On page 35 of How to Build Model Railroad Benchwork 2nd Ed., Linn Wescott discusses the sag and tilt of various “girders”. For example an L-girder comprised of a a 1x2 and a 1x2 can span 10ft with a maximum sag or tilt of 1:500 with a 150-175lb load. This is with a leg spacing of 6ft and 1x2 diagonals from legs to the L-girder.
Has anyone seen an equivalent analysis for hollow core doors?
Thanks
Alan
Doc, I have not, but I can tell you that any vertical deflection you can measure at the midway point across the long side of a hollow core door of any quality suspended on stilt-type legs with diagonals rising from the lower third, say, of the legs and intercepting the door at between 18-24" from the point where the door meets the tops of the legs is going to be negligible. I’ll bet you won’t be able to measure it except with a laser device designed to do it, or a large and very fine caliper anchored on one side at a reference point. And even so you would need something like 30 kg of mass near the upper center of the door. I think that is highly unlikely to be the case when you have it all laid out and scenicked.
-Crandell
Crandell
I suspect the same. As I need fascia for mounting wiring, controls etc, I think adding a 1x3 (or 1x4) underneath the edge would create an effective L-Girder allowing for legs only at the ends (and lots of open storage space underneath).
One would think someone would have done the analysis by now, given the use of doors in N-track etc. (Interestingly, Linn has a page devoted to hollow core door construction with L shaped legs at the corners with no cross braces).
Doc,
I am currently using hollow core bi-fold sections for shelf layout. Instead of using a wood subframe such as “L” girders, I used metal brackets that were lagged to the sidewall studs. Hollow core doors especially the bi-fold type sometimes have a slight arc to them since they have been setting upright. When mounted on the brackets, I make sure the high area is on top. I use weight to flatten the high area and then bolt from the top down through the bracket. Sag and tilt are negligible.
I for one can not see the benefit of using hollow core doors for other then scene dividers or backdrops in some instances. Most hollow core doors have some slight twist to them over time as their over all quality of construction is poor. hence thats why their so cheap. I know a lot of guys are using them but if your opposed to using L-Girder then why not open gird bench work? If you want very good quality and relatively a lot less money then buying off the rack 1x4 dimensional lumber to make your bench work then just go buy a sheet or two what ever it takes of 3/4" birch plywood and rip them in to he 1x4 strips. A- plywood is far stronger then dimensional lumber B: It is typically straight as an arrow which can’t be said for the 1"x4"
stuff you buy in the big box lumber stores. I’ve seen where one builder who has a very large layout cantilevered his bench work over 36" from the wall with no leg supports by using plywood to make his brackets attached to the wall studs.
To hollow door or not to hollow door is another discussion. I may yet go open benchwork, however, that would require some sort of strip-roadbed. Alternatively I might consider plywood and foam as the basis, although a financial analysis suggests costs might be higher.
IMHO L-girders made of 1x4 plywood is over kill for the strength needed (not that resistance to warping etc isn’t a bad idea) for something that is relatively permanent but possible to move intact.
Of course straight girders made of plywood would be equivalent to a 1x3/1x2 L-girder but then there is no web or flange to attach things to.
Birch plywood is not cheap, and there is no bench saw to cut strips. Big Box stores or lumber yards charge for more than a single cut.
I find many designs for benchwork assume a wood working shop with available tools, something that is not the case here. Ditto on spline roadbed.
Anyway, I still think someone should do the “lab” work.
Alan
Having done open grid bench work on my last two shelf layouts, I was looking for a quick fast way to get benchwork up as opposed to cutting and sawing. “L” girder as well as open grid have their place as do door panels. Metal brackets keep everything straight and neat keeping everything tucked under. Alan, don’t get caught up in the mechanics, enjoy constructing a layout.
Camero, thanks for the sentiment.
Ihave an advantage in that 1/2 the layout will be against walls; commercial brackets have an appeal rather than building them.
Still a work in design and the final result will be some sort of blend.
Doc
For what it’s worth, I have replaced hundreds of hollow core doors and you may be surprised how many have started to come unglued. Never did think to much of hollow core doors, unless they are free.[:-^]
Have fun
Lee
Lee
Interesting and something work considering.
Have you seen comments on that in forums?
I have used a “throw-away” HCD as a portable outdoor workbench while living in California. I would set the HCD on a couple of saw horses, and I had an “instant bench”. While stored, it would occasionally get one end water-soaked (our basement leaked from blocking underground streams whenever it rained). The water made the edges of the door skin a little fuzzy, but it never delaminated.
From my use of an HCD as a base to clamp my router table and bench top table saw, I’d say the HCD is plenty rigid enough for use as a layout base - even if the legs are at the ends of the HCD - as long as the door is intact.
That’s not to say I would recommend an HCD as a layout base - I wouldn’t. It’s simply too awkward to run wiring and scenery and anything beneath the track. Mounting legs is awkward, too.
One time when I was clamping the router table to the HCD “bench”, I didn’t pay attention to the clamp location, and cracked the door skin because there was no support under the clamp. This did weaken the door. And I noticed that after I had drilled a few too many holes going through the piece I was working on and into the door skin, the HCD was a little weak in that area. Based on my experiences, I would expect the door to lose a lot of its rigidity once either skin gets compromised by cutting out parts for scenery or turnout motors or similar.
just my thoughts and experiences
Fred W
I built a layout on 30+ year old hollow core doors that were deemed surplus. The only issue is the mess from drilling or otherwise mining the area under the walthers conveyor kit etc. They were immune to the Arkansas Humidity and no warps anywhere.
The reason they were surplus was because the metal doors were of better construction and more security.
I dont walk on the stuff. The next layout will be based on 1x4 inch woodwork of some kind the old fashioned way. Not very large and will be strictly around the walls with foam and other materials as a core.
The other issue about doors was wrestling with the things as a unit. 2 feet wide by 6.5 inches long each made for some interesting issues in a 11 by 8 foot room with space limitations.
At the end of the layout’s life, the hollow cores with the internal glue and cardboard did not resist the chainsaw anymore than a few moments. Chopped it right up. Easy peasy.
Probably the worse use of a hollow core is to be used as a door. I have had similar issues with bi-fold hinges coming loose or stripping out the threads when used as doors. Lance Mindheim used bifold panel doors for his “Voodoo & Palmettos” Miami base shelf layout with no problems. Lance is in the shelf layouts business and his East Rail layout has appeared in Great Model Railroads.
I’m with Camaro. I recently switched to HCDs with 2 inches of foam laminated to the top and mounted on shelf brackets. My neighbor tossed out a bunch so I rescued them from the trash collector and paid nothing. I’ve had no problems to date. My wiring is (for now) attached with blobs of adhesive caulk. I will convert to Velcro loops later. I use ground throws in HO and Peco switches in N, so I have no mechanical switch linkages to worry about. I could run brass tubing with piano wire through the foam if needed.
In defense of the lowly HC door: Although there is no question that a solid core wood door is superior, and I am sure there are variances in quality from manufacturer to manufacturer, when we renovated our former home, we installed 4 pairs of bifold HC doors and 7 HC room doors, They were properly installed and painted all sides and edges. After 38 years of use by a family of 6, when we sold the house, those doors were as good as new and not warped at all.