[Video] Part Making

Intro: [Video] Part Making

After our incestuous success making with making a tool - it's time to make some parts! Get yourself psychologically revved up as the next few hours of preparation, making bags, layup and vacuum are going to require 100% of your attention and care.

This is the next phase of the University of Central Florida 2007 ASME Human Powered Vehicle Team's fairing construction. We will be using the "negative" tools we made the previous weekend to create parts that will resemble the plug we started with.

Thanks to Lockheed Martin Missile and Fire Control....



Related
Video Large Scale Mold Making - Part 1
Video Mixing Polyester Resin

Photo: 2006 HPV Fairing next to 2007 Fairing (not yet complete)

STEP 1: Planning

When ordering Fiberglass and Core Material - order by the linear foot. Do Not Order based on Square Footage. There's an acceptable amount of loss involved with fiber layup and ordering by the square foot (like we unknowingly did) will result in you not having enough material to finish.

Take your glass and lay it out over your tool and see exactly how much you need. Then, cut your fiber for each necessary layer. For us - this required:

8 10' X 36" Sheets
8 6' X 11" Strips
8 6' X 16" Strips
Cut to fit Pieces of CoreMat

Remember, we have two tools to make one complete part (in two halves). So, this material is enough to do four layers of glass with core (3 glass layers, Core, 1 Glass Layer).

STEP 2: Planning II

Now that your material is cut, fold it like an accordion so that it unwraps quickly and easily.

Next, we make the bag for vacuuming. This requires special materials - mainly the bag material and the vacuum tape used to make the bag from pieces. Making a bag requires that your surface is clean (to prevent puncture) and you must not walk, kneel or put excessive pressure on your bag as this can cause punctures.

As for making the bag - that deserves it's own instructable. I may not have enough to document it by itself - so it's a good idea to have a mentor to show your the ropes :D

STEP 3: Tool Prep

Here's a few things you need to do before layup.

1. Sand flange and plug interior - remove all PVA remnants from tooling
2. Wax flange and plug interior - just as we did when tooling
3. Spray on PVA - just like when tooling
4. Create a Resin Mixing Stand ready with pots, brushes, mixing sticks, gloves, etc.

It is not 100% necessary, however, building a support stand can be beneficial to your back. Some scrap lumber - even recycled from your tooling stand) cut to support the tool by the flange is all that is needed. That would be step 0 on this list.

You may already be saying - "But this is just like making a tool." You'd be right - except we're using woven glass, epoxy resin, and a core material.

STEP 4: Begin Layup - GelCoat

Start by mixing a "gelcoat" using the very same Cabosil (fumed silica) and epoxy resin.

1. Add desired amount of resin to a pot
2. Mix in Cabosil until it holds peaks
3. Add epoxy hardener

Apply gently with a brush. Remember, once you add hardener - the clock is ticking. You need to go from mixed to bagged ASAP.

The resin/silica is thixotropic - that is, when you apply pressure to it, it becomes thinner and easier to spread. This coating will provide a glass smooth like finish (assuming your tool is smooth too).

Once your coat is down -- apply a coat of regular resin.

STEP 5: Layup

Layup should go down the same way you prepared. You won't have time to figure out where things go or to patchwork (which is a LOT of work) - this is why we took so much time to prepare for layup. Your best bet is to start with the largest piece, and then add on the smaller ones.

Overlapping should be about an inch. For continuity and strength, try to vary where the overlap occurs on each layer.

When you first lay down a sheet of fiber, use your hands and press it into the free resin below - manipulate the fiber cloth to get it in the desired position. Add additional resin as necessary with a brush. Finally, use squeegees to get large air bubbles out. Small bubbles (less than .5 inches) are nothing to worry about as the vacuum bag will take care of this.

STEP 6: Layup II - Jobs

You'll notice that we have 4-5 people working on layup. For large jobs, you need to have specific tasks handled by one person; such as:

1. Resin Mixer
2. Squeege'er
3. Fiber Layer (should be the same person/people that cut the glass)
4. Brush Cleaner (more on that later)
5. Resin Apply'erer

Some of these jobs can be shared - for instance, the person mixing resin can clean brushes in between batches and the person applying resin can help lay down fiber as needed. And Everyone (except the mixer) can help tease and manipulate the fiber into position when it goes down.

On the subject of brush cleaning. Clean your brushes and squeegees frequently as old resin will start curing before you're finished.

STEP 7: Layup III Core

There are many type of core -- in fact, just about anything can be used as a core material. Even garden hose! We will be using a material called CoreMat.

CoreMat soaks up resin and expands a bit. When it has been fully impregnated with resin, it turns a deep yellow color. Too much manipulation when coated with resin will damage the mat (much like rubbing wet paper towels).

To apply this type of core. Simple drench the area you will apply the core to with resin. Stick on the core and work in more resin until it's completely soaked.

Some other types of Core:
1. Carboard
2. Honeycomb (of many types including paper, aluminum, etc.)
3. Steel or Aluminum (good for super strong mounting points)
4. Foam
5. K-mat (a scored foam with fiberglass back)

STEP 8: Peel Off Bag Release and Breather

To apply even pressure, the tool is lined with a breather material - much like the innards of a soft blanket. To prevent this breather from sticking, a plastic release film is placed in the tool on top of the glass. This film is basically a plastic wrap with holes (t allow resin through).

Roll out this plastic film to cover every square inch. Folds are nothing to worry about - just get everything covered. If you need to overlap pieces due to size - give yourself about six inches.

Now unroll your breather material. Your breather should NOT have any folds in it - if you need to, use tape to keep it in place. If you need to use more than once piece to cover the entire tool - you can overlap, just keep it to a minimum.

Finally, make sure some breather goes well over the flange - this will provide a location to mount the vacuum port and valve.

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
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.

STEP 10: Finishing Up

Once your part is under full pressure, you should start to notice little bits of resin poking through into the breather. This is good! It's somewhat of a concern if you don't see resin (unless its a zone where the film release overlaps). But, there's nothing we can do at this point.

Too much resin is also a problem. At no time should resin enter the vacuum lines, valve etc. That, would be terrible.

Finally - the worst thing you can do is apply vacuum - realize you have a bridge and the release vacuum. This removes resin, adds air and then attempts to suck air out again with resin on top. So go slowly, don't apply vacuum all at once.

We flipped our tool so it would cure with minimal warping. Cure time is at least 16 hours with our resin.

STEP 11: Putting Them Together

Unfortunately, I don't have photos of this... But fiberglass tape was used to combine the two halves together.

Gray spray paint marks where windows will be cut and formed out of PETG (similar to soda bottle plastic).

Comments

[Dorkfish92]

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!

[cantthinkof bettername]

My dad made a ferring from old campaign signs.

[allbeef]

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

[trebuchet03]

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?

[allbeef]

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?

[trebuchet03]

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)

[allbeef]

thx i'll post a finnished mold/model :)

[Fledermen64]

I was wondering what that bike was for every time I passed it in the ENGR2 atrium. Very cool.

[wombat7]

what kind of bike is that?

[trebuchet03]

Designed and built by our team :) You can't exactly just buy this trike... at least not at this time :P

[wombat7]

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.

[trebuchet03]

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.

[Jeff Wills]

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: http://home.comcast.net/~jeff_wills/aerocoupe/index.htm

Jeff

[trebuchet03]

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

[dwrenne]

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?

[dwrenne]

BTW, Sorry for hogging the first post in the comment list. I tried to delete but instructables threw a big error. Diarmuid

[trebuchet03]

No worries :) Ask anything you want and as much as you want ;)

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).

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.

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.

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.

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) :)

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.

[trebuchet03]

Something I forgot to touch on... How much vacuum can you pull? There is a common misconception that you can pull an "unlimited" amount of vacuum - just like you can have as much positive pressure as you want.

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.

14.7psi is about:
a 30 inch column of mercury
a 32 foot column of water
760 torr = a 760mm column of mercury

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

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 ;)

[jpitz31]

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

[trebuchet03]

An the enclave you refer to is actually an autoclave.

Wow, I must have relapsed back to grade school geography....

enclave: "an enclosed territory that is culturally distinct from the foreign territory that surrounds it "
autoclave: said tool :P

slaps hand on forehead :P

...Rocket Nose Cones for the Titian Rocket.
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 :)