DIY help needed.

[David D]

I am not an engineer or an engineering student. I am working on a DIY project in which an 2 foot long angle iron will be secured for 15 inches and the other 9 inches will be sticking out in space. My question is how much weight will the angle iron support at the end (9 inches from support)? The size I wish to use is 1 1/2” X 1 1/2” by 1/8”. For comparison, how much if the metal was 1/4” thick?

Any and all help will be appreciated.

[RWOLFEJR]

Hi David and welcome to the forum.
Your gain in strength will be next to nothing bumping up to 1/4" thick. You will get the most gain by bumping the size of the vertical leg. For example you would double the moment of Inertia (That's a key number in determining the load carrying capability of a member) by bumping up to a 2" x 2" x 1/8" angle vs. the 1-1/2". Angle iron isn't a very good choice for a beam... especially a cantilevered beam. Also as you load it it will start to twist. Throw a gusset under the extension and you'll beef it up a lot.

Without knowing what you are doing with this... dangeling a basket of puppies over the side of a cliff vs. maybe hanging a pot of flowers off your deck... A person can only guess as to what sort of safety factor to plug into the piece. I will tell you... both a basket of puppies and a flower hanging basket will be pushing the maximum that your selection of material will handle.

When considering something like this it's a good idea to think...
"What does my gadget weigh that will be on this support?"
"Will a person ever have any remote chance of hanging off the thing along with the intended load?" (usually yes...)
"What is my total weight possible?"
"Better double that...? Triple that? (safety factor) Four times?"
"How will the load be applied?"
... And possibly several other things to take into comsideration... Then make a material selection based on the load and envelope you have to work in.

Don't want to steer you wrong and without knowing all of the conditions surrounding the situation, giving you any definite load would be ballpark at best.

Good luck!!
Bob

[David D]

Thanks for the reply, Bob. My attempt to keep from being verbose in my original post caused me to provide too little information. Here is the opposite approach.

The angle irons are for hooking a ramp onto the edge of a trailer. The trailer is 4' x 6' and I am placing a piece of 1/2” particle board 4' x 6' 8” in it to slightly extend the bed (8”). I will be hauling a motor scooter which will have the front tire against the nose of the trailer and the rear tire over the bed of the actual trailer. I need the extra 8” to allow a chock behind the rear tire. Chocks will be secured to 2 x 4's (next paragraph).

I will be securing two parallel 2 x 4's (x 6' 8”) in the center, spaced 5” apart, to keep the tires from slipping to the side during travel. The plan was to secure two angle irons under the outside edges of the 2 x 4's. They would be 24” long with 23” sandwiched between the particle board and the 2 x 4's at their outside edges. The additional inch would stick out the back with a 1/2” hole for a stud on the ramp to fit into. The securing of the angle irons to the 2 x 4's would be with holes drilled through the irons and wood screws into the boards.

The scooter weights 400 pounds (maybe a bit less) and it would NOT be driven up or down the ramp. Also, the trailer is low enough that the ramp need not be more than 4' long. Since the wheelbase of the scooter is over 4 1/2' the front wheel would be leaving the ramp as the rear wheel would start onto it.

The reason I wanted to use 1 1/2” angle irons is so the vertical would not stick above the boards. However, if I need to use 2” irons I can live with that concern.

I realize that the particle board is providing some support and that the angle irons will be screwed to the underside of the 2 x 4's (providing a little more support). The reason I said (in my original post) that the angle irons would be “sticking out in space” is because I was trying not to rely on the wood for support as I have even less knowledge of wood strengths.

So, for weight: 225 pounds (the max weight likely to be on either wheel if it is not distributed evenly) divided by 2 (the number of angle iron supports being used) = 112 1/2 pounds. Would that be right? (Yes, it would be more than a basket of puppies. ) Would the 2 x 2 x 1/8 support the 112 1/2 pounds?

[PinkertonD]

Hi David,

I think the angle iron you have in mind should be OK for an 8" overhang even though at some point there will be the weight of the scooter on it. That's a guess mind, you but it is an almost static load and if in doubt go up to 2" x 2" x 1/8".

The other point I would want you to check is the ramp. The length of it is not a simple wheelbase of the scooter issue. You need to consider the "hump" when the scooter is about half way onto the trailer. That's why you see ramps like this...
mf11014-1.jpg

Notice the lump, it is there to lift the back wheel up as the scooter moves onto the trailer and stop the belly scraping or worse, jamming and not going anywhere.

[David D]

The other point I would want you to check is the ramp. The length of it is not a simple wheelbase of the scooter issue. You need to consider the "hump" when the scooter is about half way onto the trailer. That's why you see ramps like this...
mf11014-1.jpg

Notice the lump, it is there to lift the back wheel up as the scooter moves onto the trailer and stop the belly scraping or worse, jamming and not going anywhere.

Thanks for the advice, PinkertonD. The trailer is quite low and I calculate an 18 degree angle at the bed/ramp junction. I've yet to find the clearance of the scooter. If I find the 18 degrees is still to much, I'll use a six foot ramp and the angle will drop to 12 degrees. Of course, the longer ramp will mean the entire weight of the scooter will be on the ramp at one time. For that reason I will definitely go with the 2" angle irons.

[PinkertonD]

I'll use a six foot ramp and the angle will drop to 12 degrees. Of course, the longer ramp will mean the entire weight of the scooter will be on the ramp at one time.

Umm, not so quick there Hasty-Man! There is a big difference between half the weight on a 4' ramp and all the weight on a 6' ramp. Engineering is not a simple matter of twice the load twice the size.

If you need help, then you need to tell us exactly what you have and plan to do. A drawing is always a big advantage in getting things correct and safe the first time.

[David D]

Yes, I was going to attach a drawing with my second post. However, if there is anything I am REALLY bad at, it is sketching (and I don't have AutoCad). I definitely appreciate the advice about the hump. I admit to not having thought about that. Since your excellent advice, I was able to determine the 18 degree hump would be no problem for this scooter. I checked with another owner who has trailer bed 3" higher than mine and uses a 4' ramp. He told me he has no scraping problem. Therefore I'll stay with the 4' ramp.

I do realize that twice the size does not mean twice the strength. For instance, the ramp itself, if exactly the same as the shorter one (except for length) would be weaker in the middle.

Thanks again for the help and watching out for me.

[RWOLFEJR]

This might be a stupid thought... but any reason why you can't just run the thing up at the right corner and go caticornered with it on the trailer? Might be easier than messing around with the extension?

Also... you might want to consider just buying a cheap-o ramp rather than making one? You could buy one that'd be rated for "X" weight for probably near same $ as a full sheet of wood these days?

Just tossing it out there...

Also... if you have the bike vertical when you strap it down and pull it into it's spring / shock travel about half+ way, you'll have next to no chance of it kicking out on you. If it gives you the warm and fuzzy feeling it can't hurt but I wouldn't get to worked up about it.

[David D]

Not at all a stupid thought. I had, for a few fleeting moments, considered the diagonal option when I first acquired the trailer. I guess you might say I'm a STRAIGHT and narrow kind of guy so the idea slipped away rather quickly.

After reading your post I did a bit of research on the idea. It would appear that it can be more difficult to load and unload this way. Another possible problem is it may be harder to tie down securely. I think that was probably my primary concern.

As it happens, I already have a 4X8 sheet of 1/2" particle board which I used as a temporary fence for a short time some months ago. It has been doing nothing but lazily taking up space since then. As for buying a ramp, that is also something I had considered. I have been looking for one at a very cheap price to no avail. Your comment nudged me to remember a local motor sports shop that is closing it's doors. I called but they had no ramp. Then I looked online again and found a dealer with a clearance item that was real cheap, even with shipping. I ordered it.

Will I go diagonal? Maybe. The scooter would barely fit at an angle but I should be able to reinstall my tailgate. Either way, I will use 2X4's to prevent sideways movement. It may not be necessary but I'll like "the warm and fuzzy feeling."

As with the other posters, you have been very helpful.

Thanks to all of you.

[PinkertonD]

I do realize that twice the size does not mean twice the strength.

Actually David, what I meant by that was that because you were upping the length by 50-percent to 6', increasing angle iron size by 50-percent might not be a good solution. All moot now since you have a ramp on the way.

Happy to help.

[athoke]

Hi David and welcome to the forum.
Your gain in strength will be next to nothing bumping up to 1/4" thick. You will get the most gain by bumping the size of the vertical leg. For example you would double the moment of Inertia (That's a key number in determining the load carrying capability of a member) by bumping up to a 2" x 2" x 1/8" angle vs. the 1-1/2". Angle iron isn't a very good choice for a beam... especially a cantilevered beam. Also as you load it it will start to twist. Throw a gusset under the extension and you'll beef it up a lot.

Without knowing what you are doing with this... dangeling a basket of puppies over the side of a cliff vs. maybe hanging a pot of flowers delivered uk off your deck... A person can only guess as to what sort of safety factor to plug into the piece. I will tell you... both a basket of puppies and a flower hanging basket will be pushing the maximum that your selection of material will handle.

When considering something like this it's a good idea to think...
"What does my gadget weigh that will be on this support?"
"Will a person ever have any remote chance of hanging off the thing along with the intended load?" (usually yes...)
"What is my total weight possible?"
"Better double that...? Triple that? (safety factor) Four times?"
"How will the load be applied?"
... And possibly several other things to take into comsideration... Then make a material selection based on the load and envelope you have to work in.

Don't want to steer you wrong and without knowing all of the conditions surrounding the situation, giving you any definite load would be ballpark at best.

Good luck!!
Bob

I absolutely agree - you always have to be aware of the weight you put on it and the conditions connected to the situation because you could definitely find yourself trembling in trouble because you miscalculated the situation and the weight.