care to ensure that you don't apply any sideways force to the riser - the easiest way to do this is to lift the roadbed rather than the riser.  Align the inside end of the line with each joist top, and fasten in place.  As you work towards each end, you'll notice that the outside ends of the pencil lines will become closer and closer to level with the joist tops - evidence of the self-creating vertical spiral easements

Wayne

[matthewd5]

Wayne, beautiful bench work, more photos please

Matthew

[galaxy]

I would NOT use OSB, I have read too many others complaining about it, especially if you are to glue down your roadbed as the glue and such can separate the layers and chips { as I understand it}.

Now I have a question, WHY are you not going with your first choice of extruded foam?? I used it over an open gridwork 12" on center and found it to be very nice.

I didn not, and would change it next time, to include a 1/4 underlayment of luan plywood first before I put down the foam,as IF i ever wanted to add undertable switch machines, I would like the luan to "bite into" with the srews when mounting the undertables.

My own personal opinion is that, unless you want to build a ton of weight on the table top, and if you have adequate understructure to support it, 1/2 ply should be fine. Many roofs of a different code era, have only 1/2 ply over 2x4s, so if good enough for heavy roof and snow loads, should be able to support a layout, even if you crawl on it..

[mobilman44]

Hi,

Trust me on this one....... do 1/2 (or comparable) plywood.  The pressboard can be difficult to work with, and 1/4 inch ply may flex and have a "drum effect" noise wise.   Some folks use 3/4 (or comparable) plywood, and while there is nothing wrong with that, it is (IMO) overkill, being too thick and heavy and more expensive.

[cuyama]

aflyer

I wonder how the 3/4 inch plywood would bend to accomodate 2 and 3% grades?

It works fine.

[selector]

HObbyguy

selector

You'll find that anchoring cookie-cutter strips of 1/2 -5/8" plywood for about 6-8" along the bottom and then bending it into a 3% or 4% grade over the next 18" is quite doable.  Just do support it every 10-14", including under the vertical curve, to keep it all put over the long term.  Reverse it all at the top.

I've been wondering about that.  By "anchor" do you mean run a support lengthwise underneath the ply right before the grade change starts and ends?  That's what I did last time (many years ago.)  But my vertical easements were too short and grades too steep for good operation.  This time my max planned grade is 2% and I've been figuring on about 12" easements at bottom and top by bending the 1/2" ply.  Does this sound reasonable or should I figure on longer easements?  Obviously the longer the easements, the steeper the grade in between so there has to be a bit of a balance.

Yes, you find a way to anchor the first/lowest several inches to level.  Then you bend up the next 18 inches or so for a 2% grade, somewhat longer for 3%, even longer for 4% (if you really must) so that your steamers, for example, can stay connected to the rails and maintain their tractive effort.  A piece of cross bracing or some thicker blocking well secured to the rest of the underframe will do, just so long as it is firmly held in place and serves as a firm base for the length of plywood cookie cutter sub-roadbed that you intend to bend upward to form the vertical curve.  If it were me, and the grade is to be tangent, I would cut one long length of sub-roadbed, anchor the first 7", bend it up and anchor it halfway along its length, and then reverse the process at the end of 8" if possible.  If your grade is longer than the length of a sheet of ply, you'll have to make the two lengths meet at a block where they abut each other and lay end-to-end atop that block.

Personally, I would want somewhat longer vertical curve for a 2% grade than 12".  It might work well, don't get me wrong, especially for diesels.  If so, by all means, make it that way.  It would not be wrong.  However, for longer steamers, I would add about another 6" to those curves for a 2% grade, and 3% would be closer to 24".  If we don't have the space, our vertical curves must be shorter, hopefully not to the detriment of our trains.

Crandell

[HObbyguy]

I've got two long grades to/from a 4" overpass, and as drawn (in XTrackCad) one measures 210" and the other 263".  And yes I have a long articulated steamer.  So if I go with 24" easements and assuming a perfect circular curve for the easement to the grade tangent then I will only gain/drop about .2" in height along the easement.  This will increase the grade along the rest of the track by about 0.3%.  That would leave me at 2.2% and 1.8% theoretical grade along the main runs.  Just thinking out loud and making sure that I am not too far off base.

If all that is correct then not too bad, of course there are curves to contend with and I will need to join ply sections, so in the real world the effective grade will be greater in some areas.  I plan to test and tune before "nailing it all down" but wanted to confirm a good starting point before laying down track.  This discussion has helped a bunch.

[PRR1]

Thanks to all of you for your replies. I guess this is a popular subject since I counted two more posts regarding this same question.

I believe I am going to go with 1/2" plywood. I made my benchwork into 13 separate sections. The largest size is 24" x 48" with two stringers on 16" centers. I have three small ones that I may have to put a stringer in, since it would violate a 16" distance. These would be an 18" x 20", 24" x 24" and a 24" x 26". 

Thanks

[aflyer]

Wayne,

Hi that is one large and awesome layout you have going.  Thank you for the tips on creating the grades, and  the superelevation.  I have attached a copy of my track plan below as you will see this needs to be Cookie cutter, and creates somewhat different challenges than if I was doing joists and risers.  But I can use your method for elevations. I was planning to do some superelevation by shimming the A/F rubber roadbed.

http://i236.photobucket.com/albums/ff97/gkcooper/NewTrackPlan_zps26595e75.jpg

Thanks again,

Aflyer

[fwright]

I know it's traditional with AF and Lionel layouts, but given your track plan, you might want to consider not "decking" the surface.  Just provide a plywood subroadbed (1/2" sawn plywood) where the track, buildings and accessories are located.  The lower level subroadbed can be laid directly on your joists and girders that you would otherwise use to support the flat surface.  Upper level(s) need risers.  The rest gets left "open grid" until you put in scenery, much like Wayne's layout.

For the scenery between the plywood subroadbed and flat areas, you can use plaster (or plaster cloth) over cardboard strips, or window screen.  Or just use slabs of foam cut to fit.

my thoughts, your choices

Fred W

[hornblower]

aflyer

I stopped by Lowes tonight, and can buy 4X8X.5 "hardwood" plywood for $36.00 a sheet.  I think I counted 7 ply and found no voids, at least on the edges of half a dozen sheets I looked at.

I used this product to fabricate my open grid benchwork.  Great stuff, although I see the price has bumped up a bit since I purchased mine.  Smooth finished surface on BOTH sides with no patches, 7 plies and no voids.  I would buy this grade plywood again if I were starting over.

[aflyer]

FWRIGHT,

Thank you for that insight, I may not have been using the term cookie cutter 100% correctly. I have been struggling with fully decking the lower level, not only because  I see it as a waste of plywood, but it would also make wiring the upper level much more difficult.  

If I am reading  your suggestion correctly, and looking at my plan  I will just need to deck the lower level where the track and buildings are.  

For the upper level on the long leg the deck will be cut out roughly in the shape of the track with a 1- 2 inch overhang to allow for cardboard webbing and plaster cloth. This gives me the scenery base for the upper leg.

Again if I am understanding your suggestion,  I think I can follow the same  process for the shorter bottom leg following the track with a 1 - 2 inch overhang for webbing and plaster cloth.

Thank you,

Aflyer

[aflyer]

HORNBLOWER,

That is great news, I am glad you are able to confirm this stuff worked well for you.  I can quit my search and go shopping sooner. Like maybe Friday night so I can start cutting up on Saturday.

Thanks again,

Aflyer

[aflyer]

Hornblower,

I went back to Lowes after work tonight and got my 1/2 hardwood plywood.

I have a new post out there asking for some guidance on my bus wiring and provided I get that somewhat completed tomorrow, I will be able to start cutting table top.

Thanks again for your confirmation on this product, 

Aflyer

[IRONROOSTER]

I use 1/2" plywood B/C supported on 16" centers.  Works fine.

Enjoy

Paul

[yankee flyer]

Aflyer

I  assumed your were using the "cookie cutter" method, Bad judgment on my part, but yes it saves a lot of plywood.
I cut the shapes out of the sheet and joined the pieces with a 4" or 5" splice  "scab" on the under side, using carpenters glue and and screws. This insures the road bed continues on at the same level.  With the proper use of risers you can introduce super elevation on curves or transition, "ease" into inclines.

Just my thoughts.  

Have fun.   

Lee

[aflyer]

Lee,

Thank you for your comments, I read what Wayne wrote about the risers and the ability to build in the superelevation, and you are both on the same page, I hope to be at that stage soon, and plan to do it that way.

I think I am doing a sort of cookie cutter but maybe not the in the traditional way.

I am working on posting a couple new photos on my newer post, I got part of the base level deck cut out and fitted today.

Thanks again,

Aflyer 

[crisco1]

 

  Hi

  I recommend that you use Homosote glued to 3/4 plywood.  We use elmers glue, and then srew scraps of wood to hold it down.  After 24 hrs, we unscrew the scraps of wood.  I found this at a cement supplier.

Also, I heard that you can purcase Homosote  at Menards Hardware.

 

                                                                                                                                                 Chris