Metal joists

Funny you should mention that. I visited Entertrainment Junction in Ohio last week and the construction you describe is what they are using on a very large G-gauge layout.  Call and ask to get in contact with one of their construction volunteers.  Very friendly group.

I use 2' spacing with no issues at all..

I have been using metal studs since late 1991, 2x4's at first, and starting around 1996, started using 2x2's exactly as you have described.  I found 2' for joist spacing is sufficient for any type of subroadbed.  30" migh be pushing it a bit to adequately support the subroadbed and prevent it from sagging. I first tried using OSB and 1/2" homasote, didn't like the results.  Then tried spline roadbed with spacer blocks in between (not they way Joe F uses masonite splines) and eventually settled on 3/4", 1" and 2" thick pink or blue foam board, and have tremendous success with that.  I had a cantilevered 2' shelf and it supported 25+ pounds per square foot easily. 

FWIW

Ken L

A couple of recommendations...

If you are going to run any wiring through the metal joists, find a metal joist hole punch from an electrical tool supplier.  Hopefully you have a friend who is an electrician who will have one and let you borrow one to punch 1/2" or 3/4" holes in the studs so you can snap in plastic grommets to protect the wiring.  

I used to use a step drill but it wore out very quickly.  It also took longer.  I can punch 20 holes in the same amount of time it would take to drill 1 or 2 using the step drill.     I have over 200 studs to punch holes in so I bought one on Ebay used and it has worked out great.   Perhaps with not so many studs to drill through you could use a hole-saw, but my experience is they get dull quickly too going through metal. 

Also, try to find self tapping truss screws.  They have a very flat (rounded) head, unlike the screws typically used for metal studs.  It will make joining the subroadbed easier without having to drill out for where the screw heads "pop up".  I have heard argued those screws are not designed for use with metal studs, but I have been using those screws ever since I found them in the late 1990's and they worked without ANY issues at all. 

Ken L.

Metal studs and electrical

The 2X4 metal studs have holes for piping and electrical. Special insulators are provided to allow wire to pass through these holes. You may have to cut the studs for hole placement.

If you do need to drill holes then a step drill for the smaller holes [< 7/8 inch] may be a better tool than a hole saw.

http://www.harborfreight.com/2-piece-titanium-nitride-coated-high-speed-steel-step-drills-96275.html

You can buy special inserts for different size holes or just use PVC conduit fittings for insulators.

Regards,

John

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When you are courting a nice girl an hour seems like a second. When you sit on a red-hot cinder a second seems like an hour. That's relativity.  Albert Einstein

The harbor frieght step drills..

...are the ones I used, and I wore them out fairly quickly, compared to using the punch.

Ken L.

Thanks Joe and Ken for the

Thanks Joe and Ken for the responses, will check EnterTRAINment Junction for sizing and spacing. Wiring should not be a problem as there are lots of gaps to run wires. Ken I would like to see some of your blog photos of the construction process if that is OK by you. I promise not to start another flame war

Rxalph

Steel Studs

Ralph,

for your information, I experimented with steel stud bench work, and I was disappointed with the amount of bounce or flex it had.  It was plenty strong, but just "bounced" more than I liked.

Mine was free standing, and from other's feedback, I'd wager that had a lot to do with it being free standing and not attached to wall, ceiling, or floor. 

As a result I went back to wood.

You can pick up plastic grommets at home depot for around $8 that fit in the precut holes for wiring if you choose to use those.

Share your results!

I will PM you updates ...

....when there are updates to be made.  What you saw was a quasi-experiment with using shelf brackets to attach the metal stud framing to the walls.  I was quite pleased with the results and will be going forward with that design.  However, after those photos were taken I stopped work on any benchwork to finish the ceiling and AC wiring for the lighting for the layout.  After having three decks of benchwork up in one section, it occured to me it would be more difficult to finish the ceiling work, and doing the electrical work after the benchwork was up.  So I focused on that instead, though I do on occasion cut some more pieces for the benchwork.  Most of the joist pieces are all cut, and I have begun cutting the track pieces.  I still have to punch the holes in the joists though, and when there is over 250 pieces total to punch, It will take some time, though not as much if I was using a drill.

I still have to drill the holes for the #8 machine screws that holds the shelf brackets to the joist framing, so it will be awhile before something is posted.   When I get to my local model railroad club tomorrow, I will take some pictures of the benchwork that is under construction now. We are just cantilevering the joists from the stud walls, vs using the shelf bracket concept that I'm using on the Interim P&A Layout.  I will post those here since that won't violate my policy of not posting updates of the Interim P&A here.  So it will give you an idea of what we did. 

BTW, there is no issue using the pre-punched holes that are in the studs, however, I would find there would be a tremendous amount of waste since there usually is only 3 holes per stud, and having to cut to make sure each piece had a pre-punched hole, drilling or punching the holes out yourself I would suggest, is the more efficient route.  Home Depot and Lowes sells both kind of grommets.  The kind that fit into the pre-punched holes, and ones that will fit in drilled out holes.  The  1/2" Grommet actually fits in a 7/8" hole. 

FWIW.

Ken L