Yatch Dr, vacuum sealing glass

[Nandy]

I am actuality polling all those great glass workers here that care to comment.

I saw some of the pictures from Yatch Dr and saw where he is vacuum sealing some sections of glass. I had envision a similar process but obviously there is a system out there already built for this. Yatch Dr, Can you care to elaborate a bit on the rig you are using and the process? Anyone else using similar equipment is more than welcome to comment.

I was thinking on using a shop vac and maybe some of the valves that comes with the storage bags meant to shrink their content by means of vacuum. I would have buy some of that .7 mil plastic and duct tape it together for some sections or duct tape the plastic to the side of the boat as Yatch Dr does in that picture. Does a shop vac creates enough vacuum? Can anyone comment on those valves? What do you use so the vacuum pulls air from all sections? I was thinking on using 4x8 pieces of foam with some release agent...
Im sure that gear is built for this while I am thinking on jerry rigging mine. Your thoughts might save me some time.

 

[109jb]

Re: Yatch Dr, vacuum sealing glass

The process is called vacuum bagging. Do a google search and you will find more info than you care to have.

 

[Nandy]

Re: Yatch Dr, vacuum sealing glass

Oh, the dreaded "google it" answer. I have read about it that is why I have the question on how the right I wanted to do would work. I rather get the input from users that know what they are doing rather that google my fingers away...

 

[ondarvr]

Re: Yatch Dr, vacuum sealing glass

You can sort of assemble a make shift setup, but you really don't get very good results, its all in using the correct fittings, tubing, vacuum pump, plastic sheet, resin, catalyst, etc.

A shop vac won't supply enough vacuum to draw resin into the glass, but you can bag cores into glass, its not the best method, but was used a lot in the beginning of this type of process.

You can find videos on you tube of the entire process and companies like Air Tech, Composites One and RTM North have websites with the correct products to use.


http://www.airtechonline.com/

http://www.rtmnorth.com/

http://www.compositesone.com/

I've got some pics of a small hull we did at Aksano Catamarans a short time ago, I'll see if I can post them.

I just checked out their web site and the some of the pics I took are there.

http://www.aksano.com/advanced.php

 

[109jb]

Re: Yatch Dr, vacuum sealing glass

Oh, the dreaded "google it" answer. I have read about it that is why I have the question on how the right I wanted to do would work. I rather get the input from users that know what they are doing rather that google my fingers away...

Thing is that you are asking for about 3 pages single space for the reply and then you still wouldn't understand everything you need.

I di the google search for you and found a decent basic description on the first results page in about 20 seconds. Here you go:

http://composite.about.com/od/aboutcompositesplastics/l/aa000109.htm


BTW. I ahve done vacuum bagging with epoxy layups and with prepreg. It is not simple nor is it difficult.

 

[Nandy]

Re: Yatch Dr, vacuum sealing glass

Thing is that you are asking for about 3 pages single space for the reply and then you still wouldn't understand everything you need.

I di the google search for you and found a decent basic description on the first results page in about 20 seconds. Here you go:

http://composite.about.com/od/aboutcompositesplastics/l/aa000109.htm

I think you did not understood me. I dont care any of the google results, I want to know what guys like ondarvr or Yatch Dr had to say... Given they could refer me to a link, like you did which I appreciate. I will read it later, althought ondarvr answered my questions already.

Thanks

 

[rngale]

Re: Yatch Dr, vacuum sealing glass

the correct vaccum pump is the key peice you need here. The plastic sheeting "can" be bought at the hardware store but you are better off with the bagging plastic called peal ply. If you are doing small parts you can use regular poly resins, you can use standard epoxy resins. Vaccumm bagging is now used with special resins as well for laying up an entire boat in one step now after the gelcoat and skin coat are applied in the mold but its an entire system that injects the resin at the same time. Its been around for awhile so the bugs have been worked out of it. If you are doing large layups at one you will want to get a slower curing resin to allow your self enough time to make it work correctly.

 

[Nandy]

Re: Yatch Dr, vacuum sealing glass

I read somewhere about using a refrigerator compressor to create the vacuum. That maybe better that a shop vacuum. I know is quieter.

 

[ondarvr]

Re: Yatch Dr, vacuum sealing glass

I've done it with a fridg comp, it did work, but I can't remember how many inches of vacuum it pulled.

Which type of glass work do you want to try, bagging or infusion?

Bagging is wetting out the glass and core (if used) by hand and then putting the bag over it and pulling a vacuum. It will consolidate the glass and force the core into the laminate evenly for a good bond.

Infusion is putting all the glass and core in place dry and then putting the bag over it and pulling a vacuum before any resin has been mixed. You can adjust the bag and get everything "right" before mixing any resin. The vacuum will then draw resin into the bag and through the glass.

 

[Nandy]

Re: Yatch Dr, vacuum sealing glass

Not much right now. I have a few hatch in that boat I'm selling that needs replacement. They are rotten and I was thinking to glass them. They are basically 2x3 plywood with the cushion on top. The cushion is attached to the plywood with staples which I'm not sure if the gun will be strong enough to go thru. It will have a hinge screw in the plywood as well. Nothing that either has to be done by vacuum or even has to be glassed but an opportunity to practice.

 

[jonesg]

Re: Yatch Dr, vacuum sealing glass

in your case its probably not worth the bother except to play with it.
We used to make airfoils with the process, it really excells in getting maximum saturation with minimum resin. For epoxy on a decent sized hull that spells cash savings and perfect lamination, no dry spots ( done right).

for your interest you can get hobby sized setups using mityvac etc , should come with cotton roving ( uh rope?) , clay to seal edges and plastic sheet.
Maybe less than $150. You can use refrig compressors, but you need to plumb in the guage and have to watch it and adjust, better to use poly resin.

 

[Nandy]

Re: Yatch Dr, vacuum sealing glass

ondarvr, I would probably play with the bagging instead of infusion since it looks like for infusion you would need a special resin. Of course, infusion sounds like the best process as you can set up and secure the glass. That is a great asset specially if you are trying to defy gravity...

Jonesg, do you have experience with any of those small hobby size set ups? Where to get them? I see refrigerators in craigslist all the time for free or very low price. I could get one eventually and try.... I see you mention clay to seal the edges of the plastic, would duct tape work?

Thanks guys!

 

[109jb]

Re: Yatch Dr, vacuum sealing glass

Infusion, also known as resin transfer molding (RTM) is a much more difficulte process. The reason is that you have to plan the vacuum ports and resin ports carefully in order to get the fabric to wet out completely. For example, if you have one resin port and one vacuum port, the resin will flow in a straight path to the vacuum port and the rest of the fabric will not wet out.

With vacuum bagging you wet out the fabric first, so you don't have a problem with dry glass. The vacuum extracts the excess resin from the layup giving close to the optimum resin-fabric ratio. Hand layups, not matter how carefully you do then will have more resin than necessary for maximum strength. If you squeegee the layup too much you reduce the resin content, but without the vacuum, the cloth, mat, whatever compresses as you squeegee and then the fabric "springs back sucking in air into the layup. For aircraft, weight control is crucial. For boats, not so much unless you are talking about a getting the utmost performance out of a boat. For an everyday boat, a hand layup that has a bit excess resin is fine.

For flat panels you may be able to use a woodworkers vacuum bag. You might ruin it too though. It is basically a giant zip-lock bag. Woodworkers use them for applying veneers among other things.

If I am not mistaken, the picture you originally posted shows a vacuum bag setup using a piece of wood for a caul plate. I would suspect that he is using it to bond a core in place, or to make a flat surface for the fabric layups.

For a hatch, you could use a formica table top for a "tool" plate. With the hatch on the table with the laminate layup on top of it , you would normally then place a peel ply, a perf sheet, a bleeder ply and then the bag on top.

The peel ply is a fabric that can be "peeled" off of the laaminate after cure. Dacron fabric is often used as peel ply. It basically looks like it is stuck when done, but isn't really

The perf sheet is basically a plastic sheet with a bunch of small hole perforated into it. It allows the excess resin to flow through the holes into the bleeder ply.

The bleeder ply can be a bunch of things. Sometimes just extra fabric is used or cotton cloth or stuff that looks like quilt batting. Its purpose is to soak up the excess resin that gets squeezed out of the part.

The other thing you need to do is to protect the vacuum ports from resin and maintain a path for the vacuum. You can do this by putting a square of plastic on top of the bleeder and then more bleeder and then the port on top of it.

The vacuum port attaches to the bag material by cutting a small x through the bag and screwing the port together on the bag. The port is basically a quick connect for the vacuum hoses.

The edges of the bag are sealed with a rubbery 2-sided tape that is stuck to the tool (formica table top) and the bag.

It takes a good amount of vacuum to do this. I have used a venturi vacuum source hooked to my air compressor to do it with a valve in the vacuum line. Ideally the bag will have no leaks and will closing the valve will just hold the vacuum. A "real" vacuum source for vacuum bagging will pull the vacuum and then shut off. If there is a leak then it will cycle to maintain vacuum. The venturi vacuum source I used I got from harbor freight for about $10. Here is a link.. It is sold for sucking down air conditioning systems, but taken apart is just a machined venturi block and some pipe fittings.

Finding leaks can be a trick. They many times come from small creases in the bag where it attaches to the sealing tape. Or where the sealing tape overlaps. You need to press it down real hardand work out the creases.

This is the "normal" way to do it, but the process can be varied depending on what you are trying to do.

 

[Rickairmedic]

Re: Yatch Dr, vacuum sealing glass

You could most likely use an HVAC vacuum pump which can be found on ebay used for less than $100.00 . I picked one up on ebay for $50.00 shipped . I use it for HVAC work but they look just like the ones I see the glass guys using .


Rick

 

[erikgreen]

Re: Yatch Dr, vacuum sealing glass

Look around, I picked up a high vacuum pump for $35 locally.

I just need to make up some fittings for it and I'm in business with vinyl tubing, nylon taffeta fabric (peel ply) polyester fill for pillows and stuffed animals (flow layer) and plastic drop cloth sheeting.

If I like using it I'll buy the pro supplies, but for a test setup I'm going cheap.

Erik

 

[Nandy]

Re: Yatch Dr, vacuum sealing glass

Bear with me, this will make sense...

I have a listed in the local craigslist for a Airlft vac/refill pump. It reads something like "used Airlft vac/refill pump for automotive cooling systems. This tool vacuums the cooling system of all air, refills system eleminating the need to "burp" the cooling system. It is universal." He is asking $90 for it. I have a Nissan that I have to change the compressor because it is locked. If it does everything I hope it could that is one reason for me to buy it but if it also works for this then I will try to get it for sure.
You guys give me your opinions...
Thanks!

 

[Nandy]

Re: Yatch Dr, vacuum sealing glass

You could most likely use an HVAC vacuum pump which can be found on ebay used for less than $100.00 . I picked one up on ebay for $50.00 shipped . I use it for HVAC work but they look just like the ones I see the glass guys using .


Rick

Dummy me, you answered my last question...

 

[erikgreen]

Re: Yatch Dr, vacuum sealing glass

Bear with me, this will make sense...

I have a listed in the local craigslist for a Airlft vac/refill pump. It reads something like "used Airlft vac/refill pump for automotive cooling systems. This tool vacuums the cooling system of all air, refills system eleminating the need to "burp" the cooling system. It is universal." He is asking $90 for it. I have a Nissan that I have to change the compressor because it is locked. If it does everything I hope it could that is one reason for me to buy it but if it also works for this then I will try to get it for sure.
You guys give me your opinions...
Thanks!

It sounds like it might be a venturi vacuum "pump"?

They sell those at Harbor freight for about $20... used for cleaning refrigerant out of cooling systems. They require an air compressor to operate.

If you want to clean out your coolant, use one of those. You might even be able to make it work for vacuum bagging.

Erik