Superstrut/ Channel need trailer build advice

Ask questions about Harbor Freight trailers, or questions about building your own...

Postby Chuck Craven » Fri Mar 10, 2006 8:59 pm

Yes, I have used those things and they are terrible. Some have the treads to big others the treads are the wrong pitch and some the holes are bigger than the bolts. If you put lots of bolts through your sandwich you should not have to use any connectors for the unistrut the plywood will act as the connector plates. But the angle plates that they sell, look as if they can be used by bolting through the unistrut. I think the unistrut will be about the same weight as the 2x3’s. I assume you are using the 2x3’s as cross members right? What type of axel are you going to use, leaf spring or torsion? The torsion is the easiest to use. You could get a piece of rectangle tubing and bolt that to the side lengths of unistrut then bolt the axel mounting plat to that through the floor. The tongue can be bolted to two lengths of angle iron and the angle iron bolted to the floor. That is what Cary-on trailers does. Use grad 8 bolts for that only two ½” through the tongue should work. Your floor plywood should be treated with rot-doctor before installing both sides for the roadside piece. Looks as if you have a good plan Just take lots of pictures.
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Postby angib » Sat Mar 11, 2006 8:14 am

Chuck,

I'm not much in favour of building the superstrut into the floor as then it becomes a real problem to connect the tongue and axle - those joints will now have a layer of wood in them. It also becomes more difficult to assemble the floor with its wood-metal-wood sandwich - brads/nails won't work!

Miriam,

I can't see any problem in making the basic frame of the trailer in superstrut and I'm having some ideas about how to bolt the whole thing together with a couple of conditions:
- The undrilled superstrut is used - so you have to be able to drill it yourself and I suspect it may be quite hard.
- Custom fastenings (well, standard bolts/screws, obviously) are made for some of the crtical joints.

The price of this is that the galvanised coating has to be cut - but then that's true where you would cut it to length, so I don't see that as a big negative.

I'll sketch up what I'm thinking so everyone can see and comment.

Andrew
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Postby Miriam C. » Sat Mar 11, 2006 9:02 am

Andrew, thank you againl. I would love to see what you have worked up. I agree that the connector(brackets) will need to be special.
Were you able to get to the Thomas and Betts site? I got bleary eyed just looking at the different types of brackets. I will try to do that again and get to the store to get a cad program. This :throw PC: is too slow to download the freebees. Hopefully I can find a cheapy and remember enough to get it to work.

I am not too worried about a rusting problem as My Mike assures me I will kill myself doing this. :lol: I have suggested he buy more insurance so he can finish the build in my honor.

Chuck
I need to correct my statement on the last post. We were discussing tongue attachment not axle. I was moving on too fast in my thinking.

The tongue seems to be the least of the problems. As long as the sides and crossmembers are connected well the tongue should just bracket on.
This stuff can come welded from the factory in a number of configurations, I am not sure where to buy just one stick, and buying a hundred is out of the question. :cry:

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Postby angib » Sat Mar 11, 2006 6:44 pm

OK, here's what I've come up with. This is a 'throwing open for discussion' sort of thing, not a 'comes with a money-back guarantee' sort of thing!

Image

I think the A type section on its side is enough for the main frame of the trailer - it's really just something to bolt the other bits too. There is a nice connector AB213/214 that looks like it was designed for making teardrops as it has an extra hole to bolt the trailer floor to.

The A-frame tongue is made from E section standing upright (open bottom) and is at the 'standard' 50 deg angle - this means a standard 50 deg coupler should be able to be bolted to the front end of these pieces (if a drill will go though it, after it's been stamped). The A-frame is intentionally kept short (24") to keep it strong. The exposed ends of the tongues are not pretty, although they could be cut at an angle to lessen their visibility.

The connection between the tongue and the frame is pretty critical and I don't think any standard fittings will do. A combination of a good quality 3/8" hex socket cap ('allen') screw and some bits of 1-1/4" x 1/4" flat bar should do:

Image

It has to be a hex socket cap screw because a 5/8" AF socket spanner won't fit between the flanges of the E section, so a normal hex head bolt/screw can't be used. The top illustration shows a piece of 3/8" flat bar, tapped to take the screw directly, while the bottom one has a conventional nyloc nut. I think a 3/8" screw is probably enough, but it's possible to get a 1/2" screw in also:

Image

The 1/2" version is what would be used to fasten on a torsion axle to the main frame. A leaf spring axle could probably be fitted with some short lengths of E section fitted the same way as the tongue.

Andrew

PS Miriam, don't walk lightly into a CAD program - learning to use that is probably at least half as much work as building a teardrop.....
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Postby Miriam C. » Sat Mar 11, 2006 11:20 pm

:thumbsup:
Andrew that is impressive. I will have to study it more when I get more than 3 hours sleep. I think this will work. Mike is going to look at it and determine if he knows anyone with E series in stock. He personally has never had one pass through his hands in 30 years or wholesale elec. work. Really big stuff. He is fairly sure there is none anywhere near here. What we can't read on the website or catalog is, it is special order. The factory doesn't stock because it is rarely used.

I like the A tongue better than the straight. How is that going to work backing and turning as short as it is?

The ab213/214 do look like they were designed for us. Will the floor need to be drilled and bolted in the middle and down the sides also? Places other than the corner fixtures.

I haven't thought about axles because if I jump ahead something will get left out. I think the easiest to install will get the vote. I am still looking for a strong person who knows what they are doing for that part. May have to have that part done at the local muffler shop.

We got the CAT back on Mike and he will not be lifting in my sight until the DR says he can. We are also anticipating the very early birth of our next grandchild. I have been sharing shifts with my son at the hospital, so we're getting precious little sleep.


For those of you who have never seen Superstrut, look up the next time your are in a box store with lights hanging from squared tube stuff. They run the wires through it, no conduit needed.

I am not sure I can even drill this stuff but the plain cost even less for me than the slotted. Good job Andrew! :applause:

Andrew,dear, The CAD has indeed changed a great deal. I took and intro course in 1989 and did fairly well. Don't remember a thing!!!! I got a cheappy Turbo Cad. (My dialup is too slow to get it free.) :throw PC: It is amazing how different it is. Took Auto and Micro CAD but that was in the dinosaur age. :
I will play with it while I try to stay awake if they let the kids come home. Fortunately it comes with a tutorial.

One things for sure, I am going to have one really equipped shop by the time this is built. That alone is worth the work. :twisted:

Have a good night. I am going to sneak to sleep before anything else happens.

Miriam
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Postby angib » Sun Mar 12, 2006 5:21 am

....E series....Really big stuff....

OK, if you twist my arm, I'll say the A1200 might well be enough for the A-frame too - it is stronger than 2"x2"x3/16" angle, but is only as stiff as 2"x2"x1/8" angle, so it might be a bit bouncy.

I like the A tongue better than the straight. How is that going to work backing and turning as short as it is?

This A-frame length allows the car and trailer to get to a 45 deg angle, which I think is more than any commercial trailer allows. It won't be great to back up, but that's much less of a problem than it not being strong enough!

The ab213/214 do look like they were designed for us. Will the floor need to be drilled and bolted in the middle and down the sides also?

No, I think bolting just at the brackets will do, though some through the side members around the axle mount wouldn't be a bad idea.

I haven't thought about axles because if I jump ahead something will get left out. I think the easiest to install will get the vote. I am still looking for a strong person who knows what they are doing for that part. May have to have that part done at the local muffler shop.

If you can assemble the frame, you can fit the axle - it's just four 1/2" bolts into the frame side member.

I am not sure I can even drill this stuff but the plain cost even less for me than the slotted.

Yup, drilling big holes in this metal is not to be taken lightly, but it's not rocket science.

Andrew,dear, The CAD has indeed changed a great deal. I took and intro course in 1989 and did fairly well. Don't remember a thing!!!!

OK, scrap my previous comment - if you've alreay learnt CAD, then you (did) understand the principles and that's at least half the learning task. Cheapy TurboCAD is exactly what I use - it does the job.

Andrew
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Postby Miriam C. » Sun Mar 12, 2006 8:56 am

Good morning Andrew, (afternoon)
Andrews concern:
:
but is only as stiff as 2"x2"x1/8" angle, so it might be a bit bouncy.


OK! Stiff. The factory prewelds units together so you are not losing the galvanizing (10ft sticks). Trick will be to not have to order a 100' and have to sell 90'.

My breakfast discussion with Mike C. was cutting and rusting. He tells me the contractors don't worry about it because it is electroplated. (I wish I had stayed in the business.) The electroplating on welded pieces is done after the weld. Factory welding is spot welded every three inches. This is the reason elect. contractors quit using GP (green painted stuff, which I think is powder coat).

(ugly sides?) I can try to bolt the sides on the frame to cover the places where the tongue and axle show. If I remember with the benroy one needed to cut some inches off width to accomodate the sides. This will allow for screwing into the sides of the floor also. Sound good??? This assumes I can drill it of course. I think I will ask one of the contractors for a small piece to practice on. Get thier advice. If I am real lucky they will let me in thier shop. :twisted: (Insurance co.'s will probably have that messed up from the start.)

If the axles are that easy, consider it done. Bolting stuff together is playing for me. My darling Grandson (14) thinks he and his friends might beat me to it. Seems they have been experimenting with making a trailer with bicycle wheels and boards. He spent hours looking over the benroy plans. They have offered thier highly experienced help. (They have created some really funky bikes and one even welds.) :twisted: The parents will no doubt kick my door in any day now. That or will build thier own.

Enjoy!
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Postby Miriam C. » Sun Mar 12, 2006 5:51 pm

Hi all,
I have changed the subject to reflect the name of superstrut at the box stores. They are simply calling it channel. This looks similar to the stuff you build shelving out of but it is not. It is much larger and neither myself nor, I am sure, Andrew would want you to mistake the two. This stuff is really big and weighs 19 pounds per 10 foot piece.

I apoligize if anyone is offended, I don't mean to imply that anyone doesn't know what we are talking about, if they do. However, I am very aware that in the pictures the two look alike. When you really look at the Superstrut, in person, the differences are clear. The other reason, is that the employees, those that thought they had a clue, sent me to the shelving dept.

If you have an interest in our mental build, you can find it in the plumbing section. 12gauge - 1 5/8 x 1 5/8 is what we are looking at, but without the slots. Lowes sells the half slotted 10ft. for 19.95 and 6ft. for 14.95. It looks big because it is. Because of the dynamic load properties, Andrew has suggested the 12g. I am still reading the catalog and trying to make sense of the load allowances.

We, Mike and I, really appreciate the help we are getting and hope you all enjoy the process with us.

Miriam
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Postby Chuck Craven » Mon Mar 13, 2006 8:38 pm

I took a closer look at that Superstrut. It is made from 12G cold rolled steel, 0.102” thick that is run through a rolling press to form the strut. As fare as I can tell the part has a rated strength the same as cold rolled steel sheet, before forming. Cold rolled steel has a dynamic bend ratting much lower than hot rolled steel. Another words when it bends it stays bent. It has a low memory, if bent past its low spring back point it will not return to a neutral state. That is what makes it easy to cold form with out stress cracking. I think if you use it for the tongue it will fail. It looks to me that it will take about 1500 lbs to bend it. That can easily be exceeded by hitting a pothole at 65 mph in the road with a 700 lb trailer and a medium size tow vehicle. You may want to think about a different tongue structural steel material, like a square tube. I could not find any information on using Superstrut for anything but static structural support use.
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