Author Topic: Laminating on a Table  (Read 15729 times)

Ucycle

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Re: Laminating on a Table
« Reply #45 on: April 11, 2013, 01:40:57 PM »
i will get a actual vacuum pump instead of relying on your compressor(it will be really. For me, slowly vacuum out the bag, pull the bag tight the under opposite side of the wet lam.  Trying to get the wet lam side as smooth as possible, that will less than the sanding need after the epoxy cure.   My vacuum system have a leak somewhere so i just leave it on the whole night and turn it off the next morning.  You want to keep the vacuum on until the epoxy set before turning it off. 
also i think i pull about 7-10 psi, i have it on my notebook, if you pull too hard on a low density foam, you might crush the sharp rail.
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Dwight (DW)

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Re: Laminating on a Table
« Reply #46 on: April 11, 2013, 04:50:25 PM »

Does anyone know why the shaper uses masking tape along the rail in this video while he's finishing the rails? (Fast forward to about 3:30)

How much pressure do you need and for how long must the pump operate?

What do you think about this pump?

I think the tape is being used to protect the fragile 1# EPS. The core-cell bottom foam is like a rock compared to the EPS. It would be really hard to shape the rails without isolating each side while doing so.

With 1 lb EPS you can't exceed 10 in hg. Most use between 8 and 10 in hg. (It's not PSI)
With 1.5 lb foam I can go to 15, but usually stay near 10. If you hit the crush pressure, it turns your foam into a wrinkled mess. I crushed a test sample letting the pump go full vacuum.

Venturi vacuum generators are very loud. I've never used a tiny one. I've run a big one at the plant. It will blow your ears out and they consume huge arounds of compressor air. They are poor solutions for vacuum.

It works better with a good pump and enough CFM to make it easy. The one I use is quiet too.


getsupngo

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Re: Laminating on a Table
« Reply #47 on: April 11, 2013, 06:43:19 PM »
Shape distortion is something that can happen if you're not careful.  Crushing is the really severe distortion.  A stringer/stringers, a rocker table or a rocker stick helps to maintain precise rocker as the epoxy sets up.  Then there's the issue of twist and unintended bottom contours like some added V and undesired concaves.  This can still happen when there's only a single center stringer or with a rocker stick in the bag.

I've found that 1.5 lb. XPS can handle all the vacuum bag pressure my Gast pump can pull.
Gotta keep it very light with the EPS. 

TWsup

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Re: Laminating on a Table
« Reply #48 on: April 14, 2013, 08:09:27 AM »
so what you guys are saying is that using vbag we have to have a rocker template in the bag when bagging 1lb eps.

questions:
making 5m board.
I can add a 1mm stringer to my blank, would that be enough ? it's less work/ cost that making template because I have the veneer for the stringer.
I can even add 2 stringers without too much extra effort, because of the way I'm gluing up my blank fron builders eps. overkill?
once deck is laminated in the bag, I don't have to worry about distortion when laminating bottom ?
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willi

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Re: Laminating on a Table
« Reply #49 on: April 15, 2013, 06:28:21 AM »
I vacuum bag my boards using a bag i have made out of vacuum bag material -- or some folks sell tubes --- tape one end and slide the board in -- if you are bagging on a flat table you are making a lot of work -- my opinion --
It helps to have a second set of hands as after the board is wrapped in the blanket and taped snug -- a helper is there to help slide the board into the tube bag.
First ---Wet out your lam -- I do 2 layers of 6.5 oz free lap stagger the laps with the last one being a little longer (now I use Innegera first and layer of 6.5 over it) use slow resin so the Innegra will wet out --
drape on perferated peel ply -- Important ---There are two different size hole material -- small hole and larger -- so you can pull more or less resin ...I use the large hole--
Now---Wrap in the bleeder breather blanket --- the thickness of the blanket also will determine how much resin you pull out also --thin blanket and the resin will saturate the blanket faster leach through to the vac bag and stop --thicker blanket (almost 1/4 inch what I use) and you will pull more resin --Using a bigger hole perferated peel ply and a thicker blanket you don't have to worry too much about pulling too much pressure -- I pull 11 or so and have no crush spots -- (1.5 EPS) go over 15 with 1.5 and you are asking for trouble ---
But all this is a non issue if the perferated peel ply has bigger holes and the blanket is thick.... I have nice tight no void lams with very little sanding.
Sealing the blank (sand it smooth like ice) is very important if you are going to bag the board --
 I spackle and sand --then i mix up a small batch of this slow kick resin ---I use a squeegie to keep the resin from sitting and being absorbed into the blank( put color in if you like) any resin that sits on the top (like in the rail area -- i scrape off with the squeegie (use the squeegie in reverse as a scraper) -- this gives you a seal barrier so a bunch of resin will not get pushed into the board when you bag---
A slick seal job gives you a slick glass job --i find-
Hope this helps --
aloha
willi



 


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