Building The Atma Travelear Teardrop

[aggie79]

Dave,

Your hatch framing looks great! It's almost like a 3D wireframe model of your teardrop. Overall, your design continues to get more beautiful with each step of the build.

You asked about side clearance on your hatch framing. Instead of 1/8", I used 1/4" for two reasons. The main reason is that my framing is not as stout as yours, and I wanted to allow additional room in case the hatch twisted or torqued as it was being shut. The second reason is that use a thin outside corner trim (plastic) to that wrapped around the outside hatch framing member and the FRP I used on the underside of the hatch. Of course, this trim reduced the 1/4" clearance by about a 1/16" on each side.

The 1/8" is probably okay given how your hatch is constructed. You'll probably want to consider either anchoring the hatch hinge - I believe Grant uses a screw - to keep the to halves of the hatch aligned or making some guide wedges to keep the hatch centered as it is being closed. I haven't done so yet, but will probably do some version of the former method.

Take care,
Tom

[DMcCam]

Thanks Whitney, actually we had to move the build out of the shop and back to the garage where we started. I hope to get it messy again soon.

Hiya Tom, Thank you as always for your very kind comments sir and for the hatch info. I remembered that you posted a drawing of how to do the hatch seal in your album drawn by Grant Whipp (thank you very much). I made a new drawing to scale to visualize how it would work for me.


Here's how it would look with 1/4" clearance instead of the 1/8". The extra room would give me enough space to add an inner angle piece instead of the flat aluminum backing if it needs it. As I remember, you added a layer of two of fiberglass to strengthen the edge.

I was wondering how you keep the hatch from lateral movement with the hinge. Is Grant's method a screw in each end then? Thanks again for mentoring me on my build. It sure is great!

All the best,

Dave

[DMcCam]

Back to the shop we go. We moved the AT back into the woodshop this weekend to have a warm place to work in. My brother moved it with a little help from my nephew.




I think my tongue is a little light...an 8 year old can lift it!

Thought I should work up the wiring diagrams to make sure I'm not too far off. Although I've wired simple 110 stuff, I've not done anything in 12 volt. I've broken it into 4 systems to keep it straight in my little noggin.


This is my running lights diagram.


Interior light plan.


For the 12V plugs and Fantastic Fan plan I'm thinking of separate runs of 12 gauge for safety sake or is this overkill?


Simple brake wiring to the connector.


This plan shows how the whole thing would connect in the tongue box.

Please let me know if you notice anything.

Thank you all so much,

Dave

[aggie79]

Hi Dave,

The AT is looking great. It won't be too long before it is under vehicle power rather than human power.

You had asked about how I keep my hatch centered. I had planned to do Grant's method with the set screw through the hurricane hinge; however, by an unintentional design choice it may not be necesssary. I'm not sure how to adequately describe it, but the upper mounting brackets of the struts (on the hatch) are inset toward the center of the teardrop relative to the lower mounting brackets on the sidewalls. This "canted" the struts slightly. The side benefit is that this arrangement/alignment keeps the hatch centered. We'll see over time if this stays that way.

As far as wiring, your drawings are very neat. I'm not sure the 12 gauge is necessary for the vent fan or 12 volt. I used 14 gauge which is still probably overkill. Also - as you know there are many opinions on this - grounding the negative side of the battery to the frame is probably not necessary since you are running individual grounds to all your devices.

Keep up the good work and setting the bar high for all of us.

Take care,
Tom

[Woodstramp]

Dave,

Noticed that Art Deco bust on the heading of your electrical prints. Is that going to be used on the final exterior decoration? I always thought that style was cool looking.

Would be neat if you could get a pair of those chromed ladies on the leading edges of some cool swept fenders....kind of like the way old hood ornaments were on cars. Those fenders wrapping a set of wire spoked whitewalls would be awesome.

[DMcCam]

Thank you Tom, your description makes perfect sense about the hatch centering. The only thing that could change is if one strut weakens before the other causing an imbalance of pressure? As I've only done a little residential wiring so I really appreciate the feedback my friend. 14 gauge is a lot easier to work with for sure. I didn't know whether the frame grounding is necessary at all but I saw many other member do it so that's why I added it. I'll have a mounting bolt right in the battery compartment if it turns out to be needed I guess.

Hi Woodstramp, Very cool ideas! I've always thought of Art Deco as the greatest design era especially for vehicles, it's inspiration for the whole design including the logo! I designed the bust illustration and logo text for the door graphics and there's a front bust for the hatch too (in an earlier post). I'm thinking of having the door graphics water-jet cut out of nickle or stainless...could be quite striking.

Cheers,

Dave

[Woodstramp]

Sounds cool. Don't know what water jetted metal looks like, but you might also check out some lazer engraved metal. A company my brother works for does this. Lazerd area fiinish is matte thouh. Might be a problem, long term.

As to the Art Deco. Totally agree as far as vehicles. Most of my art education came from my art major wife. First exposure to AD was at the Alabama Power buiding in Birmingham, Al. when I was a teen. Electra, the nekkid gold goddess who somehow has evaded the ire of the local biddies for so long.

http://www.roadsideamerica.com/attract/ ... a_8570.jpg

[kevingb]

I had a really interesting discussion couple weeks ago with some guys on wire size in my teardrop. I have a big tendency to over do it. If 16ga is good then 10ga is really good. But now it's like buying gold so I'm listening.

The suggestion made was using 16ga bonded 4 trailer wire is cheaper in bulk than some single 16ga spool at box store in the same length. It is good for 5 amps at 15 feet. I think the fantastic vent only needs 3 amps, and all other 12v lighting will be LED. So now rethinking my wiring, but in the back of my mind always concerned that once the shell is on, its very difficult to say oops.

I'm no where near a pro at this topic.

[DMcCam]

Hi Woodstramp, Water jet can cut pretty thick steel with extreme accuracy. The guys I'm working with on another project are cutting 1/4" steel twice as fast and cleaner than plasma cutters. The edges are almost polished. I've used laser etching for a control panel graphics. The black on stainless steel looked sharp. I think Electra in gold must be seen as art by the boys...

Hey Kevin, You're right about not wanting to screw up on the wiring for sure. That's why I've been posting my progress to get wise feedback like yours. I'm with you about over engineering, seems that's just the way my family does things too. From what I've learned so far, 14 gauge is what most cars use for everything. I figure that if I stay to 14 gauge I'll sleep easier than to worry about the loads on the circuits. 12 gauge is pretty heavy stuff and would make big holes through my spars. I found some exterior grade stranded 14 gauge 2 wire at the depot that was 2/3rds the cost of the bulk stuff. Hope it will work.

All the best,

Dave

[Wolffarmer]

For wiring I would like to use marine wire, like the flyboys use. It has many strands of wire in it and that makes it more flexible and resistant to vibration. That being said. I mostly use old extension cords for my wiring. Where I work they are so paranoid about some safety items that they don't let us replace the plugs on an extension cord. So in the back of my vehicle they go for disposal. I am not talking about the really cheap things but the real shop extension cords.

Randy

[kevingb]

Interesting on the marine wire and never thunked about extension cords. Catch a sale and your ahead.

Today I made a run to town... Stopped by Lowes, Depot and Tractor Supply... WOW... It was amazing at the price difference on same sizes. I would agree with you on 14ga. What is a few more bucks, not like we are mass produciing these things.

FYI.. I looked at my Fantastic Vent it had 16ga with a 4 amp fuse. Then reading instructions, it requires a minimum of 16ga source.

to 14ga

[Tear Les]

Hi Dave,

Have you already done the wiring? It's been a bit since the last post so I didn't want to type up a bunch of stuff if it's not going to be helpful for you.

Les

[ohbugger]

For wiring I would like to use marine wire, like the flyboys use. It has many strands of wire in it and that makes it more flexible and resistant to vibration. That being said. I mostly use old extension cords for my wiring. Where I work they are so paranoid about some safety items that they don't let us replace the plugs on an extension cord. So in the back of my vehicle they go for disposal. I am not talking about the really cheap things but the real shop extension cords.

Randy

Yup, I picked up a 100' 16 gauge extension cord, brand new for $14 at home depot. I'm using it for the tail lights (tail, brake/turn, ground). That's 14 cents a foot... not bad! Also, with LED tail lights I won't be drawing anywhere near 1 amp. I had an older 12 gauge high quality extension cord that I never use. So it got cut up for the higher current circuits.

[DMcCam]

Hi Guys, The good news is that I've been busy with work, the bad news it's left almost no teardrop time. The wiring is going slowly. If I had to do it again I'd have drilled the wall chases before attaching the inner skin. None of the wire is in yet, just drilling holes.

Great idea on the marine wiring Randy! Too bad I already had cut the wire I bought to lengths before I read about it. The stuff I got sounds similar in that it's very flexible yet has a tough outer jacket.

Hey Les, if you have any thoughts on the wiring, I'm all ears. Anything I can learn from your experience is very welcome.

I did manage to install the new stainless steel switch plates though.


This is the driver's side exterior light switch.


The two reading lights have their switches ready for wiring.


This switch in the galley is for the lights in the hatch.

Hopefully I'll have more time as the winter sets in. Thank you all for stopping by.

Dave

[Tear Les]

This is my running lights diagram.

Unless you're over 80" in width you don't need the three running lights in the center (just FYI). I'd rather have a third brake light there just to get people to quit staring at the teardrop and pay attention to the lights.

14-gauge is more than sufficient, most pre-made harness kits for boat and utility trailers are 16-gauge. I wouldn't dissuade you from using the larger wire, just letting you know it's not required.

Interior light plan.

If all that lighting is LED you don't need to use 14-gauge (though again it won't hurt). It's just a balance between space (for the wiring), cost, and weight.

For the 12V plugs and Fantastic Fan plan I'm thinking of separate runs of 12 gauge for safety sake or is this overkill?

From an electrical load standpoint...unless you're going to use multiple sockets at one time you don't need separate runs. But here's the thing...you always want to make sure any one run of wire has protection from overload (either a fuse or circuit breaker).

Each fuse or circuit breaker (cb) further up the line from the load needs to handle the full line of all loads that pass through it. That means you might have 4 branch circuits each with 10 amp fuses but if they feed to a main supply then that supply line needs a fuse to protect but will also handle the load of all the branch circuits. Confused yet?

Here's an example: let's say you determine that the max load on the whole electrical system in the camper (not including running lights since they really come from the tow vehicle) will be 45 amps. So what you need is (say) a 50 amp circuit breaker (or fuse) at the source...that's the positive terminal on the battery. Ideally it would be right on the battery (and Blue Sea Systems makes on terminal fuses), that way the main source wire connected to the battery is protected. Second best is to just get a fuse as close as you can to the positive terminal (within 7" is the standard on boats) and having nothing between the positive terminal and the fuse (or cb)...a master switch should be down line from the circuit protection.

The main source wire should run to a distribution box (typically a fuse block) and from there you'll run out individual branch circuits. Each individual branch circuit should have a load appropriate fuse (or cb) to protect that circuit.

The main thing to remember is that in every case the fuse or the circuit breaker is there to protect the wiring, not the load. Protection is about preventing a fire, not protecting a specific component (they should have their own fuses). With that in mind let's say you have a #10 wire that will easily support a higher load and off that wire you "T" circuits off with #16 wire. If you only have a fuse in the #10 run (let's say it's 25 amps) you're not protecting the wiring in the #16 runs. It would be quite easy for a load to heat the #16 wire up enough to melt the insulation and potentially start a fire and not blow the 25-amp fuse on the #10 wire. So it's important to fuse the #16 wire appropriately.

You always want the fuse for a particular circuit at the beginning of the circuit not just somewhere in the circuit.

So anyway, back to your sockets. You just need to think about whether what you'll plug into the sockets (and use all at once) will overload a 12-gauge wire. If not you can use one run to supply all the sockets. If so then you need to split them; maybe 2 on one circuit and 1 on the other, or maybe one per circuit as you've drawn. It just all depends on what the situation is.

This next part can get confusing...

Ever wonder why small 12-volt items often have a fuse inside their 12-volt socket? It's because they're being plugged into a circuit that has so much more capacity then they draw. Their load is so small relative to to capacity of the circuit that if something were to happen to them it would never blow the fuse on the circuit.

So, if you have a 12-volt socket fused for 25 amps and you have a 3-amp load almost nothing but a dead short is going to blow the fuse so the small load itself is fused to protect the circuit. Otherwise a small load could get so hot it could start a fire without blowing the 25-amp fuse (at least until it shorts out). Think it can't happen? I made my living for awhile investigating fires where that very thing did happen...often (mostly in outlets and small counter top appliances).

It's better to figure out what you want a particular 12-volt socket to support then fuse it for the item that will be plugged in rather than fuse the socket for its maximum possible load. That way the fuse will blow if something happens to the load, even if it's small.

This plan shows how the whole thing would connect in the tongue box.

I would swap places with the main fuse and the master switch.

Also as aggie79 (Tom) mentioned, it's not necessary to jumper the negative terminal on the battery to the chassis ground for any load that you have in the camper. However, since you've got a charging circuit from the tow vehicle you do need to have a complete circuit for that to work. If you're using the chassis for ground on the trailer lighting then the easiest way to get the complete circuit for the charging circuit is to jumper the battery's negative terminal to ground as well, just as you've drawn it.

This is supposed to be helpful not overbearing. If I put in all the qualifiers as I type it gets even longer.

I love your build!!!