Homemade bridging ladders

2drx4

Adventurer
I searched a bunch and didn't really come to the results I was looking for. There's lots of sand ladders, and there's plenty of short bridging ladders made from various materials (the fiberglass grate ones look pretty reasonable for short sections), neither of which are what I'm looking for.

I need something longer. A 4' ditch is not an obstacle to me. 6'-8' is about what I can fit on the vehicle, and what I would like to do, with longer being more useful.

Vehicle weight is about 4200lbs with me in it, 5000lbs is more reasonable for an actual in-use weight. Keeping these light would be better, as I'd rather not strain my back moving them around, and every pound of weight is another pound of weight that's useless most of the time.

I can't weld aluminum... Or at least I've never tried, and I'm not super stoked to buy a spoolgun just for this. I do have hole saws and dimple dies.

I was thinking two pieces of 3x3x.250 L in 6061 for the outer edges (about 26lbs there per ladder), a 1' wide strip of .188" sheet between them (about 20lbs, would blow some material out with the holesaws and punch dimples for traction), and 9' of 2x2x.188 L for braces running perpendicular to the length (9lbs or so). Fastened together using whatever I find lying around the shop, er, no, 3/8" bolts/nylocks and some cherrymax rivets. Hopefully around 55lbs per ramp, maybe a little less depending how much material I can remove with the hole saws.

I will produce a rendering of this in M$Paint if anyone is too confused.

Do people think that will be too wimpy for an 8' length?
 

Ducky's Dad

Explorer
I am not an engineer, but my guess is that substituting 2x4 L for the 3x3 L would give you more resistance to deflection with no change in weight, using the 4" leg as the bottom chord. When you fasten the top plate, try to spring a slight arch into the ells to pre-tension the top plate. An 8-foot span is a lot for 5000 pounds. 2x4x0.25 could be cut from rectangular tubing if you can't find that dimension in an L.
 

2drx4

Adventurer
The way I see it, you're never actually bridging 8'. It will always be less as there has to be something under each end to support it. Also, it's not 5Klbs per ramp. My wheelbase is over 100", so you shouldn't be able to put all 4 tires on the ramps at the same time. Also, the load is again divided between the two ramps. So I would say a more reasonable number is 1500lbs per ramp, max unsupported distance is 7'.

Feasible? I don't know, I can't eyeball engineer aluminum as well as steel.

I do see your point on increase the section height of the angle. I'm not sure what dimensions are available locally, I would have to look into it. I picked 3x3 because I know that is a normal size.
 

El Solis

Adventurer
Save your time and effort, go with Crux bridging ladders. They come in 63in length and have heavy duty options. I got the short pair and they are awesome and work as a traction device as well. I have used them for my Defender 110 and wife's LR4. I have no affiliation with them other than a happy customer. I will promote my Land Rover club though. Norcalrovers.org

Cruxoffroad.com

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El Solis

Adventurer
Just throwing out options. You said you couldn't weld aluminum and these aren't welded so could be a design option for you. I might be bad at math but I did know they weren't 8ft long. my 4 yo assembled them
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2drx4

Adventurer
Curious how thick the material is, and how tall the channel pieces on the sides are? Because I can certainly clone them, I would just need to make a pressbrake (on the to-do list anyways).

Half the reason I don't want to buy something that's off the shelf is I live in the middle of nowhere, and there is no such thing as free shipping for me...
 

El Solis

Adventurer
Reach out to Jeremy the owner of Crux. He might be able to send you some actual specs or work something out for you. He's just starting this company and I'd like to see him succeed as I think he has an excellent product and I always prefer to buy from the "little guy"
 

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