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AVRR-PA
Fireman
Premium Member
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 Posted - 05/16/2009 : 6:57:04 PM
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Hi, everyone --
A friend is building some modules or layout sections for a client and sub-contracted the basic module construction to me.
The specifications are a bit unusual but I wasn't told why - "Theirs not to reason why, theirs but to do and die..."
It has been an interesting little exercise and I thought you might like a quick overview.
Moving on, to avoid the "can't edit" problem.
Don
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Country: USA
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AVRR-PA
Fireman
Premium Member
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Posted - 05/16/2009 : 7:34:06 PM
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The spec's were/are:
The modules had to be 3-1/2" high.
They have a 1" thick foam top, which is to be enclosed by the sides - no foam edges visible.
Three modules - all 4' long, but two of them are 20" wide and one is 15" wide.
And here's the interesting part - they have to weigh less than 10 pounds, while still being acceptably rigid - no sags or twists.
Edit: I forgot to mention that he also needed them in a hurry and I had a bunch of stuff already scheduled. 
I decided to borrow some ideas from the "waffle construction" used by the Sipping and Switching Society - their methods have been covered in both RMC and MR.
The basic approach is to build something like a hollow core door or torsion box, using 1/4" luan plywood for everything except the ends (which have to withstand clamping pressure) and a couple of longitudinal elements, which I made from 3/8" plywood.
Here are a couple of overview shots so you can see where I'm going. Then I'll do a little step by step:
This is a bottom view, with the the various grid elements fitted and ready to be glued --
And here is a bottom view with the "waffle" section being glued in:
There is a solid (not "waffled") sheet of luan supporting the foam. If I wanted to save a few more ounces, I could have cut the waffle pattern in that sheet, too, but that is tedious, dirty work and I figured I could hit the weight goal without doing it.
I began each module by substracting the the true thickness of 1/4" luan (no, it's not 1/4") from the outside dimensions and cutting the two sheets of plywood for each module. Working from the actual sheets, I marked out the sides and ends. I also cut a bunch of luan ledgers to support the top and bottom sheets.
Glue-laminating the ledgers to the sides also made them a good deal more rigid.
Here are all the sides and ends and ledgers glued up, ready for assembly:
That little piece of foam and luan in the second picture is what I used as a "marking gauge" for locating the ledgers. I never use a tape/ruler if I can use actual material.
Basic assembly was straight-forward box-building. I used Titebond II on the corners and wound up wishing I had used West System Epoxy when one came apart during a later assembly step. I used an air nailer to "pin" the corners together while the glue set.
The top sheet of plywood went in without problems, since the sides and ends were fitted to it. Here's a picture of the basic boxes:
The top module in the stack is upside down and you can see that I've traced the waffle pattern onto the underside of the "deck" so I'll know where to locate the grid pieces.
Making the waffle pattern was possibly the most interesting part of the project. As the article in "MR" suggested, I was about to cut them out with a saber saw when Garth came up with a much better idea. He suggested doing it with a pattern following plunge router bit in a trim router. He made the patterns for me, very quickly, using his latest acquisition - a DeWalt scroll saw.
Here's the router bit I used/abused - it's actually a dado cleanout bit. It wasn't the ideal choice and I later switched to a longer bit, which cut a lot faster.
Here's a picture of the setup in use:
And here are three waffle sections, sanded and ready to be installed:
I think I'll post this much, lest something go wrong and the whole thing disappear, as has sometimes happened.
Don
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Edited by - AVRR-PA on 05/17/2009 08:21:02 AM |
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Country: USA
| Posts: 4600 |
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AVRR-PA
Fireman
Premium Member
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Posted - 05/16/2009 : 7:53:04 PM
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Here are the foam tops. I fitted each one individually, so it's a moderately tight press fit and won't fall out during transport:
I wanted the foam tops in place when I glued in the grid pieces because I was going to be putting some downward clamping pressure on them and I didn't want to distort the "deck."
Next step was to glue in the longitudinals. Basically, I used yellow glue but I tacked the ends and middle with 5-minute epoxy thickened with a structural filler. That was just so I wouldn't have to set up a bunch of clamps and so I could work faster. Here's the setup:
I let the longitudinal glue-up set overnight, mostly because it was late when I finished it. Then I started cutting lots of pieces parts to complete the grid. You've already seen pictures of that.
I used mostly Titebond II to glue the grid elements to the deck but used thickened West Systems to glue the waffle sections to the grid. West Systems is expensive and I was trying to conserve it. It might have been better to use epoxy throughout.
After the waffle section epoxy cured, it was just a matter of filling, sanding, priming, sanding, painting, sanding and more painting.
Here's the finished module - not very exciting:
But my customer was happy with the result and thinks there might be further work, so I'm happy too. And I've learned some stuff that I can apply to building lighter, stronger FreeMo modules.
Garth questioned whether or not all the work to make the waffle sections actually save enough weight to be worth the bother. I'm not sure that it does. But it does allow access to the underside of the deck for wiring, and that's pretty essential.
If I make any more of them, I'll hot glue or carpet-tape a bunch of pieces of plywood together and rout them all at once.
I hope some of you find something useful in this.
Don
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MarkF
Engineer
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Posted - 05/16/2009 : 11:03:11 PM
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Nicely done Don! I've seen the Sipping and Switching Society's layout in person and can attest to the quality of their construction. A novel approach indeed! I tend to think that overall, we model railroaders over build our layouts as it is. A lot of lumber to hold up very little weight. This approach is very practical.
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Mark
See my homepage at http://home.comcast.net/~prrndiv/
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hunter48820
Fireman
Premium Member
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Posted - 05/16/2009 : 11:44:58 PM
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Wow Don, I'm impressed. You do beautiful work. Definately passed the butcher stage that I am still in! Thanks for the great thread and details of the construction.
By the way, I might have just missed it but what was the final weight? Just looking at all the material, it looked like it would have been over 10 pounds.
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Best, Andy Keeney
Look out for #1, but don't step in #2! |
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Vagel Keller
Crew Chief
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Posted - 05/17/2009 : 01:07:49 AM
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Don, this is a wonderful exposition on the argument that model railroading, truth be told, is much carpentry as it is playing with trains!
Vagel
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Neil M
Fireman
Premium Member
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Posted - 05/17/2009 : 06:37:06 AM
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Hi Don, i'm impressed with the neatness of your framework. It should be very stiff.
I was just wondering - was there a reason that you didn't use aluminium in place of a wood frame to save weight? Our Australian members seem to have done that on lightweight modular layouts with success.
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| Built a waterfront HO layout in Ireland http://www.railroad-line.com/forum/topic.asp?TOPIC_ID=22161 but now making a start in On30 in Australia |
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Country: Australia
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AVRR-PA
Fireman
Premium Member
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Posted - 05/17/2009 : 08:49:20 AM
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quote:
Originally posted by hunter48820
Wow Don, I'm impressed. You do beautiful work. Definately passed the butcher stage that I am still in! Thanks for the great thread and details of the construction.
By the way, I might have just missed it but what was the final weight? Just looking at all the material, it looked like it would have been over 10 pounds.
Hi, Andy --
I don't actually own a scale that's intended for weighing in that range, so I used the "weigh your dog" approach - I weighed myself on the bathroom scale and then weighed myself holding one of the larger modules. They came in about 11 pounds -- good enough, according to my customer.
Places where I could save weight in the future:
-- waffle the "deck" piece; that would also make it easier to run track feeders since you wouldn't have to drill, just poke a hole in the foam.
-- use thinner stock (3/8 or 1/2) for the ends instead of 3/4".
-- use 1/4" luan instead of 3/8" plywood for the longitudinals.
-- only apply one coat of paint.
I need to build a couple of FreeMo transition modules; one to use between my dual gauge module and Vagel's and one to allow me to run the standard gauge track off in a curve to start another branch of the FreeMo setup. I think I'm going to build a transition module with this new "technology" and see how it goes. The 6" height of a FreeMo module should make the whole thing even stiffer.
Don
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Edited by - AVRR-PA on 05/17/2009 08:52:31 AM |
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Country: USA
| Posts: 4600 |
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AVRR-PA
Fireman
Premium Member
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Posted - 05/17/2009 : 08:51:07 AM
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quote:
Originally posted by Vagel Keller
Don, this is a wonderful exposition on the argument that model railroading, truth be told, is much carpentry as it is playing with trains!
Vagel
Thanks, Vagel. 
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AVRR-PA
Fireman
Premium Member
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Posted - 05/17/2009 : 08:56:26 AM
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quote:
Originally posted by Neil M
Hi Don, i'm impressed with the neatness of your framework. It should be very stiff.
I was just wondering - was there a reason that you didn't use aluminium in place of a wood frame to save weight? Our Australian members seem to have done that on lightweight modular layouts with success.
Hi, Neil -- nice to hear from someone in the old country. (Three of my four grandparents were Irish immigrants.)
Aluminum? That's one of them metals, right? Never touch the stuff.
Actually, I guess the honest answer is that the job had to be done quickly so I used the materials on hand and the methods I already know. Using aluminum in place of some of the wood parts would, in fact, be interesting, especially since West Systems will join aluminum to wood with enormous strength.
Thanks for starting me thinking.
Don
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Edited by - AVRR-PA on 05/17/2009 08:58:23 AM |
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Country: USA
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AVRR-PA
Fireman
Premium Member
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Posted - 05/17/2009 : 09:06:23 AM
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quote:
Originally posted by MarkF
Nicely done Don! I've seen the Sipping and Switching Society's layout in person and can attest to the quality of their construction. A novel approach indeed! I tend to think that overall, we model railroaders over build our layouts as it is. A lot of lumber to hold up very little weight. This approach is very practical.
Hi, Mark -- thanks for writing!
One important difference between these modules and the S&S modules that I forgot to point out: no legs. I don't know why the client specified no legs - perhaps he sets up on tables or saw horses. But that did mean I could eliminate some of the material (and weight) that would be needed to attach legs.
If I were building a home layout, I'd at least consider this type of benchwork.
On the other hand, the benchwork that I helped Vagel with was built with some different requirements. Specifically, it's intended to function as a work bench for a year or two, until we get around to phase two; it's intended to support our weight if we need to get up on it while working on the layout; and it's designed to allow a couple of guys to stand on it while working on the lights over the layout.
Different needs, different solutions - that's what makes artisanship interesting.
Don
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Peterpools
Engineer
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Posted - 05/17/2009 : 09:35:01 AM
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Don
Couldn't ask for more. Just a great tutorial on how to do it right> Thanks for taking the extra time to document each step. As I am getting ready to move my small switching layout into another room and add an extension to, I've picked up quite a few good tips to follow.
Peter
BCT
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rfmicro
Crew Chief
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Posted - 05/17/2009 : 4:22:47 PM
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Don,
Good project and well done. I am in a similar position building 3' X 4' modules made of 0.75" X 3" sides and longitudinals with 0.25" luan top and 1" pink foam for the top. 2" X 2" wooden legs with braces and levelers of course. I have one built with a lower level for a two tier module. I may add on a third level someday. I find the module very stable and even more so with additional modules attached.
I did submit a bid for an aluminum equivalent (per Mario's web site), but it came in >$400.00 for one module and that seemed a bit over the top; hence, back to the light weight design. I needed a light weight design that was modular such that I can move it should I need to, and for ease of building the layout without having to worry about whether I could reach all areas or not.
Regards,
Trent Mulkern
Mechanicsville, MD
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Mike Hamer
Engineer
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Red P
Crew Chief
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Posted - 05/19/2009 : 09:42:42 AM
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WOW, those are impressive. 
Ive been trying to figure out how to do light weight benchwork, not really modules but sections that will become a larger layout later on.
You have given me some good ideas.
P
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George D
Moderator
Premium Member
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Posted - 05/19/2009 : 09:58:57 AM
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I’m just catching up with this, Don. I’m familiar with the Sipping and Switching Society’s modules, so it’s interesting to see a craftsman use their ideas. I have a switching module in the back of my mind and if or when I get started, I’ll be following your method. Thanks for taking time to post this great info.
George
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