Custom Frame - 1969 Sovereign 31'

[Ndcctrucks]

My personal experience in heavy industry maintenance (railroad, then steel mill, now power plant) is that steel tube rots out from the inside. I never use it for exterior use if I want it to last longer than ten years; the only exception being the use of stainless.

Unless your galvanizing dip can be assured of adherence both outside and inside (not sure how you could clean the interior prior to dip, and not sure how you would inspect the center of a 31’ tube), you may want to reconsider channel. On the other hand, if you’re not going to keep it very long, or you’re only going to keep it in the dry southwest, then rectangular mild steel tube will make a prettier product and easier to fabricate with.

-Ken

[boger]

In keeping with the theme of annual updates, I do have some progress to share.

I spent the better part of the past week prepping and fabricating a new frame. I ended up staying pretty true to the plan I laid out last year and am still going with a mid bath conversion. I used 5x3x3/16 tubes for the main rails, and then a combo of 5x3x1/8, 5x3x3/16, and 8x3x3/16 tubes for the crossmembers and outriggers. Spent quite a bit of design and cut time taking a lot of weight out of those members.

I went with 5700 lb #11 dexter torsion axles with dexter disc brakes. I added a 3 inch lift over the original trailer. Feeling unsure about whether I should have gone with 2 inch instead, but it’s too late for second guessing now I suppose. Only once I get the trailer fully built will I be able to see how it looks.

The frame heads to the galvanizer tomorrow, which should take two weeks before I get it back.

[boger]

Bad news Bears.

After some conversations with the plant manager at the galvanizing plant, I am no longer planning to hot dip galvanize the frame. The reason is that the particular plant we use has a 6 foot wide by 8 foot deep galv tank, which means that while the frame is being lowered vertically into the molten zinc, one of the main rails will spend several minutes longer at much higher temperatures than the other frame rail. Since zinc baths are usually around 850 degrees, the plant manager feels the risk for warpage on this frame is pretty high. If the tank were 8 feet wide and the frame could be dipped in the flat position, he feels that the risk for warpage would decrease substantially.

I have galvanized many items and structures without warpage, so I am very tempted to ignore the advice and march forward, but I've come to terms with the fact that this is a unique frame and a unique dip, so I am going to heed the advice. Instead, I'm going to arrange to have it blasted and painted once I get it back and get some wheels on it.

Now I better figure out how to change the title of my thread!

[skyguyscott]

You might want to consider using POR15, a nasty-to-use but extremely effective anti-corrosion coating many here have used and swear by.

You may also want to consider using some good-quality spray foam, not only for the insulating properties, but for the added protection it affords. Consider how it protected the original frame for over 50 years. It would likely outlast you and your kid's usage.

Using both would probably be overkill, but then again, a friend of mine seems to live by the proposition that overdoing it prevents doing it over.

[boger]

Overkill is what we engineers do!

I've never used POR15, but I've read about it here as well and it sounds like a good product. The reasons I'm not going that route are the mess it makes, the air temp drying requirements in the middle of winter, and the time it will take me. After talking it over with a paint/powder coat shop that I work with, their best recommendation is a light sandblasting followed by a three coat liquid paint job. I had assumed he'd push me towards powder, but he explained that powder does not expand/contract as well as liquid paint for the application I have and I am more likely to see chipping with powder coat.

Fortunately, he's willing to pick at it over the course of a month or two using leftover material from jobs he encounters. Aside from the tongue, bumper, and a couple other small areas needing to be silver, I told him the color doesn't really matter.

Agreed on the spray foam. Stuff is amazing. For ease of install and servicing later, I'm leaning towards glueing rigid foam to the underside of the subfloor.

[boger]

Frame came back from the galvanizer and I spent a weekend doing some punch list items before sending it to the painter.

Some of things done were adding a storage area under the rear bumper, add a hitch for a bike rack, weld on the coupler/jack/propane tank holder, add some custom cutout plates for the fold out steps, add a front hold down plate, weld on a spare tire holder under the frame, and build a system to hold the black and gray water tanks.

I fit all the running gear on the frame and I'm pleased everything fit up just as expected. The 3" lift was perfect for my truck (stock F150), as it now sits level without needing much of an increase in height on the hitch ball.

I had started to really worry about the weight distribution of the trailer and how much tongue weight I was going to have due to how much I bulked up the new frame. The local grain elevator is just a couple of blocks away, so I towed the frame down there after work and took a few weight readings. The frame plus running gear was 2180 lbs, which I didn't think was terrible. However, I was jazzed to see that my tongue weight was only 200 lbs, which puts me right around the 10% mark (I would have been happy with anything under 15%). That took a huge weight off my shoulders, since making large changes at this point would be difficult.

Frame heads to the blaster/painter tomorrow, which will give me a month or so to take a break from working on the trailer and focus on other things (which I think my wife is excited about). Color is going to be semi-gloss silver for the visible areas, and black for the areas that are hidden.

[AlbertF]

Originally Posted by boger

Overkill is what we engineers do!



For ease of install and servicing later, I'm leaning towards glueing rigid foam to the underside of the subfloor.

I’d expect an engineer to earn his keep by reducing materials and cost!

I think it was Inland Andy who suggested that Airstream used fibreglass insulation because rigid foam would break down from constant flexing. If the foam board works for you in the long term, it will be evidence of a rigid frame.

[Boxite]

I certainly hope those pics of the frame were taken BEFORE the galvanizer rec’d it.

[boger]

Unfortunately it was after the galvanizer. Galvanizer was worried about warpage based on the size of the frame versus their tank size and how they would need to go about dipping it.

So, I decided against galvanizing it and am instead going to get it blasted and painted with a zinc/epoxy liquid paint system.

Bummer is that I can't figure out how to change the title of my thread since it's not galvanized anymore!

[mrdes8]

Good thread and nice metalwork on the frame. One thing coming to my mind is if you are concerned about the inside of the main tubes. Through the decades I've had the need/desire to spray several kinds of undercoating/rust prohibter products with air pressure through flexible wands, some up to 15 ft long, very effective.
Mark D

[boger]

Originally Posted by mrdes8

Good thread and nice metalwork on the frame. One thing coming to my mind is if you are concerned about the inside of the main tubes. Through the decades I've had the need/desire to spray several kinds of undercoating/rust prohibter products with air pressure through flexible wands, some up to 15 ft long, very effective.

Mark D

Thanks, Mark!

I did really want to protect the interior of the tubes, which is why I was so excited to get it galvanized (sigh). Now that I’m going another direction, my plan is to cap both ends of the main rails. Since they’re 3/16 thick, they should easily outlast me if everything is painted properly on the outside.

I noticed your profile shows Lakewood, CO. Small world - we lived in Lakewood recently for about four years before moving back to Iowa. Loved it out there in CO.

Jared

[mrdes8]

And another idea... we used to get this stuff from McMaster-Carr, a rust preventative, came from the oil drilling industry, just a little more viscous than water. We either dipped small parts in it in a basket , painted it with a brush, or sprayed it out of a regular spray bottle. I don't remember the name, clear, came in a 5 gal. bucket. I bet with a spray bottle, air hose and high pressure nozzle working from both ends you could get a lot of coverage inside those tubes. We've lived in Lakewood from 1980 - 2001 and back again in June of 2000. In between GA (3 yrs) then Reunion, Lafayette and Ft. Lupton. If you were government we lived 2 blocks south of the Fed Center, now live up on Green Mtn. We think about possible rust in a whole different way in CO. My current project is a 1946 Spartan, sat beside a horse arena on a ranch near Ft Collins for decades, the frame is almost perfect, 50-60% still original paint.
Continued success on the project, Mark D

[dbj216]

Hello from Colorado. We met on these Forums shortly after you bought your 69 Sovereign 31'. I stumbled on your thread and I'm glad I did. I'm a former Iowan from northwest Iowa. We lived in Spencer for 10 years and I still have a good friend there.

You can make a request to the Forums admiration and request a title change to your thread. And I might suggest you move your thread to the Airstream Trailer Knowledgebase found near the bottom of the Forums page. This is where a lot of folks make their project threads that involve all sorts of aspect of such a big project as a "full monte" with a frame build. And you can then add your subfloor build, insulating the subfloor (I use the rigid foam sheeting), the shell re-attach, and your plumbing, wiring, bath build, cabinet builds, and on and on.

My former 66 Trade Wind 24' had underfloor heat distribution ducts. The furnace had a bottom discharge into a plenum and the ducts radiated from there including to the waste water tank compartment. The fresh water was above the floor in front. Here is a photo of my installation. And then a photo of the flex 2" duct to the tank compartment in our 86 Airstream.

David

[boger]

Hello David! I definitely remember our discussions - they've been quite helpful as I planned out my build so far. The way you installed your waste tanks and outlets was one of the reasons that spurred me towards the mid-bath reno idea.

A forum admin was kind enough last week to change my thread title, which was great. I was beginning to wonder if there was a better place for my thread once I 'outgrow' the frame portion, and I think your suggestion is a good one.

Sorry if this is a dumb question, is there an easy way to change that myself, or is there a place to put in a request to do that?

Thanks,
Jared

[dbj216]

Hi Jared: I was away for a few days, sorry for the delay. I know of no way for us users to move a thread from one category to another. I believe the administrators can do it easily. They will just copy and paste. What I like about the Knowledge Base project threads as they will cover many topics, like frame builds, axles, body attachment, subfloor materials, wiring, plumbing, and on and on. The folks who follow these projects are generally well versed in the model and year range of the trailer in question. Most Forum categories are quite specific like refrigerators, or bathrooms, or hitches, etc. A person doing a major renovation like you are doing would have posts all over the place.

Anyway, press on regardless.

David