| | |
Kevin Jenness
|
: Dear Jason,: A vacuum press will veneer your 14' square panels as well as a 12" square panel. Obviously that is a big panel to handle and I would hate to have to work that large, but vacuum will do it just fine.: As far as other glues I try to match the glue to the project. I never use only Unibond 800. I use Unibond 800, PVA glues mostly, and sometimes polyurethane and epoxy.: Sincerely: Darryl Keil: : I will be making some large sound reflecting panels to hang from the : : ceiling in a new performing arts center. The faceted panels, which : : vaguely resemble a Stealth bomber done in maple, are 14' square, 1-: : 1/2' deep. Is this a reasonable size for vacuum veneering, or would : : a different approach be advisable? Is there any argument for using a : : different glue than Unibond? Thanks for any thoughts on this matter.Darryl: I would be interested to hear your suggestions for applying vacuum to a panel this large. I can't imagine sliding it into a bag.How would one get a sheet big enough, and how would you seal it?I recently struggled with what I thought was a large curved panel and eventually succeeded using boat building techniques. Maybe(?) this will be of interest. I would certainly like to hear suggestions about different approaches.I had to build a kitchen island one end of which had a changing radius curve (r=2'-6' approx.). The face panel was about 30" high and 5' long with a 30"rise. I couldn't see getting it into a bag, so I decided to avoid making a separate form, but rather building the cabinet structure and then veneering onto itusing an overlaid sheet sealed at the edges onto surplus material, to be trimmed later. I made an armature of plywood, overlaid with one layer of 3/8" bendingplywood. I found upon testing that so much air was leaking through the wackywood I coudn't get above 6-8" mercury on the vacuum gauge. I pulled the sheathing (how many staples?), layed on some 6 mil poly and resheathed, tapedthe edges of the sheathing with packing tape, and pulled about 15" on the gauge.I decide based on boatbuilding sources that was marginal but perhaps adequate, so proceeded to apply a crossband with PVA. Disaster- not fast enough sealing up assembly, the veneer buckled, I wound up tearing it all off and redoing the processwith Unibond, which gave enough time to get the pressure on (and I presume putsless moisture into the assembly). I used a wrinkly laminating film from Film TechnologiesInc. for the cover sheet (supposed to distribute air without a bleeder fabric) and masticfrom Gougeon Bros.(WEST system). It was quite difficult to get the mastic to seal perfectly , and it didn't like to let go of the film, so was a struggle to reuse. I did 2other smaller panels the same way, for the same reason, but I sure would like to hear of a better way. In hindsight, I might have sealed the bending ply with epoxy beforelaminating, but the edge seal would still be an issue. Perhaps I could have had a biggerbag fabricated, but it would have been hell to get such a big form inside one. I am not convinced that bagging outside a form would have given a true shape curve given theshape and materials (how could I hold the flexible materials down on a form before applying pressure?). Comments?
|
|
