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Creating a fiberglass snowmobile trailer (aka - cutter)

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Picture of Creating a fiberglass snowmobile trailer (aka - cutter)
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Here is a snowmobile cutter I built over the last winter. It is a cat chasing a mouse chasing a chunk of cheese. The cheese is the hitch and the cat is the actual trailer. It is sized to carry a banana box and a bit more. The cat's tail is a handle to open the storage area and is held closed with magnetic latches.

As I haven't made anything with foam and fiberglass in some time I wanted a project with many compound curves.

People ask if it will carry passengers. I briefly considered a rumble seat but despite our well maintained roads it seems passengers deserve a suspension. Someone without a snowmobile might consider a smaller dog or person pulled version or toboggan.
 
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Step 1: The planning and layout

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I started with a general sketch of the cat. The mouse and cheese were ideas that came later and were not originally planned.

The sketches were then turned into various scaled drawings with the layers of foam inserted within. The approximate shape of each layer was freehanded over the various surfaces but a lot of time was not spent trying to match coordinates between views. It was easier to tweak the layers as they were cut and shaped.

The measurements from the drawings were scaled up and drawn onto pink extruded polystyrene foam insulation. I started with a simpler sub assembly, the skis, rather than the main torso. The parts were cut out and glued together to create the appropriate thickness. Each section was then sculpted and shaped. This step was accomplished using a mix of hot wire cutting, saws and sanding.

As the legs were fairly simple, I started with them.
Very nicely executed and documented.
upnorthrick (author)  Dream Dragon3 years ago
Thanks.
this is one of the best Instructables i have seen. im 13 and have been learning to use fiberglass so ive been searching for some tips, by the way how much resin and cloth did you use i want to build one and go 40 mph down the road on it :-)
I recall the Q2 aircraft I helped build had two layers of glass on the outside and one layer inside except for a second layer where people or cargo would be pressing on it. A test lay up was a layer of bid (typical woven cloth), 2 layers of uni (strands all one direction) and another layer of bid. These four layers were then joined with four more layers over 1/2 inch foam and were quite strong. Since we aren't trying to build something that has to fly, I recommend three layers of glass on outside surfaces, several more on the skis or anywhere you think it could get beat up with extra layers on the surfaces bracing them, and a layer or two on inside surfaces. It is better to use too much than not enough, but I doubt you will need more than six or eight layers for smooth snow at any speed. You may also consider putting a layer of wood, metal strip, plastic snow sled, pick up truck bed mat or some other material on the ski if you expect to go over rough stuff. I didn't keep careful track, but probably used a gallon and a half of resin. If you are already working with fiberglass, try to keep track of how much you use with a certain amount of cloth, then calculate approximately how far you get with a batch of resin. I made several drawings and calculations, but then went by the seat of my pants, deciding a detail had enough glass on it when it "looked right." In hindsight, the four layers on the ears should have been six or eight as they have no core. Calculate the surface area of your project and multiply it times the number of layers inside and out. If you end up buying too much glass or resin, hopefully you or someone else will be able to use it on a later project. ******** Remember, it was rather simple to cut out flat foam side and top profiles, glue them together and add filler to get a complex looking shape. I don't think I mentioned it, but I cut notches into foam parts to align them, much as a tailor does with fabric. You might start with something boxier than a cat-- If you look closely at most cars, trucks or snowmobile hoods, they are mostly curved flat surfaces and softened corners but impress the devil out of people. Ask yourself what balloons or Tupperware would look like if covered with glass and paint.
Charlie11386 years ago
This is an amazing project and Instructables. Thanks so much for taking the time to document all this. I am curious, where did you learn to do this? What other projects have you made in the past? Also, what kind of foams can you use without he resin damaging it or dissolving it or something?? And let's say you were making somekind of sculptures for the lawn.. like a fiberglass santa or something like that.. and you wanted to make it more detailed, on the face for example, do you know of any material you could put over the fiberglass and sculpt in fine detail that would be durable? Can you sculpt bondo very well?
upnorthrick (author)  Charlie11386 years ago
I did the typical polyester resin repairs to rust outs on a car and small scraps on a beat up boat, then helped build a composite airplane in the 1980's. I patched a couple of rusty floors on our winter driving Corvairs, for the thickness graphite is probably as stiff as steel for patching tight spots like under a windshield. Since then it was pretty much odds and ends around the house, fixing broken handles, a simple box for the radon venting before we poured the basement and an equipment pedestal for our ambulance. Start small and simple, work with others to study techniques and ideas and share ideas on Instructables. You might also talk to theater people who make sets for plays, they go the other direction, using acetone and other chemicals to make styrofoam look like aged stone for MacBeth's big finale. Those, of course, will not last long out doors and are flammable indoors.

Styrofoam and polystyrene foams are available locally in sheets up to 4' X 8' in thicknesses up to 2". They can be cut with a hot wire that can be made as long as you want (although four foot is my practical limit) so you can easily cut curves or textures out of the long axis of a sheet (or airfoils for an airplane out of blocks, as we home builders have have). On the other hand, if it is going to be around gasoline or other solvents, order urethane or other fuel resistant foam. These foams CANNOT be hot wired but the urethane sands and sculpts VERY well. Automotives and hardware stores have polyester resins and glass, keep in mind wax is put in the polyester. It absorbs humidity and cures tacky for the next layer to stick all the better, the wax shields it for a glossy finish but can cause adhesion problems on the next layer. Polyester resin will dissolve styrofoam, polystyrene and other readily available foams, on the plus side it is much more UV resistant and costs less than epoxy. Epoxies won't dissolve foams, stick to just about anything but cost more and you can develop allergies similar to poison ivy, especially if you are casual handling it. Epoxy takes longer to cure, generally a good quality.

If you want fine detail, use urethane and coat it with epoxy or polyester resin without the glass, it will be fragile without the glass. I'm not a big fan of Bondo but did use it for filling some parts of the cat cutter. It is polyester based and will absorb water, if you wet sand the finish you may see your paint fall off later. Composite airplanes are filled with a mixture of epoxy and micro balloons, the balloons are tiny glass spheres that are so light they behave like dust. They are inert but play havoc on your lungs if you inhale them. Mixing more balloons with less epoxy will give a softer, lighter material that can be sculpted into very fine detail. The epoxy base needs a day or two to set but you could probably make a 30 minute polyester concoction. Keep your mix ratios consistent so you don't have hard and soft streaks in your carving. While the catalogues say it has no structural strength, it will take a fair amount of compression, it is my understanding it provides the buoyancy to the remotes that go into places like the Titanic.

I have also made molds out of combinations of wood, cardboard, foam and modelling clay. The oils in the clay keep it from dispersing into the clay. Interestingly, epoxy doesn't stick to duct tape or packing tape, so you can wrap an object or make a parting line with tape as a release agent, the strapping tape leaves a glossy finish. Every wiggle, scratch, thumb print in clay as well as dust caught under the tape will appear in the fiberglass. I haven't tried it yet but you could sculpt something in plaster, coat it with a parting material and make a mold.

Again, go on line to Wick's Aircraft http://www.wicksaircraft.com/ Aircraft Spruce and supply http://www.aircraftspruce.com/ West Marine http://ecatalog.westmarine.com/ or other such places and search for Composite Materials. Keep an open mind for projects, the cat's whiskers are made of 1/8' diameter graphite rod similar to what's used in fishing rods and golf clubs, they also have it in rectangular bars that would make killer kite sticks.
Sorry it took so long to respond on this. Thank you SO much for taking the time to give such a detailed response. I am an aspiring sculptor and can't thank you enough for this information.
upnorthrick (author)  Charlie11385 years ago
I've seen at least one book on making forms for concrete sculpture from foam, could be a more familiar medium. The last of the hotels will be closing for the season next week, expect to be trading in the bicycles for snowmobiles in about six weeks.
labelreader6 years ago
I love the whimsy of this -- all you need is a snowmobile parade to drive it in. Is it usually still snowing on July 4 where you live? =)
upnorthrick (author)  labelreader6 years ago
Snow usually disappears about this time of year, I bicycled to work today. My co-workers have been getting their snowmobiles to the various storage areas today. The ice bridge to the mainland broke up March 30 and the ferry boat began only five days later, this weekend. Snow usually returns early December but comes and goes until mid January. Summers aren't bad here, the lake keeps keeps it mellow, I've never had an air conditioner. There are also no mosquitos, which is rather pleasant.
leebryuk6 years ago
That is incredible! For better or worse I live in Florida. It's for better as the low is around 50F, and the high is 75F. Wish I had an environment to use this sort of trailer in. I might try your bicycle trailer idea. It could make for a supercool (but not practical) touring trailer. Or it could be part of a grocery getter. +1
upnorthrick (author)  leebryuk6 years ago
The ferries have quit running due to ice in the straits, the weather grounded the planes, four of us spent time on bar stools in St. Ignace. One of my fellow travelers grew up in Florida. As I said, this could be adapted to an automobile trailer. I have thought about putting something together with left over Corvair parts, the first trick would be getting the car to the shop without being arrested for having it.
That is awesome. I have a few questions: (A) how much did this project cost? (B) where do you buy your FG supplies (resin, glass, ect.) (C) How did you learn to 'glass' like that? (D) how many layers this is the body? Keep up the great work, I look foward to trying to apply some of the things you did here to a FG bicycle trailer.
upnorthrick (author)  Handsome-Ryan6 years ago
(A) I didn't keep track of cost. With odds and ends I am I am going to guess $300. I bicycle trailer should use much less material.

(B) I mail ordered most of the materials, including the metal hitch shaft and bearings, from Wicks Aircraft Supply in Illinois. The whiskers are their 1/8" diameter graphite rod. Type "Composite Materials" in the search box. http://www.wicksaircraft.com/ In years past I have also purchased materials from Aircraft Spruce & Specialty Co. http://www.aircraftspruce.com/ You may also check on line or at boat dealers for West Marine or other products.

(C) I helped build a home built airplane (Quickie Q2) in the 1980's, maybe you can find someone in your area building or modifying a plane, boat, car, etc. Wicks has a "Composite Practice Kit & Book" for $95 that looks promising. If you can split the cost with others you will also have people to bounce ideas off as you go. I wanted to build something with a lot of compound curves. However, JoAnn's fabrics has smaller diameter solid foam balls that would save time sculpting a head. Also consider the urethane foams, they sand very easily, but cannot be hot wired as the heat gives off toxic gasses. Start simple with just a figure head for a boat, truck grill or something more boxy like a mail box.

(D) I used a couple of different weaves, both about seven ounce per square yard. Weight and the cost of extra fiberglass were not a consideration so I put three layers on the outside and something like eight on the bottoms of the skis. The tail got three layers while the lid has two layers outside and one layer inside, and ended up so stiff the contact point where the tail touches the right side of the body was unnecessary. You can make simple sample lay ups to test and break, but as a bike trailer should be light weight I think one layer inside and out will work, with a second layer where you want durability. You can always repair collision damage
Thanks for the quick reply. I don't think I'm ready for anything nearly this complex yet but I am very interested in trying my hand at fiberglassing over foam.
LinuxH4x0r6 years ago
Wow! thats awesome! Too bad I don't live in MN anymore or I would have made one. Great instructable!
upnorthrick (author)  LinuxH4x0r6 years ago
Sorry you don't live in a snow belt. I'm sure the construction could be adapted to a car trailer, roof top carrier or pick up cap, with the builder choosing his or her favorite critter, character or object.
Actually it looks a little to hard for me. Don't feel sorry - They closed school here in Santa Fe, New Mexico, for only 2 inches of snow today! I miss Minnesota, but at least here they have snow days.
upnorthrick (author)  LinuxH4x0r6 years ago
It was a bit time consuming, but not too hard. If you have never hot wired foam perhaps a "disposable" foam lawn ornament or a foam mold for a concrete project would be a better start. You might start by finding someone working on a boat or composite kit plane. You can get a sheet or two of foam and 5 minute epoxy at the lumber yard for $ 30.00 and buy the hot wire for a couple dollars. Come up with some three view pictures, transfer them to foam and cut them out. Once some vertical and horizontal layers are in place you can decide whether to go on or discretely put what you have in Glade bags. My sister is going to school in Gallup, she says it is a bit warmer there.
Maybe I'll start doing something like that if I get some time. Right now I'm spending most of my free time on metal. I like the idea of making stuff with cement ( I made a cement lightbulb that I plan on using as a knob for the gears onee I get my VW). Gallup is a lot warmer than MN and a little warmer than santa fe, but hoonestly I love the cold and can't stand the heat. Where are you from?
upnorthrick (author)  LinuxH4x0r6 years ago
Had a couple of friends with VW beetles in high school, we drove Corvairs. I live on Mackinac Island, between Michigan's upper and lower peninsulas. As city ordinance bans the Corvairs and I'm not a horse person it is pretty much bicycles in the summer and snowmobiles in the winter.
HAHA! GREAT INSTRUCTABLE! That's pretty funny how it's a cat, then you can see a huge cat just drifting in the snow, or when you come into the garage at night, it is just staring at you.. nice job, it looks awesome! (added to favorites)
upnorthrick (author)  GorillazMiko6 years ago
Thanks. Snowmobile styling has been a bit funky to look at lately and cars are banned so I have taken to parking it where it will greet us when we come home....
wombat76 years ago
sweet!
Patrik6 years ago
Impressive - I love it!
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