This Method of Gluing onto Curves Sucks!

Sometimes the right tool for a job can be unusual, and this sucked only in the sense that vacuum sealing was involved. Recently [Martin Raynsford] found himself in a situation of needing to glue a wood veneer onto a curved surface, but faced a shortage of clamps. His clever solution was to vacuum-seal the whole thing and let the contour-hugging plastic bag take care of putting even pressure across the entire glued surface. After the glue had set enough to grip the materials securely, the bag was removed to let the whole thing dry completely. Gluing onto a curved surface has never been so clamp-free.

The curved piece in question was made from dozens of layers of laser-cut plywood, stacked and glued to make the curved lid of a custom-built chest. It might have been just the right shape, but it wasn’t much to look at. As you can see, giving it a wood veneer improved the appearance considerably. Wood veneers are attractive and versatile; we’ve seen for example that LEDs will shine through wood veneer quite easily.

29 thoughts on “This Method of Gluing onto Curves Sucks!

    1. It’s a wood glue with resin in it. Resin is pure chemical glue and what’s you start that chain reaction will just happen. Once that set they then opened it up and let the normal air/wood glue reaction happen. This is actually pretty clever, I ALWAYS wish I had more clamps.

    2. It depends. This is a common technique for carbon fiber or any type of two part epoxy work where the epoxy undergoes an addition cure, only requiring the two materials to be in contact to initiate the (usually always exothermic) cure.

      Wood glue is just a classification of glue rather than the actual glue itself. There are actually three primary types of wood glue.

      One is made from a chemical known as aliphatic resin. This is the traditional yellow glue that may come to mind when you think of wood glue or carpenter’s glue. Yellow glue is a little bit stronger than traditional white glue, but it dries quicker and holders stronger. You can also sand over most yellow glues without having any real problems if you plan on repainting the area, but it is resistant to wood stains.

      Urea formaldehyde is a plastic resin glue that offers water resistant properties. It is best used on indoor furniture, but is highly resistant to any type of paint or paint thinners. This type of wood glue also takes around 30 minutes to obtain a good hold on the two surfaces, but once it does obtain a bond it holds very tight.

      Resorcinol (resorcinol-formaldahyde) glue is one of the most durable types of wood glue. It is 100% waterproof so it makes a great option if you need to seal up or fix any outdoor furniture, concrete, or heavy duty repairs like boats, ATVs, etc. When applying resorcinol glue, make sure that you are keeping it away from moisture until it dries. Until the invention of epoxy resin, resorcinol was one of the most common marine glues. Unlike epoxy, it does not have gap filling properties, requiring joints to be close fitting and clamped under pressure to achieve good results. The glue comes in two parts — a red syrup and a light brown powder that were mixed to form glue.

  1. Roarockit.com has some nice vacuum bag products for this that use a neat hand pump Instead of an electric vacuum pump. I bought a few of their bags for some projects I’ve done, pretty slick.

    1. Nothing new but still a nice idea that might be useful one day!

      Now the question is how to suck the air out. A vacuum cleaner probably won’t work and will heat up (and maybe catch fire) because of the lack of airflow for cooling. For small parts one of those kitchen-vacuum-storage-thingies might work, but for larger stuff you would need a dedicated tool/pump.

      1. Many people re-purpose an old refrigerator compressor. Search the web for info. For epoxy or resin, you also need to add a trap for any liquid that’s withdrawn. For a quickie glue-up, a Shopvac will do in a pinch.

        1. Oh yes, right, i heard about this. Good idea and recycling old stuff is nice, but please dont let the content of the refrigerator cooling system go into the atmosphere. That’s bad and (at least here) you will have to pay a big fine if somebody see and report you to the authorities.

      2. A vacuum cleaner will work because the bags have a check valve so you can pump them down and then remove the vacuum cleaner. Other options would be regenerative blowers or just your generic rotary oil vacuum pump or diaphragm pump. If you really want to get fancy you could use a scroll vacuum pump.

  2. Stacking (and cutting) all those plywood “C”s seems tedious. One could take a piece of suitable PVC pipe and glue the veneer with epoxy on it, also under vacuum. Or if it has to be all wood, then one could make his own curved plywood: Glue 3 layers of veneer together (with crossed fiber direction) under vacuum over a pipe or section of it as a former.

  3. You can use a water filled bag instead of of vac sealing, something I’ve used with fibre glass moulds – it has the advantage over the vacuum approach in the fact that you loose vacuum quite quickly (certainly withing an hour in my experience), and also you can get way bigger forces.

    1. I’ve made a few fiberglass and carbon fiber parts using the vac bag method. It never occurred to me to use water, in fact I made a deep dish shape recently (cover for a outboard boat engine) and using water would’ve been cheaper and probably would’ve got the same results. I ordered a bag too, but I probably could’ve done the water trick with materials on hand. Thanks for sharing, i’ll keep that tip in mind for next time.

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