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Has anyone found an inexpensive yet effecient method for backing HDU. Aluminum or MDO are both expensive methods for this. Is it always necessary to back if you are putting it on a hard backing, like a brick wall. I have a double sided monument to put 2, 3x10 carved panels on, and a hundred bucks buried isn't appealing to me. Thanks for your comments, Jack
-------------------- "Don't change horses in midstream, unless you spot one with longer legs" bronzeo oti Jack Davis 1410 Main St Joplin, MO 64801 www.imagemakerart.com jack@imagemakerart.com Posts: 1549 | From: Joplin, MO | Registered: Mar 2000
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posted
If I was applying the HDU to a solid surface...say a Brick wall...I would NOT use ANY backing...... if the HDU was 1 1/2" or more thick...... Shep'
-------------------- Arvil Shep' Shepherd Art by Shep' -------- " Those who dance are thought to be mad by those who cannot hear the music " Posts: 1281 | From: Mt Airy NC | Registered: Mar 2001
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posted
With a working size of 3ft. x 10ft. I can understand backing the sign even for the purpose of moving it around during production without fear of breakage. This would especially be handy if the sign's shape was not rectangular.
A relatively inexpensive alternative to MDO for backing would be pressure treated plywood with a thickness of 3/4" to control warpage and add strength and all-important ridgedness.
Glue should absolutely be a polyurethane type applied heavily around perimeter and in zig-zag strokes inside the perimeter throughout. The zig-zagging allows for the expansion-contraction factor and the polyurethane glue actually cures better with moisture which will surely abound in treated plywood.
Good luck.
-------------------- Donny Pavolini Dunaway Signs Biloxi, MS
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You shouldn't need to back them up on a solid surface like that. On other jobs I have used MDO or aluminum. With MDO I glue up with West System epoxy and make sure the edges are also sealed with epoxy before painting - I don't want the plywood to rot ot delaminate behind the HDU. On projects like you describe I would use one-inch HDU and half-inch MDO; the price including time for gluing it up is about the same as buying thicker HDU. Cost-wise, we build it into the price. These are carved signs - you don't give those away (do you)?
-------------------- "A wise man concerns himself with the truth, not with what people believe." - Aristotle
Cam Bortz Finest Kind Signs Pondside Iron works 256 S. Broad St. Pawcatuck, Ct. 06379 "Award winning Signs since 1988" Posts: 3051 | From: Pawcatuck,Connecticut USA | Registered: Nov 1998
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posted
Yo! JackEE! I'm gonna disagree with the boys. HDU CAN warp for any number of reasons, particularly anything under 3"18lb. 3x10s are long enough to justify a 3/4" backing. Use cheap old CDX, prime the "he-double toothpicks" out of it, paint it and use PB240 to bond the HDU to the UNpainted plywood surface. This isn't "just my .02". You may live to regret not backing HDU of any substantial size. I live this schtuff every day of the week, small, large and VERY LARGE. Don't roll the dice, unless the customer has a lovely daughter and you just want to spend time with him.
-------------------- Pierre St.Marie Stmariegraphics Kalispell,Mt www.stmariegraphics.com ------------------ Plan on knowing everything before I die and time's running out! Posts: 4223 | From: Kalispell,Mt 59903 | Registered: Mar 2000
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We never use a backer when mounting on a hard surface, we use more mounting positions to minimize warping. We have found that HDU is a more permanent material than most we could use for a backing. Dark colors need more fasteners than light colors and thicker material needs less.
-------------------- Kent Smith Smith Sign Studio P.O.Box 2385, Estes Park, CO 80517-2385 kent@smithsignstudio.com Posts: 1025 | From: Estes Park, CO | Registered: Nov 1998
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posted
I gotta agree with Cam on this one, for a couple points... Being able to use thinner HDU literally pays for the backing, and these aren't supposed to be cheap anyway.
I just love Dibond for it's strength to weight ratio. PVC and Plywoods can get damm heavy on big panels. There are cheaper aluminum/PVC composites than Dibond, the corrugated stuff (brand name?). I havn't used them because of the edge perforations, but they should excell in framed applications.
Donny mentions the safety factor of a backing for production purposes, just moving a panel around the shop. So true. We tend to do a lot of odd shaped pieces, cut out logos and letters, etc, that would be much too fragile to handle without a backing. For those types of pieces, we laminate up the HDU to the Dibond before we even cut out the piece. A cool thing about dibond is it holds screws very well - when a cutout piece is backed with dibond, you can screw into it from behind or even screw aluminum threaded studs into it. Here is a project we did recently using thin HDU backed with it:
It's double-faced 3'x4' with the main beveled panels being 1" foam bonded to 3/4"PVC. The inset white beveled panel (also 1" HDU) is not backed with anything, nor is the black panel with the beveled gold edge. But the address oval and the big "DN" monograms are 1" HDU were backed with 3mil dibond. We absolutely HAD to back the "DN" or we could not have worked with it, nor could we have flown the trailing edge of that N so far out in space without something substantial behind it that could accept a stud. The oval has two studs behind the suspended part also. Dibond is the clear winner for us in applications like this.
[ December 22, 2001: Message edited by: Joe Rees ]
SONGPAINTER Original Sign Music by Sign People NOW AVAILABLE on CD and the proceeds go to Letterville's favorite charity! Click Here for Sound Clips! Posts: 1974 | From: Orleans, MA, Cape Cod, USA | Registered: Nov 1998
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Geez, Joe. I thought we were the only ones using Dibond for backing. Great schtuff. It's really very good for backing freestanding cut copy like Commercial Script with very thin strokes. Nice piece, BTW.............
-------------------- Pierre St.Marie Stmariegraphics Kalispell,Mt www.stmariegraphics.com ------------------ Plan on knowing everything before I die and time's running out! Posts: 4223 | From: Kalispell,Mt 59903 | Registered: Mar 2000
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posted
Thanks, Joe. I'm going to have to try dibond for a backer. I have also laminated HDU to a backer before cutting out a shape, especially on larger pieces.
Another trick with cutting out complex shapes is to cut the backing material (like MDO) into the shape, then use a hand-held router with a panel-edging bit to cut out the HDU. This makes for a perfect fit when laminating pieces together, especially when you are doing a double-face carved sign with an MDO "core". This also allows me to carve both sides individually, before laminating, which makes a larger sign a LOT easier to handle on and off the carving table.
BTW, what do you use for adhesive?
-------------------- "A wise man concerns himself with the truth, not with what people believe." - Aristotle
Cam Bortz Finest Kind Signs Pondside Iron works 256 S. Broad St. Pawcatuck, Ct. 06379 "Award winning Signs since 1988"
Posts: 3051 | From: Pawcatuck,Connecticut USA | Registered: Nov 1998
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For bonding sheets of HDU to substrates like Dibond for cutting out intricate shapes, we want a continuous bond. We spread one side with polyurethane glue (Gorilla Glue), then wet the other surface and clamp them together overnight. We can even use screws instead of clamps if we mark out our shapes first.
For attaching finished appliques in place, permanently, our favorite is a caulking tube adhesive called PL Polyurethane. (Can't recall the mfg at the moment). It's readily available in all the hardware, lumber and paint stores we frequent, and it's super strong and waterproof. You use it like Liquid Nails but about 1/4 the amount.
Cam, good point about using your first panel as a template for routing multiples. We have been using a flush cut-off bit with a bearing on the bottom. There are two problems with it - 1) your template must go below, forcing you to work by feel instead of sight.. 2)The flush bit we found that will cut through 1.5" thick HDU is also about 1/2" wide, so it kicks out a tremendous amount of dust in the process of chewing up all that material. For shallower depth of cut, the bits get much thinner and I have seen some with the bearings on the top which would be much easier to work with.
On the same subject, the coolest thing we worked up recently was a collar system for our laminate trimmer that lets us use the spiral side-cutting bits from a Roto-Zip tool for cutting templates. Very thin blades, like drill bits, make very little dust, and are still strong enough to cut up to 1.5" HDU and even 3/4" PVC. (I wouldn't recommend for wood or MDO though).
posted
Thanks guys, but I guess I'm using the same methods as you already. I was hoping to hear of a 20.00 to 30.00 backer. I have used Dibond like Joe with polyurethane glues, and also .040 aluminum panels which work pretty well but still run about 50.00 per 4x8. They just seem a little expensive for this particular use, although I understand the insurance they provide. I would like to see one of the HDU manufacturers to start pre-backing their product for their own good and ours. Less damage in transit, thicker material cheaper, a stronger more substantial panel that saves us time and problems. Thanks for the input and nice sign Joe. Jack
[ December 23, 2001: Message edited by: bronzeo ]
[ December 23, 2001: Message edited by: bronzeo ]
-------------------- "Don't change horses in midstream, unless you spot one with longer legs" bronzeo oti Jack Davis 1410 Main St Joplin, MO 64801 www.imagemakerart.com jack@imagemakerart.com Posts: 1549 | From: Joplin, MO | Registered: Mar 2000
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