Vacuum Bagging

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fallguy1000
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Re: Vacuum Bagging

Post by fallguy1000 »

Next is to calculate the resin needs. Since I am working alone today, I will pour a bit heavy.

Calculate the weight of the glass.

Use about 120%.

Use about 25-35% to wetout the core.

Here is the calc for the small piece. 15 oz of fabric at 120% is 18 oz of resin and about 6 oz to wetout the core. The core bottom side must be wetted to avoid dry sucking the glass. Too wet and it will leave air pockets when the vac smushes down on it.

This is 12 oz glass. I use about 60% of the pour on the bottom and finish the top.

For simplification, I will be making 3 mixes of about 24 oz of resin each time today. So not by the book so I can try to get a few pictures.
Attachments
D85763DC-4FB9-429A-9E62-AADD7F6C1E55.jpeg
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fallguy1000
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Re: Vacuum Bagging

Post by fallguy1000 »

Gum tape is applied.

Leave the papers on 3 sides.

Any drip of resin renders the bag leaky. A realnightmare.

Any bits of glass threads are also leak hazards.

Cut gum tape with a scissors. A knife is a mess.

Ready to wetout!
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A roll of vac tape..1/2"
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Threads are bad and will leak; work area must be clean.
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A finished corner. Put tapes all down.
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Lift tape to bond the gum tape cuts. Sorry; these are a bit out of order.
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fallguy1000
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Re: Vacuum Bagging

Post by fallguy1000 »

Wetting out is always a challenge. 12 oz fabric is really friendly. 60% under, 40% on top

Tools-consolidation roller, 9" roller cut to 3" on a 3" roller frame
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Starting at 3:12pm
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The bottom of the small part is 60% wetted.
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The underside of the core must be wetted to avoid drysuck.
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If translucent; you can move to next step.
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Other big section wetout.
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Wetter on reverse and flipped.
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All tops are wetted awaiting top glass.
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fallguy1000
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Re: Vacuum Bagging

Post by fallguy1000 »

The top glass wetout is done (no pic), then the peelply is rolled off a tube flat onto the part. No bunching is permitted.

Then bleeder release film.

Then breather media.

Then wipe any drips. I almost always have them; none today. No epoxy around the bag.

Then deglove and let hands dry. Sweat on the bag is a vac leak.

My pics are out of order. Deal with it please.

Then fold the bag over.
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Deglove and dry hands before handling bag.
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Wet gloves are trouble sealing the bag. Remove them.
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Remove drips
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Last item in the stack is the breather that allows vac pressure to moderate over the part.
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2nd to last item is the bleeder release film. It should be larger than the peelply.
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The peelply goes above the wetted glass. I do not wet it. It must be perfectly flat. Gentle pulls remove air bubbles.
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fallguy1000
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Re: Vacuum Bagging

Post by fallguy1000 »

Laying the bag is sort of its own science. You can google pleating a vac bag and watch a video on it. This bag is a 3rd rounder. They almost all develop minor leaks by the third pass.

This one had a leak...somewhere. I gave up on it. My vac pump is directly under the work. If you want a better setup; keep the pump firther away so you can hear leakage.

I had the bag closed at 55 minutes. Pretty late, but was trying to get pics in as well.

Leak repairs. Bag was closed quite awhile here.
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Leak repair closeup.
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Pretty late for a 3:12 start. I was a bit slow today going to the camera.
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Keep the bag taut to avoid a leaky ripple.
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The next 3 are in reverse order. Basically, I keep the bag pretty tight. Some guys might like a looser bag for less bridging. I tolerate it. These shots are jist to show how important it is to keep the bag laying flat.
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1C2B6399-5986-4634-ACCC-FDE3C780471A.jpeg
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fallguy1000
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Re: Vacuum Bagging

Post by fallguy1000 »

Probably a few nuances I have glossed over. This might help a few people.

Open for discussion.
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piperdown
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Re: Vacuum Bagging

Post by piperdown »

So, just to understand, you are wetting out the core and glass then vacuum? You're not using the vacuum to pull from an epoxy pot to wet out?

What brand vacuum pump are you using?
Eric (aka, piperdown)

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fallguy1000
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Re: Vacuum Bagging

Post by fallguy1000 »

piperdown wrote: Fri Oct 09, 2020 7:49 am So, just to understand, you are wetting out the core and glass then vacuum? You're not using the vacuum to pull from an epoxy pot to wet out?

What brand vacuum pump are you using?
Correct. This is wet bagging; not infusion. I have the wrong core for infusion.

I do not recommend these pumps. They are too expensive to repair. A repair kit costs more than a new pump that will work.

My pumps can also full pull 30" HG. This crushes voids and drives resin content scary low sometimes. I think running at around 25" would be better, but everytime I run low I get voids; so my system of running low has something amiss. I have a system bleeder in the vac line, but I am convinced it becomes an easier place to flow out air. A friend of mine says he had the same issue and he backed off the pump after 5 minutes.

I am using Welch pumps.

I have two of these I bought used.

https://www.zoro.com/welch-vacuum-pump- ... lsrc=3p.ds
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fallguy1000
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Re: Vacuum Bagging

Post by fallguy1000 »

Pulled the parts today.
63FFC300-E5A9-4754-BD15-A177A4851824.jpeg
95BDF939-B727-4781-8047-414D4C4529A9.jpeg
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Evan_Gatehouse
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Re: Vacuum Bagging

Post by Evan_Gatehouse »

Why are you using peel ply on the mold surface? When I was making bigger panels than yours I would want one smooth exterior surface so I kept it against the glossy mold surface.
designer: FB11/GV10,11,13/ HMD18/
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