Step 9: Bagging

Layout your bag on a blanket (for protection). Then place you tool inside the bag and seal using the vacuum tape.

Cut a hole for your port/valve in a location that will have breather. At all times during this process, make sure your breather stays in position.

Begin applying vacuum. Making sure that the bag will not "bridge" any curves.

Bridging is what happens when there is not enough bag material to match a curve - so the bag jumps over the curve creating a high stress point on the curve and a location for resin to pool (bad).

To prevent bridging, create a location where the bag overlaps and creates a little envelope - as the vacuum presses down, it will pull this envelope apart.

Vacuum Tape
NEVER allow the tape to "feel" the full vacuum. Be sure there's enough bag material near the tape to "suck down" on.
I remember lookin at this a few years back and thinking how awesome it is.... Right now I'm sitting next to it doing my math homework, haha, looks even better in person! Great work!
My dad made a ferring from old campaign signs.
hi i was wondering if you need a gas mask for working with fiberglass and also if it would be semi safe for a 12 year old to make a longboard skateboard with it and if you would need a mold. thx
Yes, you should technically be wearing a organic (carbon) filter respirator (you can pick these up for $30-$40 each and they have replaceable filter cartridges). For a 12 year old.... If it were me - ensure VERY good ventilation and have the respirator.... While Epoxy is generally considered more safe than Polyester resins - industrial chemicals probably aren't very good for younger kids (for brain development and such :p). If using Polyester resin - extra care must be taken due to styrene content... I'm not familiar with skateboard construction... But aren't they typically made from plywood?
ok so yes most skateboards are plywood but longboards (search flex dex) are sometimes fiberglass and the fiberglass ones are more durable and in general better. so for any fiberglass work is a mold needed?
So if it's flat... probably not - just a nice flat surface... A piece of glass or sheet of stout metal would likely work :) We made flat samples on a large/flat scrap piece of aluminum ;) That flexdex stuff is interesting - I think it's different than what we're doing though... They claim it's an "unlaminated" fiberglass composite... I'm not sure what that means - in fact, searching for unlaminated fiberglass on google brings me a bunch of flexdex websites o.0 What we were doing is lamination.... But it could, in theory, make a fiberglass board :p If it turns out it's not stiff enough - try again with some sort of core material (foam, wood, etc.) Now if you're going to have any curvature - you'll probably want to make a jig/mold... It doesn't necessarily need a thickness molded though (this is a guess mind you)
thx i'll post a finnished mold/model :)
I was wondering what that bike was for every time I passed it in the ENGR2 atrium. Very cool.
what kind of bike is that?
Designed and built by our team :) You can't exactly just buy this trike... at least not at this time :P
nice! i am thinking about building one and adding some electricity to it. do you have any suggestions on a certain design? i have looked at a few diy trikes so far and i definitely want to do the tadpole setup.
The design you go with depends on your fabrication capabilities... We worked at a machine shop off campus with a mill (and cnc), brake, bender, cnc plasma cutter etc. If I were to build this myself, the design would be quite different as I don't have any of that available for free :P I haven't looked at any DIY trike designs -- but do pay attention to boom height and chain routing. I can't remember exactly - but I think it was something like 200 pounds of force on the crank - 350 pounds of force on the idler mounting bolt. There's some rather (non intuitive) large loads involved.
People are amazed that a person can create about the same amount of torque as a small-block V-8. Of course, it's at far lower RPM, so far less horsepower is made. We had all sorts of problems with chain idlers when we were creating our recumbent trike: <a rel="nofollow" href="http://home.comcast.net/~jeff_wills/aerocoupe/index.htm">http://home.comcast.net/~jeff_wills/aerocoupe/index.htm</a><br/><br/>Jeff<br/>
That reminds me of a rather "cute" thing steam locomotives do... They push a huge amount of force on their piston - but for an instant, there's no RPM... So for a brief instant, you have a torque approaching infinity :p I really like the photos pedaling through the water :p
Trebuchet, That looks great. It's the best glassing video I have seen. I was wondering why there are so many layers of glass? As it is a fairing and the bike itself is taking the structural loads (I'm presuming that the bike in the last few seconds is going into the fairing). Would not a single or double layer do? What was the final weight of the sections, and how close were the two part's weights. Did you consider using foam to bulk out the base and get more strength out of the glass you were using. Also, what were the tunes used?
BTW, Sorry for hogging the first post in the comment list. I tried to delete but instructables threw a big error. Diarmuid
No worries :) Ask anything you want and as much as you want ;)<br/><br/>This is intended for an ASME competition... Where safety is paramount (this comes to play in the design portion of the competition). We're required to have seat belts and roll over protection. Having a strong fairing gives extra protection from road rash in the event of a roll over - this is not required, but it's a great thing to have. At least, this was the justification before we started building ;) Having a strong fairing last year (my avatar) was beneficial as our steering system wasn't so hot. That safety of that fairing had several real world tests including a moderate speed wipe out (leaving a rather long skid mark).<br/><br/>An unforeseen benefit is that we can stand in the fairing without damaging it (cracking, or folding etc.). So now, we don't have to make cutouts in the bottom for entry/exit as we originally planned on. This just makes it a better aero package.<br/><br/><hr/>Now, next year -- we will be going even lighter, tossing out the coremat almost completely and instead using Divinycell (also reference as Kmat - a fiberglass backed foam core scored into squares). This fairing weighs ~21 pounds unpainted and without the cutouts. We never weighed each half - but, it balances well when you're holding it, so I assume they weigh almost the same. That being said, the second half did come out better - likely because it was put under vacuum much faster.<br/><br/>I think the reason for not using foam as the core material came down to cost/budgeting. Foam would be superior in the strength department. This project was done on a VERY tight budget compared to how much one could spend on the same materials and processing. I think (I'm not sure), the budget was less than $2500. Cheap given the materials and processes used for a one off part. BUT - that includes start up capitol to make the tool. Additional parts will cost much less in materials especially if less glass is used :D Man hours however add a significant cost which was not calculated here.<br/><br/><hr/>That frame you saw at the end is our vehicle :D The bike will take most of the load - we're hoping the fairing will help with giving a little more torsional stiffness. Without any toe in on the steering - high speed high force pedaling causing a little bit of instability. Giving it about 3/4 degrees of toe in helped a lot of that (wheels want to track straight now) :)<br/><br/><hr/>The music is one song (45 minutes long) -- by The Crystal Method -- It's their workout song/mix they made for the Nike + iPod promotion.<br/>
Something I forgot to touch on... How much vacuum can you pull? There is a common misconception that you can pull an &quot;unlimited&quot; amount of vacuum - just like you can have as much positive pressure as you want.<br/><br/>This is not the case. At sea level, there is approximately 14.7 pounds per square inch of pressure due to the weight of the atmosphere above you. You can ONLY pull a vacuum of 14.7PSI - and no more. There is no such thing as negative vacuum.<br/><br/>14.7psi is about:<br/>a 30 inch column of mercury<br/>a 32 foot column of water<br/>760 torr = a 760mm column of mercury<br/><br/>This is why well pumps are located at the bottom of the well and not at the ground surface ;) If the pump were at the surface, it could only raise water 32 feet which isn't very efficient :P<br/><br/><hr/>If you want to apply more pressure than 14.7psi - you need to use an enclave. An enclave is like a hyperbaric chamber and oven combined. It applies pressure and heat to create strong (read: structurally strong) parts. F1 monocoque frames are manufactured this way ;)<br/>
Hey Trebuchet, Thanks for the info on the HPV. Actually vacuum is measured in inches of mercury. And by applying 30" of mercury on your composite layup you will get 14.7 PSI arcoss the surface of the composite. An the enclave you refer to is actually an autoclave. I have been in the Boeing autoclave out in Huntington Beach, CA, It is big enough to drive a truck into. They can pull 150 PSI and use it to cure Rocket Nose Cones for the Titian Rocket. Thanks Joe
<em>An the enclave you refer to is actually an autoclave.</em><br/><br/>Wow, I must have relapsed back to grade school geography....<br/><br/>enclave: &quot;an enclosed territory that is culturally distinct from the foreign territory that surrounds it &quot;<br/>autoclave: said tool :P<br/><br/>slaps hand on forehead :P<br/><br/><hr/><em>...Rocket Nose Cones for the Titian Rocket.</em><br/>You wouldn't happen to be able to share what that's made from would you? I understand if you can't (Martin required all sorts of non disclosure paperwork). I'm just curious :)<br/>
Yes, about 8 years ago I was taking some composite classes and we did a field trip there. They were using carbon prepreg over Rohacell foam. Cool foam, has a very high temp rating that can be autoclaved. I cannot remember if they were using any film adhesive between the carbon and the foam. Thanks Joe
that's awesome! you work for LM or did you just break in to use their stuff?
We have an adviser/mentor that works for Martin -- and Martin has sponsored us in terms of giving us a place to work :)
so you're a professional gravity car builder?
Nope - this is a Human Powered vehicle. You can see the frame at the end of the video. This is a a Senior Design course at my University. Technically, I'm not in the course - but I do help with this project every year :) We're a bunch of college students ;)
How good work you has made. Congratulations.

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Bio: Engineer making renewable energy products for African entrepreneurs.
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