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why do the lightbox panels keep separating?
Hi Fellow signboarders.
Have a job thats been driving me crazy.
customer had a exiting lightbox 7.5mt long x 1200mm high
was basically 1 long box with 5 individual blown panels with metal joiners
that read M O T E L. anyway, remove the joiner and supplied and installed 6mm thick flat panels. We used a extruded acrylic H joiner for the panel joins. The joiner wasn’t glued to the panels but was very tight fit.
The sign is facing West so the acrylic does get a lot of sun.
They obviously expand but at night when they cool down the panel joins come apart. I think we have done this method many and had success but for some reason this job we cannot get right. I want to fit some screws thru the joiner to keep the panels together but as a last resort.What do you guys so normally for this sort of job?
if you use screws, what Type and spacing works?
to little and the acrylic might bust out at the screw pointsthanks for any advice
tim
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26 Replies
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Is there a hanging bar on the panels?
If so you can fit panalocks. These are little acrylic hooks that sit level with the hanging bars and interlock with each other across the joins.
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HI Andy,
don’t really follow you on the hanging bar )
the sheets sit in a traditional lightbox with angle flashing
could probably hang the sheets but box would need modification?tim
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Hanging Strip:
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Well, most frames and boxes have some kind of ‘ledge’ within them that will accept a 5mm thick strip (about 12mm wide) that is stuck to either the front or back of the panels at the top. This strip sits on the ledge, thereby supporting the panels. ie they hang, rather than all the weight sitting on the bottom of the frame. Panalocks are like a plastic strip that will interlock with another panalock. They are then hidden by the edge trim, as is the hanging bar.
Hard to describe, easy to do……
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There’s me writing a novel and Rob jumps in and describes it perfectly with one picture! 😀
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HI Rob and Andy
thanks for the pic, never seen this extrusion before
but have seen sign panels hung before.
with the joins in the sheet do you guys use a H joiner?? -
No.
I rout the panels so they overlap. Then stick a strip on the back so you end up with a kind of ‘tongue and groove’ effect.
Not that your method is wrong, but I prefer a tighter join in the panels.
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Hi Andy,
Yep done that one before might do that I think.
do you screw fix the joins at all to make sure that stay together? -
You can screw them, but with expansion and contraction occuring all the time, screws can lead to cracks appearing. I don’t like screw fixing acrylic for this reason. What about wiring them together underneath the flashing/frame? Just drill a hole either side of the join and then kind of staple the panels together with some wire or a tie wrap. Sounds dodgy I know, but if it can be hidden under the frame it should be OK.
It’s always a nightmare working with old frames.
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That picture has summed it all up I have read so much about these panatrim signs and have never fully understood but it is so clear from that picture thanks a lot
One thought were would I buy the sections in the photo and what do you call them thanks a lot bill -
They go by various names panatrim eurotrim etc but try cherwells they will supply the extrusion, and for a small fee, make up the frame to your specified size, and also supply the panel, in foamex, perspex or composite. Sorry dont have their number to hand, but a simple search on the boards will find it
Peter
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Cheers Peter I will get on with it straight away I would like to go into the manufacturing side more and read up all the time I have even got a few jobs lined up so will have to grab the bull by the horns and jump in and DO IT
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as peter says, there are a number of suppliers…
one on the boards is http://www.uksignboards.com/viewtopic.php?t=17386others include Europoint, Cox Amari, cherwells, etc etc
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Bill,
Unlike others here, I’m not keen on Panatrim and it’s clones.
My opinion is that the three part extrusion, Signframe, from Kestrel is a vastly superior product for very little more money.
http://www.kestrelsigns.com/boxes.htm bottom of the page.
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john, this maybe a product i worked on a good while back that i never ever found the supplier of. what i mean was, i took a sign "down" that was fitted with, what looks to be this trim. but never found a source. i have used kestral for various other products over the years but never knew they did this one. i must give them a call…
"thats if, i am thinking this is the same product. hope so!" 😀
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Rob, I’ve never bought anything other than Kestrel Signframe.
I’ve had to work with existing Panatrim signs over the years, mainly to take them down and throw them away, but sometimes to replace panels, and the Kestrels stand the test of time better. They just seem to be a more sturdy and professional piece of work. We don’t do a lot of signs as you know, but every one I have done in the last eighteen years is still there and looking as good as the day I put them up. I can’t ask any more.
We’ve got to do our very first flex face sign in the next couple of weeks and I am using Kestrel’s system for that. Despite never having done one before I have every confidence in their product.
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thats good to hear john, im gonna give them a call and see if i can get some samples/off cuts just so i can see its the same thing i have in mind from the past.
i know what you mean with panatrim, some lightweight inferior copies of the stuff but i must admit that when i use the assembled system that i come up with years back, (did demo on) ive never ever had a problem with any of the ones ive done. i also like the bull nose style. but like you say, you stick to what you know and what lasts best.
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Hi, found this old thread re hanging acrylic in lightboxes. Great info and explanations here, but a couple of questions if anyone can help. How is the top hanger fixed to the acrylic and what would it be made of? Would VHB tape do or would it need screwed as well? Also, is there a need to put a similar fixing on the bottom. I have had acrylic panels in a box ( without a hanger ) which in the wind, bowed and lifted up so much that the panel came out at the bottom and fell and smashed. Obviously I want to make sure that when replaced this is not gonna do the same again. Belt and braces. And suspenders…. and all that.
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Jim,
usuall way is using a strip of the same acrilyc material, bonded with a single part adhesive like fusion. most sign suppliers stock the correct adhesive, it welds the strip and is very strong.
if the sign is over 600mm I would, for peace of mind do a bottom strip also. It is also a good idea to use spring strips at each end so the panel is held under a bit of tension.Peter
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Jim,
The ones I have dismantled generally have the strip glued to the panel, but reinforced every now and again with small countersunk bolts and nuts.
If I was going to make this type of sign I think that’s the way I would go as I have a deep mistrust of adhesives and like to see a nice mechanical fixing for security.
Nutting and bolting is fine for that as the panel and strip expand and contract together at the same rate, so there are no cracking issues.
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John, I am with you on the adhesive thing I prefer to see mechanical fixings too, although I know adhesives are now excellent if they are used in the right circumstances.
Peter, I had thought a bottom strip might be a good idea. There are two panels each approx 2400 long x 1270 high. Could you explain what you mean by the "spring strip" please.
Thanks for the help guys.
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Jim,
the spring is a strip of metal about 100mm long that fits into the upright ends of the frame, and holds the panel in place I dont have a picture, but your frame supplier should stock them,They are used especially when 2 panels are used, so that the join is held together, (panel locks are recommended though) but I would also use them on large single panels.
Peter
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Jim, I would just use an adhesive like Peter suggested, I use to use Penloc which is ideal for this sort of job.
As an engineer it was proved to me on numerous occasions that an adhesive or chemical joint or repair could actually be stronger and last longer than a mechanical type joint or repair.
This probably applies in this instance where the mechanical fixings will be very close to the edge of the acrylic panel. As long as the two surfaces are cleaned and prepared properly and the instructions on the adhesive are followed then that is all I would use.What thickness of panel are you fitting Jim because at that sort of depth I wouldn’t use anything less than 5mm opal.
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Hi Martin,
The panels are 5mm opal. Never had much experience of plastics in my engineering career Martin although as I said I know that if you get the right combinations and use the right product for the job, chemical adhesion is very strong. I am led to believe that the large motorway signs are held purely by VHB tape these days. I don’t know how accurate that is but I have noticed that there are no rivets used now.Jim
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Not to mention the old Solvite ad :lol1:
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Jim, you can get penloc from eurobond I have used it on quite a few ocassions and it has always done the job.
http://www.eurobond-adhesives.co.uk/default.asp
20 years in submarines came across all sorts of problems and different materials and also came across some very good chemical repair products, what use to surprise me sometimes was that the guy from a company who’s products you were using would say to you that they had never tried this sort of repair with it before so it was sort of like an experiment and you made the procedure up as you went along!!!!
As for the motorway signs I believe they still have rivets, as far as I am aware the latest legislation states that signs displayed on the public highway must be riveted as well as taped. A lot of places use countersunk rivets so the heads are flush and you don’t get the dome shape on the face of the sign. I always use countersunk rivets myself and if floodcoating the panel cover it after I have attached the channel.
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