Building a trailer

[Whatswrong]

,I m in the process of building a trailer from scap parts from work. The hubs are +/-3600 x4 on axles designed to carry 7000lbs minus hitch weight which I can't remember.I plan to buy 4 PR5 springs from e-trailer (5800lb axles rated) .The tires are trailer type I think about 3200lb. capacity .My frame is built out of 3x3x3/16 tubing for cross member as well as long ,8x16. It isn't a tilt bed,hitch is A frame style with a tongue to about 2 feet in front of front axle.8000lb jack,seems the tires are the weakest link ,I think my welding is average at least. As near as I can tell when the bed is completthe tires will only be about two -three inches above bed so will require about a 6" fender. This will be my first flatbed trailer.My main concern is if I will max out my pickup before I ever load the trailer.
Any comments will be appreciated

 

[Diamondpilot]

Tough to tell without detailed pics. Easier to fix now then later.

Chris

 

[sandman2234]

You can make or break it by how you use the metal. I have a trailer that is twice as heavy as it should have been simply because of the selection of metal and how it was applied and just how much bracing was added. The 3x3 tubing isn't ideal for typical trailer building, as the horizontal 3" is usually a little overkill for the 3" vertical capacities. A few ideas might be to purchase a channel of more depth (4, 5, 6 etc) to increase capacity for the same weight for the two main frame beams. You will be much happier with the trailer if you do! If you really want to cut the weight, and the 3x3 is free, consider setting up a sawing or cutting guide and make 3x3 angle out of it, but it would have to be free for me to want to spend the time/effort to do this. Use the 3x3 sq tube or angle if you do cut them as cross braces.
David from jax

 

[Whatswrong]

Sandman, in your reference to cross brace are you meaning diagonal bracing as I haven't done any of that?It was free but I still wouldn't put the energy into ripping them that sounds like a huge job ,it is already welded together ,will attempt some pictures soon.I have a vision of only needing to weld on spring hangers which I haven't purchased yet and fabricate fenders and ramps.

 

[sandman2234]

Very few people put diagonal bracing in trailers, though some incorporate it into the ends. The fifth wheel flatbed I just acquired has diagonal bracing on it around the neck, but that is almost a requirement on a fifth wheel trailer.
I was thinking that your two 8x16 runners would be best as a taller channel. There are going to be some weight concerns, compared to typical channel/angle iron construction trailers.
Before you start cutting up a bunch of metal, have you drawn out a plan of attack? If you have scribbled a drawing of this trailer on the nearest tabletop or scrap piece of paper, then figure out just how many pieces of metal, their lengths, and take that much metal and throw it in the back of your trailer and run down and weigh it. (before you cut it up). If the truck won't haul that much metal, then there is a good chance your going to be over weight for that truck. (Not always true, but a good discussion point). If you don't have all the parts to the trailer, figure out what the missing parts weigh and add them to your total. Check online for the weights of a 16 foot trailer and compare it to what your total is. Don't forget to add in the decking, screws, fenders, tires and axles, tongue jack, etc.
Adding up all of this is a lot of trouble, but nowhere near as much as building a trailer that is TOO HEAVY for you to use, so you just cut it up for scrap metal, or sell it cheap to somebody who hasn't figured out what a TOO HEAVY TRAILER looks like. Plan it out and see what happens.
David from jax

 

[Iplayfarmer]

Here's a chart from my local steel supplier that I use often for similar figuring on my own build ideas...
Vernon Steel

They have lbs./ft. information for most typical sizes of steel.

Using their numbers for 3X3X0.188 tube I get a frame weight of just under 500 pounds assuming you have three cross members in addition to the front and back. You can keep calculating to include the tongue and whatever other weight you have like decking, etc.

Just by way of reference, the channel that is the nearest in lbs./ft. to 3" square tube is 5" channel at 6.7 lbs./ft. 4" channel is 5.4 lbs./ft. You'll be about 20% heavier than a typical trailer made from 4" channel. Assuming the typical trailer is about 1500 lbs. That's an extra 300 pounds. I think you'll be alright.

 

[Whatswrong]

Thanks guys, at 6.87 lb /ft frame will weigh about 725lbs,maybe 75lbs for fenders,300lbs minimum for floor plank guessing 300lbs for suspension,even with under estimating the tongue weight shouldn't be very high.Appears it will be a fairly typical weight for 16' tandem axle trailer.
I saw a bunch of drops OR mistakes today that may make ramps ,not sure if it is heavey enough ,but think I will pick some up anyway.

 

[sandman2234]

Free steel is always worth hauling home!
David from jax

 

[Reg]

,I m in the process of building a trailer from scap parts from work. The hubs are +/-3600 x4 on axles designed to carry 7000lbs minus hitch weight which I can't remember.I plan to buy 4 PR5 springs from e-trailer (5800lb axles rated) .The tires are trailer type I think about 3200lb. capacity .My frame is built out of 3x3x3/16 tubing for cross member as well as long ,8x16. It isn't a tilt bed,hitch is A frame style with a tongue to about 2 feet in front of front axle.8000lb jack,seems the tires are the weakest link ,I think my welding is average at least. As near as I can tell when the bed is completthe tires will only be about two -three inches above bed so will require about a 6" fender. This will be my first flatbed trailer.My main concern is if I will max out my pickup before I ever load the trailer.
Any comments will be appreciated

If I read that right... You are putting 5800 (or so) lb rated springs on 3500 (or so) rated axles.
I question the wisdom of that - even though I have a STRONG tendency myself to over spec things.

EDIT:
Sorry, I just re-read it.
The AXLES are 7,000 lb., I was confusing the hub rating with the axle rating.
:END EDIT

I think you should spring it according to what the limiting factor will be, i.e. the axles.
If you "over spring" it you will have a very bouncy/jouncy trailer leaping around back there.
It will not be a trailer that you could ever load down to where the springs settle into their designed working range.

 

[LD1]

Any pics of this thing yet????

3x3x3/16 isnt going to make a very strong trailer IMO, and as others have suggested.

You really need something with more depth. That is where the strength is. I would be scared to load much over 3000-4000 lbs on that trailer with only a single 3x3x3/16 down each side:confused2: And considering you are using a pair of axles that will net 14k, or springs that put you over the 10k mark, kinda sounds like a waste of some good heavy duty axles to me. Kinda like putting a pair of 7k axles under a utility trailer:confused2:

Just to give an example, my homemade trailer (built in the 80's NOT by me) has 2x4x1/4 wall tubing down the sides and a 4x4x1/4 down the middle, And I wouldnt want to put more than 7k on it. And 2x4x1/4 is about 82% STRONGER than that 3x3x3/16

Even standard 4 " channel @ 5.4lbs/ft is going to be 56% stronger than what you have got. And a 5" @ 6.7lb/ft is going to be almost 3x's stronger.

Pound for pound, square box tubing is about the worst for deflection and strength when used as a beam. IT excells at torsional strength, but that isnt going to be needed as much for your trailer.

Conclusion: Personally, I would use all your free steel for crossmembers, supports, etc. But get a couple of 20' sticks of 5" channel. Otherwise, IMO those axles are about a waste on a trailer built like that. Unless you can get really creative on strengethening it up some.

Again, any pics yet??

 

[Whatswrong]

LD ,I'm not an engineer ,it would never occured to me 2 3 inch beams would be less than 1 6 inch ,i can see where 2x4 x1/4 would be stronger .To strenghten it that seems fairly easy if required ,I could run a 1/4x4 flat bar on each side of the main beams and I had already contemplated doing that on the out side to cap the crossmembers.As i said earlier this is my first flatbed trailer and any comment will be considered helpfull.I don't anticipate more than 8000 lbs very often if ever ,

 

[LD1]

LD ,I'm not an engineer ,it would never occured to me 2 3 inch beams would be less than 1 6 inch ,

I am not sure what you mean by this??

Some pics, even if in the form of a crappy microsoft paint drawing, would be extremely helpful.

IF you stacked the two 3" beams on top of one another, then no a singgle peice of 6" channel is not as strong. BUT, if side x side, YES, even 5" channel is going to be stronger.

And while capping the sides with 1/4" plate for strength sounds good, it isnt going to add as much strength as you think. Beams get their strength based on 2 main factors, how much mass is at their extremes, and how far appart their extremes are. Look at I-beams, or channel Iron for example. They have a lot of mass at the top and bottoms of the beam. (flanges). And the middle (web) is only their to hold them appart and does little for strength.

A 1/4" x 4" plate doesnt have any mass at the top and bottom edges.

Not to mention that would add another ~3.43lbs/foot to your 3x3, making your side rails of the trailer come in at over 10lbs/foot.

And all of that still would not be as strong as 4" or 5" channel that would weigh half of what that does.

For the cost of your "reinforcement" 1/4"x4", you could probabally just but the channel and be done. Save the 3x3 for crossmembers or another project.

 

[lostcause]

just reading the first few posts a little more, it made me think about a couple things:

you mentioned about the wheels being higher than the deck and needing about 6" of fender, and you mentioned having already welded up an 8x16 frame. are you having the fenders and wheels totally on the outside of the trailer frame, or are they going to be sticking through the deck, near the edge? if you have an 8' wide deck you would have to have the wheels stick through or else you're going to be about 9'6" (or wider) with the fenders on the outside of the frame. 7' or a little less is about all you can manage for a deck width if you put the fenders on the outside.

if you are working on making the trailer functional to the limit of the weakest link, then you are looking at around a 12k capacity? maybe for a small excavator 16' would be good, but if you are planning on using it for vehicle / tractor hauling i'd go for 18 or 20 feet in length. that's a better proportional length for the weights of trucks or tractors with implements. i know you said you had it all welded, but the good thing about welding and grinding is that you can change it fairly easily.

as mentioned many times, 3" box isn't the best thing for a trailer. section depth is king here. thickness to a point, but 3/16-5/16 material is about the max needed for trailers of this type. extra thickness is not a substitute for a lack of depth though. if that's the available section size to work with, run a second rail as a subframe on each side, somewhere toward the outside and you'll get a lot more stiffness out of it. my personal preference is channel for trailers because you get good strength to weight, and around here a thin walled tube frame won't always hold up to prolonged exposure to road salts - they often will get corrosion from the inside out.

 

[Whatswrong]

I just finished taking some pictures with my camera but will need help to post them ,the overall width is about 98" 82" between the wheelwells.The hitch pole and A-frame braces are 1/4 inch this gives a third beam for half way back ,based on all the recommendations for chanel or I-beam I may have just gained the welding expierience and not a lot of trailer but hopfully it will haul our 35hp tractors occasionally .If it has any value I built about 3/4 frown in the main beams ,I based that on the fact that any Hi-boys I'm around have a lot more than that,I realize that won't add strenght just did it to accomodate any sag from the load on it.

 

[LD1]

I just finished taking some pictures with my camera but will need help to post them ,the overall width is about 98" 82" between the wheelwells.The hitch pole and A-frame braces are 1/4 inch this gives a third beam for half way back ,based on all the recommendations for chanel or I-beam I may have just gained the welding expierience and not a lot of trailer but hopfully it will haul our 35hp tractors occasionally .If it has any value I built about 3/4 frown in the main beams ,I based that on the fact that any Hi-boys I'm around have a lot more than that,I realize that won't add strenght just did it to accomodate any sag from the load on it.

Load the pics up on the your computer. The when you click "post reply" to this thread, down at the bottom should be a button that says manage attachments. Click that.

This should open a new window with about 4 blank boxes at the top. Click the "browse" button. Go find your pics wherever you saved them at. double click them one at a time and you should see its "address" appear in that white box. Do the same with the next blank box until you have selected all of your pics.

Now click the "upload button". This could take awhile if they are large pics. Once they upload, the boxes will be blank again, and you will see them attached below the white boxes in blue:thumbsup: At this point, you can upload more pics if you want. When done with that, click "close this window". It will take you back to where you can type a reply. The just click submit new thread and your pics should appear.

 

[Whatswrong]

I just finished taking some pictures with my camera but will need help to post them ,the overall width is about 98" 82" between the wheelwells.The hitch pole and A-frame braces are 1/4 inch this gives a third beam for half way back ,based on all the recommendations for chanel or I-beam I may have just gained the welding expierience and not a lot of trailer but hopfully it will haul our 35hp tractors occasionally .If it has any value I built about 3/4 frown in the main beams ,I based that on the fact that any Hi-boys I'm around have a lot more than that,I realize that won't add strenght just did it to accomodate any sag from the load on it.

I meant to say phone camera

 

[LD1]

I meant to say phone camera

Do you know how to load them on the computer?

Does it have a SD card that it stores the pics on?
If so, it is easy to upload them onto the computer. If not, you will have to e-mail them to yourself provided you have texting.

Or you can buy an adapter to plug the phone into the computer.

But if no adapter, no card, and no texting, I am afraid they are going to stay on your phone.

 

[deepNdirt]

a 4th option would be if you have a printer hooked to you computer that also has a built in flash card reader, this is a part of your system hardware and will upload the Picture into a file on you computer...

 

[Gary Fowler]

I think if I wanted to strenghen the trailer frame, I would use the flat bar like a truss underneath. You could weld some of your 3" box tubing about 3" long to the bottom side about 3 feet from each end then weld the flat bar to the end and 45 it down to the first box and weld it to that one,continue to the next one, weld it then back up to the frame with at least 3 inches of weld to the frame. That would require that the flat bar break before the frame bent which is about as strong as you can make with minimum weight. You may also want to put in a stiffener in the middle if it looks like the flat bar is flexing. You dont want it to move or fatigue cracking may occur. I did similar to a 40 foot cotton hauling trailer using drill stem sucker rod and welded with 7018 to a 4" channel on each side. I did have a 3rd 4" channel in the middle but without the truss. It worked well and never had a weld failure

 

[Whatswrong]

I'm going to have to buy more "stuff" next weekend.I used the webcam this afternoon also but the power was off so they are to dark to be usefull ,I believe.