Polycarbonate Channel Letter Faces Warping

[RED1]

We have made two sets of 6' Blue faces, and both times with two different materials, the faces start warping.

The guys are using F-channel for the retainers. A day or two after the installation they were perfectly flat, but now after a couple of weeks, we get a photo yesterday (and I went and saw for myself), the faces are warping....as if they have no room for expansion.

My guess is the F-Channel is holding the face tight not allowing for any expansion......whereas if you use regular jewelite this does allow for some expansion. Just a thought.

We are close to Houston Tx, and now the weather is not too teribly hot....although a couple of months ago when the first set was up, it was hot.

Any ideas?

Thanks

 

[Gino]

Pictures would certainly help. Also, good pictures of such a problem.

 

[J Hill Designs]

sounds like improper channel letter construction

 

[RED1]

I will get some photos, but I will say that we have been making channel letters for over 30 years and have never seen this problem. But there is always something different.

In your experience, with say 6 to 10' letters, if you used an f channel trim cap, would you allow for any expansion/contraction?

Thanks

 

[J Hill Designs]

I will get some photos, but I will say that we have been making channel letters for over 30 years and have never seen this problem. But there is always something different.

In your experience, with say 6 to 10' letters, if you used an f channel trim cap, would you allow for any expansion/contraction?

Thanks

the larger the letter, the more it will expand...if they are tight in the 'F-track' they will pucker/warp...

FWIW looking at F-track, I would hate to service letters made with it.

 

[RED1]

Thought I sent this response a minute ago, but did not........................our channel letter guy along with our shop foreman just informed us that they riveted the faces to the f trim about every 6". To me, therein lies the problem. No room for expansion/contraction!!

 

[MikePro]

we rivot our f-molded channel letters. work just fine.
curious to see the photos, but my bet is the letters were routed the exact size of the letter backer and then jammed-into the f-molding, thus causing your warping.

since the f-molding has a an approx 1/2"-3/4" retainer, I always route my polycarb inset ~1/8-1/4" to leave plenty of wiggle-room for ease-of-production.

 

[RED1]

Yes Mike, he DID cut them the same as the letter backs! NOW, would you think that the existing faces could be "trimmed" enough to make this work, or would you scrap them? I was asked if the warping would be permanent at this point, and I don't think I can truthfully answer.

Thank Again

 

[MikePro]

also, what thickness polycarb? we use .188", I feel .125" is too flimsy in large-sizes. Not sure if that matters at all, just throwing it out there.

anywho, I think your letters should be salvageable. Still, no pictures to reference, but I'd imagine your faces are just buckling. It takes a LOT of heat to thermalform polycarb. Before disassembling, draw the inline of your f-molding onto the face with a chalk pencil (just in case!), making special note of the key points of buckling (to possibly take a bit-more-off) and jigsaw <1/8" off the perimeter of your faces, and resecure into the frame.

When I first took-over the routing duties here at our shop, I used to route everything dead-nuts perfect... til the fabricators kept giving me sh*t for making their life hell. If I inset the routes for my polycarb faces, they have more room for error when fabbing f-molding & letter returns. Same with trimcap faces, I offset the acrylic shape ever so slightly so that the trim capped letter slides-onto channel letters...rather than jamming-on, when routing everything exact to the added material thicknesses involved.