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nice but what did you do with tweety!

Erez,

how did your snuffer work when you tested it? Did you weight it? What grit did you fair and sand it down to? Does it work equally well from both sides?
Lots of questions, but I find it interesting..


A note of warning. I noticed you used your shopvac to pull vacuum when bagging it. It is very probable that the motors uses the airflow for cooling, so when pulling a vacuum your motors run without cooling. They may burn and seize, or start a fire that way. A compressor from a discarded fridge or a air-conditioner would be much better (but take care if you fiddle with the wiring yourself, so you dont put current on the housing of the compressor).

I know some folks bleed some air through into the vacuum hose to allow the motor to breath a little. However, note that a vacuum cleaner doesn't pull nearly the amount of vacuum you need to do a true "vacuum bagging". It will help you pull the fiberglass into complex corners but it will not pull the airbubbles and voids out of the layup. To start to get the advantages of vacuum bagging, a vacuum level of at least 10in-hg (I usually pull 18-20) is needed. You get maybe 1 or 2 (I'm guessing) with a vacuum cleaner.

No offense intended, just straight forward questions:

Why would I REALLY need to vacuum bag anything? I would think the cost of the pump would be prohibitive for the home user.

Also, that's a pretty wide range of vacuum pressure you recommend. If you over do it, isn't there a risk of "starving" the lamination?

btw- there is NO wind so I'm just killing time 'til the wind comes up! <img src="http://www.catsailor.com/forums/images/graemlins/laugh.gif" alt="" />

Poor Pete, a brand new boat and no wind. I feel sorry for you!


If you are building a part you want to make as light as possible and of high quality, you use vacum bagging. Also, if you need to build a complex shape, laying up wet glass can be difficult.
With vacum bagging you get a better glass/resin ratio (if you use proper bleeder cloth to absorb the surplus resin, I dont think Erez did), you also remove the possibility of voids and air pockets in the laminate. If laminating to e.g. foam, you are also sure there is contact between the glass and foam all the way (no voids). Personally, I always vacum-bag parts if I can, becouse I find the process much cleaner. Just wet out the cloth, lay it up and put it in the bag. Instead of working out all the air bubbles by hand.

A pump dont need to be expensive. An old car air-conditioner compressor is perfectly good. I used an old compressor from a frigde for two years before I was donated a vacuum pump from a scientific institution. Other venues are old milking machines, dentists and wherever they use a compressor or vacuum pump.
I got a three cylinder air compressor from a dentist when they buildt a new clinic


I know of serveral projects that have been done with refridgerator compressors. Among them a 28foot hull and a 45foot carbon mast. Just make sure you have one in backup in case the compressor dies while you make an expensive part.

Rolf


That project was just an experiment, like Tikipete said:

I never finished the snuffer since I bought a pump in order to do it better.
It weights 1 kg.
It does not work equally well from both sides.
If I was to finish this project I would need a lot of time and material to fair and sand it down, and it will probably weight more.

It is what it is: a 30$ & 2 hours - snuffer


Jake is right.


By the way Jake your web site is great, just went thru your web site the night before and had to try it for my self
http://webpages.charter.net/jakekohl/howto/snuffer_ring.htm

Erez,

here is another cheap and easy to build snuffer. It's the one we still use on our Tornado.

http://www.tornado-norge.org/stockholm2005/_DSC3495.JPG


Just bend a pice of alu tube into the shape you want (make a template/mould to bend it round if you want it to look really nice) or fill half of it with sand and heat the area you bend. Sand the ends with 80grit, then wet-sand the ends with epoxy and wrap some glass around them to hold them together. When the epoxy has cured, build a bracket to mount it to your pole.
The sand fills the area you are bending and stops "kinking" of the tube, while the wet-sanding with epoxy stops the alu from reacting with oxygen in the air so you get a proper bond.

It works almost equally well from both sides (it's slightly better on starboard tack, but I think it would be better with some more sanding and a slightly different mounting angle).
The alu dont notice the friction from the retrieval line, and it's pretty smooth without sanding.

Erez,
Another variation is to buy a wheel barrow inner tube.
They come in a variatey of sizes. Inflate it so it is just firm enough to hold its shape. Apply mould release to the rubber. Then wrap in glass and/or carbon. The wrap in packing tape that does not stretch. Increase the air pessure in the tube and this expands compressing the layup and expells excess resin. (I always prefer to use pressure over vacuum when it can be applied.)

When cured cut a slot in the side which has two benefits.
First it allows you to remove the wheel barrow tube and second is it allows you to fit a tube (for spi pole) into the edge of the ring making a more compact snuffer.

It does not take long to fair and paint in poly urethane.
All up weight around 300 grams. (0.3 kg)

Phill

That is interesting, I will try it
How did you connect the bag to the ring? It is not clear from the picture.

One more thing I want to make is a carbon spi pole
And all though I purchased a complete system for vacuum bagging and vacuum infusion I was told that to make a tube it is better to use heat shrink tape
http://www.privatedata.com/byb/rocketry/composites/glassing_tubes.html
Do you have any experience with this process?

As for my blade project, It is impossible to find marine ply wood in Israel, to import is way too expensive, so I'm trying to find an alternative.
My idea is to build the hulls from very light thin ply just to make the shape, then wrap it with glass and/or carbon and use vacuum infusion.
Can you comment on that?

You engineering types amaze me! <img src="http://www.catsailor.com/forums/images/graemlins/grin.gif" alt="" /> Refrigerator compressors!? How in the world would I use it?? Inner tube molds?!!

I have a much better idea, order one from the factory! <img src="http://www.catsailor.com/forums/images/graemlins/laugh.gif" alt="" />

Aw come on Pete. Half the fun is resolving a need or problem and developing a workable solution. If it's cool enough there might even be some money to be made. <img src="http://www.catsailor.com/forums/images/graemlins/smile.gif" alt="" />

Erez,
I have a vacuum pump made from a car compressor and industrial sewing machine. Just take the machine head off and drive the compressor with the machine motor. Still where possible I use pressure instead of vacuum. This is the same with the spi pole. I've never used heat shrink.
Basically I cut an aluminium tube lengthways to make a mould. Surface the inside with shiny packing tape. Coat this in PVA as a release. Make ends up. Make a bag from plastic and packing tape. Lay carbon layup in tube half. Place bag inside. Fold layup over the bag. Put top on. Do up hose clamps every 150mm to hold together and then inflate to around 35lbs. I have gove a high as 50 lbs but that does tend to push a little too much resin out.
The end result is a shiny black carbon tube. I may have a proper right up somewhere with more detailed instructions if you are interested I'll see if I can find it and mail it to you.
As far as building the Blade the Okume ply really is the trick.
I don't think you will get the weight and strength with very thin ply and glass. But let me look into it and get back to you.

Regards,
Phill

Pete,
For some people the journey is more important than the destination.

Regards,
Phill

AdditionallI can tell everybody that a well made alu ring snuffer will weight about 1 kg. Mine is. I think that to be quite good actually. Furthermore I second all of Rolfs comments to the extend that I favour alu rings over glass or carbon ones.

Wouter

If you're the engineering type! For the rest of us, think: monkey Vs football! <img src="http://www.catsailor.com/forums/images/graemlins/confused.gif" alt="" /> <img src="http://www.catsailor.com/forums/images/graemlins/blush.gif" alt="" /> <img src="http://www.catsailor.com/forums/images/graemlins/grin.gif" alt="" />

Phill,

if you find that tube building write-up, I am also interested.
How does your "donought" lookalike snuffer work? Does it work equally well on both sides?
Nice detail, letting the snuffer encapsulate parts of the spi-pole!
Any toughts on how much better a integrated snuffer/pole works, and how the windage is compared to the solutions discussed here?


Pete: Monkey vs. football????

Read that PM in private first! <img src="http://www.catsailor.com/forums/images/graemlins/blush.gif" alt="" />

I second that.

A refridgerator pump works as a good vacuum source. Just connect to the suction side of it and plug it in. I use a venturi pump that uses air from my air compressor shooting through a tiny orifice. A small port on the backside of the orifice pulls a vacuum as the air shoots through. A good one of these is only about $70...but requires a pretty healthy compressor to feed it.

Vacuum bagging produces much stronger laminates than laying things up under atmospheric pressure. It squeezes out a good bit of resin resulting in a much higher fiber density (which is where the strength is). Also, when using a core material (foam, balsa, etc.) it really promotes excellent bonding to the core which exponentially increases the strength of the layup. If you pull just -10 psi (20in-hg) to a 1 sq foot object, it's applying 1440lbs of pressure to the outside of the object perfectly perpendiular to all the surfaces. That's a lot of pressure!

This is a very good source of information

Vacuum Bagging Equipment & Techniques

http://www.fibreglast.com/contentpages-V...ations-230.html


Vacuum Infusion - The Equipment and Process of
Resin Infusion

http://www.fibreglast.com/documents/361.pdf