I thought I'd try to post a thread on bagging.
I think I can pull it off.
First thing is you need a flat surface with no leaks. This table is 1" mdf with two epoxy lifts sanded to 400 grit.
The back side of the table holds the bag. The bag is held on by butyl 1/2" wide. I also put my hose there on the table edge.
The table must be waxed 3-5 times before initial use. Depending upon the peelply used; waxing a single coat each time may be required. My peelply eats wax and so waxing every part is necessary or you have a nightmarish 2nd part pull and the third usually damages the piece on removal.
Here I am waxing.
An extra final pass up the middle is smart.
See the circular pattern.
A sheetrock trowel to remove any stuck epoxy.
Vacuum Bagging
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Re: Vacuum Bagging
Nice FallGuy!!! Jeff
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Re: Vacuum Bagging
Thanks for posting, I considered asking some questions on your build thread about it, but didnt want to cloudy it up with dumb questions
The mdf holds together well enough without a thin layer of glass to keep it from crumbling over time?
What kind of wax do you use?
What do you use for a vac pump?
What is your layup from table to top bag?
-bag
-peelply
-x layers of glass
-foam
-x layers of glass
-peelply
-table
????
What does epoxy lifts mean? You put 2 coats of epoxy on it to seal it and get your smooth surface?fallguy1000 wrote: ↑Thu Oct 08, 2020 12:15 pm This table is 1" mdf with two epoxy lifts sanded to 400 grit.
The mdf holds together well enough without a thin layer of glass to keep it from crumbling over time?
What kind of wax do you use?
What do you use for a vac pump?
What is your layup from table to top bag?
-bag
-peelply
-x layers of glass
-foam
-x layers of glass
-peelply
-table
????
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- Joined: Tue Jan 12, 2010 12:25 am
Re: Vacuum Bagging
Dewaxing is next. I like to go relatively soon. Not so much for a patience issue, but I find it easier physically. Once the wax dries hard; it is harder to dewax.
I tried commercial waxing equipment, but found by hand is the best. Except it is a little taxing.
Start with old cotton sheets. Use a circular motion. Be nice to your back. I do one side at a time. Turn the dewaxing rag and shake it out now n then. A pita, but needed. Here I waxed and dewaxed an 8 foot section by 4' wide in about 20-30 minutes.
I tried commercial waxing equipment, but found by hand is the best. Except it is a little taxing.
Start with old cotton sheets. Use a circular motion. Be nice to your back. I do one side at a time. Turn the dewaxing rag and shake it out now n then. A pita, but needed. Here I waxed and dewaxed an 8 foot section by 4' wide in about 20-30 minutes.
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Re: Vacuum Bagging
No questions will be deemed dumb.narfi wrote: ↑Thu Oct 08, 2020 12:30 pm Thanks for posting, I considered asking some questions on your build thread about it, but didnt want to cloudy it up with dumb questions
What does epoxy lifts mean? You put 2 coats of epoxy on it to seal it and get your smooth surface?fallguy1000 wrote: ↑Thu Oct 08, 2020 12:15 pm This table is 1" mdf with two epoxy lifts sanded to 400 grit.
The mdf holds together well enough without a thin layer of glass to keep it from crumbling over time?
What kind of wax do you use?
What do you use for a vac pump?
What is your layup from table to top bag?
-bag
-peelply
-x layers of glass
-foam
-x layers of glass
-peelply
-table
????
There is no glass on the mdf table. The two epoxy lifts were done to ensure no leaks. If you look at the picture; you can see some fairing compounds. This table was formerly 34 feet long. Seams at 8 feet were epoxy bonded and faired flat. The epoxy lifts were done to make a perfectly smooth and flat surface. I used about 48 ounces of epoxy per lift. I wanted to make sure the coating leveled out nice.
I use Grignard Mold Magic Release wax.
I purchased two used Welch Lab pumps. I would not recommend them. I recommend buying two commercial vac pumps from a company specializing in veneer vacuum bagging. The welch pumps are super expensive to repair; more than the cost of a new, modern pump. You need a continuous duty pump. Slow epoxy stays under vac 6 hours. Tropical epoxy is under vac 9 hours. Then the part stays on the table 8 more hours (usually overnite) before demoulding. The reason for two pumps is my components are really expensive. The epoxy in the parts I am building is about 50-100$. The core is the same. The glass less. The labor is big. I figure the current parts would cost about two days lost time if I have a pump failure.
The large hull panels would cost about $2000 if we had a failure. We did blow a belt once and switched pumps. Right now, one of my pumps is leaking...super costly to repair.
I will explain the stack in the pictures forthcoming.
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Re: Vacuum Bagging
After waxing the table, you need to peelply the mould. I peelply always; even for a single sided lamination.
The side of the lamination is an issue. I always like to laminate outside up or any radiuses up. Otherwise you need to placehold which is another discussion.
You get a piece of peelply smaller than the table, but larger than the part and tape it to the table. I don't like this peelply, but I have a bunch of it, I prefer the redline stuff used by airline industry. It releases from the part a bit easier.
I am rolling a bit far for a table full of scrap glass. The part to glass is 55" high, wider than the table. Is 38" high, so a piece of peelply 44" is about right. Cutting is done with an electric shears for a projdct this big. I use gorilla tape to tape the peelply down.
The side of the lamination is an issue. I always like to laminate outside up or any radiuses up. Otherwise you need to placehold which is another discussion.
You get a piece of peelply smaller than the table, but larger than the part and tape it to the table. I don't like this peelply, but I have a bunch of it, I prefer the redline stuff used by airline industry. It releases from the part a bit easier.
I am rolling a bit far for a table full of scrap glass. The part to glass is 55" high, wider than the table. Is 38" high, so a piece of peelply 44" is about right. Cutting is done with an electric shears for a projdct this big. I use gorilla tape to tape the peelply down.
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Re: Vacuum Bagging
I used to use masking tape, but this peelply is super slippery and only ship tape works.
The peelply must be pretty tight or the bunching will appear in the part.
Tape all around. Mark the part location with a sharpie. This is to know where to pour epoxy. Foam core is held together with plastic raptor staples. The gun is $225. Under 2 boxes of staples were used for the Skoota. Foam is easy to repair or add onto. Epoxy fills the seams.
The peelply must be pretty tight or the bunching will appear in the part.
Tape all around. Mark the part location with a sharpie. This is to know where to pour epoxy. Foam core is held together with plastic raptor staples. The gun is $225. Under 2 boxes of staples were used for the Skoota. Foam is easy to repair or add onto. Epoxy fills the seams.
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Re: Vacuum Bagging
I am actually going to laminate two pieces in this go.
The first steps are the same.
I don't show it, but a second piece of peelply is made for each part for the top. That piece is rolled onto a tube. Roll it on end to start. Roll off start to end!
The second part. It has a radius. This is best laminated up or there will be no glass on the round. Three inch cardboard tubes are used a LOT. Here I am rolling up the top peelply onto cardboard for easily rolling it onto the wetted part.
The first steps are the same.
I don't show it, but a second piece of peelply is made for each part for the top. That piece is rolled onto a tube. Roll it on end to start. Roll off start to end!
The second part. It has a radius. This is best laminated up or there will be no glass on the round. Three inch cardboard tubes are used a LOT. Here I am rolling up the top peelply onto cardboard for easily rolling it onto the wetted part.
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Re: Vacuum Bagging
At some point, you need to cut glass for your parts and roll them onto tubes. You can overlap glass on the bottom and it will be pretty flat.
I will post pictures. I will avoid a caption. The glass is carefully marked so you can follow your work.
There is not a lot of time for trouble or confusion.
Disregard the picture of the breather fabric. It is in here by accident.
I will post pictures. I will avoid a caption. The glass is carefully marked so you can follow your work.
There is not a lot of time for trouble or confusion.
Disregard the picture of the breather fabric. It is in here by accident.
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Re: Vacuum Bagging
Next is to measure and cut release film. I already had a piece done. It is cut for the whole area under the bag. It is reusable. This release film has a pinhole on 10mm centers to bleed resin to the bag. It also keeps the breather from sticking to the peelply and table. It is bleeder release fabric.
Then the breather film is also cut and rolled onto a tube.
Then the breather film is also cut and rolled onto a tube.
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