How-To Video Building a DIY Travel Trailer – The Frame

Our friend and master DIY’er Joe Mooney of Homesteadonmics is back at it again! This time he’s working on a Travel Trailer build, currently welding the frame together to create the basic shell. This will end up somewhere at the crossroads of a Teardrop Trailer & a full size Camp Trailer. Stay tuned as his project transforms from this base frame into a full fledged aluminum clad roadworthy companion!

From the Forney welder to the steel & aluminum, down to welding tabs, our six stores have everything you need to make one of your own!

About The Project – By Joe Mooney:

Building the base frame of this DIY Travel Trailer project started about two years ago when I was asked if I wanted an old axle from a Travel Trailer that was getting a larger axle installed.   Being an opportunistic user of what some would call junk… I said YES!  And that was the start of a rather long developed build that is now becoming a travel trailer!

After getting the axle, I figured I’d build a simple ‘angle iron’ utility trailer frame that I could pull with my 2006 Jetta TDI.  And maybe add some sort of lightweight teardrop style camper later on.  Well, as time passed, so did the Jetta with it’s 300k miles.  And the trailer sat just collecting dust and rust until I figured what the new plan would be.  And so the Travel Trailer plan developed.

Extending the Base frame…

The first step was to lengthen and widen the trailer from the angle iron utility frame that I originally built.  This definitely isn’t the ideal start to a travel trailer, incorporating different profiles and steel thicknesses, but it’s what I had to use.  I made all of the extensions with 2×3 14ga tubing coming off of the original 2×3 3/16th angle frame.  Each of the extensions off the sides and the back was also supported by the original frame angle that was positioned horizontally and had been left slightly wider than the original frame.  This keeps the new sides from ‘pulling’ outwards on the original frame.

As a matter of dimension the original frame started at roughly 5.5’W x10.5’L and with the new additions sits now at 7’ wide and is 13’ long for the foot print (lengths do not include tongue)

Building the upper frame…

The upper frame is constructed of 1×1.5” 16ga steel tubing for the sides and roof and 1×1” 16ga tubing for the front and back walls.

Starting the upper frame began with laying out a basic roof outline on the base frame, using it as a template, and then welding four wall posts up from the roof assembly.  Once this was done I then dragged it off of the trailer base frame and then flipped it over and set it back on the trailer base frame and tacked it into place.  Boom!  Walls and a roof started!  Once these were in place I then welded vertical ‘studs’ to infill the side walls and roof.

Next I added the back wall and connected it to the base frame at a 45 degree inward slope to give a clearance section for the back of the trailer.    The next big step was adding the front wall and then bending the front ‘radius’ sections.  This was accomplished in the old school method of a torch and an old water tank we used as a form.  Once those bent sections were in  tacked in place I then in filled horizontal pieces and went about framing a doorway and adding metal tabs to provide mounting points for window frames and interior wood framework.

So that’s about it for the general frame build.  The next steps are to prep for paint and adding all the window frames and other support members prior to adding the aluminum ‘skin’ to the outer shell.  This is currently underway and will be in the part 2 video of this series!    Thanks for watching and stay tuned for more on this build!


Chromoly vs. DOM Tubing

Steel tubing has many uses, ranging from bicycle frames to roll cages to rifle barrels. Two of the most commonly specified types are chromoloy tubing and DOM tubing.

Most steel tubing is made by cutting rolled steel into thin strips that are cold formed length-wise into a tube shape which is then welded together. Further processing creates the desired mechanical properties, dimensions, and finish. Seamless tubing is also available.

Chromoly tubing

Chromoloy tubing is made from a family of low-alloy steels that contain chromium and molybdenum (SAE 4130 or 4140), along with the iron, carbon and other elements. The chromium adds strength, hardenability and a level of corrosion resistance to mild carbon steel, though Chromoly is not as corrosion resistant as stainless steel.

Chromoloy is heavier than aluminum alloys, but its high strength-to-weight ratio makes it desirable for aerospace components and race car parts. It is also used in automotive gears and crankshafts, gas delivery tubing, and machine shafts.

ERW

Electric resistance welding (ERW) is a type of welding process that uses the heat generated by passing a high-frequency electrical current through the metal, along with pressure to hold the parts to be welded together for a specific length of time. ERW can be used for spot welding and also for welding tube seams.

DOM Tubing

Drawn-over-mandrel (DOM) tubing is not made from any specific alloy – it can be used with mild steel, chromoly or another alloy, such as SAE 1020 or 1026 steel.

DOM tubing is often incorrectly referred to as “seamless tubing” because the seam is almost invisible. DOM is a process that takes the rough cold-formed steel tube and continues to process it further to smooth out the internal surface of the weld seam while improving its mechanical characteristics. This is accomplished by annealing (heating) the tube to soften it so that it can be pulled over a tapered steel shaft (i.e. “drawing the tube over the mandrel).

The mandrel is a little thicker than the inner diameter of the tube, and as it moves through the length of the tube, it smooths the inner surface while stretching it wider. The tube is also drawn through dies that shape and size the outer surface. The combination of mandrel and dies achieves the required wall thickness, inner and outer diameters.

The DOM process creates a more concentric, uniform product with dimensions more closely toleranced to a customer’s exact specifications. DOM tubes also have superior mechanical properties, including increased hardness and tensile strength and a sound welding seam. This makes them ideal for use in mechanical parts, such a hydraulic cylinders and automotive components, without requiring further machining.

Seamless Tube

True seamless tubing is made from a heated cylindrical steel billet (or blank) which is hollowed out with a rotary piercing process. The solid billet is rolled between two rollers toward a tapered mandrel pointing at the end of the billet. Forces from the rollers create an opening at the center of the billet’s cross section. The opening grows, forming a tube as the billet continues to travel over the mandrel and through the rollers. Once this rough tube cools, it is further processed to achieve the desired thickness, diameter and finish with either a cold or hot forming method.

Cold drawn steel (CDS) is 1018/1026 steel tubing with uniform microstructure, tight tolerances, high strength-to-weight ratio, high tensile strength, thinner tube walls, and a superior surface finish compared with HSF tubing of the same steel grade. It generally requires no additional machining and is used in race cars, truck and auto parts, and hydraulic cylinders.

Hot finish seamless (HFS) tubing is less costly than CDS tubing and can be easily machined to exact specifications. It is used for rollers, sleeves and hydraulic cylinders.

 

References:

https://steeltubeinstitute.org/drawn-over-mandrel/