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Fighting the vacuum bag9/28
I would like some ideas on how you guys deal with loading vacuum bags. In this case I'm loading as many small panels as possible. I've tried ropes down from above with spring clamps holding the 2 ends open, but still fighting trying to get things in. Mine is capable of holding a 4x8 sheet. One day I'll be found suffocated inside the thing! Thanks for your ideas.
You climb in after your parts. Going in head first and trying to drag the parts in behind you is asking for trouble.
I like to have a thin sheet of something already in the bag before loading the actual parts. I then just prop the front open with a couple of sticks, to get started, especially when working alone. But I also have a short length of 1.5" pvc in there to act as a roller, which takes care of the bottom corners snagging. It will have made it's way toward the open end by the time the parts are in, so easy to retrieve then.
Keith, do you push the pvc ahead of the work; with the work,as you load, there by not snagging the corners? Good advice.
No, I place it back about one foot back from the front edge, then as it rolls along, it is holding that front end up, so there is no weight on the bottom digging in. A little tugg on each side takes care of the top , like slipping in under the covers when you go to bed.
By the time you advance 8', it will end up about 3' from the back end, where it is easy to retrieve.
If you do enough large parts, you might consider acquiring a flip-top press.
I found myself laminating a number of workpieces that were 6-8' long and 24-30" wide. I now have a 5'x10' flip-top table. No need to "climb into the bag" to arrange anything.
Yes Charles, that would be nice, but with the space I have in the shop vs the no. of times I use it, not worth changing. I'm geared up shop wise for maybe 2 or 3 jobs at once and too many machines. A drop down table with flip press may be the answer 1 day. Need to find the wall space.
Without knowing what your parts are or how they relate, I will offer two suggestions.
1. Run two bags off one pump with a valve manifold to isolate the bags while loading/unloading. This can reduce the number of individual parts per load. An extra bag and a couple of valves are not too expensive if you are in production. You can use smaller setups if pressed for space.
2. Gang together related parts with their veneer skins and handle them as units. If you have a drawer bank, for instance, lay the blanks up together with door bumpers for spacers with a common veneer top and bottom sheet, and cut apart with a knife after pressing. In this way you can lay up multiple parts on a common "cookie sheet" with a common top platen. If you are using pva glue and two bags, you can maintain a reasonable flow, cutting and seaming while parts are in the presses.
Your process using fabric and breather mesh seems overly complicated for flat panels. I have used similar materials for sharp curves, but for flat work we usually use 1/4" melamine coated particleboard for platens. Air evacuation is achieved by a grooved MCP platen inside the bag underneath the MCP "cookie sheets" that parts are loaded in on. Multiple parts can be problematic as the bag tries to shift things around during suckdown, but consolidation of parts using spacers and common platens works best for me.
All that said, life has been easier since we went to frame presses.
Kevin,I'm guessing you round over the platen sheets to protect the bag from puncture? Or maybe just soften the corners? This seems necessary.
Yes, we break the edges and soften the corners of the cover sheets, as well as laying a sheet of poly over all to keep glue squeezeout off the membrane.
Get a 4 x 8 x 1/4" sheet of melamine. This will sit on top of your platen inside the bag. It can slide in and out. Pull it almost all of the way out, resting on sawhorses, to load a bunch of small panels. Then slide the whole shooting match into the bag. No sticks required. We ran our vacuum press this way for many years and it works great. It's easy to keep the 1/4" sheet clean, and you can throw it away if it gets glue on it. Also, always press your pieces face down, so that the substrate acts as a platen.
All good information. Nothing like a good forum to toss and receive ideas. Thanks