Frame the floor or not

[sschevel]

Planning on using 3/4 inch finish sided ply.
Trailer frame will be 4X9
Box will be 5X9

Do I need to frame the floor so protect the 6 inches sticking out each side if I plan to bolt the 3/4 to the frame to every cross member front to back? Meaning Front, 2nd, 3rd, 4th, 5th, and rear cross member.

If no frame under the plywood, I would weld in short supports to extend out under the door on both sides to provide for someone sitting there.

Question is can 3/4 finished plywood handle a load extended out 6 inches without a frame under it?

Guy

[caseydog]

I bolted my 3/4 ply right to the frame, but my floor does not go out past the frame.

If you want to avoid a wood frame on top of your steel frame, I would make sure you have steel going out to the edge of your plywood. If you can weld supports under the door, why not weld supports down the entire length of the TD?

CD

[sschevel]

Why not run supports down the entire frame?

Because this is a build to stretch the 4X8 frame to 5X9. It is far easier to stretch the length by adding a total of 2 feet of steel and 4 weld joints. However to move the trailer from 4 to 5 foot takes 6 more feet of steel and 12 more welded joints. Making it heavier.

Other option to put out a support from front to back would take 10 feet of steel per side (9 front to back and two 6 inch stand outs). This would add much more weight.

So the question is, can 3/4 support a 6 inch, 9 foot long overhang on both sides and support the tear?
Course the galley will provide support and in the Grumman, there is that front storage/shelf that can also provide support for the walls so there may not be that much downward force over the 6 inch over hang now that I am thinking about it......

Guy

[bobhenry]

Throw the frame away and use the axle assembly and tongue and find someone throwing away a couple sections of square tube hand rail.

[Ageless]

To answer the original question . . . .the 3/4" will not sag in 6" unless you are 300+ lbs and stand on the edge. Once the walls are solidly attached, they will add to 'stiffening' the structure.

[bobhenry]

To answer the original question . . . .the 3/4" will not sag in 6" unless you are 300+ lbs and stand on the edge.

That means I can't set in his doorway

[Ageless]

You can; it's part of the wall and supported by the floor.

No other comment . . . . . .

[sschevel]

Sure you will, as I will likely use some small angle iron and make a small steel extension under the doors as these will be the highest loaded area along the entire 9 feet.

As for the hand rails I noticed them in your posts and that looks great.

I'll post a few more photos in a few minutes as an update.
Right now I am waiting on a 4 foot C iron from HF. I will use 2 foot of that to lengthen the frame out to 9 foot (1 foot each side) and retain the cross members for the floor.

[Woodbutcher]

I am doing the same as you right now. I have a wood support running the full 5 ft width front and back. This coupled with the solid 3/4" plywood running the length should be more then enough. I'll try to post up pics on Tuesday when I finish. I am also putting in a drop well for feet. I also took out the 2 center cross rails and bolted them inside the side rails to firm up where the 2 four ft sections were joined. That made a huge difference in the strength.

[Woodbutcher]

Here is where I am now. This is the underside rear before the skin.




Here it is skinned.


Here is the bottom with the well and wheel wells installed. The small strips are a build up to get over the Nuts. It makes it so the 3/4 ply sits flat on all the frame rails. When I bolt it down it will not torque out of shape.





Finished top side.



Here is what I plan on for the beds. The cushions will extend over the wheel wells to give me 60" inside.

[sschevel]

That floor looks great!

I am thinking of getting my plywood floor made to 5X9 and placed down on the frame and once lined up correctly, trace the frame touching the wood (so that would be the left and right rails). Then flipped over I can take my router and take away just one layer so that the entire wood floor will sit on the entire mental frame.
Then back to the frame, I will mark the holes in the rails onto the floor, pull the floor and drill a tiny pilot hole. Flip again and taking a fostner bit drill from the top down to inset the bolts that will hold the floor to the frame. Likely 4 on the first cross member and then 3 per member the rest of the members. Still planning on using 6 cross members if HF would hurry up and send the replacement side rail! I am already making plans to skip that and modify the frame build, just means I have to purchase more angle iron.

Guy

[Woodbutcher]

The 5x9 is a great idea. That is what I would have done if I didn't have a foot well. Just my opinion, but give some thought to the build up strips to level the floor to the frame. It only took a few minutes and you have more wood to bolt through. Also by routing out the ply you are making the floor that is carried out over the frame thinner thus weaker. Also did you add in a cross brace to stiffen the side rails where they join? Really helped. Good luck which ever way you go. Here is how I strengthened the frame. I also moved the axle back 5".

[sschevel]

Good point on the strips and will rip them from a 2X4 for the cross members.

Now for the frame joint. My first thought was to splice in a 1 foot section and make 2 welds on each side, not use a cross member inside them and retain the cross members to do their job across the trailer (for 6 cross members spaced at leading edge, 2 feet, 2 feet, 1 foot, 2 feet, trailing edge.
Now thinking perhaps stronger and better to splice the trailing edge onto the rear of the frame to gain the extra foot. I could get then go the full 5 foot wide at the back.

Today is a nice day, I think I might go get my plywood and some angle iron so I can finish off this trailer frame and be done with it!

Guy