Benchwork question

Discussion in 'FAQs' started by spitfire, Feb 14, 2003.

  1. spitfire

    spitfire Active Member

    Hi All

    I have a question concerning the legs for benchwork. I'll be using 2x2's for the legs (unless anyone has any better suggestions). The benchwork itself will be 1/2" plywood on 1x3 joists. My question is, how far apart should the legs be? For an 8' x 32" module could I put legs at the ends only, or do I need another set in the middle?

    Thanks in advance!

    :D Val
  2. TR-Flyer

    TR-Flyer Member

    Hi Val:
    Our 2'x 4' modules use a 1x 4 frame around the perimeter with 1x 3 cross bracing. The tops are 3/8" ply. The "standards" for the club showed one brace. I did this and 2 of my four tops warped. I wouldn't space the 1x 3s any further apart than 16 - inches. I also wouldn't space the legs further than 4-foot. I think a 1x 3 spanning 8-foot will sag, just from it's own weight.

    Proviso, If you make 1x 3 "beams" i.e. take a 1x 3 and set it on the 1-inch edge, then screw a horizontal 1x3 to the top of it, making an "L" shaped "beam", then that would be able to span further. It would also allow you to screw through the horizontal 1x 3 into the bottom of your ply table. This will let you move things later on without unnecessarily tearing up scenery, track etc.

  3. Ty Rayles

    Ty Rayles Member

    Val I think you should use a set of legs in the middle as well.
  4. Paul Davis

    Paul Davis Member

    I've used only one leg on my entire 8'x11' layout using 1x3,s Those 1x3's will take a lot of weight. I do screw the rest of it to the walls so that may make a difference.
  5. 60103

    60103 Pooh Bah

    If possible, try to put the legs in from the ends. For an 8' section, I think that 2' in would be ideal.
    If you use L girder, you shouldn't have much sag even with support only at the ends. (Leg position may may determined by other factors than engineering.)
  6. Jim T

    Jim T Member

    The 2 X 2 legs on my 4 X 8 layout are in 14" from the ends. None in the middle, but they do have some 1/4" ply gussets and some 1 X 2 cross bracing. It's the construction out of the book "From Set to Scenery" and is L-girder construction.

    Cheers, Jim
  7. Clerk

    Clerk Active Member

    Here is a picture of my benchwork, L girder of 1 x 3 and 2 x 2 legs. The outside frame is 1 x 4

    Attached Files:

  8. Gary Pfeil

    Gary Pfeil Active Member

    Val, A rule of thrumb is to bring the legs in from the end 1/5 the total span. For 8", bring the legs in 19 or 20" from the ends. Now you say the benchwork is 1/2" ply on top of 1x3 joists. What do the joists sit on? L girders? I've always liked L girder construction. A girder made from a 1x3 and a 1x2 will easily span the five foot between legs. For 1/2" ply, keep the joists about 16" apart. Of course part of the beauty of l girder construction is the ability to move the joists easily to accomodate depressions of the "ground" below track level for scenic reasons.
  9. scoobyloven

    scoobyloven Member

    i must be stuck in the stone age on bench work i only use 2x4's for the whole thing and i put a 1/4 inch plyood on top and then foam i did the 1/3 thing and had brother zilla kill the layout on a move i build my layout in no larger than 56 inches long. and i sue bolts and a door hinge for the legs so when it come to move it i just pull out the bolts and fold up the legs and then slide the bolt back in to hold the leg to the under side of the lay out it sound hard but i have a drawing on how i did it i'll post it for you and any one else how would want it ..
  10. rockislandmike

    rockislandmike Active Member

    Ditto what Gary said; the structure is much sturdier with the legs 1/5 from the ends. There's a book out about building benchwork that recommends this as well as other tips - it's by Linn Westcott I think ???? (( it's at home ))
  11. Gary Pfeil

    Gary Pfeil Active Member

    Dick, I hadn't looked at your photo earlier, from what I see it is not L girder, it is, well I forget what it is called! But it uses butt joints where L girder has the joists overlap the girder and the joists are screwed to the flange of the girder from below. An advantage of your type benchwork is less vertical space required, so that for a given height of roadbed, there is greater clearance below. With L girder, the joists are above the girders, doubling the depth needed. One of the big plusses of L girder is that joists need not be cut to an exact length to fit. they overhang the girders and the ends can be cut to form the edge along the aisle, allowing graceful curves and such.
  12. Vic

    Vic Active Member

    Hi Val, Everything you've gotten here is darned good advice but if I may please allow me to make a feeble attempt to simplify what everyone has said by means of this crude drawing.

    2x2 legs are more than adequate. Just remember that they have to be crossed braced on the sides and ends as shown. Drywall screws are great for building benchwork and will hold everything just fine. From what you described I think you are wanting to build a "flattop" table. Putting the legs in the corners will be just fine for that and make your interior joists on 16" centers. If you are using L-Girder construction just move the legs in 1/5 of the total length of the table and cross brace them as shown.

    Hope this helps:)

    Attached Files:

  13. Vic

    Vic Active Member

    Hey Val, One other thing just crossed my mind....Basement floors are notorious for not being level:eek: but that won't be a problem.

    When attaching the legs to your frame work use some large "C" clamps to hold them to the frame work and adjust them using a level to where the top edge of your frame work is level and then fasten them in place and cross brace them.

    Also, if you are going to have two or more "tables" joined together, put the end cross braces on the backside(s) of the legs.
  14. sumpter250

    sumpter250 multiscale modelbuilder

    I use a 2" X 4" 'I' beam, made from 2 pieces of 1"X2" on a 3" strip of 1/4" plywood. These are mounted on 2"X2" legs. In spite of the strength of the I beams, I put legs at 4' intervals.
    The total length of this module set is 12', there are four sets of legs.

    Attached Files:

  15. spitfire

    spitfire Active Member

    Why I love this forum!

    Wow! Thanks for all the excellent advice everyone!

    I'm not sure about the L-girder concept for this layout - I think it's used when you want risers and a lot of changes in the scenery elevation - is this right?

    I think my approach is called open grid. I am now leaning towards 5/8" plywood and I'm quite prepared to build the outer frame from 2x4's if necessary. I plan to build it upside down then flip it. I'll probably use some kind of levelling hardware on the bottom of the legs.

    In the diagram below, I have indicated a dashed line where a center support could be, but given the max width of 32" (some sections are 24") I don't think I'll need it.

    Legs (and diagonal braces) will be bolted on for a possible future move.

    :D Val

    Attached Files:

  16. aartwmich

    aartwmich Member

    Hey Val...sounds like you're getting CLOSE gf!!

    My two cents: I drew this up in cadd real quick and generated a jpg(not pretty). I don't think you need the 45 degree braces as the shelf will stiffen everything nicely, but I would use 2x2's for the legs.

    Have fun!!

    edit..oops, sorry about the width, I thought Dave had it set so that the max allowed wouldn't require side scrolling:rolleyes: I'll have to experiment

    Attached Files:

  17. MasonJar

    MasonJar It's not rocket surgery


    Hi Val,

    I built my 4x8 the way you are describing (with 1x3 and 1x4 frame, 2x2 legs), except I used 1/2" ply to get flexibility. I used "cookie cutter" methodology to get the transition in elevation. Worked pretty well.

    Anyway, all that to say you will need the braces, especially if your table legs are going to be longer than about 2 feet. It is amazing how wobbly the thing gets. And just imagine once there is some plaster scenery, locos, rolling stock, buildings, etc.

    A suggestion for the "levelling mechanism": try 1/2" bolts about 3 - 4 inches long. Just drill a pilot hole for them in the bottom of each leg, and turn them almost all the way in. You can then level the table by adjusting each leg as required.

    Good luck.

  18. 60103

    60103 Pooh Bah

    Val, as masonjar says, it's not rocket surgery. It's art. Like photography, there are a hundred combinations that will come out with the same result.
    I use L girder because it's a bit more forgiving of bad carpentry. In 8 feet, it probably doesn't matter much where the legs go. I never had much luck with 2x2, but I think I got a cheap batch -- no two legs had the same dimensions.
    Levelling will be a matter of whether you plan to move the layout or not. if it's permanent, use the clamps, level the main bechwork, screw the legs on and cut the top off. if you may move it, put the bolts in the bottom. Bolts will keep it clear of the concrete which is reputed to have deleterious effects on wood.
    L girder takes more vertical room, but you can move the cross pieces if they get in the way of switch machines or low scenery.
  19. Catt

    Catt Guest

    Val,2x4s are total overkill.1x3s and or 1x4s are plenty strong enough for your benchwork with a 1/2" plywood top.That is unless your gonna dance on the darn thing :D
  20. spitfire

    spitfire Active Member

    But Catt - that is exactly what I plan to do once I'm done all that work!

    :D Val

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