The Tongue Weight of a Bare, HF Trailer

[charliehm]

I just finished assembling my HF 40”x48” trailer (with 12” wheels) per their instructions and wanted to see how closely their design had achieved a 10% tongue weight. So, I set the trailer on three bathroom scales.

Lt. wheel: 62#
Rt. wheel: 64#
Tongue: 12#

At 8.7%, that tongue weight comes in a little light, right? (But to the upside, the trailer is 47 pounds lighter than the advertised shipping weight of 185 pounds, which allows me an extra 5 gallons of fresh water. Yeah!)

An aside:

“Why”, you might ask, “would anyone own three sets of bathroom scales?”

Last week I didn’t. But my intention is a light-weight, custom design (built over the wheels and partly on to the tongue for a 52”x92” chassis), so I needed a means to track weights as I build. Goodwill was selling used scales for $4/each. So, I added a pair to the one I already owned and then adjusted all three so they would read the same when equally loaded at mid-range.

My current tongue weight is a meaningless number because of the mod I propose, which is to extend the bed 24” (and the tongue, too, of course). That would normally invalidate the bolt pattern for present axle position, but my guess is that by rotating the frame 180 degrees and by making my additions at what has now become the forward edge, I can leave the axle where it is. (The spring assembly will need rotating as well --which is no biggie-- as isn’t changing the axle position if I have to, because I’m assembling with bolts rather than welding. So far, at least).

In other words, instead of having the axle at its designed 38% of the load platform and 23% of overall length (as measured from the rear of the trailer), my modifications to the frame will put the axle at 41% and 31%, respectfully. (In other words, my estimated center of gravity will be 10" forward of my axle, which is at least the right direction if not the right position.) But those numbers and estimates are probably just meaningless numbers until I start driving screws nails and gluing up panels).

What seems to matter –-if I correctly understand the many helpful posts on such matters-- is having the chassis as close to the tow vehicle as possible (for aero-dynamics) and the axle as far away as possible (for backing ease and to dampen towing sway) while still loading the hitch properly (which can be partly achieved by changing how the interior of the chassis is built and loaded).

Hence, my need for scales and for weighing as I build (and, also, a fairly flexible design that I can alter as needed).

Charlie

PS What will my design look like? I'm still sketching, but think of a boat on wheels --i.e., curves in both plan view and elevation, and you'll see where I'm headed. The features I want to include are: a porta-potty tucked away in an air-tight closet when not in use; a fold-away shower; an interior galley with double sinks and burners that runs forward to aft on the stbd side (rather than port to stbd across the rear of the chassis); a foldaway dining/projects table (e.g., map reading or fly tying); a single bunk of the back-packer style (i.e., to be rolled up and stored each day when the floor space is needed). Standing room will be achieved with a popup roof. That's a lot of features, but on paper at least, they all seem possible.

As for the shape, by using curved sides --rather than the flat sides of a tradional TD-- I can pick up rigidity and keep my weight down, as well as build on a narrower frame than the standard 4'x8', which eases the load on my tow vehicle, a '90 Tercel.

[cracker39]

You could have weighed each of the 3 points separately with one scale. All you'd need to do is raise the other two points to the same height as the point on the scale, to the balance would be correct. That's how I will weigh my chassis with the sides and other parts on it to get an estimate of my axle placement for the correct tongue weight before I construct it.

[charliehm]

Dale,

You're right. I completely overlooked doing the weighing with your method (or a variation) which uses a single scale, not three.

If I know the distance between a fixed point and the moving point that is exerting force on the scale (i.e., the length of my lever, which can be obtained with a tape measure), then I can calculate the implied total weight of the object by using methods and formulas such as Angib provides in his very readable presentation of the science underlying his tongue balance spreadsheet (i.e., parts 1-4 of his presentation).

Much thanks for your suggestion. I'll try it the next time I want to do a weighing.

Right now, the trailer has been pretty much disassembled for realizing that I want to attempt a dropped floor, rather than going with my original plan of building upward on the frame as the manufacturer intended. The sides will still be curved forward to aft like a boat, but I want to capture the space that would ordinarily be lost in the undercarriage. Gaining that 6 inches makes interior arrangements so much easier to accomplish, as well as facilitates echoing the lines in profile of a moderne/moderniste, a look I really like. So, right now, I'm back to springing battens and doing mockups, though I did buy steel yesterday, as well as a small AC welder, so that the tools and materials would be at hand once I do commit to a design.

Again, thanks for your suggestion.

Charlie

[cracker39]

YW. I hope to learn to weld when my son-in-law helps me build my chassis. He has a nice welder that I bought him a few years ago, so I thiink he owes me some welding and instruction.

[charliehm]

Dale,

It's been ten years since I've had a stinger in my hand, and then it was in the context of welding classes I took at the community college, not experience gained on the job. But regaining the hand-eye co-ordination needed to lay down good, clean beads again ought to be like relearning to ride a bike. It's not a forgetten skill. Just one that's gotten a bit rusty. Some practice time in the booth all I need.

I agonized for a week over which welder to buy. For sure, I couldn't justify the expense of a "real" DC welder. Hobart's Stickmate 205 AC seemed like a good compromise and an excellent machine. But in the end, I couldn't justify its cost either. I'm going to be sticking together 1/8th inch material, and not a whole lot of that, either.

HF had a small, AC welder for sale that seemed like it would do the job of modding one trailer. The internet price --which the store honored -- was $30 lower than the in-store price, plus this week there was a 10% coupon on Chicago Systems welders, which they also applied. So, for less than $75 bucks I could put a welder in my shop. I've already got leathers, gloves, and a wide-screened hood. So all I need is some rod, for having picked my steel yesterday. (Some new, and some scrap at $0.38/pound.)

A suggestion: if you want to learn to weld, try the community college in your area. The welding instructors tend to be excellent, and the some of the classes are structured on flexible basis in the sense that you can determine your own hours and goals. You can walk in, tell them what welder you have at home, what project you need welding skills for, and they will teach you just want you need to know, rather than all there is to learn.

That was my experience, anyway, though at the time I didn't have a welder, and unemployment was paying my tuition under a jobs-retraining program. So I was in a booth 25 hours/week for six months. I was happy as a clam. I had been trying to learn to weld for 25 years and had signed up for classes before in every community where I lived. But always, by about the second or third week, we'd go on overtime at work and then to 7-10's and then to 7-12's, and I have to drop the course out of sheer survival. (Eat, sleep, work. You know the drill, I'm sure.) So, having a couple of free months --and some one else to pay for my classes and equipment-- was a blessing I'll always be grateful for. I could bolt my trailer, but it will be a better product for welding.

Check out the community colleges. The costs for welding classes aren't outrageous, and you can burn all the rod and chew through as much scrap as you want in a work-like setting where the equipment is good and the instruction and support are excellent. You can make your mistakes and no one is going to lose patience.

Charlie

[cracker39]

Thanks for the info and encouragement, Charlie. I am hoping that I can learn from my son-in-law. He has been a welder by profession and worked as a fabricator, building the mobile lift devices that airlines use to load meals onto the airplanes, until after 9-11 ended his job due to airlines cutting back. His wife, my step-daughter also learned to weld from him, so I think I can too, or hope to anyway. We'll see how it goes when we build my chassis.

I am not sure what type of welding unit he has, even though I paid a couple of dollars under $1000 for it at Tractor Supply about 4 yeaars ago, so it will probably weld anything he needs it to. The only problem is that I'm sure that it uses 220VAC and I only have one outlet on my back porch and need to work in my carport in front. So, we may have to assemble the chassis in the shop where he keeps the welder, and affix the torsion axle on it temporarily with "U" bolts to get it home so that I can work up my cabin pieces and weigh it all for proper tongue weight and axle position. Then we can take it back to the shop to weld on the axle mounts I will make from pieces of "U" channel. The reason for making and using mounts welded to the chassis is to keep from drilling holes in the side frames which can weaken the structure.

Learning to weld isn't a necessity, I just like to know how to do things my self. If I should find that I need to make another trailer, and need to weld in my carport, I can just run another 220VAC line to the front of my house for power.

[charliehm]

Dale,

That you'll be able to learn to weld isn't something you should have any doubts about. How much practice you'll need before the logic of the process becomes second nature is the huge variable.

One way to stack the odds in your favor is to get a welding mask that you are totally comfortable with, something that feels like a ball cap rather than the head piece for a suit of armor. Also, get one with a wide viewing screen. (Those narrow, little windows that come standard are for guys with young eyes, not us old folks with bifocals.)

Another huge help in getting a good puddle going is to prep your material thoroughly by cleaning it, rather than trying to weld dirty. (And even seemingly clean mill scale is dirt.) A 4 1/2"- or 5" grinder with a wire cup is essential.

Another suggestion. Run the 220V line to the carport now before you need it. There's advantages to working in a shop, and there's advantages to working out-of-doors. But what is best is having the flexiblity to choose as weather and the project's size determine. To wire my shop -- which is a fair distance from the house and my main breaker-- I simply bought 10/3 encased wire (suitable for in-ground use), dug a trench from the breaker to the shop, and then feed the wire through PVC. (Don't use iron pipe. That creates problems. Something about impedence or whatever.)

One last suggestion, and then I'll get back on topic. Borrow an introductory book on welding from your local library. The book will have more info than you'll need, but doing the background reading helps make in-person explanations a lot easier to understand. People who already know how to do something tend to forget how much a beginner doesn't know and tend to rush through things that are obvious to them, but aren't obvious to a beginner. Also, how your hold the stinger, how you move in and out of the puddle, etc. are all things that can be done a lot of different ways. Only by experimenting do you find out which ones work best for your body, as opposed to someone else's. (And a classic example of that is left-handers trying to learn from a right hander. My son, a left-hander, writes with his left hand but fishes and uses tools with his right, because I was who he learned from. But he shoots left-handed, because it was his grandfather, another left-hander, who taught him that.)

Charlie

[TonyCooper]

Funny this topic arises at this time. I was in the market for a new MIG welder to use in the shop and around the house. I could not justify a high end unit so when HF had a recent sale I splurged for this unit.

http://www.harborfreight.com/cpi/ctaf/d ... umber=6271



My neighbor is an ex-welder by trade (now a NC Highway Patrolman) and will be teaching me the basics. He told me that for what I'd be using it for this unit was more then enough. I have used an arc welder years ago to build a trailer out of an old pickup truck bed, but have not touched one since. He'll teach me how to properly do things...

My wrought iron porch railing needs a little repair work and I could buy the welder and do it myself for 1/2 the cost of a section of the rail!

I am so looking forward to it. Another toy!

[toypusher]

Toy,

What great new toy! I want one of those too, but can't get one right now. Closing on a new house the 28th of Nov and haven't put current one on the market yet. Plus I have been unemployed for 7 months and unemployment compensation just ran out at 6 months. Next week I have to try to get a part-time job somewheres until after new year. Then I guess I will have to get a real job so I can build the second teardrop and have it ready to camp in the spring I can weld good enough to get by, but I think that my nephew (Certified welder that works for Harley Davidson) will have give me some lessons when I get around to make my new frame.