Stage 3 Frame and Floor

One of the most important tools from now on is a Sliding Drop saw mounted on an extendable table with rollers

When designing the frame you need to consider where the inner ply wall joins will be so there is always timber frame at the join point.

Extra timber needs to be in the frame to accommodate mounting points for lights and many other items that will need some material to screw to.
I integrated two pieces of ¼” steel plate 150x100 into the frame where the awning was to be attached at the top and when fitting the awning drilled and tapped 8mm metal threads in the plate.

The frame was made of miranti timber using mainly 19x41mm and at high stress points 19x65mm was used like at the door entrance and outer edge of frame, note this is the finished size for the timber. There were two advantages using 19x41mm timer over 19x19, strength and straightness.

19x19 miranti is commonly used in many vans but I found that I could obtain much straighter timber from the timber yard in the larger size and the increase in weight was not that much. For example one side of the van framing weighed 30Kgs so using timber half that size saved only 15Kgs and overall the entire frame was 120Kgs, including the ceiling and ensuite dividing wall. There was no compromise when building the frame but I would expect the amount of timber in a standard van using 19x19 for the entire frame would weigh about 40 to 50kgs.
The roofing frame was 50mm deep at the edge and 65mm deep in the centre. The main part of the roof was 15mm higher in the centre to help rain runoff and give extra strength.

Full Frame

Part of frame dimensions using CAD

By using CAD all I needed to do is print the section of frame I was working on. It made it very easy to fabricate the frame from the drawing, but it needs to be drawn in CAD first.

JR

Hi Jimbo & Dieseltojo,
Thanks for the support, this was a once only project and at times I did get a bit to deep into things but was trying to get it right first time.

I am sure a caravan can be build at home with nowhere the time wasted on the finer detail as I did. My problem is I needed to build the van in my mind first, always worried I would get so far and find out I did not allow for something.

PS I think we have another builder on the forum that is making me look like an amateur.

JR

Stage 3 Frame and Floor Cont.

The shape of the frame side walls were drawn on the garage floor and then used the floor outline drawing as a template for the LHS and the RHS walls of the van.
The frame needed to be braced until the inner wall was attached


JR

Stage 3 Frame and Floor Cont.

From my experience I found the bottom front corners of my old Jayco frame started to fatigue and the frame started to separate from the chassis. This was probably more due the chassis design as well and also due to the torture the van went though during its life. I don’t think the manufacturers ever meant the van to go on some of the roads we took it on.

Only ever used roads that were on maps


Metal strapping added to the front bottom corners of frame for strength


Frame and chassis overall view LHS


JR

Great work JR I a'm following with great interest,I find it very informing as to van make ups and the way you are putting it together. Yours Loub

Hi JR

Great thread, I am waiting with interest the next stage you post.

Congratulations excellent job. keen to see how it all fits together.


Cheers
Norm

Stage 3 Frame and Floor Cont.

The frame was screwed and clued.
The inner ply walls where then glued on with Weldbond, this then made the entire frame very strong. Even though the frame was glued and screwed it became apparent that once the ply walls were glued to the frame the method that the frame was held together could have been staples and still would have been OK. Naturally staples are not as good but I can see that staples are not as bad as they sound as all they do is hold the frame together until the walls are attached and then the frame is strong anyway.

Liquid nail was used to glue the frame and the floor to the chassis and Weldbond to glue the inner ply walls to the frame.

Why not use Sikaflex?
Answer: to be honest I was not aware of the product and probably would have used it to glue the floor to the chassis if I had known. Four years down the track the liquid nail has shown no sign of cracking, also probably due to so many tech screws holding the floor down and the softer riding suspension.




Floor
The floor is 12mm ply, there are other products available that will cover in on go but again I stuck to a proven product.

I did not fit the floor until the wall frames were made as the chassis was outside in the weather while making the frame. The floor ply top side had no protection, the underside was undercoated and two coats of Hammertone enamel applied. Once the floor was screwed down I filled any blemishes and screw heads with filler so no indents would appear through the vinyl.

On the outer edge of the chassis 50x25x2mm RHS was used to allow H4 treated pine edging to be glues and tech screwed.

The floor was then laid over the chassis and to the outer edge of the treaded pine edging, the floor was also glued and screwed, this then gave the walls a large body of timber to screw to around the outer edges.

The front treated pine edging was a thicker section to allow for a taper to follow for the angle contour at the front.



Five sheets of 12mm ply were used for the floor, 50x25x2mm RHS was used to support the floor between the main chassis rails and cross rails.

12mm ply may seem a bit thin but the 50x25x2 RHS was place so there is not a great span between supports.

JR

Stage 3 Frame and Floor Cont.

The 50x25x2 RHS running down the centre of the chassis had an extra 50x3 plate welded on top so the two sheets of ply could be butted together and allow the Tech screws not to be right on the edge of the ply.

The centre 50x25x2 RHS had a 50x3 steel strap welded on top to accommodate where the ply was butted together down the centre. Not the Liquid Nail oozing out, now 4years old.


These screws are just so good, I had a full range stepping up in 5 to 10mm lengths


Ones the ply floor is down, vinyl floor covering was laid to the outer edges and the walls sit on top of the vinyl, carpet was laid in the front section of the van around the bed

Vinyl extended to the front to give the wall a straight edge to mount on


JR

Geez! JR, the rate you are going you will have finished yours before mine. And you have upped the anti so now I have to post some blueprints and CAD plans to match yours.

I just wish there were more threads around like this because when I started out there was very little. Just so much information to be passed onto those thinking about having a go at their own van. I know that all vans tend to separate from their chassis at the front and JR has put forward his answer in his design. Every timber framed van should have it.

I suggest anyone who visits this page and gets something from it; sign a visitor’s book in acknowledgement. Just post a comment in this thread to say you have been here and appreciated the effort.

Magazine article material I reckon. Building & renovations / modifications should be a regular item in the C&M mag as well. Now if we can only convince someone to write an article every month. Hmmmm Please feel free to PM Simon with your suggestions.

Cheers
ALLAN

I built a box trailer for my father about 45 years ago and even though it has had a few changes and rebuilds it is still going strong and owned by my daughter. I also built a flat bed trailer, 4 metres by 1.8 meters for a special purpose trailer about 15 years ago and it also is stil going strong.
I admire both JR and Bussy for building their own caravan but I would never even attempt it myself.
Great work, both of you.
I will just look at your experiences.


Hank