What are you up to in the workshop?

Cost I'd say, box section, particularly bigger ones are the dearest steel profile of all to buy due to them having to be welded during manufacture.
 
Anyone know why some trailer manufacturer's use two pieces of channel welded together instead of a single piece of box for a drawbar?

Cost I'd say, box section, particularly bigger ones are the dearest steel profile of all to buy due to them having to be welded during manufacture.

It may be cost.

However I have a feeling the channels welded together may have more "Meat " , ie substance in them. Definitely thicker on the corners , and bottom and top. Sides probably the same thickness.
 
I'd rather a box section with a consistent 8mm wall and one robotic weld than 2 channels with 10mm flanges and 6mm webs and 2 possibly dubious welds
 
Most of the trailer manufacturers now use box as far as I can see.
Box would be kinder to the tractor tyres too as you have a rounded corner rather than square of channels
 
Anyone know why some trailer manufacturer's use two pieces of channel welded together instead of a single piece of box for a drawbar?
I would think it has to do with the difficulty in welding anything to a heavy wall box which has large radius corners. Take for example a flat plate being welded onto the bottom of the box for an axle. You can only get a proper fillet weld on approx 45% of the perimeter, whereas with a square corner on two channels you can get a proper fillet on 100% of the perimeter.
 
I would think it has to do with the difficulty in welding anything to a heavy wall box which has large radius corners. Take for example a flat plate being welded onto the bottom of the box for an axle. You can only get a proper fillet weld on approx 45% of the perimeter, whereas with a square corner on two channels you can get a proper fillet on 100% of the perimeter.
Don't see many axle brackets welded to a drawbar :whistle:
 
Don't see many axle brackets welded to a drawbar :whistle:
I was not speaking specifically about a drawbar but trying to explain my thoughts on why the use of box section is not as good as two channels. Weld inches if you understand my point or lack of.
 
The reason for it in some cases is instead of being made from a length of channel, they're usually flat sections folded into the shape of channel using a pressbrake. The flat section being usually cut out with a cnc plasma cutter. This way of doing it is quicker, cheaper and more accurate.

Secondly, if you cut open one of the drawbars, they're usually folded over at the other edge. I've attached a picture of the cross section. It may not look like much but the piece in the middle helps strengthen it.

A trailer drawbar can be thought of as a cantilever beam in bending. A measure of the resistance of the beam to bending is known as the second moment of area, and is related to the cross sectional area of the section. Basically, more material or more meat means more strength. Because of that bit in the middle, it would be stronger than box section of the equivalent external dimensions X and Y and the same wall thickness as in the drawing.

IMG_20191007_104205.jpg
 
I was not speaking specifically about a drawbar but trying to explain my thoughts on why the use of box section is not as good as two channels. Weld inches if you understand my point or lack of.
Yes I did get your point but the question was raised in relation to drawbars, most chassis rails are made from channel.
 
Fine job.
Did you weld all that with a stick welder.
Aye stick welder. About a box and a half of Hilco rods gone into it.
Nice job, there's a few boxes of rods gone into that one! Is it 100mm box iron with 10mm wall? I'd put a full length 100x10mm wear plate underneath also, a strip here and there won't last with a heavy loader.
80mm box all round MF. 8 mill box in the bottom and 6 mill in the rest of the frame. It's a fair weight at that and we reckoned it's more then enough. The tines will snap before the frame twists.
 
Aye stick welder. About a box and a half of Hilco rods gone into it.

80mm box all round MF. 8 mill box in the bottom and 6 mill in the rest of the frame. It's a fair weight at that and we reckoned it's more then enough. The tines will snap before the frame twists.
Plenty strong alright. I made one in 2003 for the 3cx and used 100x100 x 10 mm wall to make it heavy as the 3cx can be very light on the front if you haven't got half a ton of an implement hanging there. I made mine as an 8ft wide dung fork and has 13 KV tines on the bottom and two each side. Cost me €800 for materials alone back then, it was the first time I ever used a Mig welder I remember.
 
Plenty strong alright. I made one in 2003 for the 3cx and used 100x100 x 10 mm wall to make it heavy as the 3cx can be very light on the front if you haven't got half a ton of an implement hanging there. I made mine as an 8ft wide dung fork and has 13 KV tines on the bottom and two each side. Cost me €800 for materials alone back then, the first time I used a Mig welder I remember.
There's 18 tines in the bottom and the 4 side ones and for them along with heavy duty ferols or bushes the price was 1130 inc vat. Haven't paid for the box iron yet but the total cost will be under 2k all in anyway. 7ft 7 in width.
 
What's the bit of flat iron on it edge between tine 5 & 6 and 13 & 14 for, did you drill it yourself?
It's to help put a bit of extra strength into the bottom box iron. The quick hitch brackets at the back were made with a 6 inch tail on each that likewise is welded onto the bottom box as well for extra rigidity. We got a local metal fabricator to plasma the holes.
 
It's to help put a bit of extra strength into the bottom box iron. The quick hitch brackets at the back were made with a 6 inch tail on each that likewise is welded onto the bottom box as well for extra rigidity. We got a local metal fabricator to plasma the holes.

Was there much lineing up of the bushes or were the holes accurate ? Is the much of a price difference buying the box with bushes already in ?

Looks a tasty job weather would want to dry up fairly quick
 
Was there much lineing up of the bushes or were the holes accurate ? Is the much of a price difference buying the box with bushes already in ?

Looks a tasty job weather would want to dry up fairly quick
The holes were fairly accurate but just to be sure we had all the bushes and tines in place on the floor before tacking them in place. I would say there's about 1000 to 1200 saving on that size fork over a bought one.
 
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