UNDER CHASSIS CARGO STORAGE FOR THE AIRSTREAM INTERSTATE

In a previous post titled UNDER CHASSIS STACKER STORAGE, I described how I created a holder for a series of Valterra stackers.  This current project also involved the re-capture of chassis space, but for a different purpose.  Unlike some other Class B RVs and most if not all Class Cs, the Airstream Interstate does not have exterior storage compartments because Airstream leaves the body of the Mercedes Sprinter unmodified when it makes its upfit.

This is a Roadtrek 190 Popular.  Do you see those hinged compartments at the very bottom of the body?  At least a few of those open into under-floor storage compartments, of which the brochure (PDF) states that there are two.  

We don't have any of those, so if we wish to re-capture space below the floor, we can't go in from the side.  We need to go up from below.

The space I'm going to talk about in this post is perhaps best illustrated by this unfortunate image that was posted in this Sprinter Forum thread, uncredited, in a PDF euphemistically titled "Sleeping Sprinter".

Sleeping, indeed.  In the case of this upfit, you can see that a battery box appears to have been installed in this same void space to which I refer, where I've annotated the source-less photo with this yellow arrow to so indicate.  Our batteries are inside our coach, so we will never need this space for a future battery.  Therefore, I'm going to show a different adaptation of it. 

I have been coveting that void space for years, wondering what productive thing I could do with it, but it did come with a constraint:

Aaaarrghhh, I hate it when that happens!  The damn propane line for the hot water heater was placed smack dab in the middle of the space.  Why couldn't Airstream have scooted it out of the way?  

But it also came with a built-in advantage.

There's an unused support structure already integrated into the chassis. Perhaps it was intended to be used to hang a battery box. 

The propane line that runs to the hot water heater is a copper line encased in PEX (presumably just for extra protection). It is fairly durable and so as long as I pack only soft objects into this area, objects that avoid whacking the line, it will be fine.

The project, then, consisted of fabricating a shelf with attachments so that this space could be utilized.  My general steps are described below, and I'm going to provide more detail than I sometimes do, just to encourage people to tackle DIY projects like this.  As I've said in other posts, it's not that hard if you break it down step by step.  I'm a middle-aged woman with no DIY background and I learned how to scope projects and work with metal.  This stuff is do-able by ordinary people.

The difference between this carrier and my last carrier is that this one was designed to have an inset liner of spread metal, and so rather than being a simple butt-jointed skeleton in which the two side rails overlap the end rails, it had to serve as an inset frame in three dimensions.  So it's a bit fancier, in a sense, with compound cuts.  I can't find a decent line drawing on the internet to explain what I mean, but hopefully these pictures will convey it.

First, let's start with the raw materials.

(1) A scrap of spread metal left over from an outdoor table project, measuring approximately 12 inches by 21 inches; (2) 4 feet of 1 inch x 1/8 inch angle iron, (4) about 1 foot of 1 inch x 1/8 inch bar steel, (3) about 1 foot of 3/8 inch all-thread, (4) 2 corner braces, (5) #12 x 3/4 inch self-drilling hex metal screws with neoprene washers (which I'll explain later), and (6) various 3/8 inch hardware including nuts and washers.  All off the shelf at Lowes. 

Here's the main tool for the prep part of the job.

A 14-inch chop saw with a metal-cutting blade. We don't have a table or anything, so I simply put it in our driveway.  It gives our neighbors something to think about. 

Well, how do you use a chop saw that is plopped directly on the ground, you may wonder?

I squat in front of it.  With legs pulled back wide like this, I can avoid the sparks that are thrown, which is important because I do all this work with bare feet and legs (Houston in July).  I'm an old gardener so my squatting skills are pretty good, given the extent to which I have used them over the years.

A rectangular frame in 3-D will require the upper portion to be a simple rectangle, while the underside pieces must be cut at 45 degrees in order to mate together properly.

So I start by nipping off the ends of a few of the steel segments.

I draw a lot of notes to myself on my workpieces, whether they be steel projects or sewing projects.  That way I don't get confused.  I hate do-overs.

The chop saw has a 45 degree setting, so you can nip off those initial corners like this, without disrupting the vertical portions which have to remain "straight up and down", in other words, at 90 degrees to the long axis of the piece.   

It's difficult to show some of this properly on a 2-D computer or device screen.

I cut these off but they both appear 90 degrees whereas the two on the left are actually at 45 degrees to that plane. 

Here you start to get the idea of what I mean, although now the opposite visual effect is happening due to the oblique view - everything looks like it's 45 degrees whereas only the bottom sides are cut that way.  

Chop saws don't actually cut so much as they melt their way through bar steel and angle iron via frictional heating (throwing a great shower of sparks in the process).  For that reason, the cut ends end up being a mess.

The metal gets smeared. 

Those smears (burrs) have to be removed with a bench grinder.

I was hoping to get a nice spark-throwing picture but it didn't turn out. 

As with sewing, to the extent possible, I fit one piece, then put it up against the next piece, and it becomes self-evident what has to happen next.  I rely more on iterative common sense and less on technical measurements.

Now you can see it.  The one on the bottom needs its corner nipped off at 45 degrees in order to fit with the one to the right.

Here's what the frame looked like when finished, as held together with welding table magnets.

I cut that cross piece to nest in the same plane.  That way the spread metal could drop right in and the entire assembly would accommodate it. 

This project was a little backwards because our rig was not at our house when I did the metal cutting. It was in its off-site storage locker instead.  Normally I would make a cardboard template first, then design the metal workpiece off the template.  But because the rig wasn't here, I took rough measurements, made the cuts, and then re-verified with the cardboard before my husband went to all the trouble to weld this. It was a little backwards, but we have other projects in progress (as usual) and there were time constraints.

I measured my cut tray, took the cardboard template over to the locker, and re-verified against the battery well.  

Here's what it looked like when fully drawn, with corner braces added just as an approximation.  The final positions of the corner braces had to be established carefully due to the subtle curve in the side of the Sprinter.

At this point, an unforeseen complexity entered into the project (as they always do).  Unlike my Valterra under-chassis rack which floats semi-freely on top of our ground effects supports, this one was going to sit quite close to the body of the Sprinter (inside panel).  Therefore, I had to go to special effort to add attachment points to it, as I wasn't going to simply be able to wrap bungee cords freely around all sides of it such that they joined and hooked in the middle.  So I had to incorporate attachment provisions into the design, before it was welded up.

Cue the next major annoyance:

The one on the left is from a fabulous internet retailer called Strapworks.  The one on the right is this piece of junk from Home Depot.

EDIT:  My husband took a look at this thing on the right and said, "Nnnnnope!"  He hates installing junk on our rig. We may eventually go back and retrofit some of the D-rings on the left (which I have on order) but in the mean time, we're just using wrap-around bungees, as you'll see below.  The side clearance of the tray is too narrow to add and remove the bungees because of the thicker hooks on their ends, so we just mounted it with them already in place.  Dedicated bungees, in other words.  Can't be removed without removing the entire piece, which I would be loathe to do.  

My projects are often one step behind ideal because I simply cannot source parts locally, and I don't always have time to wait 2 to 5 days for shipping.  Every time I find a new source of valuable stuff, I order a collection of what they offer preemptively, so I'll have it on hand.  The next time I build another under-chassis storage option, I'll have the best hardware available to me in advance.

Shopping locally is often an exercise in frustration, and a classic case of "from the ridiculous to the sublime", because when it comes to D-rings, local retailers carry really small, and really big, and virtually nothing in between.  They are rated for twenty pounds or four thousand pounds - that is all.  At the big end of that scale, this is the useful mega-ring that my husband and I installed as one of our security enhancements (not discussed in blog posts).  

Next came the weld-up.  My husband keeps saying, "You are going to take that welding course later this year.  It's only two days long."

These pics are fun to take, because of course I have to do it with my eyes closed, and I never know what I've got until I upload the pics from my SD card.  Nooooo!!  Don't look at the liiiight!!!!

After the welding and my paint job, then came the mounting.  But first, look at this:

HOLY CRAP!  It's amazing what happens when one removes eleven years worth of road grime!!  It's clean!!

It'll get dirty again, of course, but I might as well start with a clean slate.  You can see the six holes pre-drilled above, for the screws that mount the shelf to this inner body wall.

And the neoprene washers go on the outside, so that they will press against the body and help prevent water from getting in those screw holes.  

This is a little tricky because this structural member itself is actually threaded (3/8ths) - I don't know why.  But it's hard to get that nut on top tightened down because of the clearance issues.   

And now for the money shots:

You can see there's plenty of clearance below that propane line. 

Initially my husband was like, "What the hell do you plan to put up in there?!"  Answer:  Squishy things that won't be damaged if they get wet.

Like my knee boots, for instance.  They're quite heavy, the real thing, woodsman-style.  I don't think anyone would desire to steal my stinky lady boots, would they?  So these are good candidates for storing down there. 

Of course I sewed tarp envelopes to fit the items destined for the space, to keep the dirt away.

Also in there:  Multiple kayak accessories.  None of which are worth a damn without the kayak itself, so I wouldn't expect any of it to be a theft target. 

The amount of space I've recaptured here is probably more than what one of our unmodified overhead cabinets holds.

There's those two packages on the rack, and there is still space remaining.  

Another view:

Anyway, I'm as pleased as punch.  Yet another storage expansion achieved, and the pressure to find space for everything I want to take on longer, more elaborate trips is duly reduced in yet another new way.

No pressure, no DIYamonds.  Ohhhh, yeahhhhh.