# Benchwork advice



## dboone (Mar 22, 2021)

I working on my benchwork design for my layout. I'm going with L-girders with a flat top of 1/4" luan and 2" foam. I'm struggling a bit with the benchwork for a curvy part of my layout and would like to get some input from more experienced folks. I've included two pictures below showing the a couple of designs I am playing with. 

My primary concern is the little triangular piece being supported well enough. It's about 15" by 15" and despite what is illustrated, the luan and foam for the triangle will be cut from the same piece as the circular part. I was thinking that with the diagonal design I'd construct a little bit of open framework that would support the triangular bit. If I go with the perpendicular design I'd add a joist connected to just one of the L-girders and then butt joint the joist to the joist from the straight section for extra support.

My other concern is that going with the perpendicular design is the joist being cantilevered too much. Not having worked with this type of construction, I don't know it's limitations well. 

Any advice would be appreciated. If it would be helpful I could sketchup these designs a little more to illustrated my thoughts.


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## mesenteria (Oct 29, 2015)

I'm not sure which 'triangle' is of concern. I see lots of triangles in the diagramme, some defined by dotted lines. If you mean the part at lower center, just off the first L-girder, and comprising part of the blob, why not extend the L-Girder?

In the lower diagramme, that isolated L-girder is not going to do you any good as it is depicted. Instead, lengthen the end 1X4, and its parallel partner further up. Don't have them 'sistered'. 

Also, the two closest supporting legs: as you show them, out of the corners, that's a recipe for a collapse the first time someone has to do an emergency grab to steady himself. All legs need to be in the corners of the L-Girders, AND cleated or blocked to prevent movement. Probably also braced with 1X2.

If it were me doing this, I would craft a box frame of 1X4, perhaps strengthened with cross-bracing, and make it just big enough to fit under the blob. Extend the topmost depicted L-girder under the long frame. Mate one side of the new box frame to the lengthened L-girder. Then build legs with braces and blocking to make sure it acts like one whole when you have it standing upright with some bellies leaning on it to reach something. In fact, I make it a practice to screw my rim joists or long sides of frames into studs through the drywall. In several placed. Also, I make my benchwork to run around the room, so once it is screwed into studs here and there, there is NO movement possible.


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## 65446 (Sep 22, 2018)

*db*, my friend,
you doesn't need L girder if you are going with an all flat top..Just make a simple box bench(s) on legs with some cross members and pin the top to them (like a heavier framed ping pong table)..
I believe you're misunderstanding why an L girder system is employed..

YouTube:
"L girder model train benchwork"
Scroll way down about 31 vids to: "HO Scale Union Pacific 12x20 Layout Progress........"
by RailfanRick

Without even opening video we can see how it's used, or how it looks, anyway...
I didn't open the Vid as I know the system..But I'll bet it gets even 'goovier' !! 🌄🛤


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## 65446 (Sep 22, 2018)

📌
PS,
I just watched it. It's a perfect display of L girder logic/construction...
The joists are moved around atop of the Ls to get correct position for the risers to then be attached to them..Ls allow joists to be screwed down to them from below.
Short horizontals at top of risers are cleats..You can skip them but they help you to get SRB either perfectly level or can be used to bank (super-elevate) track/roadbed on curves, if you wish...


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## dboone (Mar 22, 2021)

mesenteria said:


> I'm not sure which 'triangle' is of concern. I see lots of triangles in the diagramme, some defined by dotted lines. If you mean the part at lower center, just off the first L-girder, and comprising part of the blob, why not extend the L-Girder?
> 
> In the lower diagramme, that isolated L-girder is not going to do you any good as it is depicted. Instead, lengthen the end 1X4, and its parallel partner further up. Don't have them 'sistered'.
> 
> ...


The triangle I'm referring to is the white bit that extends from the lower section of the straight section of benchwork. The dotted lines are just guides in sketchup and can be ignored. Extending the L-girder could work.

This diagram is still in progress and I haven't yet drawn in the cross brackets for the legs or even the legs for the "blob" section yet. The L-girders shown in the diagram extending over the blob are just the girders, and I haven't drawn in the joists yet. Trying to figure out the best placement of the girders before I add the joists.

In looking at "How to Build Model Railroad Benchwork", Westcott doesn't show the legs being connected to anything other than the L-girders. That's why I have the legs in corners. Something for me to consider though.


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## dboone (Mar 22, 2021)

telltale said:


> *db*, my friend,
> you doesn't need L girder if you are going with an all flat top..Just make a simple box bench(s) on legs with some cross members and pin the top to them (like a heavier framed ping pong table)..
> I believe you're misunderstanding why an L girder system is employed..
> 
> ...


The reason I am playing with L-girder construction is the increased strength and lighter weight rather than the advantage regarding the use of risers and stringers. Overall it looks like a bit simpler construction than open grid too. I'm not committed to anything yet though.


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## 65446 (Sep 22, 2018)

Negative.
What I'm saying is, to make a flat table, L girder is not for that..
If you watch the video I recommended, that's what L-g is for; to allow the joists (which hold risers)
to be located where needed..For your table top style just make a simple box frame with 1X4s and screw the top to it, no L necessary. Weight of frame is not an issue. And L-g is probably, with all the screws [and glue ?] in it, heavier than 1x4s performing the same function...
If you change your mind and decide to have grades, then go open-grid or L girder..


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## flyboy2610 (Jan 20, 2010)

One of the big advantages of L-girder construction is to able to reposition the joists to clear any switch machines or other under table objects. It is very useful no matter what is above the table top.


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## mesenteria (Oct 29, 2015)

telltale said:


> Negative.
> What I'm saying is, to make a flat table, L girder is not for that..
> ....


L-girders are for lateral stability, rigidity, and strength over distance. If you want to get up on a 12' yard assembly, as I have to because I like my benchwork and tracks at chest height, then two parallel L-girders will be much more suitable than 12' 1X4's. Or 12' 2X4's. Or 2X6's.

L-girders can support slabs, or they can have risers and cleats on joists, spacers, and braces between them, or have cantilevered joists if needs be. That means they can support plywood, concrete counter tops, or open grid and sculpted terrain using carboard weaving or window screen covered with ground goop.

I'm not prepared to say that our friend is making the right choice for his benchwork, regardless of how long it might be, but it isn't true that L-girders are not to be used for a simple flat top layout. In the case where two slabs of plywood or foam need to be abutted to form a longer module, the L-girder is an excellent choice to ensure one can get up on it to fix things or to lay tracks.


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## CTValleyRR (Jul 26, 2014)

The strength of the L girders won't be a problem. On 16" centers, they will be plenty strong enough to support any conceivable layout. The problem will be if you have too much overhang, you can actually tip your layout by leaning on a cantilevered piece. Adding legs in strategic locations will fix the problem.

It's very easy to overthink and over-engineer benchwork. It doesn't have to be bomb or earthquake proof.


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## dboone (Mar 22, 2021)

CTValleyRR said:


> The strength of the L girders won't be a problem. On 16" centers, they will be plenty strong enough to support any conceivable layout. The problem will be if you have too much overhang, you can actually tip your layout by leaning on a cantilevered piece. Adding legs in strategic locations will fix the problem.
> 
> It's very easy to overthink and over-engineer benchwork. It doesn't have to be bomb or earthquake proof.


So, rather than having just two L-girders on the round part it would be better to have 3 or even 4? Or go with 2 L-girders, but maybe attach legs to the joists.


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## traction fan (Oct 5, 2014)

dboone said:


> I working on my benchwork design for my layout. I'm going with L-girders with a flat top of 1/4" luan and 2" foam. I'm struggling a bit with the benchwork for a curvy part of my layout and would like to get some input from more experienced folks. I've included two pictures below showing the a couple of designs I am playing with.
> 
> My primary concern is the little triangular piece being supported well enough. It's about 15" by 15" and despite what is illustrated, the luan and foam for the triangle will be cut from the same piece as the circular part. I was thinking that with the diagonal design I'd construct a little bit of open framework that would support the triangular bit. If I go with the perpendicular design I'd add a joist connected to just one of the L-girders and then butt joint the joist to the joist from the straight section for extra support.
> 
> ...


dboone;

I'll deal with supporting the triangle first, since that's the simplest.
Look at the upper diagram because that shows the bracing more clearly. You show two, parallel 'L'-girder beams running the length of your table from top right, diagonally down to approx. the center. The one closest to the triangle, should be extended beyond the end of the table and out to the edge of the triangle.

On the white, round, area, extend that lower L-girder joist to the right, and all the way across the end piece of the main table, and bolt it to the main table at both ends. Then put a leg out near the other end of that joist, so that it is supported by those two legs at the main table, and at the outside end. I would set this new leg in about 6'-12" from the end.

The upper joist, on that round white area, I would angle. Move the end closest to the table up to the next internal table joist, the one close to the point where the round white blob first goes off the main table. Secure one end of it there, and run it diagonally out to the new leg on the other L-girder. Of course, this joist will need to be longer, in order to reach.

L-girders can be joined to each other at any angle. Let the top, horizontal, plank extend beyond the vertical plank. Then lay the extended top plank over the top horizontal plank of the other L-girder you want to hook up to, at the spot where you want the joint. Trace the edges of your extended top plank on the other L-girder, and cut away part of the top horizontal plank of that L-girder that you want to attach to. Lay your extended top plank on top of the vertical plank of the other L-girder and screw it down. Both of the vertical planks should touch each other , and ideally have mating angles, but you don't need the fancy carpentry. A simple block, or metal angle bracket, can be used to join the verticals. Your "Building benchwork for Model railroads" book may show how L-girders can be joined, or cross each other.

Unless you plan to crawl on top of the white area, that should be enough support. If you want to beef it up more at the lower left of the white area, you could run another L-girder joist from the new leg area to the L-girder I first mentioned that supports the triangle. I would also use the 1/4" Luan throughout, including the area shown in white. I suspect you chose not to show the brown Luan in that area, so that it would make it more obvious what area you wanted advice on.

Traction Fan 🙂


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## dboone (Mar 22, 2021)

Ok a point of clarification that I didn't state in my original post. My plan is to make this part of the benchwork so that it can be separated and moved at some later date. So I really need to make this in two parts. 

What I've done here is take the little triangle bit that is in the lower part and diagram and move it from the circular/blob part to the straight part. This has made dealing the circular part much easier. I need to do some clean up on the diagram below including shortening the L-girder in the middle that extends to far. I have also not yet drafted the braces for the legs and I will include two more legs a little extra support one being under the triangular bit in the bottom of this diagram and another in the middle of this diagram giving extra support to that L-girder in the circular/blob section.


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## CTValleyRR (Jul 26, 2014)

dboone said:


> Ok a point of clarification that I didn't state in my original post. My plan is to make this part of the benchwork so that it can be separated and moved at some later date. So I really need to make this in two parts.
> 
> What I've done here is take the little triangle bit that is in the lower part and diagram and move it from the circular/blob part to the straight part. This has made dealing the circular part much easier. I need to do some clean up on the diagram below including shortening the L-girder in the middle that extends to far. I have also not yet drafted the braces for the legs and I will include two more legs a little extra support one being under the triangular bit in the bottom of this diagram and another in the middle of this diagram giving extra support to that L-girder in the circular/blob section.


That's why it's usually better to give full details up front.

Make two frames, one for each section, as near to the perimeter as you can. They need not be square / rectangular, although that makes the cutting easier. Make sure the two frames have a parallel side in common, and that no joists overhang on that side. Add T or L girder joists to the top of that, on approximately 16" centers. Bore the parallel sides for carriage bolts and wingnuts to hold it together (make sure you level the surfaces before you do... you don't want to find out the hard way that one module sits higher than the other. You can have your joists overhang, or use cleats if you need support outside this frame. Make sure each frame has enough legs to stand independently.


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## traction fan (Oct 5, 2014)

dboone said:


> Ok a point of clarification that I didn't state in my original post. My plan is to make this part of the benchwork so that it can be separated and moved at some later date. So I really need to make this in two parts.
> 
> What I've done here is take the little triangle bit that is in the lower part and diagram and move it from the circular/blob part to the straight part. This has made dealing the circular part much easier. I need to do some clean up on the diagram below including shortening the L-girder in the middle that extends to far. I have also not yet drafted the braces for the legs and I will include two more legs a little extra support one being under the triangular bit in the bottom of this diagram and another in the middle of this diagram giving extra support to that L-girder in the circular/blob section.
> 
> View attachment 558092


dboone;

Your new diagram looks pretty good, though a little too "leg happy." You certainly don't need the two additional legs you're proposing, and can really eliminate one or two from the present diagram. As long as you have L-girder bolted to L-girder along the dividing line between sections, you only need supporting legs near one side of that line. The bolts will keep the two sections aligned with each other, just heed CTValley's advice about leveling everything first.

Those bolts will also support one end of the circular blob section. That means the two right hand legs on that circular section are unnecessary. The legs of your rectangular, "main table", section will support the end of the circular one where the two sections join. Those same two legs on the lower end of the rectangular section will also provide plenty of support for the triangle, through the extended L-girders.

Remember, L-girders can't bend. When you build an L-girder think of it as more of a bridge, rather than a trestle. If an L-girder is supported in two places, then you don't really need any additional supports in between those two points.
Also, the end parts of the two L-girders that extend downward, and to the left, under the triangle, are every bit as rigid as the other part on the opposite side of the legs. The triangle's L-girders could easily support hundreds of pounds as drawn.

The L-girder that runs between the two inner legs that I'm suggesting you eliminate, should move to the right and be bolted to the L-girder frame of your rectangular section. The L-girder at the lower-left of the circular blob should be lengthened, and connected to the blob's L-girder that will be bolted to the rectangular section. In fact, you could simplify your benchwork by running one longer L-girder from the section joint , out to the leg on the lower left.

You could also build your benchwork exactly as shown, and it will work. However it does have some excess legs, and they slightly increase your lumber cost, the layout's weight, and your building time, for no real structural advantage.

Good Luck & Have Fun;

Traction Fan 🙂


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## dboone (Mar 22, 2021)

That make sense, TF, but I do have a question. If I move and/or eliminate the L-girder on right side of the blob, the L-girder joist that is supporting the lower left section will have to move about 2" or so to the right increasing how much the luan/foam top is hanging out beyond the joist. How much overhang is too much?


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## traction fan (Oct 5, 2014)

dboone said:


> That make sense, TF, but I do have a question. If I move and/or eliminate the L-girder on right side of the blob, the L-girder joist that is supporting the lower left section will have to move about 2" or so to the right increasing how much the luan/foam top is hanging out beyond the joist. How much overhang is too much?


dboone;

If all it needs to support is its own weight +scenery and trains, then a 12' overhang will be OK. However, if people are going to lean heavily against it., or climb on top of it, then 1/4" luan and 2" foam may not be enough without an L-girder underneath it. Either the 2" foam, or the 1/4" luan plywood, are each pretty strong in their own right. The glued together combination of both will be even stronger. If you want to add strength to an overhang that is not over L-girders, and/or legs, there are ways of doing so. One would be to add a second layer of 1/4" luan , on top of the foam. Another would be to use the "fascia board" that edges the layout as part of a different shaped "L-girder." A fascia of 1/8" - 1/4" thick luan can be 6" or more high, and glued to the 1/4" luan baseboard. The angle between them could be reinforced with small pine blocks glued at 2" - 3" intervals.
I used a variant of this technique when constructing the rounded end section (called "Cape Ripiculous") of my layout. (see photo)
It is extremely strong, and even acts as a sort of "crash pad" if I bump into it. (My disability affects my balance, and I tend to stagger, and flop around, at times.) When I bump into it, the rounded end section absorbs the shock and, because of the foam inside, it actually bounces me back off it a little bit. 

regards;

Traction Fan 🙂


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## dboone (Mar 22, 2021)

My latest revision.


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## mesenteria (Oct 29, 2015)

This looks pretty good. I don't know if you see it the way I do, and I understand it's only a conceptualization, but the vertical L-girder supports are backwards in some cases. The flange should be against the fascia plates of the larger modules or longer L-girders. In fact, when you go to do this, consider chopping off a bunch of 4" long lengths of 1X2 and screw them tight to the other sides of the L-girder legs to serve as blocking. Extra support. Even then, you'll want sway braces or maybe triangular gussets (if you like the look) on any legs that may get kicked inadvertently.

Depending on how long your L-girders are in the frames, the ones parallel to the floor, you can make them out of 1X4. You rip them on a table saw at the 1.25" mark, leaving 2.25"-ish to serve as the vertical fillet. I have only ever built them that way, up to 10' long, and they're quite strong with me in the middle. They'll crack some, maybe whine a bit, but they'll hold. I glue liberally, and use a 1.5" wood screw driven vertically down through the flange into the top surface of the fillet, each screw about 1 foot apart. This, as I said, is very strong.*

*You'll want to take your time when you go to select any dimensional lumber that will probably bear a fair bit of weight and get stuff that is true and only has few and minor knots. You want good strength, and to not have to straighten any lengths while you try to line up the flanges with their fillets.


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## dboone (Mar 22, 2021)

I'm still thinking on the bracing for the legs, so I don't have them in this diagram. 



mesenteria said:


> You'll want to take your time when you go to select any dimensional lumber that will probably bear a fair bit of weight and get stuff that is true and only has few and minor knots.


I figure I'll be sorting through the lumber at Home Depot for a good hour. LOL


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## flyboy2610 (Jan 20, 2010)

Looks good, but the cross pieces below the table top only need to be 1 x 3 (or 4's, your choice). They don't need to be full fledged L-girders. Along the top edge of the cross pieces attach a couple of 2" lengths of 2 x 2's. From the bottom of the 2 x 2 cleat, drive a screw upwards into the table top. This allows the joist to be moved if needed. Screwing from the top of the table down into the joist means you can't move the joist, and you lose one of the nice features of L-girder construction.
You can see what I mean in this picture. The cleat is screwed to the side of the joist, then a screw is driven upwards through the cleat into the bottom of the table top, enabling the joist to be moved if needed.


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## traction fan (Oct 5, 2014)

dboone said:


> My latest revision.
> 
> View attachment 558285


dboone;

Congratulations. It looks very good overall.
One thing strikes me. The entry aisle between the two circular sections looks quite narrow. How wide is it? Is it possible to angle the blob on the lower left a bit further to the left? This would give you a wider aisle, without changing the area of the layout at all. Another possibility might be to angle the whole left section further to the left, by making the angle between the left & rear rectangular sections wider than 90 degrees. I don't know whether either of those modifications will fit your room, or even if you want a wider aisle. The only other change I'd make would be to fill in a small triangular section of the upper left corner of your aisle. This would be to angle your yard, and get some more track length in it. I have suggested this several times, so I presume you have rejected that suggestion, which is your right of course.

I'm going to disagree with mesenteria's idea of adding a third plank to your L-girder legs, and his suggestion of using 1 x 4 lumber. Nothing terribly wrong about either of those ideas, but they aren't really necessary and simply add weight + a little cost to your benchwork. Using diagonal bracing (1 x 2s) is a better way of keeping the legs stable.
For warp resistance alone, I'm also going to disagree with flyboy's suggestion of making your crosswise joists with plain planks vs. L-girder. Of course you can use plain planks, many have, however, planks can warp, L-girder can't. Again, nothing terrible about using plain planks, but using L-girder for every wood part is a better system, in my opinion.

I do agree with the idea of picking out the straightest and kiln dried lumber you can find. You are a lot more likely to find this type of good quality lumber at a local lumber yard, than at Home Depot, or Lowes. Their lumber is often second rate at best, and I have seen some there that I wouldn't have take if it were offered free. I don't have a fireplace, and firewood is about the only thing some of Home Depot's "twisted snakes" would be of any use for.

Overall, good job!

Traction Fan 🙂


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## dboone (Mar 22, 2021)

traction fan said:


> dboone;
> 
> Congratulations. It looks very good overall.
> One thing strikes me. The entry aisle between the two circular sections looks quite narrow. How wide is it? Is it possible to angle the blob on the lower left a bit further to the left? This would give you a wider aisle, without changing the area of the layout at all. Another possibility might be to angle the whole left section further to the left, by making the angle between the left & rear rectangular sections wider than 90 degrees. I don't know whether either of those modifications will fit your room, or even if you want a wider aisle. The only other change I'd make would be to fill in a small triangular section of the upper left corner of your aisle. This would be to angle your yard, and get some more track length in it. I have suggested this several times, so I presume you have rejected that suggestion, which is your right of course.
> ...


That section is 18" at its most narrow point. I'd rather have 24", so it's a compromise.

Is that what you mean by filling in a small triangle? I think I might have overlooked that suggestion before, and I'm not sure I understand it. How would that enable me to put my yard at an angle?


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## dboone (Mar 22, 2021)

Nevermind. I got confused on which corner you meant. That corner of the layout is in the corner of a wall. A triangle there would make it too hard to reach into that corner to work.


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## traction fan (Oct 5, 2014)

dboone said:


> Nevermind. I got confused on which corner you meant. That corner of the layout is in the corner of a wall. A triangle there would make it too hard to reach into that corner to work.


dboone;

Your drawing of the triangle is correct, but as you say, in the wrong corner. It should be at the other end of that same aisle. If your layout is wide enough that you won't be able to reach across it with the triangle in place, then I guess you can't do it. Too bad, the yard tracks could have angled across parallel to the aisle edge of that triangle and onto the "city downtown" section, nearly doubling their lengths.

Traction Fan 🙂


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## dboone (Mar 22, 2021)

I can fit 40 40' box cars on the yard as it is. That's enough for me.


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## dboone (Mar 22, 2021)

Here is the latest.


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## CTValleyRR (Jul 26, 2014)

I think you need one more joist in the center of the upper blob.

Do you have a track plan yet? Because if you're planning to mount under-table turnout motors, you will need to ensure that none of your joists interferes with their placement.


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## dboone (Mar 22, 2021)

I'm not sure I know which part of the blob you are talking about. Do you mean here?










I think I've finalized my track plan, but I found I was looking at too much. I'll be looking at it again shortly with a little bit fresher eyes. I didn't think about the switch motors. Luckily the L-girds give me some leeway.


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## CTValleyRR (Jul 26, 2014)

Nope -- left to right across the middle of the circular area where you have the long run of 4 beams without a joist. If you look at what you have established as a distance between joists, you will see that you exceed it in that area.


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## dboone (Mar 22, 2021)

Oh, those vertical (and diagonal) pieces are joists.


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## traction fan (Oct 5, 2014)

dboone said:


> Here is the latest.
> 
> View attachment 558848
> 
> ...


dboone;

Your benchwork looks good.  

BTW I now have a zoom account, thanks entirely to my wife's knowledge, and effort. Send me a PM if/when you want to do a video consult.

regards;

Traction Fan 🙂


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