Which bag would you folks recommend for making boards using sandwich construction and doing vac lams? The bag I have is 4’x8’. Thanks in advance for any help.
My bag was the most expensive part of my setup.
26’ of 4mm PVC. Folded in half I have a 13’x4’ bag and it’s nice and strong. Should last a while. Less than AU$70.
Since I’ve started Vac Bagging (3 years?) I’ve used Fiberglass Supply’s 4 mil.x 32" poly tubing. I think I ordered 25 to 30 yards and I make about 3-4 boards from each. I used to vac about 4-5 times per board, now only 1-2 times. And… I could get 3-4 boards from a bag.
I use their gummy tape to deal one end and blue making tape to seal the open/close end.
If there’s another style bag that works better/longer let us all know!
Once I ordered the poly bag from fiberglasssupply and they didn’t have any available, so they sent me another vac bag from a different material. Think it was nylon or something, at any rate it was green tinted instead of clear like poly.
So, I used the green bag for a good number of pulls, probably 4-5 boards’ worth, and since it was performing well, I didn’t think much of it. Decided to retire it and use the poly bag that finally arrived, and that’s when I really noticed a difference.
the poly bag tears WAY WAY WAY easier, on my very first pull I put three good holes in it, just trying to pull the bag tight over the rails. It punctured itself on the pointy ends of deck lams, and was just generally a pain in the ass. Next time around, I’ll be ordering more of the “green stuff”, whatever it was. It was much tougher, MUCH.
I also used the green stuff with success for one board so far. I haven’t handled it very carefully but I think it will last a while. From my fiberglass supply order form, its:
M13-7883 Cut per yd Up to 3 yd, WL 7400 36" Diameter Nylon Bagging Tubing
yeah i have a pvc bag and i plan to upgrade to silicon
have you thought about a waterbed bladder
Shwuz, I ordered 10 yd stretchlon 200 from Fiberglass supply. It’s a thin green film. It’s inexpensive too, only $2.89 a yd for 4 -15 yards. That could be what you got from them.
It came in sheet form not a tube/bag. I had to make that myself using the two sided seal tape. It’s pretty tough, but the RR epoxy seems to stick to it a bit. I’m new to bagging, so I’ve kept my first couple of projects small until I get better at the process. I got the stuff caught/pinched in one spot and made a hole when I took the part out. I was able to use clear packing tape for a repair. Seems to work pretty well still, but loses the stretch at that point. I am impressed that this film works as well as it does. I thought the stretch would make it difficult to get some parts to pull together, but it works great. I made a 44” sandwich longboard skateboard for my first test at the new set up, and was able to put a touch of concave in the deck with the bag. The timber is ¼” basswood in 3/8” strips (some stuff I had around for a kayak project). I was surprised at how well that film pulled the deck to the foam. I thought it might stretch and let the parts separate.
I’m pretty sure that the company that fiberglass supply buys through is a Airtech. They are a great company! Unfortunately they are really meant for the big guys. I think the green film you’re talking about is either Econolon (its 1.5 mil) or WL7400 - High temperature nylon (Its 2 mil). I bought some of the 36" tubing material and I was amazed. I’ll never go back to polytube. Unfortunately you need to buy the stuff in 1000+ quantities. I’ve asked and the said that they would have no problem rolling it into 4 - 250ft rolls. It would cost about $110 per roll (thats about 44 cents per foot) and it definately lasts.
I get many, many pulls out of the nylon bag tubing from ACP. I also use their ez-vac bag connector and the quick-lock bag seals. I’ve bought (twice only) the 5-yard pre-cut tubing. I can then put a quick-lock along the bag just longer than the length of my board and leave the rest of the tube rolled up, and use another quick-lock on the end where the board goes in. Like Les, I’m down to only into the bag once or twice per board.
I am using the 4mil x32" poly tubing. Works OK, but the first time I pulled the bag over the board I got to holes, tears really easy. I’m using duct tape to seal the ends and any holes that happen.
You’re a PNW boy, so this’ll prolly work for a quick, easy an dirty set-up for you.
Home Depot has rolls of poly tubing at the checkout, in a stand, along with string, for covering up you lumber purchase before putting it on the roof of your vehicle to avoid getting stuff soaked on your way home through our persistent rain storms. Big, long roll of it; I usually just make sure to grab myself a couple of board lengths every time I’m in there. I just make sure I’ve got extra at each end; screw the tape; just tie a knot and you’re good to go. If they don’t have a stand set up, ask them where they’ve got it; the tube is about 30" wide; mebbe more; you pick the length and has real nice Home Depot logos printed on it.
It’s not the most durable, but if you’re careful putting the board in the bag (a 3rd and 4th hand are very helpful), you won’t get any tears and I’ve pulled this stuff to 20psi + with no real issues. Because it’s poly it does pleat though; the only reason I’d go to silicone would be to eliminate the pleats and re-use the bag…I get about 3 pulls outta the freebies before they get too gummed up or spring a hole.
I hate to jack my own thread, but which of the three listed pumps would you guys recommend? I only do boards for myself and friends, so I’ll probably only be vaccing one board at a time, in the future you never know though. Maybe a little run down on what each pump is capable of, or not capable of for that matter. Thanks.
As long as you rbringing up Vac Pumps… (ha!)
I have a GAST pump that seems to have lost/is losing it’s ability to suck!
I took the top off and cleaned the foam filters in there. Is there anything else I can do to get it up to par?
Also, Hi Benny!
I have the 11’6" ready to glass, just waiting for glass.
I tried the Ultimate to glue down balsa. Couldn’t wait to try it after you suggested. The lastest board is 8’, HD 1#EPS (using Ultimate held the rocker!), redwood nose and tail blocks and rails. Without glass/epoxy on top it weighs out at 5#! Should be under the 1#/1’ as suggested in an earlier post. I’ll be using 4oz. S Glass top and bottom. Would you (or anyone else) suggest more glass, deck patch? Without the glass under the balsa the deck/bottom (flast areas) seem soft. could be good/bad?
Gees I love Sways!
I’m with you, Les. I’m in the middle of a non-sandwich composite too.
PU glue to stick Oneula’s bamboo (in a vac bag - see? Not a total thread hijack ) to 2# EPS on a 6’1" quad fish. d-cell rails… and an amazing set of Hanalei Fins & Pro Box boxes straight from Robin “handshapes” Mair on Kauai (awesome to deal with, so much advice on fin selection & placement, fast shipping, great instructions, very attractive prices…that’ll be a whole 'nother thread once the fins are installed ).
Before glass & boxes, the shaped board was just over 3#. Wow. And as strong as you can imagine. I knew this one wouldn’t be a big flexer, so I figured the fish shape needed the least of that of any…
Laminated the bottom last night…
Hey Benny, that is one nice looking board. So hurry up put those fins on, can’t wait to the thread on that one.
Where did get the bambo?
I’m still using an old frig pump, just keep adding oil. I even let it run for almost 20 hours and no problems. It’s even the pump that looks like a pill that everybody says “don’t use this one” .
I currently have the 6cfm model that is pictured there. Frankly, it is way overpriced for that particular vacuum pump. Those pumps are oil bath pumps which means that you will also need to buy oil and change the oil as well. Also, oil bath pumps emit an oil vapor once in a while so that’s also something to think about. But the 6 cfm pump will pull up to 29" Hg which is more than most pumps. I was planning on selling mine but then I realized I would be doing other projects as well that might require more vac.
If you’re still set on that pump, I would suggest checking ebay, there’s alot of sellers that will sell you that exact pump brand new for $200+shipping. But if you’re just doing boards check out acp’s pump. It isn’t an oil bath pump which means that there’s no need for oil or getting oily and it is cheaper. It will pull up to 20" Hg.
'hope that helps
Yeah, thought about “upgrading” to something else. Will see how it goes - hopefully the 4mm can last a little while. Got clear, thick tape to patch holes while I keep my eyes open.
Are waterbed bladders clear?
I don’t use anything like that. I use an old fridge compressor with a homemade vac regulator.
Rather spend THAT kind of money on materials for boards
“Homemade vac regulator”? please share! how do you make it?
Oh, my vacuum pump? a friend gave it to me with 6 quarts of oil…he sells vacuum pumps and was getting rid of some of his old stock and he knew that i was looking for one so he just gave it to me…pretty cool ja?
For the regulator/switch check my post at: