Oka 059 camper body

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02 Nov 2012 21:20 #1 by dandjcr
dandjcr created the topic: Oka 059 camper body
Forum Home > On the Road > Oka 059 camper body

Paul Scherek
Member
Posts: 136
Greetings all,
I have been swapping emails with Tony about ways and means of building camper bodies and have benefitted hugely from some of his suggestions.
It is not too late to make changes, so if anyone has any suggestions, comments, questions or criticisms, I would be glad to hear them.

My design is broadly similar to Tony's - a full height box with a section at the back that opens up. The difference is that Tony's opens up to be a bedroom while mine opens up to be a sort of outdoor living area with full fly-screen protection. The table and chairs at the rear are free-standing and get taken outside when the back 'porch' is in use.



Like Tony, I will use a frameless design using composite panels and rely on adhesives to hold the whole plot together. The whole body should weigh about 450 kgs, and the chassis frame I have made weighs 162 kgs. I am hoping that fully loaded and ready for the road, with all water and fuel tanks filled, weight will be around 4,700 kgs. It seems light, but I have listed everything I can think of on a spread sheet with weights and that's what it comes to. Hope I don't get a nasty surprise when it is finished.....



I had some water tanks made up by Atlas Tanks. They are light and said to be suitable for off-road use. If they burst, I will have a few slabs of beer for emergencies.....

The 160 litre fridge/freezer will be home made, using an Ozefridge eutecic system with 75mm composite panels. I haven't run it up yet, but so far I am very impressed with the Ozefridge unit. They have got some very sensible ideas.

The wall panels have cut-outs to fit standard RV windows, but I am hoping to build my own if I don't run out of time. The windows I have seen to date all look really flimsy and tacky, and they all seem to stick out by about 20~30mm. Might as well have the body that much wider and use flush windows. Besides, I really like louvre windows which just don't seem to be available for RVs.

I finally decided upon a fixed roof for the un-edifying reason that cassette toilets seem to spend a lot of their time smelling pretty bad, and I want a bathroom that is hermetically sealed off from the camper. Also, it makes for a much stronger body which is desirable as I am hoping that the body will have the strength to damp out the cabin wobbles that come from the slight chassis flexing.

The bed base, internal benches and the bathroom wall are all stressed members to help with strength. I am using slots and tabs on the composite panels to help in assembly.



When buying the composite panels part of the exercise is having them CNC routed which is remarkably inexpensive. With enough time spent preparing the drawings it should (I hope) make assembly a doddle, a bit like putting Lego together.

The whole under-bed area is storage, most accessible from outside but some from inside. It holds the second spare and three jerry-cans, plus all the usual essentials. There will be two toolboxes hanging down from the chassis outside the fuel tanks. These will hold four MaxTrax on one side, and a high lift jack, oils etc on the other. The aim is to keep all heavy items as low as possible.

I am currently suffering from "analysis paralysis" trying to choose a supplier of composite panels. Vanglass seems to have points on the board, having supplied (amongst others) Peters panels, and they have certainly put up with some serious off-road use.
But Yandina in Queensland is a long way from the Bega Valley and getting them back here could be tricky. I could put the tray back on the Oka, but the whole exercise would mean probably 5 days just to get the panels home.
Anyway, that's enough for now. I hope this gives rise to a bit of group discussion.
Cheers,
Paul
September 5, 2011 at 12:34 PM Flag Quote & Reply

David Hallandal
Member
Posts: 133
Vanglass Supplied the panels for my OKA and have taken some major abuse over the years including the Anne Beadell Highway.
However I used TCT Monopan panels on my trailer and extremely happy with the result, with a substantial weight saving of the OKA panels but lacks some of the thermal properties of the Vanglass Panels.
I used 25mm panels on both projects.

--
David Hallandal
OKA-131 Home Page
OKA Camper Trailer
XT and LT Service Manuals on CD For Sale
20mm Spring Hanger Upgrade Kits For Sale

September 5, 2011 at 6:04 PM Flag Quote & Reply

Hank Onthewater
Member
Posts: 80
Very interesting reading!
About Ozfridge: I got one 3 years ago (and built in my boat). Very happy with it. Mine has an eutectic tank, and my unit is using water from my drinkwater tank for cooling; much more efficient than aircooling (translated in benefits: shorter dutycycle and less amp use). If the tank is empty then it is time to go home anyway. BTW, it still works well with 40 liters of water, and below that the fan of the aircooling will have to work harder/longer. The water tanks on most vans is in the coolest place anyway: right underneath, out of the sun, and whilst driving it gets 'cooled'. Unless it is right behind the engine.....
Campervan/trailer as David's: I like your outfit! Your sleepout on the trailer looks very similar as the one i have on my van. When I wanted to buy my van, I didn't want the trailer to start with, but the then owner didn't want to separate, and now I could not do without it.
Will follow this post closely, for more new ideas. for example. Yesterday I measured the max size of lights to be fitted in the current space, and you just gave a ready made solution. Thanks.
Hank
--
May fair winds be behind you, sun above, clear waters below, and a safe port ahead. And when in OKA van: replace "clear waters" with "firm ground".

September 6, 2011 at 12:08 AM Flag Quote & Reply

Peter_n_Margaret
Member
Posts: 198
Hi Paul.
Quick question......What is the rear overhang?
1.8M is the maximum legally allowed when on the road (60% of the wheel base).

Second.... I suggest that 75mm of urethane is not enough insulation for a freezer (and urethane is almost twice as good as styrene). The lid of my DIY freezer gets condensation on the outside and it is 125mm thick. The rest is OK at 150mm thick. My fridge uses th3 standard 35mm plus an extra 50mm that I added all around (except the door, which I must fix some day).
Will come back later when I have more time....
--
Cheers Peter, OKA196 Motorhome. www.oka4wd.com/xt196.htm



September 6, 2011 at 5:38 AM Flag Quote & Reply

Paul Scherek
Member
Posts: 136
David Hallandal at September 5, 2011 at 6:04 PM
Vanglass Supplied the panels for my OKA and have taken some major abuse over the years including the Anne Beadell Highway.
However I used TCT Monopan panels on my trailer and extremely happy with the result, with a substantial weight saving of the OKA panels but lacks some of the thermal properties of the Vanglass Panels.
I used 25mm panels on both projects.

Hi David,
Well that's another vote for Vanglass, it is good that they do have the points on the board.
Your rig looks fabulous - with the trailer, it seems you could sleep a lot of people - sort of like a travelling motel.
Cheers,
Paul
September 6, 2011 at 7:51 AM Flag Quote & Reply

Paul Scherek
Member
Posts: 136
Hank Onthewater at September 6, 2011 at 12:08 AM
Very interesting reading!
About Ozfridge: I got one 3 years ago (and built in my boat). Very happy with it. Mine has an eutectic tank, and my unit is using water from my drinkwater tank for cooling; much more efficient than aircooling (translated in benefits: shorter dutycycle and less amp use). If the tank is empty then it is time to go home anyway. BTW, it still works well with 40 liters of water, and below that the fan of the aircooling will have to work harder/longer. The water tanks on most vans is in the coolest place anyway: right underneath, out of the sun, and whilst driving it gets 'cooled'. Unless it is right behind the engine.....
Campervan/trailer as David's: I like your outfit! Your sleepout on the trailer looks very similar as the one i have on my van. When I wanted to buy my van, I didn't want the trailer to start with, but the then owner didn't want to separate, and now I could not do without it.
Will follow this post closely, for more new ideas. for example. Yesterday I measured the max size of lights to be fitted in the current space, and you just gave a ready made solution. Thanks.
Hank
Now that is something I hadn't considered - using the water cooling. I had just assumed that would be fine for a boat, and ignored the facility. I have a 50 litre stainless steel water tank right under the fridge. It is next to the gearbox - I will have to see how hot it gets, but I wouldn't think it would pick up too much heat. Thanks for the tip!
Cheers,
Paul
September 6, 2011 at 7:57 AM Flag Quote & Reply

Paul Scherek
Member
Posts: 136
Hi Peter,
I am sailng very close to the wind with overhang at 1791mm. I may need to fill the body up with sacks of cement to stretch the wheelbase a bit.... Working on the 'nominal' wheelbase of 3045mm I should be okay, just under the theoretical 1827mm allowed. At the moment, with no weight and the suspension at full stretch, the wheelbasae is under 3 metres and I am a couple of mills over with my 1791mm overhang.
That is a worry about the fridge insulation. I thought I was being generous with 75mm but it seems a re-think may be in order. Mine is to be a combined fridge/freezer which probably makes matters worse.
Back to the drawing board......
Cheers,
Paul
September 6, 2011 at 8:13 AM Flag Quote & Reply

Hank Onthewater
Member
Posts: 80
Hi Peter and Paul (is there a Mary somewhere?)
on fridges: Peter is right: the more insulation the better, but with with 75 mm you are already twice as good as most commercial units. I have installed a few units (on boats) and generally have used 75-100 mm poly-urethane, and up to 150 mm for the freezer compartment and bottom if physically possible. The bottom of the fridge is the coldest part! So heat loss the greatest (funny, that we talk about heat). No, loss of heat is the greatest when opening a vertical hinged door, therefore a top-opening fridge/freezer uses far less amps than a standard front opening one. With frequent door openings such units could increase the running time of the compressor 50 to100%. When opening a door all the cold air 'falls out', when opening a lid all the cold air stays in the 'box'. It is probably true that one saves as much amps by having a top opening lid than by thick insulation. And having both: one can run the fridge for an extra 1 or 2 days without starting engine or recharging batteries in some other way.
Then there are many different qualities of polyurethane. This is good but techinical article. www.excellence-in-insulation.eu/site/fil...olyurethane_foam.pdf
And yes, somewhere compromises need to be made, fridge walls of 100 mm or more, eat into the precious living space, or make the fridge considerably smaller.
And for me having a classic 3 way fridge in my van? That will be replaced with an Ozfridge when I do a complete remodel of the interior, and that will happen when I win Lotto, and that will happen when pigs fly.
FWIIW
Hank
--
May fair winds be behind you, sun above, clear waters below, and a safe port ahead. And when in OKA van: replace "clear waters" with "firm ground".

September 6, 2011 at 10:22 AM Flag Quote & Reply

Peter_n_Margaret
Member
Posts: 198
Where does the second spare wheel go?
Maybe just a casing on the cab roof?
--
Cheers Peter, OKA196 Motorhome. www.oka4wd.com/xt196.htm



September 6, 2011 at 6:07 PM Flag Quote & Reply

Paul Scherek
Member
Posts: 136
Hi Hank and Peter,
I will have to live with the 75mm insulation, or start again from scratch. As it is, the eutectic plate is practically touching the inside walls and theouter walls are just touching the bed on one side and the sink on the other. It would be easier to put in another battery......
Peter, one of the spares is under the bed (accessible from outside), and the other is in the usual Oka place. I wanted a full spare wheel - while I never had trouble changing motorbike tyres on the road, I think changing these things could need a wee bit more skill - and strength of back.
I would really, really like some alloy wheels. Apart from the ease of handling them, saving nearly a quarter of a ton would be just lovely. Money is one restraint, and also intuitively alloy wheels on a heavy off-road truck just doesn't seem right. Wheels on my various bikes suffered lots of bends, and the bikes didn't way nearly so much as an Oka. I am still wondering.....
Cheers, Paul
September 6, 2011 at 6:54 PM Flag Quote & Reply

Ewart & Vivian Halford
Member
Posts: 117
Hi guys, Peter a question for you. Is the body mounted on the chassis rails or the OKA mounts?
Ewart
September 6, 2011 at 7:01 PM Flag Quote & Reply

Peter_n_Margaret
Member
Posts: 198
Ewart, I built a chassis frame for the camper that had main rails and mounts that were identical to the original bus body that I took off. The one exception to that was that I moved the 2 rearmost mounts from the end to the main chassis rails because I cut out the spare mounting cross members and put in a N-S member to mount some fuel tanks on.
I also connected the "box" to the cab and made the whole thing a single structure, like the original.
Check this out too ... www.epicycles.com/
In particular ... www.epicycles.com/Truck%20Blog/2010-01-01/2010-01-01.htm Just ignor the body mount detail though. Having a ridgid chassis is one of the OKAs main advantages.
--
Cheers Peter, OKA196 Motorhome. www.oka4wd.com/xt196.htm



September 7, 2011 at 5:23 AM Flag Quote & Reply

Ewart & Vivian Halford
Member
Posts: 117
Thanks Peter.
The Oka apears to have a unique chassis, one body builder would bolt it to the chassis rail the next one would do it the same as the tardis but the single point at the front. I have tried to get body flex but have not seen more than a few millimeters.
Ewart


September 7, 2011 at 7:30 PM Flag Quote & Reply

joseph baz
Member
Posts: 332
On my previous shop i had the oka rhs of the chassis chained to the panel beaters straightening jig then we jacked the lh front and the lh rear showed exactly the same distance to the floor as the front,no noticeable flexing of the chassis,i think it's a safe bet to use a frame similar to the bus body straight on to the chassis a kinetic frame will be a waste of efford on the OKA but recommended for Fuso or Isuzu
Cheers,Joe
September 7, 2011 at 7:51 PM Flag Quote & Reply

Ewart & Vivian Halford
Member
Posts: 117
Paul, Vanglass is you faverd choice but have you looked at local fibreglass businesses to see if they can make the panels for you to your specifications.
Ewart
September 7, 2011 at 9:36 PM Flag Quote & Reply

Tony Lee
Member
Posts: 540
Composite panel suppliers are pretty thin on the ground. You also need to be aware that there are several possibilities for core foam, all with reasonably different costs and physical properties. One in particular - styrene - just dissolves when contacted by petroleum products so needs a special adhesive (and jerry cans that don't leak inside later)
Others use foam that is perfect for a fixed cool-storage building but is too soft to use for flooring.


To stay a little offtopic on the subject of fridges. I think the bit about all the cold air falling out when you open an upright fridge is a bit of a phurphy. Specific heat of air is hugely different (in terms of heat per unit volume) so replacing all of the cold air with ambient air a few times a day would require so little extra run time that it can be just about ignored. I see the problem being the very poor insulation afforded by the door seals and edges of the box. Result is the same, just the physics is different.


Re Vanglass. One criticism was that one side of the panel is just raw chopped-strand skin sanded and filled with a couple of coats of flowcoat. Said to avoid the clinical effect of gloss white panel inside and outside, but not to everyone's taste. They are now looking at bonding a light pre-manufactured smooth skin to the back side of the panel to give a smooth finish both sides.
--
Tony

picasaweb.google.com/114611728110254134379

September 8, 2011 at 4:36 AM Flag Quote & Reply

Paul Scherek
Member
Posts: 136
<Paul, Vanglass is you faverd choice but have you looked at local fibreglass businesses to see if they can make the panels for you to your specifications.>
Hi Ewart, As Tony says there is a big variety of core and laminate possibilities. The local 'glassers' here said "Oh yeah, we should be able to work someting out" which didn't fill me with confidence. Also Vanglass and others have CNC routing facilities which our local blokes don't have.
I am not committed to Vanglass yet. I am also considering a crowd in Campbelltown (Liner Transport) who use Divinycell (PVC foam) core which (IF one can believe what is on the net) has better qualities than Polyurethane cores. It is said that Polyurethane cores become friable and break down over time. Who knows - every composite panel supplier seems to think that everyone elses panels are duds.
Tony, on my previous camper I tested my Waeco 'fridge over two 6 hour periods. One period had the door closed for the duration, the other I opened and closed the door every hour. There was no statistically significant difference in run time.
I also tried the same test with and without fans circulating air at the rear coils of the fridge - this test resulted in about 15% less run time.
Cheers all, Paul
September 8, 2011 at 7:42 AM Flag Quote & Reply

Tony Lee
Member
Posts: 540

>> "Tony, on my previous camper I tested my Waeco 'fridge over two 6 hour periods. One period had the door closed for the duration, the other I opened and closed the door every hour. There was no statistically significant difference in run time.
I also tried the same test with and without fans circulating air at the rear coils of the fridge - this test resulted in about 15% less run time." <<

Yes, specific heat per kg of air is one quarter that of water so not a big difference, but of course the densities are hugely different so weight of air inside the fridge is just about zero. Means that the energy required to cool that tiny weigh of air is also just about zero - just as your experiments show. (this is why testing a fridge with nothing inside is not a good idea. Need to add thermal mass so the inherantly slow response times of the refrigerator system gets a chance to stabilise)

Was the run time more or less with the fans than without. First thought that run time with fan would be longer because you are circulating colder air around the door seal area so heat gains would be greater.


--
Tony

picasaweb.google.com/114611728110254134379

September 9, 2011 at 6:52 AM Flag Quote & Reply

Paul Scherek
Member
Posts: 136
<<Was the run time more or less with the fans than without.>>
I worded that badly. The fans were external at the rear of the cabinet, blowing fresh air over the cooling coils. The run time was 15% less with the fans on. For all tests I had a 'standard' fridge fill of 24 stubbies pre-cooled in the house fridge.
September 9, 2011 at 10:15 AM

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