11'6" three berth ply/foam/aly composite caravan

[hossesdad]

thanks KC. For me, welding offers surprises, few of them good. I had a lesson forty years ago. I made a bracelet out of welding rod. The welder didn't offer me a second lesson, I think now he was telling me I should quit while I was ahead.

[hossesdad]

squared the frame today. Found two tapes, four clamps and a club hammer useful. once welded, checked, was out by less than 1/8th" on the diagonals.



Grinding, fitting and welding the cross-members.



when it came time to turn the frame over, I got out the Kubota and the boom pole I made a couple of years ago. Pole lifts 1000lbs half way out from the tractor. Every bit was cut from something else except the three point pins and the chain. You will see a towball on there, handy for taking the trailer to pick things up with the pole. Frame isn't heavy, I can lift it, but it is awkward.



Frame upright. I will hang it upright again later to get the fillet welds on the cross members.



The frame lying upside down. I don't have helpers, it is all done myself.



Close up of thje boom pole in case you want to make one. There are slightly more opinions on boom pole design than there are on teardrop design.



If you want to help me line the a-frame up, come on over. Don't let the fact I am in New Zealand stop you

[hossesdad]

ebi, my daughter, helps me with whatever I am doing, she wants to put a smiley face or too into a post so here goes. she says she wishes you a merry xmas and a happy new year ! (she's six and two months). (Yes, it isn't Xmas here either).

Children are fantastic, with their help you can do in an hour or two stuff that used to take ten minutes

[hossesdad]

tried the torsion axle and a wheel out for size. Might change the tyre for something lower profile yet. The rig is still upside down here, of course.



welding on the frame was practice for welding on the drawbar. Took KC's advice and stuck with 6013 rod. I have an inverter welder, changed over to DCEP. 120 amps on 3.2mm rod. Nicer welds, it's a good BOC/ Linde machine. You can see in one of the pics that like many amateurs, starting and stopping is the problem. I can only weld left to right and just about only horizontal! But every project I learn something new.





where the torsion axle halves go, I added gussets and ran 3mm flat plate along both sides of the frame rail. As much as anything, to stop the well torqued high tensile bolts and high tensile washers crushing the 2 1/2"x 1 1/2" x 1/8th" tubing rails. I have some infilling and grinding to do on this section.



The tongue is 125% of Angibs minimum and I feel good about that. 75x50x4mm tubing (three by two by 3/16ths inches). (It is about 1400mm long to allow for a big box on it). I took a deep breath and said a small prayer whenevery I welded there. Came out okay, I think. This is the coupling plate before the grinder and the high speed wire brush get to it. What do you think? Tips always appreciated. (yes I have been naughty and struck the arc in the middle of the plate a couple of times to warm a new rod).



This is where we are at. I turned the rig right-side up with the tractor, doing some fillet welding in the horizontal position as I went. The gussets made of heavy angle iron (about 2" x 1/4") on the front of the first cross member are a tip a good welder once gave me. He said never to weld across the drawbar (he was fixing the sagging single pole drawbar of a very old trailer of mine where someone had done just that) and to do this instead. I have looked around and some very good trailers have this reinforcement. Most of the welding is underneath the angle iron, along the sides of the drawbars. Some minor welding to do elsewhere and then off to the galvanisers. While they are hot dipping it, I will be starting on the walls.

[KCStudly]

Welds look good!

[hossesdad]

Thanks KC your encouragement helps.

I wish we had the range and prices of tools and materials that you do in Humerica. I have been using a box of MIlwaukee Thunderweb drills and they are excellent, but the range 1mm to 13mm in .5mm steps costs $140 NZ here. I am travelling to Tallahassee and Minnesota in June, my luggage for the homeward trip might include a Milwaukee brushless li-ion drill to replace my twenty year old Makita and other stuff. (Mind, I have a Hitachi E5OV, it it?, corded drill and that is hard to beat, it is quality writ large. It will put a 25mm auger through a 250mm dry treated pine gatepost without complaining, if your wrists hold out )

[KCStudly]

How do you convert the power supply for the battery chargers to work on your household voltage/current?

[Johnysteam]

Looks good mate. Whats the thickness of your coupling plate?

[hossesdad]

How do you convert the power supply for the battery chargers to work on your household voltage/current?

I have a step down transformer, subject to wattage that would do it. But you have a good point. I can buy bare tools and batteries in your country and buy the charger here, depending on brand. It may just be greed and meanness that are driving me. Warranty problems, hassle, and the problem of persuading people 5ah batteries can go in a plane (there are several flights in this trip) might make purchasing tools here wiser.

[hossesdad]

Looks good mate. Whats the thickness of your coupling plate?

Like your build, Johnysteam. The coupling plate is 10mm thick, about 3/8ths I think. It comes from the coupling manufacturer... Oddly they were out of stock locally so I would have been quicker to make one.

[hossesdad]

I finished the chassis today and lifted it out of the back. It is flying high to get above the gateposts on the turn.



I popped it on the top of my utility trailer. It overhung all round but its legal; I hung flags on the corners, strapped it down tight and drove it twenty-five miles to the hot dip galvanisers. I towed it with my wifes car; if I had stopped quick and the chassis had shifted into the car, I was planning to keep moving and just leave town.

[hossesdad]

Having said goodbye to the chassis for a week, I went back to working on scarfing the floor. My favourite tools for this are a small electric planer and a big Makita belt sander.



Fitting up was fairly hard, the boards weigh quite a bit and I was on my own. Turning them over to sand some more lost its pleasure pretty quick. I might have made a better job of fitup if I had waited for my wife to come home (its saturday and she is in town with Ebi). But I like to get on, I try not to get hung up on details. I had ripped up some 16' 6x2's into 2x2s which will go on the bottom of the walls later, meantime they help for supporting the floor.



We got there. It is quite a big caravan, as you can see from the floor, , although I have one foot to trim off the length and six inches to come of the width ....an allowance for for my idiotisms, It seems important the floor is square so I am going to cut it square, it is hard to square it when glueing. I am going to build the walls on the floor before I cut it and and the extra space will help when I am glueing and cramping.

You might wonder why I am building a bigger caravan. Actually, my wife and I have agreed I will do a lightweight teardrop later on for the long distance runs. The caravan is the minimum three of us can go skiing and sailing from and my wife can use it when she is working away somewhere....she loves privacy and having her own things around her. I have plans for ten years for the caravan, then Ebi can have it, so I want it to last.



I put one coat of epoxy on the scarfs and let it sink in, then redid any dry bits.



I have minipumps on the epoxy and hardener, from West, a great help. One squirt from each =a good mix. If I was doing bulk I would weigh it too.



This is the colloidal sillica going in to make glue. As Swoody said earlier in this thread, epoxy is just a coating until you thicken it. The real beauty of epoxy is it keeps its strength as you fill gaps with it, provided you mix in the right filler.



I finished the glueing and drove about ten screws each scarf and added a clamped beam to put on a bit of pressure, not too much. We have money laid aside for a 1400 sq ft shed but I haven't got around to building it It was a scramble with the covers when the rain came



The area of our property where I am working is run down, it is due for renovation next summer; that end of the house is being knocked down and rebuilt which is why the gutters leak, the concrete is ancient and most things seem to be falling down. I aint painting it just to knock it down

I am interviewing tomorrow but I might start the walls next week. I may have to do a design first! So far I have been keeping my options open.

[hossesdad]

Thanks, swoody!

I'm playing around with laying up fiberglass on foam (XPS). The foam needs to be heavily textured to get decent adhesion, and I figure I might as well use an epoxy-silica paste spread on to fill the texture before the layup. Saves some weight and cost, and seems like it ought to work. What do you think?

sorry, rruff, I thought you were asking swoody, so I didn't reply! INow I have got to the point of making a decision about glues and your question rang in my mind. I have come back to thinking of using an epoxy silica paste to glue on the skins. I will try it tomorrow in a larger scale test on both foam and ply and foam and aly and post my experience in a few days. I have tried all the possible glues, I like gorilla and P5000 or its equivalent here (can't remember whether P5000 is the old one or the new one right at this moment, and its dark outside), most of them would do, results are impressive, but I cannot see any reason not to use epoxy, bit cheaper than good glue, strength higher, flexibility is taken care of by the foam in a careful design, spreading isn't harder and clamping needs about the same or less. People have suggested epoxy isn't flexible enough but it holds together wooden canoes and big boats and those seams work like crazy. A boat going over waves would be like a caravan picked up from both ends and shaken in giant hands.

Or am I missing something, or even several things? It happens. If I am, let me know now. I shall be forever grateful. I am not afraid of mistakes, I have got used to them

But perhaps your question is whether you can use polyester resin on top of epoxy in a layup. Swoody would know likely the answer, I don't, but the boat building fraternity don't believe in it, eg:

http://www.boatdesign.net/forums/boat-b ... 21806.html

I cannot see any reason why an epoxy fibreglass layup wouldn't stick to filled epoxy, in fact, there are places in boats where that is usual (over the silica/epoxy fillets in stitch and glue designs, for example, it is usual to put fibreglass reinforcement and in those small areas, it is always epoxy). Boatbuilders are demanding of performance, as one should be when delamination could drown your family, as opposed to lightly sprinkle them with leaked rainwater. , so I don't think your walls will come adrift.

I will have to get on to your threads tomorrow, rruff, and find out where you are at.

[hossesdad]

Decided to work indoors on the walls and roof and consequently to do the two side walls and the roof in halves. Therefor needed a 8'x6'6" trestle table so cut down a big 2x6 (which we call a 50x150) into 50x75's and made up two 1600mm wide by 815mm high sawhorses and those, with some cheap ply i have in stock, will form a comfortable height worktable in a spare room that is stripped to the bone for renovation so won't mind a bit of sawdust, foamdust, aluminium filings and epoxy.

Here are the oversize sawhorses. (I have planed the tops flat since the photo). The only sophistication is that the crosspieces are routed one inch into the legs.



Business took up most of the day, next thing is put up the table and get the vacuum pump ready for 3 or 4 psi vacuum bagging

Here is the vacuum pump, retired from a dairy farm. It works (thanks, Ben). It is a vane pump, very interesting, the cylinder is eccentric and the vanes sweep it from slots in the axle or pivot, staying in touch with the outside by centrifugal motion, I guess, Bens dad says if the vanes stick, run kerosene through it to free them. But it pumps a vacuum right now, there doesn't seem to be any sticking. In a dairy it must have pulled a big vacuum for three or four hours at a time, I need a small vacuum for three or more hours. I may use some pulleys to run it just fast enough, run it off an old central heating motor I have (about 3/4hp horsepower), maybe fiddle it to make the electric motor run slow. Any smart ideas, anyone? It is the only vacuum pump I could get and it is too big for the job. Not going to risk my good vacuum cleaners. How do you make an electric motor run slow without ruining it? (Can't ruin the motor, it is heading for the concrete mixer and a life of labour although it is lazing about on the floor of the shed and doesn't know it yet.). I have a 2.5horse compressor motor but that is too much power for the tiny vacuum I need.



And here, at a cost of $535 NZD, is 28 square metres of 0.9mm 5005 aluminium. I was going to use harder aly but I got some and tried working with it (bending lengths over an edge) and it was too tough on me.

[KCStudly]

Nice pump! It has a pretty big pulley on it so, so long as your motor is already relatively low speed, it might be just fine with a small pulley on the motor. Variable Frequency Drives (VFD's) are available for 3 phase motors but they are kind of expensive and there is a learning curve to setting them up. Also, to run them at relatively low speeds you want your motor to have at least Class F insulation, or better yet, be specifically designed for use with VFD's. I'm going to guess that your motor is single phase(?).

You could always rig up a jack shaft to step the motor down using another stage of chain/sprocket or pulley/belt reduction, but that might be a distraction that isn't worth your time.

Is there any label plate info on the pump? What speed does it want to run at? Same question for the motor. Once you have that it is simple ratio math to dial it in. (Which reminds me, you can also get adjustable rate V-belt pulleys; some are mechanically adjustable that lock in, others are spring loaded and can be adjusted on the fly using an adjustable motor base plate.)