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New idea for girders

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  • Member since
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  • From: Richmond, VA
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New idea for girders
Posted by carl425 on Wednesday, March 27, 2019 11:02 PM

I recently discovered my favorite lumber yard sells 5/4 X 4 yellow pine boards.  I've decided to use these for my girders instead of the traditional L of 1 X 4 and 1 X 2.  With the cross-sectional area being equal the strength should be close to the same.  The 5/4 X 4's priced at $1.16 per foot vs $.67 for the 1 X 2 plus $.91 for the 1 X 4 make the 5/4 X 4 $.42 per foot (26%) cheaper.  I'll use pocket holes to attach the joists to the girders so I don't need the flange created by the 1 X 2.  Also it'll save me the time of assembling the L's (I figure the time to drill the pocket holes is about a wash with drilling pilot & countersink for the regular screws). And... regular screws, if you're not careful, sometimes split the flange.

Anybody see a problem with this idea?

I have the right to remain silent.  By posting here I have given up that right and accept that anything I say can and will be used as evidence to critique me.

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Posted by SeeYou190 on Thursday, March 28, 2019 5:59 AM

I googled 5/4 by 4, and it just looks like a slightly thinner 2 by 4. Am I missing something?

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It sounds like you are not going to use two of theseto make an L. 

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Maybe a drawing would help, or somebody smarter than me will understand the question.

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-Kevin

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Living the dream.

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Posted by mbinsewi on Thursday, March 28, 2019 6:37 AM

5/4 lumber starts out as boards 1 1/4" thick.  After finish milling, and drying,  it's usually somewhere between 1" and 1 1/8"  It can vary around the country, believe it or not, from mill to mill.

I don't see why it wouldn't work for your girders.

Mike.

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Posted by gregc on Thursday, March 28, 2019 7:26 AM

SeeYou190
Maybe a drawing would help,

one concept of L-girders is all screwing is done below the layout so that they remain accessible after track and scernery are added.   

The "pocket holes" avoid the need for a flange and the 5/4 lumber is probably sturdy enough to not need the extra rigidity provide by the flange which also provides a horizontal surface to screw upwards into.   time will tell

greg - Philadelphia & Reading / Reading

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Posted by Pruitt on Thursday, March 28, 2019 7:51 AM

The 1X2 and 1X4 of the L-girder tend to stabilize each other in terms of warpage after they're built up. This is very important when using even the "select" grade of pretzelwood from the big box stores. Your 5/4 supply may be of better stock and less prone to warpage.

You would need a 2X5 to obtain roughly the same envelope dimensions as the L-girder. Just fyi. Your lumber will probably work just fine.

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Posted by SeeYou190 on Thursday, March 28, 2019 10:28 AM

gregc
5/4 lumber is probably sturdy enough to not need the extra rigidity provide by the flange which also provides a horizontal surface to screw upwards into.   time will tell

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Sounds like you need to build a "test segment" of your layout design to prove it will work.

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I did, and it answered tons of questions.

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-Kevin

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Living the dream.

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Posted by mbinsewi on Thursday, March 28, 2019 11:10 AM

SeeYou190
Sounds like you need to build a "test segment" of your layout design to prove it will work.

The pocket holes will be fine.  They have a jig for that, much more precise, and better than trying to "toe-nail" it by eye.   Geez, every body wants to keep redesigning bench work, like it's the first time man kind has built such a structure.  I just don't get it.

Plus, IF you feel the need, there are all kinds of structural metal brackets and hardware you can use to strengthen the joint.  Every hardware store, either big box, or local, has a whole section on structural hardware.

Mike.

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Posted by carl425 on Thursday, March 28, 2019 11:25 AM

mbinsewi
Geez, every body wants to keep redesigning bench work, like it's the first time man kind has built such a structure.  I just don't get it.

In fairness, I don't get everybody wanting to re-invent the wheel either - until I have an idea. Smile

I blame my "problem" on Randy.  I think he is the first one that said the ubiquity of quality, modern power tools has mitigated many of the advantages of L-girder.  I still think girders and joists are the best way to make irregular shapes, but the pocket hole jig has eliminated the need for the flange on the girder.

I have the right to remain silent.  By posting here I have given up that right and accept that anything I say can and will be used as evidence to critique me.

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Posted by UNCLEBUTCH on Thursday, March 28, 2019 11:54 AM

mbinsewi
, every body wants to keep redesigning bench work, like it's the first time man kind has built such a structure. I just don't get it.

There isn't any '' drama'' in having it sufficient enough to be acceptable.

We must attemt to reach NASA specs. Just incase we want to try stem cell research. We need to have at least 10 pages of step by step instructions,including band aids. The more money spent the better it will be. We must do better.

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Posted by rrinker on Thursday, March 28, 2019 12:02 PM

 Did I? I built most of my last layout with a hand saw and miter box because I lived in an apartment and was afraid a power saw would make too much noise.

 I just never had much of a problem being able to cut a reasonably straight line with either a hdn or power saw, straign enough to make edge-joined grid type benchwork come out square (oh and use a square when connectign the outside corners - so they are, you know, square). I'm no master carpenter, that's for sure, but it ones of those things I like to do occasionally - I was the nerd on the college track taking all the advance classes in high school but ALSO taking wood shop because I liked it. I just never found it difficult to measure and cut accurately - which was always one of the selling points for L-girder, that you didn't have to be so accurate. Just the way I was taught, I guess, take your time, do things right. Don't rush it and be sloppy. The old "measure twice, cut once"? I do that, and many times measure a third and maybe fourth time before cutting, just to be sure I got it right. Still manage to cut the wrong side of the line sometimes even though I always mark the scrap side with a big X. So I start over again, rather than make a sloppy joint that's a saw kerf too short.

                                    --Randy


Modeling the Reading Railroad in the 1950's

 

Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.

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Posted by mbinsewi on Thursday, March 28, 2019 2:22 PM

Carl, I did not mean to say that you were trying to reinvent the wheel, that 5/4 will work fine.

It was just the tone of some of the comments that set me off.  I'm all better now.  Smile, Wink & Grin

If I was to build another lay out, I'd just use 2x4's, as I have before.

Mike.

 

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Posted by carl425 on Thursday, March 28, 2019 3:01 PM

mbinsewi
I did not mean to say that you were trying to reinvent the wheel

No worries - even if you did Smile

I have the right to remain silent.  By posting here I have given up that right and accept that anything I say can and will be used as evidence to critique me.

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Posted by maxman on Thursday, March 28, 2019 3:48 PM

carl425
I've decided to use these for my girders instead of the traditional L of 1 X 4 and 1 X 2.

carl425
Anybody see a problem with this idea?

If the 5/4 X 4 is intended to eliminate the need for the 1 X 2, then my answer would be "yes".  That 1 X 2 is intended to add strength and stability to the 1 X 4.

If you fix the 1 X 4 supported between two points and lean against the middle it will deflect away from you.  Once you add the 1 X 2 it may deflect, but quite a bit less. I believe that the traditional method will result in a stronger beam than what you would get with the 5/4 X 4 used alone.

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Posted by Buckeye Riveter on Friday, March 29, 2019 8:52 PM

Maxman essentially has explained it correctly.

In engineering terms the L girder concept is attempting the prevention of localized buckling or twisting out of the vertical plane as well as providing a larger section modulus to conteract the moment forces. A T, I, or a C section can do the same thing. 

If you really want a stout L girder, turn it upside down and attach a piece of strap metal to the bottom of the 1x4 with round head 1/2 wood screws at 6" centers. 

Wood is a very forgiving material. 

Celebrating 18 years on the CTT Forum. Smile, Wink & Grin

Buckeye Riveter......... OTTS Charter Member, a Roseyville Raider and a member of the CTT Forum since 2004..

Jelloway Creek, OH - ELV 1,100 - Home of the Baltimore, Ohio & Wabash RR

TCA 09-64284

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