Sleeving a steel tube question?

[andreuther]

What size steel tube would I need to sleeve over a 2'' steel square tube? I am trying to extend the tongue about a foot and i'm not sure what size is best. I can't find anyone near my home that sells steel tubing. If you know where I can order it please send me a link and the suggested size. Thanks!

[Redneck Teepee]

First off it would need to be a seamless square tube to get the snuggest fit, because the most common is ERW welded and has a slag protrusion inside.

Next you would probably order a 2-1/2" sq. x 3/16" seamless wall or closet to it in a gauge wall. Don't have a steel book in front of me to see what exactly is available in wall dimensions.

If you are just looking for a short coupler to add another 2" sq piece to lengthen your tongue, you can purchase a weld on hitch receiver and cut off what you need at your local auto parts for about $20 bucks or so, it is as sized above and seamless.

Or I would try Mc Master Carr if just a short piece is needed, also you being in Groveland you could plan on visiting Modesto Steel on your next trip to the valley floor if that's doable. Larry

[Treeview]

Look at this chart:

http://www.alro.com/datacatalog/007-tubingandpipe.pdf

It seems that a 2.25" tube will have 0.125 walls leaving EXACTLY 2" ID. Any machinist knows that a two inch plug doesn't go into a two inch hole. YOu need some tolerances.

And, like the poster above said, weld bead will protrude inside.

Sliding tongues aren't as easy as they seem at first.

Tom

[Redneck Teepee]

http://www.etrailer.com/Hitch-Accessori ... aQod7TwAfA


http://www.amazon.com/Towing-Hitch-Rece ... B003Q3LZ7A


For a shorty you can use these, just make sure of your ID sizes and lengths before you order. They will be seamless.

[andreuther]

I'm considering using this as a sleeve:

http://www.northerntool.com/shop/tools/ ... 707-_-CONF

My next question is if I plan to extend the tongue by 1 ft. how much of the original tongue should the sleeve cover on both ends? Should I use all 4 ft.? Meaning it would cover 1.5 ft. on both ends with a gap of 1 ft. between. Is there a minimum length of insert?

Below is the trailer I am planning on doing this to.

[KCStudly]

That receiver tube looks beefy. Maybe too beefy for your light weight goal.

I think it depends on how much of the tongue will extend past the front of your cabin, and how the rear of the reinforcing is tied into the floor.

Have you looked at Angib's tongue strength link from the Design Library under the Resources tab, above.

Also have a look at his Ultra Light design that I mentioned in your other thread. This would be a good way to strengthen your extended tongue while also adding some tie in for the front part of your floor.

The temptation may be to add a big old honking piece of steel to strengthen and reuse the existing piece, but that will add weight that is perhaps less efficient than just changing the piece out, or going to the ultra light style A-frame and killing two birds with one effort. The fab work, material cost, and welding effort are all pretty much the same at this point in the game, so I would look closer at the big picture and not just at a patch job.

$.02 as requested.

[andreuther]

I didn't see that link at first and it is a little different then what I was thinking but very cool. I would love to do that A frame design, my only issue at this point is finding someone to do it with my limited budget near my very small town. Modesto might be an option but I don't want to make that drive unless i can get it done that day and within a reasonable price. What to do, what to do?

[KCStudly]

Start by getting some hard numbers. Figure out where you want the cabin to be on the chassis and what your final cabin size will be (from your other thread you said 7 ft, but that might not allow for a full size mattress and wall thicknesses. You have to figure the optimum location for your side doors and how they (with trim) will interact with your fenders. (Do the "sit and spin" from a laying position, allowing a wide enough door for your feet and knees to swing thru, and that is where you want your door relative to the mattress.) Now you can figure out how much of your cabin will hang off the front and back, and you can zero in on your required tongue length better.

With your light weight goals, you probably won't be able to have much of a tongue box, maybe just a battery box (or that may have to go in the rear to get your balance). Better yet, to keep things light, use battery operated puck lights and no complicated electrical wiring.

If you want to stay with a single tongue, study the tongue design link above and use that to help you decided if you need to beef up the existing unit. There are other ways to add tongue strength w/o adding as much weight as that sleeve would. Bob Henry used a very effective under slung flat bar truss method on one of his builds.

I guess my underlying message is, if you want to build 5 wide under 700 lbs, you will have to have a thorough plan and stick to it. If you just build as you go and only add, add, add, you will likely end up heavy.

[andreuther]

My design is very similar to the Northern Lite design with a small galley above a 7' cab. I'm not worried about strength as much as I am about the length. With 12'' of the cab overhanging the back of the trailer frame (this will set the axle 28'' from the rear of the cab) that will make the tongue length only 2'6'' as the trailer frame is 8'6'' from ball to rear spar. I think I need at least a 3' tongue for this build and 3'6'' would be ideal. I agree that the sleeve adds weight that I would rather not have, but without the ability to weld I feel like my options are limited.

[bc toys]

If it where me I would weld on some steel (light weight) angle iron to the rear of that trailer and leave the tounge the way it is thats my .02$

[KCStudly]

How is the tongue currently attached to the rear xmbrs? Is it welded?

If so, I would rather see you use a 2 ft section of that receiver tube; cut the existing tongue off 6 inches in front of the 1st xmbr; slide the receiver on the stub, insert the tongue 6 inches into the receiver; and use four 3/8 inch bolts, 2 each at 1-1/2 inch from end, 3 inch space, 1-1/2 inch from other end at both lap points, bolted thru the side of the receiver at mid height. Use square U-Bolts around the tongue member up thru hard blocking in the floor immediately behind your front wall and a few inches ahead of your splice.

By making the splice at the very rear of the tongue, and by only bolting thru the side of the splice at the rear you will not weaken the critical highly loaded portion of the tongue near the front wall.

You should still do the tongue strength math for your geometry, size and thickness of tongue, given your new dimensions, to be sure that the existing tongue is still adequate for the task. If it is not, it would most likely be lighter to buy a new piece of 2 inch with slightly thicker wall, than to add such a big piece of sleeve.

Okay, so let's look at that. 4 ft of 2-1/2 sq x 1/4 wall receiver will weigh about 7 lbs/ft, adding 28 lbs. (ref. http://www.omegasteel.com/pdf/weight-per-foot.pdf). Half that length is only 14 lbs.

Let's assume your existing tongue is only 1/8 inch thick 2x2 (or lighter), at 3 lbs/ft (same ref.).

So if the tongue math says you really should have 2x2x3/16 wall, that's 4.3 lbs/ft.

For theoretical Option 1, I'm going to assume that your existing tongue is about 6 ft from tip to a point 6 inches ahead of the front xmbr. So, take away 18 lbs (3 lbs x 6 ft) and add back 30.1 for a one foot longer tongue tube (7 ft x 4.3 lbs) plus 1 ft of the receiver for the butt splice at 7 lbs (7 lbs x 1 ft). So that's 37.1 - 18 lbs, or a gain of only 19 pounds (plus bolts).

Whereas, for your proposed Option 2 if you cut and extend using the 4 ft sleeve you would be adding 28 lbs (plus bolts), and it would be closer to the tongue adding tongue weight. So 28 lbs plus the original 18 lbs equals 46 lbs for comparison.

If the math says that your existing tongue tube is still beefy enough in the extended position, Option 3, you might save a little money just buying 2 ft of receiver and not buying thicker tube stock. Add 14 lbs (7 lbs x 2 ft) plus the original 18 lbs for comparison and you are at 32 lbs.

So like I said, with about the same effort, you can likely save some weight and still beef up your tongue to meet the design goal outlined by the tongue design recommendations.

Remember, in a light weight build, every time you don't sharpen your pencil you are adding unwanted weight; and over the course of a build all of those 10 to 25/ct additions will end up multiplying out. Before you know it your 700 lbs goal becomes 1000 lbs.

[andreuther]

The tongue is welded to both xmembers, is 1/8 thick, and is 62'' long from the front xmember.

The only reason I thought the 4 ft. receiver would be best is because I was under the impression that I would need at least 15'' of insertion for strength. If you think 6'' is enough then I am more than happy to save some money and weight. If I add weight to the tongue does that mean I could shift the cab back a few inches to offset that weight?

I am still trying to find a welder that can help me out and just go the A frame rout, but I have a feeling the cost is going to be more than I am able to afford. Here's is a thought, it I could find the steel do you think it would be possible to bolt on the A frame, or is welding my only option?

Thanks for all the help!

[KCStudly]

Dam. My Firefox has been crashing on me lately and I was just composing a rather involved reply when I lost it. (I don’t seem to be able to compose any other type. )

IMO welding would be better. It is fairly permanent, and if configured and executed properly will not be subjected to loosening or failing over time. Welding can greatly simplify a joint, leaving it lighter than a bolted joint and usually stronger, too. For angled joints, especially the acute taper at the front of a long A-frame, I feel that a welded joint would be easier (… but keep in mind that welding is a readily available go to option for me).

I feel the need to be clear about why I feel it would be okay to use a shorter sleeve, IF it is located near the axle cradle. The beam arrangement we are talking about for your single member tongue options (if you decide to go that way and not with the A-frame) will be most highly stressed in bending directly under the front of the front wall (or if we look at the trailer by itself at mid span between the coupler and the axle frame). The highest shear forces will also be at the front wall (or at the axle frame for the trailer by itself) and at the coupler. The sleeve will create stress risers at its ends that could be detrimental in bending by concentrating the forces at specific points (so you would want to avoid putting the sleeve ends in “bad” locations, whereas the main tube will already be (must be) sized to handle the shear loads and the sleeve will not affect the inner tubes shear strength. By using the square U-bolts to unify the tongue with the floor and front wall, and abiding by the tongue guidelines in Angib’s link, for the arrangement that I am suggesting (option 1, once your tube wall thickness needs have been confirmed) I believe you would be good.

It now occurs to me that even if your existing tongue’s wall thickness is adequate for the longer situation, you could still save weight by replacing it with a longer piece of same kind, and using the shorter piece of sleeve. (Again, this is all assuming that it checks out against the guidelines at the new length and loads.)

I guess it all comes back to your design priorities (light weight) vs. skill set and available tools vs. cost.

There is a saying that I like for occasions like this; “You can have it: good, fast, cheap… pick two.” These little campers don’t build themselves and they don’t come free of cost. You may want to do a realistic estimate of how much the cost of materials will be for your project before you commit too far. It is my honest opinion that many of the budget based builds have understated costs by builders who did not keep strict track. It is also my opinion that the best way to control cost is to not keep track . (I kind of wish that I had not kept such good records on my own expenses. )

A brief discussion about thru bolting and box tubing: Normally for a bolted joint you would want to install an anti-crush sleeve (sometimes abbreviated to "crush sleeve"). This would consist of a length of round tubing or pipe that the bolt fits thru closely which prevents the bolt from crushing the box tube. There are two methods of installing them. In the first method you would drill a thru hole the same size as the OD of the crush sleeve, chamfer the sleeve at both ends, insert it and weld it from both sides. The second method is to drill one side of the box tube for the bolt size and the other for the crush sleeve with the larger hole located against whatever will be clamped by the joint; simply insert the sleeve and it becomes captured by whatever you are bolting up.

This prevents the walls of the tube from flexing in and maintains stress on the fasteners. Without them the fasteners can become loose. On critical joints where this can be an issue it is important.

All that being said, for the receiver tube sleeve splice we are discussing, I don't feel that crush sleeves would be as important. For one the receiver stock is generally very thick, so less prone to flexing; and for this type of splice you are essentially pinning the joint, not bolting it. So I would be comfortable using nylon insert self-locking nuts and just snugging them up "wrench tight" (don't G-O-rilla them).

If at all possible, I think the A-frame is the better option for your application. $0.02

[andreuther]

You have convinced me, I am going to find someone that can just weld the A frame and pay the price. Any idea of what size tubing I should look for?

[KCStudly]

Use the tongue design guide linked previously.