First large sign, supports

[fozzyber]

I have a order to do a sign, it is 4'x8' double sided and will be installed between posts.
I am thinking 2" sign foam each side, but my first and main concern is support.
I could use 2 1/2" sheets of mdo as a center support,
( 2" signfoam, 1/2" mdo, 1/2" mdo 2" sign foam)
but I have seen some people use steel , but dont know how to secure or make the steel supports,
can anyone give any advice? I'll post a pic of design latter.

[joe]

Congratulations on your commission.

I'll be posting a little later on sub structures for HDU along with a few photo's. You should gets lots of expert advice since there are plenty of good artists and craftsmen posting

Here's my initial thought. HDU isn't very good as a structural material. At this time I'm only use it for 3D work. It's so expensive and and weak. For years I used 15lb at 1.5" now I seldom use any thicker than one inch and apply it to 3/4" MDO. 18lb. Duna is my favorite

Second thought is to use steel for the undercarriage. A good welder can save lots of time and money.

Do your posts go under the sign or on the outside? I love making decorative posts with flutes. These are made from 2" rough cedar and 4"X4" treated posts in the center. I'm not too fond of skinny little weenie legs beneath a beautiful sign. They should look sturdy and attractive.

http://i38.photobucket.com/albums/e115/jcrumley1/Dump001.jpg

Joe Crumley
www.normansignco.com (http://www.normansignco.com)

[fozzyber]

Here is my first design, I might be diving in deep but we have to learn....
As far as welding, I got that covered.

[fozzyber]

if I did a frame this is what I would think.

[kurt_rose]

I'll be watching this thread closely, thanks for starting it Fozzy. Signs are the direction I wanna go and I have been wondering about substructures.

[tuck]

Jerry,

I think you're on the right track but Joe is correct, you don't need 2" thick HDU. If it were me, I would use 1" HDU with a 1/4" deep rout and laminate it to 1/2" mdo with some Gorilla Glue. I would cut the mdo to the same shape and size as the HDU sign panels and take care to finish the edges of the mdo with filler for any holes and plenty of primer and paint.

Assuming you will be making/using decorative wooden support posts similar to what Joe has posted, all you then need is 2 x 2 pressure treated "nailers" screwed to the insides of each post. Then you screw through the sign panels into the nailers and that's how you attach the panels to the posts. This is something I would do at the job site so as to make this puppy easier to transport.

Since your panels are 8' wide, I would add one more 2 x 2 between the panels, in the middle, running vertically and cut short several inches from the top so you don't see it. This will make your panels plenty stiff. I can do a diagram for you and post it if you don't understand.

Now, if you want the sign to be "boxed in", as in a capped top so you don't see the backs of the panels, that's a slightly different animal.

[marysvillesign]

I think you can simplify the internal frame, increase structure and have it look attractive as well. This was planned for 1x2 steel with .375" flat plate that was to be laid into a flush pocket.

[fozzyber]

I probably went over board on framing but I have 2 thing going against me:
1: a degree in Architecture from LSU
and
2: I live in Louisiana, ie... hurricanes!!!!!!
I am not the expert but I would prefer to over build a little.


I think you can simplify the internal frame, increase structure and have it look attractive as well. This was planned for 1x2 steel with .375" flat plate that was to be laid into a flush pocket.

[tuck]

The idea behind laminating plywood to the back of HDU is to give the panel lateral strength as well as something for screws to hold to. Without a plywood backer, a large HDU panel mounted between post can be broken easily enough. Someone can put their fist through it or kick it into pieces if they have a mind to, so a couple of steel bands behind it won't prevent that from happening in and of themselves. Plywood will, though. The only time I don't use a backer is when an HDU panel is mounted directly to an existing wall or other substantial structure.

I hate to tell ya this, Jerry, but there ain't enough engineering in the world that would make an HDU sign, or most any sign for that matter, "hurricane proof". It's akin to making something "vandal proof". It can't realistically be done. A determined vandal will do his work, whether with paint or pick ax. So will Mother Nature.

[COBOB]

Mark, can you share any tips on how you do attach a HDU panel to a wall? I am curious.
Thanks,
Bob

[tuck]

Mark, can you share any tips on how you do attach a HDU panel to a wall? I am curious.
Thanks,
Bob

Depends on the wall. If it's a wood wall, I use wood screws. If it's a concrete wall, I'll use TapCon screws (you have to pre-drill, of course). If it's drywall, I'll use standard drywall mollies.

One way to hang signs on a wall with no visible fasteners is with a "hanging bar", but this is only good for interior signs. I can elaborate if anyone is interested.

[marysvillesign]

I wouldn't call those drawbacks. Looks like some pretty good experience behind you.
Always a challenge to find the right fit of cost vs. use. I'd agree with Mark that you can't get paralyzed planning for things you can't control. Do the best job you can and I think your off to a good start. Please post some finished pics.

[COBOB]

Thanks for the info Mark.
Bob

[fozzyber]

I under stand the idea of the plywood and agree, needs a backer, but at 8' it seems could get a bit wobbly.? That is why I was wanting to add steel.

Jerry


The idea behind laminating plywood to the back of HDU is to give the panel lateral strength as well as something for screws to hold to. Without a plywood backer, a large HDU panel mounted between post can be broken easily enough. Someone can put their fist through it or kick it into pieces if they have a mind to, so a couple of steel bands behind it won't prevent that from happening in and of themselves. Plywood will, though. The only time I don't use a backer is when an HDU panel is mounted directly to an existing wall or other substantial structure.

I hate to tell ya this, Jerry, but there ain't enough engineering in the world that would make an HDU sign, or most any sign for that matter, "hurricane proof". It's akin to making something "vandal proof". It can't realistically be done. A determined vandal will do his work, whether with paint or pick ax. So will Mother Nature.

[tuck]

I under stand the idea of the plywood and agree, needs a backer, but at 8' it seems could get a bit wobbly.? That is why I was wanting to add steel.

Jerry

Yes, and I have rethought my idea of just one vertical 2x2 in the middle in addition to the nailers. If it were me, here's how I would build it:

1" routed HDU laminated to 1/2" MDO plywood. This makes each panel 1 & 1/2" thick. I would laminate the HDU panels to the MDO with Gorilla glue. If you've never used this glue before, say so and I can give you some tips. It's really good stuff for this kind of application.

Now, I would indeed use 2 horizontal stringers between the post to fasten the panels to, but I wouldn't use metal and especially not steel. I would use pressure treated 2x4's. Those, together with the MDO plywood, will make the sign plenty stiff and make it easy to fasten the panels to the stringers with screws. You can't screw into steel. If you're convinced you need to use metal instead of wood for an internal frame, use aluminum. Get a metal fabricator to weld you up a frame out of 2" sq. aluminum tube. That would be plenty strong and easy enough to screw to with a little pre-drilling. But I'm telling ya, metal in this instance isn't gonna really gain you anything plus it adds considerable expense.

Another thing to consider is the width/thickness of your post. You want the sign to sit inside the post, right? Two 1 & 1/2" thick sign panels plus the thickness of 2x4's between them = 4.5". If it were me, I'd use 6x6 p.t. post and cover them (dress them), on all 4 sides with 2x lumber skirts (maybe cedar?) to make the post 8.5" square or thereabouts. See what Joe Crumley has done. Yours is a pretty big sign and you want big beefy looking post, dressed up nicely, to compliment your fine-looking signage.

[fozzyber]

thanks Mark, I have worked with gorilla glue, the tips I know are: rough surface, spread glue, mist with water, (just a little bit), put pieces together and put about a million pounds of weight on it.

And I have been thinking on the thickness issue, and I was planing on using 6x6s, I think my next step is to design the posts then see how to mount.

Jerry

[tuck]

Another thing to consider is to use 1" white PVC instead of HDU and you won't need a backer. ;)

[fozzyber]

I have always heard do not use PVC outdoors b/c it will warp badly
I have seen it warp in the sun and can believe it. What are your experiences?

[servant74]

Mark,

Is the hanging bar like a French Cleat used for hanging wall cabinets sometimes?

If not, a pix would be nice for inexperienced folk like me!

[tuck]

Jerry,

Thinner and dark colored PVC will indeed warp in the hot sun. I think you'd be fine with 1" thick, routed down maybe 1/4", BUT DON'T TAKE MY WORD FOR IT! I have used 3/4" PVC and it does fine, but I've never made a PVC sign 4x8 like yours, and mounted like you will mount yours. We need our resident expert, Joe Crumely, to weigh in on this, and I do apologize if I let my mouth get in front of my brains! ;)

Jack, you posted your question in the wrong thread but yes, hanging bars and French cleats = same thing.

[GlenP]

Hey guys...and gals. A good friend of mine does allot of hdu work and uses mostly duna corafoam. He uses metal frameswork sandwiched inside the hdu. I personally think a sign full 4 x 8 needs some thickness to have that nice proportion to the size and also look bold but not too heavy. The thickness of the two outer parts will depend on how deep you are routering or blasting. Size of steel inside will depend on site mounting conditions. Is it a windy area etc. 4 x 8 is a big face if the wind is heavy. Nobody wants to see a sign bent, buckled or perhaps broke. I think I would use 1 1/2" for the outersides and either 1" or 1 1/2 for where the steel is going. One thing me friend has advised me to do is ALWAYS fill inner voids and not leave them empty. He told me that a inner air space will expand at different rates than the foam and may cause issues. He also silicones areas where the steel leaves the hdu to allow the steel and hdu to expand at their own rate.
Last note is about the sign design. Love the design Jerry. Do you think there is enough negative space above the name and between lines of text? just a thought. Dr. Crumley is the pro when it comes to that.:cool:

[joe]

As we become more familiar with HDU our techniques are getting much better. For years we've been inserting aluminum rods, Electrical Conduit,
Angle Iron for stifness.

Down here in Indian Country, I've left those old techniques on a dusty old trail. When fabricating a free standing ground sign I'm now using a sheet 1" Duna front and back but I seperate those panels by 2" of scrap around the edges. This makes an extremely non flexable panel.

I've posted this technique as a step by step on "How to Prime HDU". It's at the bottom of the page.

Another advantage of having a hollow panel is it allows the inclusion of wood bolting plates. You can scew into these without worry of HDU bolting failures. I'm writing a quickey little article on "Screws & Bolts in HDU". Bolts hate HDU and will give up the ghost with viberation and weather. I'll post it in a few days.

http://www.signtalkforum.com/phpBB3/viewforum.php?f=6

Joe Crumley
www.normansignco.com (http://www.normansignco.com)

[tuck]

Joe, do you think Jerry could use 1" PVC for this project instead of HDU?

[joe]

Mark,

Absolutely.


As you know, PVC is much tougher in most ways than HDU but each of these panels render very different effects. Both are excellent substrates but have their own disadvantages. For example it's more difficult to make a wood grained or textured sign with PVC and it's down right heavy.


I'm still fond of MDO. If it's sealed up and painted correctly that material will last for years. It limits the user to making a panel type sign but carved HDU pieces can be added.


Joe Crumley
www.normansignco.com (http://www.normansignco.com)

[tuck]

That's what I was thinking, Joe. Looking at Jerry's design, I don't know why he couldn't use 1" PVC, which should eliminate the need for backer boards and end up with a more durable product.

From my local supplier:

1" Duna HDU 4x8 = $208.00 ea.

3/4" MDO 4x8 = $74.79 ea.

So, needing 2 of both = $565.58 and you still have to cut and glue the backers.

1" (25mm) Celuka Ex-cel white PVC = $184.37 ea. x 2 = $368.74

$565.58
-$368.74
----------
$196.84 savings in materials, no labor/time for cutting and gluing backers, and a superior product in this instance.

[joe]

Tucker,

Please read my previous post about not using interior bracing. It's a thing of the past.

Joe Crumley
www.normansignco.com (http://www.normansignco.com)

[tuck]

I did, Joe, but I'm not sure what you mean about "but I seperate those panels by 2" of scrap around the edges". Please explain. :)

[fozzyber]

I think What Joe is talking about is basically building a "hollow core" sign.
As I understand it he is routing 2 panels, then taking the drop off pieces to build a thicker sign around the edges but on the inside. He is increasing his (fb) (as I recall my structures) All he is doing is increasing the thickness of the sign to get a stiffer panel thus increasing bending resistance. :)