Perseverance

[tomhawk]

This is a post about a trailer I have been working on for several years. My initial plan was this was a retirement project. Only problem, I did not retire. This limited the time I could spend on the project. Over time, a little here and a little there, progress was made. We have been camping with it for over a year; we have towed it over 3000 miles.

I have very limited shop skills. I learned as I went along. This project gave me an excuse to purchase a number of tools I had always wanted to own. Very little of what I did is that novel. I borrowed a lot of ideas from posts folks made on this site. I will just cover some of the details I found interesting to me.

I wanted a small trailer for camping. We had rented a teardrop camper in California to drive up the north coast a few years ago. My wife thought this was much better than tent camping.

I wanted it to be large enough for a full size bed mattress and long enough for me (6'3").

I liked the idea of a galley for convenience in cooking. I like to cook stuff when I camp. A few folding chairs under the shade of the raised galley hatch made for a pleasant picnic venue on our prior trip to California.

The design I picked was essentially the profile of the "Rimple" listed in Andrew's design library.
Design_Library/Design_Library.html. I had no idea if I could do rounded surfaces but I was willing to try. Foam covered by canvas seemed like an attractive medium.



We settled on an inside cabin floor dimension of 56" X 80" with a 56" x 27" galley. The floor to ceiling distance is 48".

The 60" X 110" floor was constructed from top and bottom layers of 1/4" plywood in a sandwich surrounding a 3/4" foam core. I could have saved some weight had I used some 1/8" plywood, but I was unable to source it locally.



5 gallon used industrial alcohol containers filled with water make good weights for gluing. I used a router to smooth the corners where fabric will later be wrapped. The assembled floor was liberally applied with "the mix" (70:30 ratio; polyurethane-varnish:mineral spirits). The floor is quite stiff. It weighs 108 lb.



I decided to push my meagre woodworking skills and make doors. It gave me something to do during the winter when it was too cold to work long in the garage. I used a single sheet of 1/4" plywood sandwiched with foam and then covered with canvas. I put in some Wiley windows and made some custom screens to fit them. I cut some window panes from scrap 1/8" plexiglass. I think two doors are an important feature.

Here are various parts used for the doors. By far the costliest part of the doors were some new keyed door latches purchased from a mail order trailer parts supplier.



Door and frame ready to install.



It was time to think about a chassis.

[philpom]

I'm curious to see more, it seems you are doing a good job to this point. My original plan was to complete my camper in something like 6 months and that was back in June of 2020. Spoiler - it's still not done!

I think the advantage you have when taking time is to carefully think through each step and consider all of the details. I don't typically build from plans, I build straight out of my head, it's the creative process I enjoy and I don't seem to get that from following instructions.

[tomhawk]

I may have had plans but it felt like I was just making it up most of the time.

I wanted a a 5'x 9' trailer. I was not finding a chassis that fit my plans.

I was a total noob. My metal working experience was limited to opening tin cans. I decided I should be bold.

I opted to fabricate the chassis. This involved learning to weld. I would recommend this to anyone. Don't listen to the folks who try to discourage.

I enrolled in a stick welding class at the local community college. We were a fairly mixed group of students. There was a retired farmer and a construction contractor but mostly young men hoping to gain a skill for employment. One of the students apologized to the instructor for dropping out of his class a previous semester. He explained he had been in jail since then. The shop classroom we worked in had all sorts of equipment that I will never own in my garage. I really enjoyed this class.

I have found this is a worthwhile skill. I made several objects before tackling the chassis including a welding cart, a firewood rack and a fence post driver. Since the fence post driver seemed to be holding up after driving a bunch of steel posts, I felt confident the welds of my chassis would hold together too. I also looked at a Harbor Freight trailer in light of my new skills and felt I could do better. My welds often don't look so attractive but they are strong.

The chassis I decided on consists of an "A" type design using 2" X 1" X 1/8" tubing for the long stretches. Andrew's tables indicated that is plenty strong enough for the anticipated weight of this trailer. This design borrows much from Alaska teardrop viewtopic.php?f=27&t=51991

All steel pieces were cut to size using an angle grinder tool fitted with a cut-off wheel. The tongue is 40". Here is the hitch adaptor piece ready to weld to "A frame" pieces. I clamped a bit of square tubing to the adaptor section to help align the pieces for welding. This helped assure everything was flat and symmetrical.
. . .

Here is the tongue welded up. I tidied it up a bit with a grinder before painting. I also welded on a loop of 3/8" round for safety chain attachments.



One of my least favorite fabrication tasks is drilling holes in metal. I needed to drill some 1/2" holes to mount the hitch ball adaptor.


I used a Dexter #8 Torflex axle derated to 800 lb. When you order an axle there are a number of dimensions that must be described. Based on your input, they build a custom axle just for you. This process was very stressful but I seem to have hit all the numbers OK. The axle fit the trailer perfectly. The tires are 13" trailer tires.



The axle was attached to the chassis with the supplied 1/2" bolts. I used a torque wrench to tighten as instructed.



A rectangular frame of 1"- 1/8" angle was welded to the chassis to provide bolt attachment spots for the floor and lights and license plate and fenders. This probably contributes very little to the overall structural integrity but having all the connection spots was convenient. Here is the chassis minus the axle.


The floor was attached with 6 3/8" carriage bolts to tabs on the rectangle. Much later, I applied Loctite to the threads.

When this was assembled, I visited the County assessor and was awarded a license plate for the trailer, sight unseen for $20. I was somewhat disappointed that no one wanted to even look at the trailer. Iowa requirements seem somewhat more relaxed than many other states.

I installed a Harbor Freight trailer light kit and attached the license plate to it. Now it was road legal!



The weight of the chassis with wheels and fenders was 220 lb.

This is obviously not the cheap way to get a trailer.
The cost of the steel, fenders, axle, wheels and lights came to $730. I also had to buy a stick welder and pay tuition for the welding class. However, factoring in the entertainment value, the new skills and tools, this was money well spent.


After driving around a bit and trying my hand at backing up (yet another skill to master), I removed the sandwich floor from the chassis.

It was time to work on the cabin.

[tomhawk]

The composite 9'x 5' floor actually contributes to the structure of the chassis. Had I planned a 4'x 8' floor, a single sheet of plywood or OSB would work on a trailer chassis designed for 4'x 8'. Once I went to a larger size floor, a single sheet was no longer an option. Since the "A" frame of this trailer is so minimal, a very strong composite floor like the one I used is critical.

The bottom edge of the floor was rounded with a router so the glued fabric was not wrapped over a sharp corner that could damage it.

With the trailer floor positioned bottom side up, I attached an 8" strip of canvas to the bottom edge of the floor that would later be used to wrap also onto the wall segments. I did not want to glue the fabric to the bottom of the trailer when it was facing down when it was hard to see what I was doing.


I then painted the underside.


When it dried, I then flipped the floor right side up and attached it to the chassis again using 2"x2" pieces of 1/4" plywood that had been soaked in "the mix" for washers. This provided a 1/4" space between the chassis rim and the floor to minimize water damage from pooling between the floor and the chassis and to reduce friction damage to the wrapped fabric by contact with the chassis.

The wall segment had sufficient unglued canvass on the bottom edge to overlap the wrapped floor canvas segment and then be folded over on its bottom edge to form a "drip edge" as advocated by GPW.

To cut or shape foam, I often used a hot wire cutter powered by a 45 year old car-battery charger. It has none of the fancy circuitry newer chargers have that prevent them from working properly as a hot wire power source. I used a foot pedal style ON/OFF switch to control the delivered power. I highly recommend using such a switch. The wire was .032 gauge welding wire in at least 3 foot lengths to have sufficient resistance to moderate the amperage preventing the power supply from shutting down. This process is extensively covered here by George: viewtopic.php?f=55&t=55323. Here is an example of such a tool:



To cut curved patterns I attached the wire to a fragment of plywood anchored at the center to make a compass like object. I always wore heavy gloves when hot-wiring foam. I never burned myself.

Wherever possible I wanted to cover the foam segments with canvas on the work table and not in situ after attaching to the cabin. I was able to do this for the walls and the flat portion of the roof. This provided many ergonometric advantages for my aging body. This also made the application of canvas more consistent with fewer bubbles. I always covered both outside and inside surfaces in quick succession; there was never any detectable warping of the foam when the glue dried. The curved portion of the roof and hatch were covered with canvas after assembly though. For convex surfaces this worked well.

I did not prewash the Harbor Freight canvas. Foam surfaces were cleaned with rubbing alcohol and perforated with a wallpaper scorer. The fabric was moistened somewhat with sprayed water. I used Titebond II diluted with 10-20% of water to make it flow better. I used some 6" wide plastic drywall spatulas to spread glue into the newly applied canvas and remove bubbles. Although it was not common, when bubbles occurred, I used a 20g needle to inject the bubble with some 50% diluted glue and smoothed the bubble away with a spatula. I also used a clothes iron to flatten some bubbles after moistening. Sufficient fabric extended beyond the edges of the foam so I would be able to overlap and glue the flaps of adjoining foam pieces during the final assembly.



I screwed and glued a 2 inch strip of 1/4" plywood around most of the floor perimeter. This would provide reinforcement for the attachment of the wall foam pieces similar to the method used in George's foamies. A groove in the foam was made with a hot cut wire to nest into this strip. This groove allows the plywood strip to be flush with the foam wall surface. The unglued flap on the edge of the wall segment was glued to the plywood strip and the excess fabric was trimmed once the glue dried.



With glued fabric fastened to the floor on both sides of the wall, I agree with George that this is a very robust connection of the wall to the floor.



I started with the flat wall segments of the front of the trailer. Note the fabric flaps on the bottom of the inside walls prior to gluing to the 2" plywood strips.


At this point over three years had elapsed since this project began.

[tomhawk]

I installed the door frames and then measured where to cut the rear wall segment to fit.



The trimmed rear wall foam segment ready to canvas before installation.



I wanted a strong point over the front of the cabin and another to support for the galley hatch hinge in the rear. I constructed an I-beam type structure that could span the 5' wall to wall distance. This was composed of 2" wide strips of 1/4 plywood glued together. It seemed quite strong, stiff and lightweight.



I installed the I-beam that connects the driver and passenger side door frames followed by the canvased rear wall segments

At this point it seemed a camper-trailer-like object was beginning to take shape.
This is a view from the rear of the trailer.



Not so great great stuff
I made an error measuring one of the walls that left a small gap between the wall segment and the door frame. To fix this, I tried filling the gap with Great Stuff (I had been warned). This, of course, over expanded and warped the wall enough to compromise the door from closing properly. I did not realize this until it was too late to easily start over. I ended up adding some weather stripping and wood strips to fix the seal. It is less than optimal cosmetically but functional. Since then, I have used only caulk and foam fragments to fill gaps.

I had not noticed, prior to this project, that cheap 1/4" plywood has a bendy dimension along the 4' length and a less bendy dimension running the 8' length. You can bend curves with much less than 2' radii. Lengths of any size may be generated by scarf joins(arrow). A flap disk on an angle grinder was used to make 2" bevels on each ply pieces needed for the scarf overlap join.



A 1"x 1" composite plywood rib was made to reinforce the curved portion of the rear wall that meets the inside of the closed hatch.
It stiffens the rear side wall edges that are not connected to other foam or floor edges. It is where some weather stripping will be attached to better seal the hatch.



The ribs were installed on the curved rear wall edge with latex caulk adhesive (arrow).

A 48" x 56" sheet of 1/4" ply covered with 1/2" foam and canvas served as the bulkhead between the cabin and the galley.

This photo shows the newly formed galley located back of the bulkhead.

Some supports for the galley counter and drawer were installed.



I was time to work on the galley hatch.

Tom

[tomhawk]

The dining room table was used for gluing up the curved hatch struts when it was too cold in the garage for adhesives to set. I used the plastic from boxed breakfast cereal to prevent glue from sticking to clamps and other undesired surfaces. The dried glue peels off this plastic readily. A bunch of newspapers spread around was sufficient to prevent glue from damaging the table or floor.


I made a compass guide for my router with a scrap of ply wood. It was attached to the router with screws. I anchored the center with a nail. Having never used a noisy router before, this arrangement was somewhat terrifying but it worked well anyway. The curved cuts were plenty precise.

By gluing these strips to perpendicular curved plywood, the composite structure is strong and rigid.



The skeleton for the hatch consisted of several reinforced plywood ribs. Later, bent foam will fill in the spaces. Instead of 2" foam that was used for the rest of the cabin I used 1" foam for the galley hatch.

[tomhawk]

To provide a strong point where I could attach this beam to the top of the rear wall, I inserted a 9" x 1" x 1" composite wood strip into top of the wall foam on both rear side walls.

The wooden inset strip was glued into the foam slot with caulk (A). The bulkhead is visible in the picture (B).



I attached the I-beam with some glue and screws above the wood strip "hard point" on both sides. This provided a robust beam for attaching the galley hatch hinge. A 4' "piano hinge" style hinge attached the galley hatch to the I-beam.



Slightly more than 5' lengths of foam covered with canvas were glued with caulk to the top of the walls to form the roof. Once roof segments and the I-beam were installed the cabin structure began to be much more solid. I used a reciprocating tool fitted with a blade to trim the excess overlapping foam to fit the wall.

Notice the draped fabric on the top of the wall. This will be wrapped and glued over the edge of the roof to form a continuous canvassed surface.


The free flap of the fabric already attached to the bottom edge of the floor was wrapped upward and glued onto the bottom 4" of the wall. The free fabric on the base of the wall of the was then glued over this glued fabric. The edge of this fabric that extended below the floor was then folded back on itself and glued to form a "drip edge" to channel water away from the wooden floor to reduce moisture induced rot.


Tom

[jakejakejake]

That curved framework for the galley hatch is art! Love the I beam too, should be plenty strong.

[kstills]

This is a post about a trailer I have been working on for several years. My initial plan was this was a retirement project. Only problem, I did not retire. This limited the time I could spend on the project. Over time, a little here and a little there, progress was made. We have been camping with it for over a year; we have towed it over 3000 miles.

I have very limited shop skills. I learned as I went along. This project gave me an excuse to purchase a number of tools I had always wanted to own. Very little of what I did is that novel. I borrowed a lot of ideas from posts folks made on this site. I will just cover some of the details I found interesting to me.

.

My man.

[tomhawk]

I was concerned about the difficulty of bending 60" segments of foam for the curved roof and galley hatch portions. I opted to make two 30" width sections that are connected along the center line by a plywood spine.

The 30" wide portions of 1" foam were shallowly scored with a hot knife and then slowly bent while heating with a heat gun. I found it difficult to bend foam thicker than 3/4" with a heat gun. Scoring 1" foam 1/3-1/2" with the hot knife made it possible for me to bend it. Here is the tool I used to kerf the foam. It would do 5 parallel cuts at once.

If the sheets are scored too deeply, they tend to fracture while manipulating. This made segments that could be glued to the spine and filled the 60" span. I used two layers of bent 1" foam to result in 2" thickness similar to the walls and roof for the front wall. A single layer of 1" foam was used for the hatch. I chose the scored surfaces to be hidden or on the inside of the hatch.

After adding the first inner layer of bent 1" foam to curved portion of front wall, this layer was troweled with a thin layer latex caulk just before the outer foam segment was attached. I allowed this to dry for at least a week before doing more. If one were in a hurry, I suppose some other glue would set quicker. I was not in a hurry. Since such a broad surface is glued, the strength of almost any glue will work well. In combination with the wrapped canvas, it will be very solid.

Final(second) layers added to curved front wall. Ready to smooth out with spackle.

Here is the view from the inside of the front curved portion. Note the I-beam connecting the two door frames (passenger and drivers sides).
I attached some u-bolts to the beam with the idea of having some hanging straps to help passengers climb in and out. It is plenty strong for that but it is not something I actually found useful for that purpose. It is nice to have a way to hang stuff from the ceiling. I have suspended some battery powered lanterns there.

Covering the concave portion of the curved surface inside the cabin with fabric was very painful. In retrospect, it might have worked better had I preshrunk the fabric. It was hard to avoid bubbles in the glued bonding. There must be a better way to do this!?


Time to work more on the hatch.

Tom

[jakejakejake]

Looking good Tom!

When I did the fiberglass on the curved front of my build I flipped the whole camper upright so that I would have gravity working in my favor and it worked out great. Actually, I tried to do it overhead the first time and failed miserably. Maybe this approach will work for you?

[tomhawk]

The gravity issue is certainly aggravating for me when you are trying to glue canvas to underside of an object. It keeps getting unglued. My solution was to use lots of thumbtacks. Flipping over would be a big help. I think my bigger problem was due to canvas shrinkage.
I can imagine if canvas is glued to a convex surface when the canvas shrinks it just compresses itself onto the foam. Others have described this as tightening up the structure. This seems like a desirable feature. On the other hand, when applying canvas to a concave surface, the shrinking canvas is induced to lift off the canvas producing bubbles. I am thinking that shrinking is not a factor in fiber glass? Unlike cotton fabrics where water can alter its properties, glass is an inert matrix?


Tom

[tomhawk]

I forgot to mention in the previous post a feature of scoring the foam before bending. I used a clamped straight edge guide to assure that the scores were square to the foam piece. I also bent by heating and pressing down on the overhanging foam clamped square to a table edge. These two factors constrained the subsequent heat bending to a radius of curvature square with the side of the foam. This resulted in a precisely curved surface.

Here is a trial fit-up of the galley hatch.


A foam fragment attached under the hinge forms a gutter to channel any water off to the the exterior, passing through the hinge area out to the side similar to that used in George's #1.


The foam gutter was installed under the hatch hinge. It has been tested by sprinkling with a hose and has so far worked fine in a few light rain storms. It has not been in a serious rain event yet, but I am hopeful. I have a remnant piece of foam that I could use for a wider gutter. I might redo this in the future.


Foam sections were attached to the galley hatch framework with latex caulk. A flap disk on an angle grinder was very effective to trim excess plywood to make corners smooth before covering with canvas. The completed hatch, covered with foam and canvas, weighed 22 lb. This is an important number to consider when you try to figure out how much weight the gas struts will need to accommodate.


Tom

[Shadow Catcher]

Looks like a very good how to, and I somewhat doubt you do not have a good skill set

[jakejakejake]

I am thinking that shrinking is not a factor in fiber glass? Unlike cotton fabrics where water can alter its properties, glass is an inert matrix?

Thats correct, no shrinkage in the fiberglass cloth or resin/cloth matrix after cured. Preshrinking sounds like a good idea. Hopefully someone more in the know can elaborate on the preshrink process, and offer some tips.