Making a Vacuum Bag

[Tenson]

Can I please get some recommendations of where to source bits of making a vacuum bag in the UK?

I need vinyl sheet and vinyl cement.

I actually have some 'Plastic Weld' which I guess might do the job but it is very thin and fast to evaporate so I'm not convinced I could paint a strip and then apply it along the seam of a bag.

Finally I need some hose connectors. I have a vacuum pump I got from eBay and the thread for the vacuum inlet measures 16.5mm I'm not sure what thread this is? I guess as the pump is made in China it is not going to be BST but it looks closest to 3/8" BST?

[mekanik]

Hi Tenson
I have done some bagging and just used some clear plastic sheeting that i had for a slip membrane to go over my floor insulation before i laid a screed, just sealed the ends with gaffer tape. you could just secure your pipe direct to the pump adapter and fix with jubilee clip.
What is the bag for? veneering flat work ? vacuum infusion ?
Have a look here
http://www.easycomposites.co.uk/#!/starter-kits/resin-infusion-starter-kit.html
This will give you an idea of the materials that are available, this site is not the cheapest so shop around when you've seen what you want, the proper bags cost an absolute fortune for what they are, i bought some that are used for vacuum storing bed linen/clothes ect seems to be the same stuff as the expensive type and the have an adapter built in.
Regards
Mike

[Tenson]

This is for veneering. I will use it on a regular basis so I want to make it well.

[mekanik]

The Vacuum Storage Bags i mentioned have a seal on one end, just looked at mine and it's 900x1200. I did post a picture on the forum for someone that was asking what type of glue to use in veneering that showed the setup i was using, unfortunately i lost all my photo's and 4 years of other stuff when i had a PC incident but it should be still on the forum, search veneering and see if it comes up, the job i was doing was flat and it came out fine(was a proof of concept thingy), if you find it you will see some blue material in the bag and some white tubing, the blue stuff is a plastic mesh and the white is spiral cut tube (stuff for tidying wires), think maplin was cheaper than the composite site. this just ensures the vacuum reaches all parts of the surface as i was concerned that the bag would just suck down locally @ the vacuum inlet.
Hope that helps
regards
Mike

[Tenson]

I have a vacuum storage bag the sort used for putting clothes in storage. It is way too delicate and gets leaks after just 2-3 uses.

I want to know where to buy suitable vinyl sheet and the cement. JoeWoodworker sells 30gauge vinyl (is that about 700 micron?) but he is in the US so shipping makes it silly to buy there. FabricUK sell clear PVC sheet but do not mention the thickness. Do I need a specific type of PVC sheet?

[mekanik]

Just had a quick surf, what you are after is silicone sheet, just type vacuum veneering silicone sheet. that should give you plenty of options.

[Tenson]

I don't think that is what I want it is super expensive and I'm not sure I can glue silicone together easily at the edges. I need vinyl sheet.

[mekanik]

That's why i went for the slip membrane(just because i had some) and it works fine with the gaffer tape to seal the edges, when you pull the vacuum the whole bag goes as tight as a drum. all i can say is it works for me. just cut the taped section off remove job and put in another one. If your doing regular production runs you might want to make a vacuum table but you will need the expensive silicone for that.

[Boyan Silyavski]

I will make my self very soon a vacuum table for sheet forming, vacuum infusion. May be you could get some idea from vacuum infusion.

So its basically a table with some vacuum seals and some switches. You could do similar and use the double seal idea to seal the bag/ there is no bag in fact/. Take a look at the video below, its for vacuum infusion, but the principle is what i like, That vacuum seals the vacuum and only a cheap sheet of plastic is needed, in your case instead of the methacrylate sheet in the video.

Its just an idea that might work better on the long run


https://www.youtube.com/watch?v=AvLIRrkp5CY&list=LLcRNm6Ytsdil06xrwUMiqgA& index=6

[Tenson]

I'm going to get some of this to make a durable bag - http://www.attwoollsmanufacturing.co.uk/fabrics/clear-pvc-fabric-2/clear-pvc-fabric-0-5mm-thick-flame-retardant/

This one is 0.5mm but they do a 0.7mm version too if more strength is needed.

I just need to find the best adhesive for it. I've done a bit of testing with some clear PVC strip I had and very few adhesives bond strongly. Super-blue seems to be the best. Joe Woodworker recommends something called HH66 but it is really expensive to import from the USA. I tried some PVC pipe cement but it didn't work well at all. You can get 'vinyl repair glue' for things like blow-up beds and pond liners but it comes in small tubes. Still I might give it a shot at £3 a tube. Then there is Scotch-Weld Vinyl Adhesive but I'm not sure it is suitable for this kind of sheet rather than solid PVC.

[Boyan Silyavski]

You need an adhesive that glues all to all, that looks like silicone. Or you could use strong 3m double sided tape. The good tape sticks so well to any material that no way you could un glue it

[Tenson]

The material is PVC. I've tried some general purpose solvent free glue and it is poor. Or do you mean I should try silicone adhesive?

[Boyan Silyavski]

The material is PVC. I've tried some general purpose solvent free glue and it is poor. Or do you mean I should try silicone adhesive?

Its not exactly silicone, just looks like silicone. Do you know the glue that glues all to all and is weather resistant and flexible. They sell it here in Spain in every big shop. In a plastic bottle like silicone. Its for automotive use. I am just now going to the shop where they sell glues, so will post a picture later. Its called Ceys Total tech I used the one on the left , i think that the only difference is that its transparent

17719

[Tenson]

We don't have that in the UK. It looks like 'PinkGrip' but maybe it's differnt? http://www.everbuild.co.uk/pinkgrip/pinkgrip-1

I wonder what the technical name of this adhesive is?

[Boyan Silyavski]

We don't have that in the UK. It looks like 'PinkGrip' but maybe it's differnt? http://www.everbuild.co.uk/pinkgrip/pinkgrip-1

I wonder what the technical name of this adhesive is?

No, what i am saying is maybe some kind of polyurethane or silicone, what you say is polyester type glue, similar to what they use to fit doors and windows at houses, very easy to spot, look at sheet and when you see that " Do not use on polystyrene/Styrofoam/expanded polyurethane "

[Boyan Silyavski]

While searching for other glue, i found this one, that seems it will definetely do the job:
PU18 Black Flexible Polyurethane Adhesive (http://www.easycomposites.co.uk/#!/resin-gel-silicone-adhesive/structural-adhesives/pu18-black-flexible-polyurethane-adhesive-sealant.html)

[Chonker]

Hi, I came across this thread, I'm in the process of setting up a vacuum press of my own. I've been struggling also with the difficultly of finding equivalents to the components on the joewoodworker website in the UK. I think I've found most of the equivalent stuff for the EVS pump and now I'm trying to sort out the bags.

I've been digging around and I think the adhesive required to bond up the bags may be A3701 Plasticised PVC contact adhesive.

[GEOFFREY]

Hi Tenson, I think that pond liner (butyl) or inflatable boat repair material (hypalon etc.) would work very well and good adhesives are readily available for those materials. G.

[Tenson]

I had good success with my vac bag. :peaceful:

http://i608.photobucket.com/albums/tt169/tenson_uk/vac-bag1.jpg

I used this PVC - eBay item number: 252175735357

I then tested various glues including PVC pipe cement and opted to use cyanoacrylate (superglue). I used medium viscosity 'BontIt' from here - eBay item number:140938448838

I found the superglue tacked within a few seconds of contact which made assembly of the seams reasonably easy. If you fold the PVC over to make a seam it wants to spring back, so fast initial bond is helpful. After an hour of setting it is very strong indeed, but remains flexible enough to fold the bag for storage.

Regarding the seams, I cut the main bag piece and folded it in half. I then put a line of glue down the left and right sides to join the edges and kept one end open as the mouth of the bag. Make sure you start glueing from the closed / folded-over end of the bag and work your way towards the open end. Follow this I then cut two long strips of PVC and folded them over the left and right edges of the bag with more glue to give greater strength. Make sure these pieces overlap the closed end of the bag because I left a tiny bit exposed and it wanted to leak air at the corner of the main bag fold.

http://i608.photobucket.com/albums/tt169/tenson_uk/Glue.jpg

For vacuum tube entry I use a male 'pneumatic / air line' push fitting for 10mm tubing (eBay item: 271290823788). To attach it in the bag I cut 2x pieces of 5mm acrylic in a disc shape with a hole in the middle. I threaded the air-line fitting into one and bonded it inside the bag, with the air-line fitting sticking out through a hole. Then I placed the other acrylic disc (with a slight bigger central hole) over the top to sandwich with the bag material. Basically the two discs hold the bag material between them and I threaded the push fitting into the bottom disc.

I also put a one way / non-return valve (eBay item: 121665943577) in the air line so I can disconnect from the vacuum pump without loss of vacuum.

To close the mouth of the bag I simply fold it over twice and clamp it between two strips of wood using g-clamps.

http://i608.photobucket.com/albums/tt169/tenson_uk/Vac-Bag-2.jpghttp://i608.photobucket.com/albums/tt169/tenson_uk/Vac-Bag-3.jpg