Best way to join pieces to be longer?

[tygress]

Hello! I am making a sign for my boyfriend’s Chicago themed bathroom and I want to make it 30" long and 3.75" tall. I am using two-tone 1/16" Gemini Duet acrylic for the top layer and 1/8" white acrylic for the base layer. I have 3M 467MP for the adhesive between them. My plan is to use the JointPanel option of Boxes to make the interlocking teeth for the base layer.

The image below shows the sign I’m making and the two ways I’m thinking of making the base layer. Would they be equally strong? Do I need to do anything to ensure they stay together? Something is making me think that three pieces would be superior, but I don’t know. The sign itself is actually 3 pieces as well as the red parts are separate from the grey parts.

Thanks for any help anyone can provide. It actually got so cold today I got my first orange button of terror!! Gotta love Chicago weather.

[evansd2]

Three layers like that with joints that are offset from each other will work well. I’d say you’re definitely on the right track. The way you have it lined up now you’ll have two uncut layers at all points across the length of the sign, that’s a smart way to do it.

[dwardio]

@tygress

Would they be equally strong?

Generally, more joins equals less strength. With a two-piece base layer and a three-piece top the joins will be well spaced and not on top of each other. Which ever you decide on, consider cementing the base-layer joins with “Weld-On”:

Best adhesive for clear acrylic bonding

I am in need of finding a glue/adhesive to bond two clear pieces of acrylic together without the glue being evident. I have used super glue but you can still see where t was. I am making awards and need for adhesive to be invisible. Any reccomendations? Thank you

[deirdrebeth]

The only thing I might add is “puzzle pieces” to join the two invisible layers - so they can’t pull apart from each other…but I’m a horrible gluer so need all the help I can get

This design uses what I’m talking about on the back pieces:

Yet another picture frame

This one is more like a traditional frame, with the 8"x10" picture fitting into the back side, and a 1/4" overhang on the front side. It’s made of three 1/8" plywood layers. There’s a hole for hanging, and small pilot holes for screws for turn buttons. Thanks to @evansd2 for inspiration on the corner joints (“Planar butt jointing techniques”)! The joined pieces in the corners might seem to be made of different types of wood due to the visible contrast. Not so! The difference in lightness and…

[tygress]

I am using “puzzle pieces” in the form of teeth. Like this:

Thank you for thinking of it, though! I want this to be sturdy and stable.

[tygress]

Hmmm, I will definitely be buying this adhesive. I’m not sure it will be easy to put in the teeth but I’ll try it for sure.

[tygress]

Sorry, I might not have been clear. Those were the choices, I didn’t intend to use two base layers. I am EITHER going to use the purple layer OR the blue layer, plus the Morse layer on top.

[evansd2]

Well then I’d go for the 2 piece. Like @dwardio says, fewer joints will be stronger and less work.

As for your teeth they’ll work but if you’re optimizing for strength you might want something deeper with fewer teeth. Something more like:

The point of your puzzle piece teeth is just registration, so it doesn’t need to be complicated. By using deeper teeth like this you prevent a single line where there’s too much “joint”.

Your original teeth design will definitely work, but something with a single tooth like that will be a bit stronger.

[timjedwards]

When fitting two pieces together, you optimally want them cut from opposite sides (flip one and cut the mirror image of your design) so the slight angle of the cuts come together for a satisfying, strong join.