First Outdoor Sign

[hippo]

I suppose it's inevitable, you get a ShopBot, and eventually you'll get a sign job. Well here's my chance.

I've got a sheet of 1" sign foam, and I'm trying to figure out how thick my relief should be. The sign will be outlined in full 1" thickness. What's the thinnest I should allow in the middle, and how much of it can I get away with?

So far I've been limiting my relief to 1/4" leaving 3/4" thickness everywhere, but I'd like more detail if the sign won't collapse.

Also, how should I mount the finished sign to wooden cross members? Lag bolts?... Something else?

Thanks!
-Dan

[rookie432]

Dan,
Congratulations on your first outdoor sign project. Make sure that talented wife of yours gets to paint it
. O.K. you can get away with a 1/2" relief comfortably You can even push it deeper if you use a backer board. THis brings me to the mount. I would Mount the signfoam to a sheet of MDO outdoor plywood. You have two options here 1) cut the mdo just slightly smaller than the shape of your sign and mount the foam panel or 2)cut it larger and use the oversize as another painted outline if it lends itself to the overall design. Either of these options will allow you to carve the foam fairly deep as it is fully supported from the back. This also gives you a solid wood sheet to mount to your posts.

Hope this helps

Bill

[pfulghum]

Bill,
Will signfoam warp due to cutting just one side?
For example, doing this is solid wood or MDF will cause warp due to the change in stress on one side?

-- pat

[rookie432]

Pat,
The short answer is yes...It can warp. Actually had this happen on my first foam sign. when you carve one side you will release the surface tension and if the sign is facing the afternoon sun it will want to curl in a bit. 2 solutions...make sure you paint both the front and back side of your sign with equal coats of paint. Paint will shrink in the heat of the sun and if you only have it on the face of your sign it will greatly increase the curl. Second use a backer board like the MDO I reccomended before. Use fasteners in the corners through the face. I recess them and make plugs out of foam to cover. Then use a good outdoor adhesive evenly spread on the back of the foam to make contact to the MDO Backer. The MDO will want to move as well but if you seal the edges well and double post mount the movement will be minimal. It doesn't hurt to oversize your lag bolt holes for the backerboard mount to the posts to allow for a little movement. Of course this is only one way to do this. There are tons of other mounting possibilities but this is about the most straightforward mounting setup.

Hope this helps.

Bill

[joe]

I'm like Bill when it comes to HDU warping. The glueing up of two dis-sumular material will often warp due to the different expansion rates.

One easy method to stabalize HDU is the application of fiberglas cloth to the back or common screen wire with epoxy. Sure stiffens them up too.

[hippo]

Thanks guys. That's some good advice. I'll have to find a local source for the MDO. I'll call the lumber yard.

I hadn't even worried about warping. Now I've got all new worries... Thanks :P

Yep, the wife will be doing the painting. I'm trying to do a relief of a sailboat, with waves and birds and stuff.

I'd like to make the mounting invisible from the front, so I'll probably try t-nuts in the MDO, or embed the bolts between the layers when gluing, so I can attach it at the back without showing.

I'll try to post some pics as things progress.

Thanks,
-Dan

[rookie432]

Dan,
The tee nuts or boltimg from behind will work but HDU isn't dense enough or strong enough to hold the fastener by itself. You mauy want to cut an oversized hole and fill with epoxy then tap the epoxy to hold the fastener.
I like the fiberglass tape backer as an option too. I have used the MDO in the past to have a substrate to fasten to. But if I were going to mount my sign between the posts and not actually on the posts I think I would go for the fiberglass tape option. Great Idea.

[hippo]

I think I'm leaning towards the MDO. The base has 2x4's going from post to post already. I was going to bolt the MDO to the 2x4's with the bolts protruding from, or going into the MDO and the Sign foam glued on front.

Better ideas?

-Dan

[rookie432]

That will work Dan but keep in mind that the sign foam has the capability to curl a bit. As Joe mentioned you will have different expansion and contraction rates and with a possible curling foam panel just glued to the MDO the foam could pull away from the MDO backer. I would still hide some mechanical fasteners in the 4 corners of the sign.

2 cents

[joe]

Dan,

I wish you well on this project but you really should let it go to a more experienced craftsman.

I'm firmly in the camp of aprenticeship or at least some experience with a craftsman. What we have here is a lack of materials knowledge and experties in fabrication. Who knows about design.

This isn't meant to be mean to you. I have posted, to adnosium, helping craftsmen along the path of creative sign work. And I've been selfless in my dedication to this end. However you need to step back and make a few trial sign. Put them outside to weather. Try some of the recommended techniques and materials before you actually make the first sign.

While I'm very glad the CNC's are on the market, the down side comes when rank ameatures go in with know knowlege of pricing, materials, or longevity of product.

I'm convinced he will do it however!

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