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  • what boards can be used for making a large sign?

    Posted by Phil Davies on September 7, 2004 at 5:04 pm

    First post ”here goes ” got a sign to do 4800 by 1200 basically two full sheets side by side i was going to use two sheets of 5 mm foam screwed straight onto existing ply boards as they are in good nik, unable to fit in panatrim frame as the sign is inset ,i was just going to trim with stockframe !! my only concern will the boards warp in the heat as there is no room for exspansion as there would be if fitted in panatrim, unsure about 5mm foamex in the long term, any advice would be appreciated thanks in advance.

    Colin Crow replied 19 years, 8 months ago 6 Members · 8 Replies
  • 8 Replies
  • Robert Lambie

    September 7, 2004 at 5:13 pm

    your right mate, they will expand/contract and buckle the sheets over a period of about a month. much sooner in the sunny days we are having at the moment.

    if like you say you have an inset aear that has a wood backing. try using 1 inch by 1 inch alluminium angle. but used in the reverse method.
    its hard to explain. lets say you have the foam in place and you flip the angle into the rebate so the angle holds the face of the sign and you screw from the sides into the wall of the rebate? does that make sense? 😕

    if not, reply here and i will post a small diagram later tonight of what i mean.. im usless at explanations like this 😉

  • John Childs

    September 7, 2004 at 8:16 pm

    I did a silly (and expensive) thing once.

    A customer asked for a forty feet by eight feet perspex sign with an aluminium frame. “No problem” says I and promptly ordered the frame and panels from Kestrel in Birmingham. When it arrived we laid it out on the floor, I looked at it and worried about two things.

    1. Expansion over forty feet, especially as there was only a 50mm frame to accomodate it.

    2. As it was to be fixed to the building by the frame, with the panels floating, it wouldn’t take much distortion before the panels popped out. As far as I could see the slightest wind would have the panels flying off down the high street.

    I rang Kestrel and asked if they had done anything this big before and they told me that they had once done one which was a little bit larger. I thought “Oh great, I’m not a trail blazer” and asked how it performed. They told me it had blown down. Thanks for the timely guidance lads.

    I made the decision that no way was I going to take responsibility for that and told the customer that the only way I was prepared to do it was by using aluminium sheets fixed direct to the building as this would positively fix the panels and also spread the load to a bigger area of the building fascia. A whole lot safer.

    So, that was it, ten sheets of powder coated aluminium, butted up to each other, and no expansion problems. The sign performed well and looked good until the day my customer went broke and the liquidators removed it.

    The point of this waffle – none really, except to say that you would be better using aluminium, dibond, or anything else where expansion is not an issue.

    Oh yes, and also to advertise the fact that ten years on I still have a forty by eight aluminium and perspex sign at the back of my workshop if anyone want to buy it. It only cost me £1200. 🙁

  • Phil Davies

    September 7, 2004 at 8:18 pm

    think i need a diagram 😳
    how much should i allow for exspansion/contraction ??
    what,s the best way to join the two boards in the centre ??
    would others use 5mm foamex for this size sign ??
    thanks again for your reply mate

  • Robert Lambie

    September 7, 2004 at 8:57 pm

    here is a brief diagram of what i meant by using an alloy angle to hold in the panels. reversing the angle and screwing in from sides, into recess walls hiding the visable fixings.

    to be honest mate, i very seldom use fomex of any make.. unless for interior signage. there is too much hassle with it.
    i would advise, as john has said. using allouminium sheets or rynabond/dibond/alucolour or the new one on the go.. (cheaper) leboard (i think its called 😕 ) you can get it at europoint display as well as alucolour.
    rynabond at amari plastics and dibond at righton plastics or cox.

    using the angle to hold the sign in place is much safer no matter what material you use. if using the above metals/rynabond etc you could silicon the back and angle the front and you wouldnt need to worry about any join fixings. if you prefered, you could use a couple of screws on the join with coloured caps.


  • Phill Fenton

    September 7, 2004 at 10:30 pm

    I’ve used 5mm Foamex for signs this size before – but only in conjunction with a panatrim type of frame – this is essential as the frame allows the panels to expand and contract without buckling.

    The panels hang inside the frame from a rail fixed to the top of the panels – this way they can expand and contract moving within the frame without warping.

    When fitting a frame in an inset you will have to load the panels from the front (instead of sliding in place from the side). Make your frame about 2cm shorter than the total length of the inset to allow one end section to be removed temporarily while the panels are loaded into the front of the frame. Definately use fixings though the front face at the join straight into the backing board (using packing pieces behind the panels to keep them the same distant out as the frame holding the panels). These fixings will not cause the panels to buckle as they can still expand in the other (non fixed) directions. If you don’t fix the panels at the join they will be sucked out in the first high wind (and because you have to load from the front – there is no possibilty of fitting a lower rail).

    I usually make my panels 10mm less than the external frame measurements (length and height) – but you may have to reduce the height even more to allow for loading from the front – however, at a 1220mm drop – the panel is quite easy to flex and tuck into the bottom once the top rail has first been located.

    I’ve done a number of signs of this size this way before – these have survived high winds (due to being fixed at the join) and yet remain flat and unwarped.

  • Phil Davies

    September 8, 2004 at 6:47 am

    great advice thanks guys,
    im alot wiser now ! 😀

  • Adrian Hewson

    September 8, 2004 at 6:07 pm

    Currently doing a sign 12M by 1.3 using two sheets of alucore (honeycombed aluminium)

    I have these in sheets of 20ft by 5ft if you are interested (they are hard to buy on their own as most places make you buy a MOQ but could sell you one if you were interested.

    We virtually never use foamex except inside either

    Regards Adrian

  • Colin Crow

    September 8, 2004 at 9:48 pm

    Again, had problems with foamex fixed all round (cheapskate customers request) Dark vinyl areas heated up and buckled horribly. Also had a case of an 8′ x 4′ x 10mm foamex panel rip right through its screw cap fixings and never found it! Only lasted 3 days – never again.

    If you must use foamex, always suspend it like a curtain to avoid buckle. I think they work on 1% for normal expansion which doesn’t sound much but still means 24mm over a 2440 board.


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