Wooden trailer frame?

[Shallowatereds]

Is it crazy? 4x4s with half-laps and a 3" steel pull bar thru the middle?

[asianflava]

No, but it will end up heavier than using steel tubing.

[Chuck Craven]

Is it crazy? 4x4s with half-laps and a 3" steel pull bar thru the middle?

Well my utility trailer is PST wood 4 X 6’s with a 4 X 4 in the center 4’ wide 8” long.
It’s heaver than my 5 X 10’ off road steel tear frame!

Chuck

[Shallowatereds]

I tow with an Expedition, 5.4L v8 with a full towing package. I think I'm rated to 7000lbs or so, so weight is not an issue.

[angib]

If you look at the Lightweight in the Vintage Plans menu item above, you'll see that has 2x4 wood chassis rails with half-laps, although it does also have some important diagonal braces from the coupler to the front of the trailer body.

Personally I hate half-laps as they just introduce notches that act as stress-raisers to crack the timber - I would always prefer to see longitudinal and transverse parts passing over/under each other or, in the case of most cross-members, simple butt joints used.





Andrew

[Joanne]

Welcome aboard the list!

Ok, sure you can build a wood frame. But it leads to the question, "Why would you want to?" I can see absolutely no advantage to a wooden frame when there are so many good options to make or buy a metal one.

I certainly don't mean to belittle your idea, but it seems like you are planning a trailer that is heavier, less strong, and needs some careful design to ensure that the suspension and tongue don't tear away from the wooden frame. There seems to be little if any benefit to this approach.

Sometimes an approach that seems to make sense during the planning stage turns out to be a real pain during the building stage. (I rebuilt a boat trailer for my frame and it took me longer, is much heavier, and didn't save me much $$)

Anyway, that's just my .02 worth.

Regardless of how you decide to build, I hope you have a lot of fun and I'm looking forward to the photos!!

Joanne

[Shallowatereds]

Thanks, Joanne. I was more thinking out loud than anything else.

Heavier isn't an issue, and I'm not so sure that the strength in a properly built wood frame would even be an issue. If I were hauling goats or cattle maybe.

[Joanne]

Thanks, Joanne. I was more thinking out loud than anything else.

Heavier isn't an issue, and I'm not so sure that the strength in a properly built wood frame would even be an issue. If I were hauling goats or cattle maybe.

Hi Casey!

Thinking out loud is a good idea. There are a lot of folks here with a lot of knowledge to share. After seeing photos of the boats you built, you certainly don't need any woodworking input from me!!

Your boats are BEAUTIFUL! You and Doug H can start your own boatbuilding forum. If you include homebuilt kayaks, half this group could join you.

I'm really looking forward to seeing how your tear turns out.

Joanne

[Alphacarina]

Heavier is always an issue . . . . unless your Uncle owns Exxon

If you could take 2500 pounds off of your Expedition, you could probably get 25 MPG with it - Taking 1000 pounds off of a towed trailer probably saves you 3 or 4 MPG for the life of the trailer - If you tow it 50,000 miles over it's lifetime that 3 or 4 MPG probably amounts to the entire cost of the trailer

If your Uncle does indeed own Exxon, forget all the above . . . . I suspect you or he are at least major shareholders, hence the Expedition in your driveway

Don

[Shallowatereds]

Just thinking out loud again....

I figure I would need 60 lin ft of 4x4 d.f. to build a 5x10 wood trailer. Doug Fir weighs approximately 2lbs/board foot. 60 lin ft of 4x4 equals 45bd ft.

90lbs for the basic frame? Does that sound right? Can't be a whole lot more than a steel frame. Unless I'm missing something. Which is entirely possible.

[Gerdo]

No need to over build. As Don said, weight means lower fuel mileage. Rolly Nelson built his entire TD out of wood. http://tnttt.com/profil ... file&u=580 He deffinitly can give you some pointers. I put too much thinking into making my frame bulitproof. My frame, steel, is overkill. You will get a ton of strength once you build the TD body. Some have called the body a "Torsion Box". It is very strong and rigid. Don't get me wrong you deffinitly need solid pionts to mount the suspension and tongue. Do alot of research before you start building.

[jay]

4"x4" / 12"= 1.33 bf per lf

1.33 bf x 60 lf = 80 lf

80 lf x 2#lf = 160#


maybe:

3.5" x 3.5" / 12" = 1.03bf per lf

1.03bf x 60lf = 61.8lf

61.8 lf x 2#lf = 123.6#


add to either: water saturation weight from driving to and from campground for 3 days in the pouring rain.

[Shallowatereds]

Ok. So, how much less than 160lbs can a steel frame weigh?

[Trackstriper]

Casey,

Nice boat, so you know how to work with wood.


Thinking out loud with you. I tend to think outside the box most of the time. If you really want to build the frame out of wood you can do it, although, like Joanne, I'm not quite sure why you would want to go to all of the trouble vs. going with a steel frame.

You'll have to basically do your own designing on the frame. As Andrew mentioned, avoid the half laps if at all possible.

Pros....Aircraft wing spars can be built from wood very successfully. Wood essentially doesn't fatigue and you can call it Nature's composite if you want to make it sound cutting edge. The coefficient of expansion will be just the same as the plywood of the floor and any wood used in the sides. You know how to keep the water out of the equation, at least for a while, so rot shouldn't be a problem in the short run. As I recall Douglas Fir is relatively light, but has a tendency to split more than some other woods, so you might have to watch how you fasten to it. All in the design. Have you noticed how many steel floor joists we have in our homes?

Cons... You may have to fiddle around with making custom steel hangers for the springs to effectively distribute the loads to the wood. Same thing for the ball coupler. You have to add in the weight of the hardware and fasteners. I think that it wouldn't have to weigh any more, maybe less than steel if you were to push for some serious design. The problem is that there is probably very little empirical data on wooden trailer frames in the 21st century. The steel framed trailers work quite well and they would be a whole lot less work if you count the time trying to figure things out. If you overload a steel framed trailer, things tend to bend a good bit before they fail by breaking. You won't get that in a wood frame, so you have to overbuild a bit more.

I think that's why most folks on the forum will still point you toward a steel frame. It works, and if it ain't broke, why fix it?

J.B.

[Roly Nelson]

How light does one want to go? I know my 1/4 Nelson Stacker (wooden body only) weights only 95 lbs. Now if I wanted to lighten the trailer weight of 145 lbs, I would simply eliminate the trailer frame, then just fasten 3ft of angle iron on each side, mount torsion axles to them and bolt a 2" pipe tongue directly to the bottom of the tear. Probably would top out at below 200 lbs........... Light enough?

Roly, sorry, thinking out of the box again.