Building the Frame – Part I

The Yellowstone Project

The Yellowstone River

If ever there was a place where it can literally touch your soul, it would have to be Yellowstone. It’s a magical place of sights, sounds and silence. The reason this place has such a personal special appeal is because it’s also the place where this project was conceived. A while ago, my extended family decided to take a long road trip from the sunny shore of Southern California to Yellowstone and the Grand Teton National Park in Wyoming. The one-way distance of the trip is a little more than 1,000 miles. Although our vacation time was limited due to job obligations, we have decided to really take our time to enjoy the journey as much as the destinations. The trip was almost a month long. Our journey took us from Southern California to Las Vegas, where we stayed for a couple of days, then Utah, Idaho, and finally arriving to Yellowstone after almost ten days of traveling.

Our mode of transportation was a 36 foot long Class A rental Recreational Vehicle (RV) with two slide-outs.

Because of rental restrictions, we weren’t able to tow the family car. Hence, we had to rent a car at Yellowstone. Our extended family consists of four adults, two teens, and one fur kid weighing in at 9.6 lbs.


Here we were at a typical RV Park with full hookup. We usually drove only 2 to 3 hours starting in the morning. We stopped often along the road for sightseeing. Each day, after a long driving trip, okay so it wasn’t that long, it sure was nice to be able to enjoy the rest of the day starting with a hot lunch and a nice warm shower.

Yellowstone is a place of toxic eye candies. The thermal hot springs with their scalding water look deceivingly calm and soothing but signs were everywhere to warn you of their deadly effects.

The Grand Teton Mountains

Right next to Yellowstone is the Grand Teton National Park. The snow covered mountains with their jagged edges seems very eager telling you of their violent pasts.

Despite the harsh environment, in the right season, delicate faunas and florals were everywhere. The flowers’ delicate petals and their blend of pastel colors seems to beckon you for more of your undivided attention.

For city folks like us, spotting wild life became a sort of game. We challenged each other to see who can spot the next unseen animal first. Sometimes, it wasn’t that hard when all the traffic would stop and people jumped out of their cars to take pictures!

Design Goals

But I digress, while enjoying a camp fire at one of the campground fire pits, my dear wife with her indefinite wisdom has made a statement something to this effect: A perfect RV is a luxury Class A RV with two large slide-outs that you can cut into two: The “House” part and the “Driving” part. While you are driving on the freeways, the two parts are together so that you can enjoy the comfort of a luxury RV. At near your destinations, when the driving is often difficult and small unimproved roads are hard to navigate, you can check in the “House” part of the RV in the local RV Resorts or camp grounds and make that your home base. The “Driving” part of the RV can be used for sightseeing and exploring the primitive campgrounds. I knew at that instant that I’d take on the challenge. Perhaps, now you can appreciate the goals of this project.

What I am trying to do is breaking the conventional RV design rules and designing the most extreme compact “House” part of an RV.

So, what were the overall design goals?

1.       The overall box dimensions are 18 feet 8 inches in length and 98 inches in width. The tongue will add in another 42 inches to the overall length. The height of the trailer is about 11 feet give and take a few inches

2.       The Gross Vehicle Weight Capacity (GVWC) is 7,300 lbs. since I am using two Flexiride axles with a combined 7,300 lbs. capacity

3.       The empty weight of the “House” is estimated to be 5,000 to 6,000 lbs. maximum. I am trying to hit the low end instead of the high end. Admittedly, these figures were very aggressive

4.       There will be two slide-outs each having 15 feet in length and 7 feet in width. You will notice that there are about 2 feet of trailer body that are not occupied by the slide-outs. This was the last minute change that I’ve made since I wanted to have a dedicated space for the generator with sound insulation and forced air ventilation. This area is divided into upper and lower areas. The upper area is used for storage accessible from inside of the slide-out. The lower area is used for generator, fresh water tank, electrical boxes, and batteries, etc. So, although the trailer box is a little more than 18 feet, the effective floor space is as big as a 32 feet trailer without slide.

The basic trailer frame plan is as follow:

Frame Plan

The frame will be equipped with two electric Ultrafab stabilizers one at each end. Each leg of the stabilizer can be independently adjusted so that you can level the floor even for very uneven surfaces. The frame has gussets and a “box” design so that there is almost no flexing. My dear wife won’t tolerate any floor flexing even a minute one!

Frame Building

With all materials purchased and cut to exact dimensions, it’s time for the rubber to hit the road.


Initially, all the pieces had to be laid out in their respective positions. Then a lot of clamps were used to hold them together forming the basic frame. When building the frame, you really have to plan out which layer has to be built first, then build the next layer, and the next layer in order to keep the corners square and the frame flat and the overall measurements to stay within design tolerances.

The initial feeling at the start of the project was a sense of overwhelming and despair. During my career as an engineer, I have done a lot of large projects. Many of which were hundreds times more complex. However, never before I am facing some of the components which weight as much as I do or more and I am all by myself!


The most difficult task of building the frame is to make sure that the corners are square and the whole frame makes a perfectly flat plane. In order to achieve those objectives, I’ve built two end tables with near perfectly flat surfaces using a table saw’s surface as the reference. The tables were placed at each end of the frame being built. Various parts are placed onto the tables then clamped together. Tape measures, levels, and squares were used to tripple check all dimensions and flatness. When all frame components were clamped together, I actually had to take a day off from the project, then rechecked all dimensions and flatness again before proceeding to the next task: Tack welding.


That’s my son helping with the welding. He took pity on me and volunteered to help despite the fact that he has never seen nor touched any of the welding equipment. Brave kid! This now has become a family affair. Later on, other family members also joined the fun. They all have passed a crash course in welding offered by…me. After only a couple of weeks, these young guns can lay some pretty mean welding beads. They can even weld better than I can. Not that I am that shabby. I actually took several classes for welding and subsequently certified for Aluminum and stainless steel welding. I took some solace on the fact that I’ve trained them well.


It was a bear to flip the frame to weld the other side. The placement of the axles was quite difficult. I had to build a special jig to ensure that the wheel alignments are parallel to the frame. Otherwise, you will destroy the tires in a very short manner. This was pretty much the recurring theme. We had to build all kinds of specialized jigs as the project progresses.


Those are nice Aluminum wheels. I had to special order them instead of the standard steel wheels.



Finally, the frame was professionally done. You wouldn’t think all this can be done inside a garage but due to the compactness of the frame, it was possible. Here you can see the front Ultrafab stabilizer.


This picture shows the rear Ultrafab stabilizer. This is now the basic trailer for the rest of the components to be built upon.

Fullup Frame

From this perspective, you can clearly see the added body section at the end where the lower half with its electronic tray was depicted. The generator will be located on the right looking from the rear forward, the rest of the lower half will be used to store fresh water tank, batteries, electrical panels, etc. There will be two large doors which can be opened so that the entire lower half is accessible for maintenance. The upper half is accessible from inside of the slide-out for additional personal storage.

We will stop here for now. Next post, I will show you the next layer of the frame and the trailer wiring to meet federal mandates. You may wonder why there was a title in the post referring to this project as “The Yellowstone Project”. In my previous career, many of the companies have some cool names for their teams or projects: Lockheed Skunk Works, Boeing Phantom Works, the Manhattan Project, just to name a few. So, I thought it would be so cool to name this my “Yellowstone Project”. Hopefully, for my next trip back to Yellowstone, I will be able to bring this baby to its birth place where the original idea was conceived.






2 thoughts on “Building the Frame – Part I”

  1. Following along. I can relate to the welding, it takes patience and a lot of measuring to get a good result. I’ll be interested where you locate the tanks as I am thinking of redoing mine. At the least, I will enclose what I have for drains and tanks, heating and insulating the space as I go along.


    1. Lance,

      Thank you for following along with my pet project. At the moment, here are the planned locations for the tanks:

      1. The fresh water tank is about 50 GAL and will be located inside the back storage area and will have full insulation. The fresh water tank can be larger if needed. I have a lot of space in the back.
      2. The grey water tank is about 40 GAL and will be located inside the frame right behind the wheels. There will be drain port out to the street side of the trailer.
      3. The black water tank is about 35-40 GAL and will be attached to the frame of the street side slide-out so it will move with the slide-out. This design calls for some heavy duty slide-out structure design since the full 40 GAL tanks weighs close to 400 lbs. Beside the weight consideration, I would also have to put up with a separate drain port from the grey tank but I’d rather not deal with black water leak. I am planning to have a built-in flush valves for the tanks as well. I haven’t thought about insulations for the black and grey tanks. It can be done easily with 1 1/2″ Styrofoam insulation.


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