Standoffs for clear acrylic signs

[redprint]

I have a client requesting acrylic signs that are 39" wide by 51" tall, using 1/4" clear acrylic. They want 4 edge standoffs, one in each corner. Is 4 edge standoffs sufficient to hold this size and thickness of sign to wall without bowing? Would it need any support in the center of the acrylic to keep it from bowing inward? Is it normal to have a standoff in the middle of a larger sign installed onto a wall? I have never installed acrylic using standoffs, so am totally green as to how many standoffs you would need compared to the size of your sign. Also when using edge standoffs, do they allow for expansion of substrate? These signs will be installed inside. I also have many others they need that are using holes in acrylic for standoffs. Is there a tolerance of how close to the edge and space between standoffs? Anyone's experiences with installing acrylic with standoffs would be greatly appreciated to know what I can expect. Thanks for all your help and info!

 

[a77]

You could do them in glass and not worry about the bowing.
1/4" will bow in my experience at that size
You can put some standoffs in the middle and use tape on them (i.e. only use the base of the standoff so you don't have bolt and bolt head showing on the front).
I would just use your local glass supplier. If you got thicker with acrylic it will probably cost a lot more than glass.

 

[Gino]

Last Thursday, we put up a 3' x 5' PVC 6mm with only 4 standoffs and it didn't bow. We also put up 3pcs 3' x 4.5' PVC without any bowing. PVC is more flimsy than 1/4" acrylic. Don't put a standoff in the middle. That will look dumb.

 

[Billct2]

I agree, no stand off in the middle, unless it would be completely hidden. I've done 6 standoffs for pieces that size and it looks fine.

 

[a77]

6 standoffs should be good.
In my experience, I did a 4 standoff job with 1/4" acrylic, almost the same size as yours, and it had a bow in it.

 

[Bly]

Acrylic expands a fair bit due to temperature variations so for large signs I'd go at least 6mm thick, preferably 10mm and use at least 6 standoffs.
Polished edges looks classy too.

 

[henryz]

Maybe go to 3/8" or 1/2" ? if you are concerned.

 

[Gino]

6 standoffs should be good.
In my experience, I did a 4 standoff job with 1/4" acrylic, almost the same size as yours, and it had a bow in it.

Well, perhaps your measurements were off a tad. At only 3' x 4', there is no need for 6. Each one can bear about 60lbs of weight. Adding more will not solve bad measurements. It'll just bow twice as much.

 

[a77]

Well, perhaps your measurements were off a tad. At only 3' x 4', there is no need for 6. Each one can bear about 60lbs of weight. Adding more will not solve bad measurements. It'll just bow twice as much.

Actually, the piece of acrylic had a bow in it before putting it up. I'm not sure if it was bowed when it came in, but after a night in our shop. From now on I use glass for indoor and thicker acrylic for outside.

 

[CanuckSigns]

We use a rule of thumb of a stand off every 3 feet, if it's in the budget I prefer 3/8 or 1/2 acrylic as it's more rigid and it looks so much better for something like a lobby sign.

 

[txwrapper]

We have made literally hundreds of 1/2" acrylics displays with stand offs. Sizes ranging from 4' X 4' to 4' X 8'. Always use a minimum of four 1" standoffs mounted about an inch inside on each corner. 1/8" would more than likely bow with just edge standoffs IMO I would try to talk them into standoffs mounted in the corners and not on the edge.

 

[Gino]

Actually, the piece of acrylic had a bow in it before putting it up. I'm not sure if it was bowed when it came in, but after a night in our shop. From now on I use glass for indoor and thicker acrylic for outside.

I've never heard of a natural bow in a piece of acrylic, unless it was on an uneven surface or being forced somewhere. How can a 3' x 4' have a bow in it ??

 

[a77]

I've never heard of a natural bow in a piece of acrylic, unless it was on an uneven surface or being forced somewhere. How can a 3' x 4' have a bow in it ??

I don't know. Glass supplier screwed me last minute couldn't make the deadline, so I ordered a piece from local plastics/cnc shop and that's what we ended up with. 1/4" thick, 54" x 33". If that is not common, then that is good to know. I got turned off to acrylic and have used glass for indoor since.

 

[redprint]

Awesome, thanks everyone for your thoughts and comments!

 

[WB]

Yup.. If installed correctly the standoffs will hang the acrylic. If you drill the holes in the incorrect location you'll add tension on the panel and that's when the "bowing" will occur.

Depending on your stand offs you can over size your holes in acrylic which will give you a little wingle room.