Acceptable amount of layout top overhang?

Kevin,

From what the Mod-U-Rail assemblies look like on-line it looks to me like they are ideally suited for a top with no overhang. Since the assembly is wood though you might want to buy some 1x8 pieces of pine and add these as cross pieces along the sides of the module between the legs. Then get some of those stamped metal shelf brackets and to support the overhang and anchor it to the 1x8 cross pieces. Final assembly should be very rigid and the 1x8 cross pieces give you plenty to drill into for anything you want to add.

S

I was thinking stamped metal shelf brackets for overhang support, too, though I've never used them for this purpose.  Generally they have a pretty good weight rating, IIRC.

If you mean over the benchwork framing,I would say very little,and inch at most. OSB is a little more forgiving than plywood. You can frame the benchwork to stick as much as 18 inches or even more over the legs with L girder benchwork. I used2X4s,my legs are a foot back or more.

 

 

 

 

Dale H

Kevin,

 

Overhung extensions cause vertical forces and moments(same vertical forces times the distance on the overhang from the layout supporting framework). The deflection of the unsupported sheetboard is influenced bt the point of load (force) application on the overhang, force magnitude, thickness of the sheetboard and distance(spans) between the vertical supports of the sheetboard. These vertical supports must be framed into the layout supporting framework and carry the vertical forces and resultant by connection into this framework. If you apply a wood shape, 1"x 2" or 1"x 3", with the 2" or 3" edge vertical and attach shape to the outside edge of the unsupported sheet and also to the vertical span support members the deflection should be elimated.

 

I use the L-girder construction method in building my layout framework with overhung areas you can do a web search on L-girder construction for model railroads and overhang.

This should give you assistance in resolving your question.

 

If you mean unsupported plywood with no edge bracing, you should have very little overhang.

 

However, the ability to set legs back under the layout is one of the key features and advantages of an L-girder design or even of a strong grid system.

 

Naturally, for a small layout, stability must be taken into account, but larger layouts usually have plenty of mass to prevent tipping when someone leans on an edge.

 

 

 

 

Jim

Kevin,

I'm not sure about the overhang, I know in the smaller scales you don't have that problem because there really isn't that much weight involved unless you have a huge plaster mountain hanging out there.  Both Jim and Dale seem to have given you some great advice.  The L-girder system has been around for a long time and works very well.  I agree with Jim, you can move the legs back out of the way from the edge.

 

Jim, your layout looks tremendous, nice web site.  

Thank you for all of your responses.

 

I've decided to forego the overhang idea.  I've finally (I hope) come up with a plan which I will post on the "What did you do on your layout today" thread.  I'm going to start writing that post right after I hit "submit" on this post.

 

Regards...

Would a 2 inch overhang (3/4" plywood set on Mianne benchwork) be o.k.?

 

This would be a small 3 x 5 layout.

 

Thanks for any replies.

EMD,

 

I think that would be fine.

 

Some would prefer to see a dark edging (fascia) around the layout for a "framing" effect, but structurally it should be no problem.

 

Jim

Jim, Many thanks!

I am having a similar issue.  I am setting up a two level layout with a section of the top overhanging 18 inches to serve as a bar.  (I am going to place plexiglass 6 inches above rails.)  I am using angle iron to support the cantilevered 3/4 in plywood; 2 pieces 2 feet apart that extend into framed area.  

EMD,

 

Here is a photo of my layout with Mianne Benchwork.   The 3/4" plywood overhangs about 3".   Very stable.

 

Paul

 

My framed 3/4" plywood top hangs over 20" from the support structure.There is no need for the ply to overhang the framing.Check out the pics.PS: Kevin,we would love to see a few pics of your progress.Nick

 

Looks very good, gives one hope for any future 3" extensions.

 

 

Wow, Nick.  Wow

Nick, I just noticed the last sentence of your post

 

Just so you know, the "wow" was referring to the 20-inch overhang.

 

I'll be sure to post photos.

Paul, Thanks for the pic.

A 2" or 3" overhang with 3/4" plywood on a 3x5' layout!
Yeah, I think you are ok there.  I guess the real question is why build it like that?  What is the plan for a fascia to finish off the front?  I'm thinking a two piece crown mould wasn't part of the plan. 
Just stick the plywood out there... ?  I don't know.  How are you planning to finish off the edge?

Hi William,

 

This is just a small layout/project.

 

I am using some existing Mianne benchwork which is approx. 32" x 62"

 

I was initially planning to do a switching layout, but decided on an a small oval.

 

To do O31 curves (and have some distance to the layout edge), I will use a sheet of plywood that is 36" wide x 66" long, therefore there will be a little overhang.

 

As far as the fascia, I will probably cover the layout with a piece of carpet & let the overhang edges be wrapped by it.

None

Very little if any seems to be the going answer here.  I guess I lucked out with mine as I have about an inch overhang.  My wife plans to make some curtains to give it more of a finished look someday.  

Great info on building the frame work