Platen Size As To Project Size


From original questioner:

I have a bottom platen size of 44 x 80 in a 4' x 8' vacuum bag. My project is a speaker cabinet thats 13" x 10" x 62". On the top I use a platen thats 14" x 64" .What I was wondering is since bottom platen is quite a bit larger does this pull to much on bag seams. Each of my platens have all edges routered with a 180 degree edge. This does work nice because I dont have alot of bag to try to take up and gather.

From contributor ja

Are you pressing the box, assembled? I think that's what you are saying. I think the seams of your bag can take it, although if you had a narrower platen on the bottom, it might be a bit easier. Do you use an air bladder inside?

From contributor Je

Yes box is assembled with 3/4 MDF and a 1 inch MDF face thickness. Box has internal supports. I have no Bladders inside. This will be the 3rd set of boxes I've done. Platen came with this vacuum set up from a freind. I have not cut platen down from original size. The bag I used this last week got pin holes along the seem and bag was 6 years old. Was wanting to make sure it wasnt the wrong pull on the Vacuum bag from the agle I have from box to platen. ordering a new bag tommorrow. May make a narrower platen and dry test it. should I go a few inches bigger thank Box in each direction. I was taking Vacuum to 12hg

From contributor la

The bags I've made have 2" seams with common vinyl glue. They have never come apart. I have placed them so they wouldnt set on the work, just at the sides of the platen or form. Also, I have arranged the bag so it "wraps" the work instead of forming a "tent". The only problem was gouging the material with a sharp corner.

From contributor Je

Very Cool that you make your own bags, what brand is the Vinyl glue that you use? and would I prep the two matting surfaces on my bag where the glue goes with isopropal alchohol or another chemical? do I brush a two inch wide layer of glue at edges for a good wide seal?
I did a 180 degree edge on my platens both top and bottom. Dont have that sharp corner against bag. Also the top platen I use above cabinet is only 1 inch bigger in each direction, giving me 1/2 inch of over hang all around top. thanks

From contributor la

I have gone to plastic suppliers to buy exotic adhesives. I happen to try the stuff at home depot and it worked as well or better. Oatey X-15. I have heard some use the 40ml pvc as a press membrane. Cant see thru it though. I dont think there is much prep.