Need help designing front and rear Cross Sections.

[lawsonpix]

Starting my 4x8 build. My plan starts with a 5’ 6” overall width limit so I can fit my TD under my Deck for winter storage. This will keep the rain and snow off my TD when I’m not camping.

I read that keeping the body width at (or under) 4’ will allow me to use standard size Aluminum and Plywood. I’m planning on using ¾ ply sides, so that makes my trailer width 46 ½” (48-3/4-3/4=46 ½)

Now I need to know how long to make my trailer base. I have a shape,


How much trim? Mounting area? “Whatever is down there” will I need to mount the base of my curve to my trailer?

[Kharn]

I would use carriage bolts instead of flat-head machine screws, flat heads won't have much engagement vs plywood and you can use torque washers to increase the carriage bolts' contact with the wood. Use a ripped down 2x4 to make the transition from the floor to the curve, but you'll probably need to change your design so the contact areas are more favorable.

Aluminum is also available in 110" width for use on tractor trailers, so I wouldn't necessarily feel constrained by the materials.

[lawsonpix]

Thanks, Kharn

Carriage bolts. Great tip. I'll do that.

I know I can get other Aluminum. But my local metal guy has plenty of 4ft in stock so it's just easier. Plus I want a 4ft Teardrop.
http://metals.shopjfi.com/catalog.aspx?d=Sheet%26PLT&c=Aluminum&s=Plate

You said "change your design so the contact areas are more favorable" what do you mean? Add more space between the skin and trailer? Lower my spar?

[Kharn]

I would move the spar to the rear so a 2x4 can be made into a wedge to connect the spar to the floor with a 1"+ wide contact area against both the floor and spar.

[KCStudly]

Another option, if you want the profile curve to continue down to the bottom of the frame, is to extend the floor forward and attach the wedged shape ripped piece under the edge of the floor with a slight gap to the frame (better to allow a little clearance and seal it up, than to have an interference and have trouble getting it to clear/fit right). This piece could have a blunt tip at the bottom that would provide some thickness while still backing up the front wall outer skin.

A similar wedged piece/spar could then be fastened on top of the edge of the floor to back up the lower edge of the inside skin (a toe kicker).

[citylights]

Nice shape!

[tony.latham]

Lawsonpix:

I'm on build #3 and the smartest (okay, luckiest) thing I did when I started my first build was to buy a copy of Steve Fredrick's Teardrop Builders's Shop Manual. It's about 250 pages and full of pics. You can get a download copy here: http://www.campingclassics.com/shopman05.html

It'll answer a million of your questions and trust me, you'll have them. His hatch method is fairly easy, creates the best seal out there (that's my two-bits) and there's no spring back issues.

Google around on this forum to get a few more opinions on his manual. But I've been a woodworker my entire life and it has helped me tremendously.

Tony

p.s. I've built one 4x8' using the Grumman profile and you'll lose 8" of floor space by rolling in the bottom front of your teardrop. 8" is a half mile in a tiny space.

[kayakdlk]

For your question "What goes in here?". My teardrop is 5' wide so I cut a 5' 1""x2" board at and angle and screwed/caulked it to the front of my frame (I first coated it with epoxy on all sides, and used caulk between it and the frame) . The roof ply then connected to it. After I epoxied and cloth the roof I used black caulk to fill any gap at the bottom lip

For your question "Need this dimension so I can size my trailer" On my build it was less that a quarter inch, but I am not sure how it affects your trailer dimension. The area you highlighted is in front of the trailer frame and not part of the frame length. I am also assuming your sides will come down over the frame

I second Tony's suggestion of getting Steve Frederichs build manual. Invaluable insight, tips, pictures (His web site and his builds have lots more), and Steve even answers emails when I had questions on his book and techniques.

Good luck with your build

Dan

[bc toys]

take a 2x4 and rip a wedge out of it and replace it with the 1x2 you are using that would fill in the area you have open

[lawsonpix]

Thanks everyone, these are all great ideas

Nice shape!

Thanks! took me over a month to get it just right

take a 2x4 and rip a wedge out of it and replace it with the 1x2 you are using that would fill in the area you have open

Sounds like the simplest and strongest idea.



Just as an FYI, this is my side profile:

[citylights]

The front connection is a little complex, will require some creative wood cutting, but it will be strong and maintains your shape.

I noticed you are using 3/4 plywood and aluminum skin. That is exactly what I did in my build. You might want to check out my build log.

One thing I wish that I had done was use composite sandwich sides instead of 3/4 plywood to keep the weight down. Don't get me wrong, 3/4 is stout and easy to work with, but the weight adds up. No big deal if you are towing with a 6 cylinder or better, but it is a big deal if towing with a 4 cylinder vehicle. At 1800 lb, my teardrop will never be towed with a small car.

[lawsonpix]

At 1800 lb, my teardrop will never be towed with a small car.

1800 pounds?!!? Wow that's a lot! That weight requires breaks in my state. My truck tows 3400 lbs, but my car tows 1500 lbs. (I have a 5 cylinder lol ) I'm shooting for 800 lbs. or less. I don't want to deal with installing breaks or maxing out my tow weight limit.

I checked out your build, pretty impressive!

[citylights]

At 1800 lb, my teardrop will never be towed with a small car.

1800 pounds?!!? Wow that's a lot! That weight requires breaks in my state. My truck tows 3400 lbs, but my car tows 1500 lbs. (I have a 5 cylinder lol ) I'm shooting for 800 lbs. or less. I don't want to deal with installing breaks or maxing out my tow weight limit.

I checked out your build, pretty impressive!

800 lb is light even for a 5x8 teardrop. Mine is 5x10. To stay at 800 lb or less, you need to think light weight construction technique throughout (and I don't think you are going to get there with 3/4 plywood, unless you skeletonize it.)

Check out this thread and graph of teardrop weights.

http://www.tnttt.com/viewtopic.php?f=2&t=56787&start=105

[lawsonpix]

Check out this thread and graph of teardrop weights.

http://www.tnttt.com/viewtopic.php?f=2&t=56787&start=105

That's the chart I got my weight estimate from. My teardrop is 4x8, most of the 4x8s on that chart weigh in at less that 1000 lbs. Unless I'm reading it wrong. is says: length times width, 4x8 = 4+8+4+8= 32

Some of my weight saving ideas:
Trailer: 1x2 channel: saves 34 lbs vs 2x2 box.
.032 aluminum skin vs .040 or .050
12 inch rims vs 13 rims
1/2" floor vs 3/4" floor
minimal shelving in kitchen.
No doors in kitchen.
No water storage while driving.
No doubling up on wood. ie: build the complete kitchen then slide it in.
No solid wood shelves in cabin, ie: integrate preexisting IKEA shelves into my cabin. See photo:

[lawsonpix]

3/4 plywood weighs 60 lbs.
1/2 plywood weighs 40 lbs,
1/4 plywood weighs 22 lbs

Check out this chart:
http://parr.com/PDFs/PG_plywoodthickness.pdf