The Geek's Lair

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The Geek's Lair

Postby GeekFisher » Sat Nov 17, 2018 10:23 pm

Teardrop (Squaredrop) build

Project summary
I wish to build a squaredrop that can sleep 3 (2+1 child), dimensions are 78 wide x120 long x52 high, exterior. It needs to have A/C for Summer and some heating for Spring, Fall and maybe Winter. It will be insulated and skinned. It also needs to be able to stand some gravel washboard roads but no real obstacles (no crawling and no mud) but still be as lightweight as possible as gas ain’t cheap in Canada, sadly. The roof needs to be able to carry 2 fishing kayaks and eventually, support a rooftop tent.
ImageImage
Frame
All yellow parts are 2x2 0.125 square tubes and red parts are 2x2 0.125 angles. Would that be strong enough? Orange part is the axle placement, 62 front-38 back
Image
Axle
I first settled on a 2000lbs 72in H/F axle with a 60in center spring. With a regular 8 spoke trailer wheel, would the offset made overall lenght of the axle+wheels and tire close to the 78 exterior dimensions? I do not want the wheels to look recessed in the camper. The axle is 62/38 front/rear ratio which is supposed to be OK.

Wheels and tires
I’m pretty much setted on the standard 8 spokes trailer wheel in black with 205/75R15 tires to give a bit more clearance to the camper. I might try to find a deal on aluminum wheels though, as they look nicer and are a tad lighter.

Floor
I planned on sandwiching 2x2 (most would be pressure-treated, worth it?) between either 1/4 subfloor plywood (ext. grade glue) weatherproofed with tar or 1/8 HDPE sheets for the very bottom. Insulating it with Isoclad 1.5in with the air barrier facing the ground. There would be a polyethylene vapor barrier and then, either 1/8 plywood or 1/4 subfloor, still wondering on that one. Here is the floor framing scheme :
Red is pressure treated :
Image
Walls
I planned on doing them a bit like the floor, with 2x2 pressure-threated, trying my best to space them 16in center. Insulation will be Isoclad 1-1/2 like the floor. I am wondering if 1/8 plywood both inside and outside is enough? I plan on adding some kind of vapor barrier. Do I need to add Tyvek white stuff as an additionnal air barrier?

Roof/Ceiling
The roof « truss » will be glued over the walls. They will be 2x2. Still the same Iso Clad insulation foam with it's air barrier outside plus a vapor barrier polyethylene inside. Like the walls, I am wondering if I could get away with 1/8 plywood instead of 1/4 or more ? I also planned for either a MaxxAir or a Fan-Tastic Fan, depending on which one sits lower so it's not in the kayak's way.

Galley
I would like to include a small sink with a manual pump (can't recall the popular teardrop well known model though) with a small counter and a 2-burner Coleman stove that I might put on a rail table, keyboard drawer style. I would also like to put a Koolatron AC/DC fridge and an AC 700w microwave. I will also put an house window AC with triple "docks"
Image
Cabin
There will be room for a queen size bed and a 29"x74" bunk bed. The bunk will sit higher and will have some small cabinets under it AND into it. I also planned 3 domes lights:
  • One in the bunkbed
  • One on the driver side of the fan-tastic
  • One on the passenger side of the fan-tastic

They might be driven by "night tables" incorporated switches, not sure yet. Talking about these night tables, they will be equipped with 12V cigarette outlet and a dual port USB charger. I will also put a USB charger in the bunk bed area.
ImageImageImage

As you can see, I also hope to integrate a "TV" on the bunkbed privacy wall. This will be no more than a computer screen with integrated speakers. I would also like to add 12V heater even if I know these are battery drainers. Roadpro 300W seems promising, I will use thicker gauge wire and a 15amp certified cigarette outlet for this one. I'm just not sure about its location yet. I would also heat with a 120V small heater if AC is available but more often than not, I will be boondocking.

There we go, I hope you enjoyed the reading and I am looking forward for comments and suggestions ! I expect to build the frame in the few next weeks and complete as much as one can do during christmas holidays !
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Re: The Geek's Lair

Postby KTM_Guy » Sun Nov 18, 2018 12:10 am

Looks well thought out. And since you asked. :lol:

I wouldn't use any pressure treated wood anywhere in a camper. It's not needed, just keep the water out.

You might want to put a small fan (computer) in the wall for the bunk bed. Up high to move some air in the bunk area. Reversible would be good so in the warm month you can pull air out and in the colder months draw warm air from the main cabin in.

300w 12v heater is 25 amps, 100AH battery taken to 50% gives you 2 hours of run time, as long as you don't use any other power. It just doesn't make sense to make heat out of 12v battery power. Look into a Little Buddy heater or better yet one of the Chinese diesel heaters that has combustion air.

On the galley, it's small to start with we like to have room to store food and cookware. You said you plan to mostly boondock, and you have a microwave? Are you planning a generator? Same with the AC, my feeling is if I need AC it's to hot to camp. And I live where we get over 100, 100 degree days (38C). We'' go north or up to the mountains when it's hot.

We went round and round with where to put the cooler (for now, at some point we will get a Snomaster 12v freezer/fridge). It was decided to keep it in the TV, a) to free up space in the galley and b) if we head out for the day we have the cold drinks us.

Washboards are probably the hardest thing for the trailer. I was reading an article where a guy was trying different axles, springs, adding and removing leafs. Then he thought to air down the tires. He always aired down on the TV but didn't for the trailer. He now airs down to 10-15 psi on the trailer. Has made huge differance and he can keep much higher speeds now.

Whats your plan for power?

Good luck with your build.

Todd
Last edited by KTM_Guy on Sun Nov 18, 2018 12:08 pm, edited 1 time in total.
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Re: The Geek's Lair

Postby Atomic77 » Sun Nov 18, 2018 12:55 am

First off, good luck embarking upon this journey! It will be an uphill/ downhill- twisty/turny ride so get ready. ;)

I am basically following what Todd said. Skip the pressure treated wood. You will be unnecessarily adding weight among other things to your build.

1/8" or 1/4" floor? I would rethink that one. Seems light. Your sources may be different, but here I can get true 1/4" Baltic or 1/4" Luan (3/16" actual.) I wouldn't go lighter than that on anything. I would want a 1/2" floor. Mine is 5/8" but we walk on it.

I like the idea of the bunk, but concerned about air flow in a confined space. The computer fan is an idea, but if I were sleeping up there I would want a small window, vent, something. You'll be surprised how tight and confining things can get.

I didn't read anything about power supply, yet you have a fridge and 12V heater? Either of those will suck a battery flat in a couple hours. And the microwave and A/C will require shore power. I have dual AGM's and my fridge alone will kill them in a little more than a day. Also, will the TV/ computer screen be 12V?

Curious about the flat front. Do you prefer it to rounded? Because curved doesn't add as much difficulty as one would think but adds considerably in aesthetics and reduces drag. (Then again I'm a curve guy so that could just be me.) You mentioned a skin, but didn't say what kind of skin. Just curious.

Have fun, best of luck and we're here for ya.

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Re: The Geek's Lair

Postby Wolfgang92025 » Sun Nov 18, 2018 12:36 pm

Guess I have a different point of view based on my build.
My trailer is close in size to your plan, but about 2' longer and weighs in at about 2000#.
I used 1/4" exterior with 1/8" interior skin and the opposite for the floor with 1/8" on the button. Roof is 1/8" on both side except for the hatch, were it 1/4" on the outside. None of my supports are more than an 1" thick, most of it is only 1/2". It is all sandwich construction with PL construction adhesive holding it together. About the floor thickness, 90% of the floor is covered by the mattress. This will distribute the weight over a larger footprint. Even without the mattress the 1/4' floor supported my 160# without much concern, but it did flex some. High heels would not be good. :lol: :lol: :lol:
The only place you would want stronger supports is were the down force for the possible roof tent is concentrated.

Just my 2 cents....
Wolfgang

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Re: The Geek's Lair

Postby lfhoward » Sun Nov 18, 2018 3:28 pm

I like your design ideas. Nicely thought out and your CAD (Sketchup?) drawings make it easy to visualize what you want to do. I would heed the advice above, as these are all experienced folks weighing in. In addition to being heavy, pressure treated wood is also potentially toxic and won’t hold paint or glue well.

I built a trailer similar in external shape to yours. My build thread is linked in my signature if you’d like to see how I went about it. I think 2x2’s in the side walls may be overkill, and 1x3 or 1x2 framing will be sufficient. The reason is that you’ll be gluing and fastening plywood over both the inside and outside to make a strong monocoque structure (and you can insulate the middle of the wall sandwich). Some folks don’t bother with stick framing and just hollow out a 3/4” plywood sheet for the middle, leaving sections for support and gaps for insulation. I would do it this way if building my trailer over again.
My off-road camper build on an M116A3 military chassis:
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Tow vehicle: 2008 Jeep Liberty with a 4 inch lift.
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Re: The Geek's Lair

Postby GeekFisher » Sun Nov 18, 2018 11:20 pm

I noted about the pressure-treated ! The fan idea is good. Computer fans cannot be motor-reversed and their blades are designed to flow one way. What about putting 2 fans, one sucking and one blowing air, independant controls put next to the curtain so accessible from both the bunk and the cabin?

I planned on 2xGr.31 Deep cycle batteries with a solar panel. AC will also be present and I have yet to figure the A/C part out even if I hliave some ideas.The purpose of the dual Gr.31 batteries is to provide more autonomy but also to equilibrate weight as I feel the camper will be pretty rear heavy because of the galley... I want the galley to be pretty modular, I may not carry A/C and Microwave if I do not have to. Food is to be stored in the fridge and the cabinets over the galley.

As for the flat vs round, I expect to put my solar panel on that flat part, that is the main reason why.

Any input regarding trailer frame strenght ? Also, input on 72" H/F vs overall width with tires on 0 offset rims ?

Thanks for you replies guys, it is really appreciated !
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Re: The Geek's Lair

Postby KTM_Guy » Mon Nov 19, 2018 12:12 am

With the computer fan I was thinking the whole fan could be reversed not flipping a switch to reverse. If you are going to have a door to the bunk area the two fans would be good but if it's just a curtain then one opposite the opening would be good.

I used 1/8" 2X2 tube for my build. There is some flex before I attached the cabin, but seems good now. I talked to my brother about my frame after I had it mostly built (he is a welding engineer) and he ran some numbers for me. 2 X 3 X 16 gage is stronger that the 2 X 2 x 1/8. But the design needs to be well thought out where joints are, and adding reinforcements for the axle and things like that. Also light gage steel is less forgiving in welding that thick. My next camper will be 2 X 3 and either 16 gage or 14 gage.

If you are planning on going with two 31 batteries you might want to look into two of the 6v golf car batteries. The same or a little more AH, about the same size maybe a little taller, for less than half the price. Check out the Duracell's at Sam's club for the best price.

Todd
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Re: The Geek's Lair

Postby friz » Tue Nov 20, 2018 11:56 am

I found these pods on Ebay. They are perfect for mounting outlets under my shelves.Image

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Re: The Geek's Lair

Postby GeekFisher » Wed Nov 21, 2018 11:00 am

KTM_Guy wrote:With the computer fan I was thinking the whole fan could be reversed not flipping a switch to reverse. If you are going to have a door to the bunk area the two fans would be good but if it's just a curtain then one opposite the opening would be good.

I used 1/8" 2X2 tube for my build. There is some flex before I attached the cabin, but seems good now. I talked to my brother about my frame after I had it mostly built (he is a welding engineer) and he ran some numbers for me. 2 X 3 X 16 gage is stronger that the 2 X 2 x 1/8. But the design needs to be well thought out where joints are, and adding reinforcements for the axle and things like that. Also light gage steel is less forgiving in welding that thick. My next camper will be 2 X 3 and either 16 gage or 14 gage.

If you are planning on going with two 31 batteries you might want to look into two of the 6v golf car batteries. The same or a little more AH, about the same size maybe a little taller, for less than half the price. Check out the Duracell's at Sam's club for the best price.

Todd


I didn't think about the 6V batteries, good idea ! How many crossmembers do you have currently on your frame ? Mines are planned out of 2x2 angles.
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Re: The Geek's Lair

Postby GeekFisher » Wed Nov 21, 2018 11:20 am

lfhoward wrote:I like your design ideas. Nicely thought out and your CAD (Sketchup?) drawings make it easy to visualize what you want to do. I would heed the advice above, as these are all experienced folks weighing in. In addition to being heavy, pressure treated wood is also potentially toxic and won’t hold paint or glue well.

I built a trailer similar in external shape to yours. My build thread is linked in my signature if you’d like to see how I went about it. I think 2x2’s in the side walls may be overkill, and 1x3 or 1x2 framing will be sufficient. The reason is that you’ll be gluing and fastening plywood over both the inside and outside to make a strong monocoque structure (and you can insulate the middle of the wall sandwich). Some folks don’t bother with stick framing and just hollow out a 3/4” plywood sheet for the middle, leaving sections for support and gaps for insulation. I would do it this way if building my trailer over again.

I used tinkercad for the CAD designs. This is a web-based 3D program mostly used by kids, so easy to learn/use. I will look at the 1x2 but I'll need some strenght for the roof rack and the bunk bed and the doors. I might be better to keep 1x2 ou 1x1 for cabinets framing ?
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Re: The Geek's Lair

Postby GeekFisher » Wed Nov 21, 2018 11:23 am

Wolfgang92025 wrote:Guess I have a different point of view based on my build.
My trailer is close in size to your plan, but about 2' longer and weighs in at about 2000#.
I used 1/4" exterior with 1/8" interior skin and the opposite for the floor with 1/8" on the button. Roof is 1/8" on both side except for the hatch, were it 1/4" on the outside. None of my supports are more than an 1" thick, most of it is only 1/2". It is all sandwich construction with PL construction adhesive holding it together. About the floor thickness, 90% of the floor is covered by the mattress. This will distribute the weight over a larger footprint. Even without the mattress the 1/4' floor supported my 160# without much concern, but it did flex some. High heels would not be good. :lol: :lol: :lol:
The only place you would want stronger supports is were the down force for the possible roof tent is concentrated.

Just my 2 cents....

2000lbs ! I hope to be way under that, my target is 1000 dry and 1200 full (with batteries and water) ! yours is 6'6"x12' ? Can I see your trailer frame / floor frame design, it would help me.

Thanks,
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Re: The Geek's Lair

Postby GeekFisher » Wed Nov 21, 2018 11:42 am

friz wrote:I found these pods on Ebay. They are perfect for mounting outlets under my shelves.Image

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I don't plan on any undershelves 12V but I will use something similar:

https://addison-electronique.com/multip ... ip-66.html

Each side of the bed embedded in the "mini night tables" and one in the bunk bed area. I might put more of these all around the trailer and galley. Might use doubles or triples instead of doubles and put a voltmeter somewhere else.
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Re: The Geek's Lair

Postby KTM_Guy » Wed Nov 21, 2018 12:50 pm

GeekFisher wrote:
KTM_Guy wrote:With the computer fan I was thinking the whole fan could be reversed not flipping a switch to reverse. If you are going to have a door to the bunk area the two fans would be good but if it's just a curtain then one opposite the opening would be good.

I used 1/8" 2X2 tube for my build. There is some flex before I attached the cabin, but seems good now. I talked to my brother about my frame after I had it mostly built (he is a welding engineer) and he ran some numbers for me. 2 X 3 X 16 gage is stronger that the 2 X 2 x 1/8. But the design needs to be well thought out where joints are, and adding reinforcements for the axle and things like that. Also light gage steel is less forgiving in welding that thick. My next camper will be 2 X 3 and either 16 gage or 14 gage.

If you are planning on going with two 31 batteries you might want to look into two of the 6v golf car batteries. The same or a little more AH, about the same size maybe a little taller, for less than half the price. Check out the Duracell's at Sam's club for the best price.

Todd



I didn't think about the 6V batteries, good idea ! How many crossmembers do you have currently on your frame ? Mines are planned out of 2x2 angles.



My cross members are a mix of 2X2 X1/8 angle and 1X2 12 gage tube. That space in the middle is where future water tank will be. Abour 30 gallons. Centered over the axle.

Size your roof spars for your insulation. The roof rack typically mount to the side wall. Make sure you have solid backing to have something to screw into. A stud should be under the backing down to the floor. Did you say how you are building your walls? Stick built or skeleton method ?

If you are wanting to be 1,000-1,2000 pounds finished weight for a trailer that size you need to thinking “ultralight” ALL THE TIME. Instead of using 3/4” wood ask yourself can I use 1/2” or 1/4”. Weight adds up fast.

Todd


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Re: The Geek's Lair

Postby GeekFisher » Wed Nov 21, 2018 1:27 pm

KTM_Guy wrote:My cross members are a mix of 2X2 X1/8 angle and 1X2 12 gage tube. That space in the middle is where future water tank will be. Abour 30 gallons. Centered over the axle.

Size your roof spars for your insulation. The roof rack typically mount to the side wall. Make sure you have solid backing to have something to screw into. A stud should be under the backing down to the floor. Did you say how you are building your walls? Stick built or skeleton method ?

If you are wanting to be 1,000-1,2000 pounds finished weight for a trailer that size you need to thinking “ultralight” ALL THE TIME. Instead of using 3/4” wood ask yourself can I use 1/2” or 1/4”. Weight adds up fast.

Todd

I expect to use 1-1/2 thick Isoclad stuff (foam with air barrier) for everything except maybe the floor so 2x2 made sense when I designed. I don't know the difference between skeleton and stick build. I thought about going kinda house-like, studs every 16in centers (when possible...) with studs where the partition wall will be since I plan on insulating this wall but not the galley walls as it doesnt need it. Roof spars would be cantilevered on the side walls if that makes sense (it might not, in the end...)

I don't want to use anything thicker than 1/4" for plywoods. Here is where I am so far:
  • 1/4 outside and 1/8 inside for sidewalls.
  • 1/8 at the very bottom and 1/4 on inside floor
  • 1/8 roof and ceiling
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Re: The Geek's Lair

Postby GeekFisher » Wed Nov 21, 2018 10:21 pm

An image worth a thousand words.

Gray is roof spars
Red is wall
Green is door frame
Yellow is vent fan framing
Blue is bunk bed and its "privacy" wall.
156696
Bunk will also have some support from unswe since there are cabinets there, bunk will kinda be cantilever'd on the cabinets.
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