Breather Mesh, who's using it, top platen or not?

[Peter Quinn]

I've just ordered sone breather mesh to play with in the vacuum bag. I'm thinking for flat work instead of a kerfed top platen. Anyone using this for flat work, do you still use a solid top platen, and thoughts or experiences with it?

[Alan Lightstone]

I use one for flat work. Don't use a kerfed top platen. The breather mesh replaces it.

[Erik Christensen]

almost all of mt vacuum press work is with a solid bottom platen and breather mesh top - can't remember last time I used a top platen

[John Lanciani]

I guess I'm cheap, I just use scrap insect screen instead of "breather mesh" when my panels don't fit between the grooved platens I have. I do find that my panels are consistently flatter when I use platens, though.

[Matt Day]

I use the breather mesh for the top of flat work as well - works great! Just remember to cut a small piece for the hose attachment location and to use a small piece of 1/4" ply there. My model/hose is probably 5 years old, so the newer ones may differ.

[Jim Tobias]

I've been using the breather mesh for about a year now and it sure saves time cutting matching pieces for top platen. Wokrs well.

Jim

[HANK METZ]

I simply use a discarded plastic net onion bag laid around the suction fitting and no platen. Draws down nice and tight every time.

- Beachside Hank
Do not use remaining fingers as push sticks.

[Mike Henderson]

I use breather mesh but I find that plain old window screen works about as well. I like to use a top platen on veneer. It tried using only the breather mesh but get better results using a platen. If I'm in a hurry, I don't use anything on the top of small stuff - just breather mesh on the bottom or a grooved platen. But I roll the top with a roller through the bag after the vacuum is pulled - to make sure there's no bubbles.

Mike

[Larry Edgerton]

I am thinking of replacing my two 9' presses with a vacuum setup to save space in my new smaller shop. Can you guys recommend a good book to explain the fine points that is fairly up to date. I have a large pump and vacuum regulator from medical surplus, but that is as far as I have gotten.

Thanks, Larry

[richard poitras]

I am thinking of replacing my two 9' presses with a vacuum setup to save space in my new smaller shop. Can you guys recommend a good book to explain the fine points that is fairly up to date. I have a large pump and vacuum regulator from medical surplus, but that is as far as I have gotten.

Thanks, Larry

Joewoodworker (Google it) site has a lot of information on vacuum presses, bags, and veneering

[Peter Quinn]

I see lots of info on veneer work, is anyone using vacuum bags to make door stiles from multilayer laminations? I've done this with traditional pressing, but it sure hurts turning all those clamps. I wondered if it gives enough pressure.

[John TenEyck]

I see lots of info on veneer work, is anyone using vacuum bags to make door stiles from multilayer laminations? I've done this with traditional pressing, but it sure hurts turning all those clamps. I wondered if it gives enough pressure.


Yes, I've done this quite often. My 22" Hg vacuum pump works just fine for the curved, laminated door rails I've made. I don't make the laminations any thinner than I would for a mechanical press, usually between 1/8" and 1/4", and the vacuum press pulls them down tight w/o problem. When I make curved doors, this is my preferred way of doing it, because I can use the same mold for both rails and the panels.


John

[Jamie Buxton]

I do a lot of veneering, mostly of furniture-sized panels. I tried and abandoned breather mesh years ago. Those air molecules are teensy teensy things, and will slip through tiny openings. I get strong even pressure without the mesh. I also don't use a kerfed platen, for the same reason. My bags have a perforated hose which I arrange to be close to the edge of the panel. That's sufficient.

[Jamie Buxton]

I see lots of info on veneer work, is anyone using vacuum bags to make door stiles from multilayer laminations? I've done this with traditional pressing, but it sure hurts turning all those clamps. I wondered if it gives enough pressure.

Do you mean you want to make the stave core material? A vacuum press should be able to do that -- it applies about a ton of force per square foot. However it would be easier just to buy the stuff. The door shop down the street from me buys it in 4x8 sheets. Here's a link to one manufacturer http://www.washingtonhardwoods.com/userfiles/library/Quality%20Door%20brochure-3203.pdf

[Jeff Duncan]

I see lots of info on veneer work, is anyone using vacuum bags to make door stiles from multilayer laminations? I've done this with traditional pressing, but it sure hurts turning all those clamps. I wondered if it gives enough pressure.

Peter, I'm assuming your not talking about stave core but gluing up multiple layers of solid to make up a stile? I do this every so often and it works great. I was a bit skeptical at first as I read some posts about vac bags not putting enough pressure for this type of clamping. In practice I found quite the opposite, not only can it clamp as well as bar clamps, but it works better! If your stock is really clean and flat you can get seems that are almost invisible! I do turn up the press to about it's max setting....about 25 in I think.

One thing I highly recommend if your going to do these with any frequency is to make up a good support structure. I built a simple plywood box about 9" square by 8' long that is nice and straight to keep my stiles dead flat while clamping.

Oh and I do use mesh for most projects.....don't think I've ever made a top platen though.

good luck,
JeffD

[Peter Quinn]

Peter, I'm assuming your not talking about stave core but gluing up multiple layers of solid to make up a stile? I do this every so often and it works great. I was a bit skeptical at first as I read some posts about vac bags not putting enough pressure for this type of clamping. In practice I found quite the opposite, not only can it clamp as well as bar clamps, but it works better! If your stock is really clean and flat you can get seems that are almost invisible! I do turn up the press to about it's max setting....about 25 in I think.

One thing I highly recommend if your going to do these with any frequency is to make up a good support structure. I built a simple plywood box about 9" square by 8' long that is nice and straight to keep my stiles dead flat while clamping.

Oh and I do use mesh for most projects.....don't think I've ever made a top platen though.

good luck,
JeffD


Jeff, I was referring to laminated stiles, not stave core with skins. I get a lot of floor board cast offs, once flattened and reliefs milled off I can achieve 3/8"-5/8" layers. Any solutions for limiting slipping side to side or is this not an issue with the bag?

[Keith Hankins]

I use it works great and I don't use a top platen. One word of caution soften the corners or it will bugger it up a bit. I will use a piece of cardboard over the corners if it's sharp but if it's more rounded and close to the edge (fills the bag) I don't bother (as in the picture below). Works great. I would recommend springing for the rolled version instead of the folded. My first piece I got folded and what a total PIA to get it flat. The second time around for my latest project that was very long 8' I sprung for the rolled and it was much better. If you have to cut it the edges can be a tad sharp, so I cover the edges with painters tape to protect my wood from scratches. Yo may see a slight crosshatch pattern in some woods depending on its hardness. I love it though and not had any issues.

http://flic.kr/p/cBfFYd

[Erik Christensen]

for vac bag alignment I just put a couple of 23 gauge pins in the pieces to keep them from moving around while sliding into the bag and drawing a vacuum - the pins are so tiny they never show and I don't worry about placement as a carbide blade never notices them

[Mel Fulks]

I used to wonder why our wood stave core stiles many times had a long bow when the cores had been machined perfectly straight. The glue we used was always the plastic resin type (powder mixed with water).When Titebond 2 came in we used it,but it was thicker and messier .We would always put glue on both surfaces. A factory told us we could add water.We were told 5 percent would reduce viscosity by 50 percent without reducing strength. I am now convinced that the added water in Titebond and the required water of the PR glue caused those bows which made us do an extra machining.I have heard that the no water quality of the 2 part PR is why many prefer it. I have the best results with polyurethane glue and NO WATER .Those pcs. Stayed the straightest.But this is new,so still would leave a little extra wood on the faces. I have no experience with vacuum presses. Certainly interested in the glue related observations of anyone even occasionally using engineered stiles.

[Jeff Duncan]

Peter, that's what I thought! I'll generally laminate when I'm doing 2-1/4" thick paint grade doors as the paint hides the layers;)

A couple observations, with thicker stock I don't have any problem controlling the pieces. I use 3 pieces and glue up using regular old titebond 1 with a glue roller. I can usually get glue on enough pieces to make up 3 - 4 stiles at a shot. I move pretty fast and get them stacked and in the bag as quickly as I can. I place them in one at a time and line the edges of each piece up by hand quickly moving end to end. Add another stile, line up it's edges....repeat. By the time you get your last stile glued and inserted the previous ones will have started to tack and will not want to move much. Throw a net on top, close the bag, and start the vac, while it's starting to suck down keep going back and forth making sure the edges stay aligned. Doing it this way I only need about 1/4" extra material on each side. If you need to conserve material more you can line up more accurately and use a pin in each end....I just hate brads or pins as inevitably I'll miss at least one of them and find them the hard way....when milling:o

Also I've spoken to several door guys and most agree to use an odd number of laminations, 3,5,7 etc when doing this. Not sure how much it makes a difference but I just took their word on it.

Mel, not sure why you would have had the problems with wood stave bowing? I don't use stave cores so I can't help you out there. Silly question, but did they have a stable and checked for flat surface they glued them up on? I've seen guys gluing stuff up on sawhorses before not realizing what they were doing! That's the only thing I can think of since if both faces were glued on at once, the water shouldn't affect one more than the other???

As for the Poly glue....I really hate that stuff:( It's messy and takes far too long to dry for my purposes. Having said that sometimes you have to adapt and if it gives you the results you need.....then you make do! In the vac bag I use mostly plain old yellow glue on solids, and cold press for veneer work. Other stuff like epoxy on occasion, but the dry times for stuff like that in a vacuum can get awful lengthy!

good luck,
JeffD

[Alan Lightstone]

FWIW, in this month's FWW, an author of an article on veneered banding does use top cauls with breather mesh. Just another guy's method, but I thought I'd mention it.

I just use Masonite covered MDF for the caul, BTW.

[Larry Edgerton]

I see lots of info on veneer work, is anyone using vacuum bags to make door stiles from multilayer laminations? I've done this with traditional pressing, but it sure hurts turning all those clamps. I wondered if it gives enough pressure.

I made my presses with 16" LVL's and threaded rod so I can use an air ratchet. I do a lot of reproduction work with Versatech and I could not get it together fast enough with clamps when doing big laminations. Much better than clamps.

Larry

[Mel Fulks]

The gluing was done in a large I-beam type press with huge adjustable acme threads and a perfectly straight base.It was a system used for decades before Iworked there.When I have used same general system other places they also reported they had noticed same thing and had always made skins thick enough to have a 1/4 inch for straightening after gluing. Some of the stiles would come out straight ,some would come out bow up ,some bow down.It was not anything as simple as uneven support.Most could be faced and planed perfectly straight and stayed that way (the stiles) My take on this is that one side soaked up more water and glue kept it in that elongated position producing some bow.I do know that for me use of unthinned yellow glue or polyurethane glue without water produces a straighter stile than water mix plastic resin glue.Its my understanding that they make the two part PR glue for that reason,that is avoidance of introducing water.The poly glue can be messy , but all seem to agree that you just put in on one side so that helps.There is poly glue sold by Custom Pak that is low foam and been independently lab tested for waterproof structural use but I have not yet tried it.Any one else tried the water base PR glue for engineered stiles? Please report.

[Mike Henderson]

I assume you mean Plastic Resin when you use the abbreviation "PR". Also known as urea formaldehyde, sometimes abbreviated UF.

Mike

[Peter Quinn]

Also I've spoken to several door guys and most agree to use an odd number of laminations, 3,5,7 etc when doing this. Not sure how much it makes a difference but I just took their word on it.


JeffD

Thats been my understanding too. A "core" and a balance layer on each side, or as many balance layers as necessary to create the thickness required. Even if the core is the same thickness as the balance layers. Ever try to get three people to decide which movie to go and see? With two people, often one persons feelings on the subject are stronger, and one just pulls the other in their direction. But with three people, you just wind up going no where, indecisive. No one player is strong enough to pull the other two in a single direction. Or so it seems, unless all three were all leaning the same direction to begin with, then you have a bent lamination, or a movie with a cult following, or a really bad metaphor :D.


Mel, I was introduced to a guy at the lumber yard who was telling me about a product called isoset that he like very much for window and door fabrication. Its a two part emulsion based adhesive called isoset. I think it may be water based, so I'm not sure that helps your bowed issue. I guess it was made to replace UF adhesives due to the nasty side effects of formaldehyde. Its available in 5 gal units only from Ashland, the manufacturer. He says its extremely strong, can be used for structural glue lams and finger joints, highly water resistant. Water clean up too.

http://www.ashland.com/products/isoset-structural-adhesives

Thanks all for your input thus far. The breather mesh comes tomorrow, I can't wait to play with it.

[Mel Fulks]

Thanks Mike,yes ,plastic resin.I was clearer in earlier post.Some may wonder why we used it.That started long before there were so many type 2 and type 3 glues available.UF was type2 ,easy to mix and has long working time.Until temp exceeds 80 degrees or so.Two men working together could get a good number of stiles in clamps at one time.I still use it for some things.I have no doubt there is old material out there recommending it for stiles,there are just better things today IMO for that purpose.

[Jeff Duncan]

As a side note on glue, I believe another advantage to the plastic resin glue is the resistance to creep. Supposed to minimize springback when doing curved moldings. I guess yellow glue has more movement. I haven't had the need/opportunity to play with the plastic resin yet though so this is all based on others perspectives;)

Peter, I've also been told to only use really straight stock when gluing up stiles and not to depend on the bow of one to counteract the others. In some woods though, like hard maple for instance, it's tough to get a full batch to stay perfectly straight. My method is to put the straightest in the middle with opposing bows on the outside. I've found this method to work pretty well for me. I should say that when I say bow I'm talking about maybe 1/8" over 7'....anything much more than that gets put aside for the rails.`

JeffD

[Larry Fox]

I use a kerfed bottom platen with Breather Mesh on top with no top platen and it works great. I use Unibond 800 which is a 2-part UF glue and could not be happier with the results. Currently working on a project with 96 sq/ft of veneered panels which I covered with shop-cut veneer using the method above and the panels all came out great.

[Mel Fulks]

To better explain my comments about water in glue I did an experiment .A straight quarter cut piece of cherry 1/8 x7/8 x31 1/2 inches was held lengthwise between clamped blocks with just enough tension to hold it in place without any deflection.Removed the strip ,wet it and put it back.It bowed 1/8 plus.There is nothing in my shop accurate enough to measure the few thousandths it elongated.But obviously that seemingly insignificant movement caused the bow.For laminated work that will be nailed in place thinned yellow glue or water mixed plastic resin glues are fine.Not for stiles.Thanks to Peter Quinn for telling me about Isoset.Looked it up last night. It is a two part product needing no moisture to cure and they point out the no water advantage .I get the impression that it does not require a long clamp time.