Build: Frame Trial

Bench Seat [+]

Flanged Tube [+]

To make sure I was on the right track with the camper’s design and to give these nylon connectors a good test out, I decided to build a part of the camper that will be frequently used and one susceptible to quite heavy dynamic loads – the chairs!

The layout of the chair’s structure is highlighted in red in this design to show you what we’re testing out.

The measurements for the bench seat framework are 750 x 450 x 750mm (L x W x H). At both ends of the chairs are cupboards/access doors, for both inside and outside access.

In the close up, you’ll notice I’ve used Flexliner’s 15mm winged/flanged extrusion which allows for a 19mm board to be placed flush inside the frame.

Putting it together

Chair Frame [+]

I put in an order for all the connectors I’d need and the special flanged tube. The standard 25 x 25mm tubing for the legs I just sourced locally.

After a few mitre cuts and a rubber mallet on the job, I quickly had the frame up.

I wanted to keep the frame simple at first, to see where it needed reinforcing the most.

Testing it out

The first test was then of course, to sit on it! Hopping on I could tell it had a lot of movement at the joints, obviously some stiffening was needed (& expected). Apart from that though, strength/compression wise, it felt more than up to the task.

Chair Testing [+]

Next I wanted to see if having the aluminium sheet walls fitted to all sides of the frame would stiffen it up enough.

Since the front & back of the chairs will be covered in sheet metal & riveted on anyway, these would act like large gussets and prevent the frame leaning & twisting (at least on the X axis).

I didn’t have any sheets large enough for this test so I had to make do with using strips of flat steel (& a thousand clamps).

The difference was like night and day! Both my wife and I were quite comfortable on it together and could easily hop on and off as we pleased without the frame leaning or twisting in either direction.

Final tweaks

Chair Corner Brackets [+]

All that said, we can’t actually have sheet or anything covering the two open ends of the chairs, since these are the cupboard/access doors, but we do need it to be reinforced or it will lean & twist. I figured some corner brackets should do the trick and it was a bonus that they would also act as little door stoppers for the internal cupboard doors.

3D Corner Bracket [+]

Since I built this, my wife has bought me a 3D Printer (from Winplus) and I have been able to come up with my own printable designs for the corner brackets (& lots of other parts). Here’s a little teaser pic.

Drop a comment below if you want me to tackle a particular part of the build next. Happy building!

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Design: The Tailgate / Platform

Tailgate / Platform

I have been investigating many different methods & materials to build the drop down platform. I haven’t decided which way to go yet, but I do know which way other camper manufacturers construct their drop down platforms.

First off, as you’d expect, most of them use aluminium. As far as the construction goes, this is usually an outside box frame with 4 or 5 internal supports, all made from 40mm aluminium box tube. Cover the frame with aluminium sheeting (tread plate or normal) at around 3mm thick, to act as the floor, you then have a sturdy platform to walk on. This seems like the common construction method and if you didn’t want to spend too much time figuring out the various load spans & ratings of other materials, I would recommend going with this approach.

Platform Box Frame [+]

However, if you wanted to dig a little deeper into the engineering sides of things, I think there may be some improvements to be made here. According to my rough calculations, a box frame & sheet described as above would weigh around 35kg. That’s not terribly heavy, but if you were planning to manually lower & raise the platform yourself (like I am), plus have a storage box attached to the back, you may start to wonder whether you’ll need assistance from another person just to lower or raise it (not ideal in my opinion!).

Composite Panels [+]

The box frame and aluminum sheet would both weigh around 15kg+ each. So I’ve looked at alternative flooring materials to compare the weight and performance (e.g. load spans) to that of aluminium sheet. Composite materials are of course available (at a price) but do offer many advantages (i.e. thermal breaks, etc). Some of the sheet/panels I’ve researched had high enough load ratings that you wouldn’t even need as much support underneath, which would save us considerable weight in the box frame itself also.

Here are a few of the flooring panels I’ve come across so far:

• Duflex Panel (foam core, honeycomb, end grain balsa)
• FRP Grating (frp, pultruded grating)
• Grating (aluminium)
• Expanded (aluminium)
• Honeycomb Panel (aluminium, polypropylene)

I’m currently still reviewing viable options & costs for the platform flooring material. If anyone has experience in this area or ideas that could help with the design & construction of this platform, please leave a comment!

Design: The Frame

Having more or less decided to stick to my 4th revision design from my previous post, here are some pictures of my first attempt at the tube frame design of the camper:

Cantilevered frame over dual cab; external access to storage

Bench tops and seating

Drivers side storage access

The frame is made from 25 x 25 x 1.6mm aluminium tube and the tube connectors are from Flexliner’s large range of various multi-direction/angle connectors.

You may note from the pictures, most of the connectors are black, these are normal nylon connectors whereas the green and red connectors would be the steel core & steel core with thread, respectively. I was thinking the threaded connectors (designed for feet, castors & the like) could possibly make for a good fastening point with the floor. For the floor I was thinking of 12mm marine plywood.

Drop Down Tailgate / Platform

Suspended Tailgate / Platform [+]

Unfortunately I have doubts whether I can use this type of framing system for the drop down tailgate/platform. The loads it would see could be up to 300kg (3 or 4 people) and without proper support underneath (as it will be suspended by cables) the frame would simply cave in on itself. I may need to look into a stronger (perhaps welded?) solution for this.

Aluminium Framing: A new hope!

One thing that’s been on my mind for awhile is the Qubelok tubing which is only 1.2mm thick. We’re going to have some pretty decent stress loads on this frame with the drop down tailgate & the fold-over bed hinges, etc, which was always a bit of a concern for me.

On a visit to my local Aluminium supplier Aluminium Express, I noticed they also sold Qubelok connectors and something else there that caught my attention. They looked like extra long tube connectors and were more like nylon than plastic. I enquired about them and found that they are actually a different type of tube connector altogether and made by Flexliner!

Flexliner Connectors [+]

Flexliner’s tube connectors are longer and made for 25 x 25 x 1.6mm tubing which is a standard size, more readily available and cheaper than most Qubelok suppliers! They are made from a stiff (but flexible) nylon and are much more vibration & stress proof than Qubelok which can snap on corrugations, etc. They even have welded steel-core versions available for applications requiring a bit more compressive strength (click the photo to expand).

For me, this was an amazing & timely find that’ll provide that extra bit of security knowing the frame will be that little bit stronger being 1.6mm instead of 1.2mm.

As you would guess the connectors are a little bit more expensive. Qubelok connectors are around $2.50 each whereas these Flexliner ones are around $4~ each but I think it’s every bit worth it. Another big advantage is designing the frame in 25mm tube sections instead of 25.4mm!

Stay tuned for my tube frame designs coming soon…

Design: First drafts

Here are a few of my initial design concepts whipped up relatively quickly in Sketchup (3d design software).

These give us the general layout idea(s) and help alleviate any major design flaws at this early stage (before moving onto the frame design):

Sketchup First Test

Design v1 – Potential ‘rear entry’ design.

Design v3 – Another ‘rear entry’ design, early stages.

Design v4 – Tailgate/platform entry style.

Design v5 – Extended bench area at the rear – this was intended as a way to create another bed platform.

Design Tailgate / Stairs – Potential stair and cable positioning.

Once we get deeper into the design there will be a lot of issues to overcome. This has a lot to do with what parts we’ll be putting in (& where to fit them), such as water tanks/heaters, sinks, cookers, gas bottles, batteries, etc, which will likely change the dimensions of some of the storage areas, but you have to start somewhere!

A detailed look at construction: #2

I recently came across these photos 1 & 2 of the construction of a camper. You can see how the frames are constructed and wouldn’t you know it? They use Qubelok!

That means no welded frames, all plastic connector joins and the outside aluminium sheet/skin holds it all firmly together.

They’ve also managed to have the fibreglass lid (likely around 20~kg) attach to the frame with a piano hinge (aka continuous hinge) with seemingly no ill consequences (they’ve sold a lot of these units over the years).

Here are some of the construction features I’ve been able to determine from photos and other sources:

• The Foldover Lid/Bed is a made from foam-cored fibreglass (Check out ATL Composites for some examples of foam core sandwich panels)
• The upper tent is made from Billabong Dynaproofed 10.9oz canvas – (Wax Converters Textiles)
• EPDM Rubber Sponge dust/weather seal is used for where the edges of the fibreglass lid and body of the camper meet when closed up.
• The entire internal frame is made with Qubelok and if you look closely at the photos linked above, you’ll see the connectors are held in place by either rivets or clamped with a nail punch/pinching tool.
• The benchtops act like large gussets for two of the corners and the other side has two small triangle shelves to strengthen those corners.
• 100mm Aluminium ‘I’ Beams are used as the support base with a 12mm plywood floor.
• You’ll also notice the thick aluminium angle on the inside edge of all 4 corners of the camper, allowing the bolts for the jacking points to go straight through, making for a stronger brace.

The other construction methods are fairly straight forward and can be determined from the various photos available online.

Next post will be about some of my early concepts of various Qubelok/Aluminium Frame camper designs. Happy building!

Aluminium Framing

What are some aluminium framing methods?

During my research into ‘weldless’ aluminium framing methods I came across many techniques and products that could be used to build a camper. Some of which I have mentioned before but will repeat for completeness.

8020 Framing System

8020

The most impressive would be the 8020 framing system which is basically extruded aluminium profiles that through the use of various fastening methods can be joined together to form a strong, vibration proof join in many different angles. The system is available from a few different suppliers under a few different names but they are essentially the same concept.

The pros:

• Quick to assemble
• Easy to use
• Strong and Vibration Proof

The cons:

• Price
• Weight could be a factor, they would definitely weigh more than hollow square tubing

Gussets and Rivets

Gussets & Rivets [+]

Another method was that used on air plane fuselages. This uses mainly rivets and gussets to join tubing together. It’s an effective method of fabrication and relatively easy for the DIYer. This would probably be the cheapest method of fabricating an aluminium camper frame.

The pros:

• Cheapest method I’ve found
• Only basic tools needed

The cons:

• The gussets may be in the way when installing walls, bench tops and cupboard doors.
• Extra care/planning would be needed to ensure you don’t have gussets in the way of moving parts or where a nice flush finish is required.

Qubelok

Qubelok / Connect-It [+]

The easiest method I’ve come across so far is something called Qubelok or Connect-It depending on local suppliers. It’s a framing system that uses plastic connectors that slot into 25.4mm (1″) tubing. It is surprisingly strong, especially when building in cube-like structures. The plastic connectors are around $2 each and are available from 3 to 6 way connectors.

The pros:

• Fairly cheap connectors
• Easy to build (just hammer it together)
• The Qubelok extruded tubing is available with an offset lip so you can mount bench tops or glass ‘flush’ within the frame (pretty cool actually)

The cons:

• The aluminium tubing isn’t really a standard size and the anodized finish makes the price of tubing a little higher than you’d expect. Especially the lipped tubing.

A little more on these tube connectors

I wondered whether these plastic connectors would be strong enough for building a camper. Especially one like the Wedgetail or similar with the fold over lid.

Qubelok 4×4 Storage [+]

The Qubelok/Connect-It system is actually really popular in the 4x4ing and touring communities. They use them a lot to make slide out drawers and shelving for their camping and 4×4 equipment (fridges, cooking, winch gear, etc).

I’ve heard of a few reports though where these plastic connectors will crack over corrugations or if you put too much weight on them, which gave me a few concerns.

I pondered over this and thought that as long as you didn’t overly stress any particular join and if you reinforced some of the joins with gussets it may be the best of both worlds. (E.g. Easy to build & still strong)

So that’s where I’ve started. I would design a Wedgetail style camper out of Qubelok/Connect-It components and where I had to reinforce it I would use gussets.

On to the design!

Choosing the material

So which material should you use?

I’m not particularly biased towards any material so I’m hoping I can take a honest look at all materials available to see what works and is not too difficult to work with.

Wood

Wood – a lot of caravans and slide ins use wood frames, I don’t mind working with it but I’m also aware it’s not as permanent as metal. Here in Melbourne also, the weather could cause a lot of issues fast. There is also the question on strength. This camper needs to fold out every which way and seal well. There can’t be any twisting or movement.

 

Fiberglass

Fiberglass – definitely worth a look at. Lots of caravans & campers are using this as the base construction material. One slide on (the Innovan) even has their entire internal structure made from a fiberglass mould. So is it easy to work with? If you had to make all the moulds and do every step yourself, I would think it would take a lot of time and effort. Once off constructions would be easier (no moulds), but the final finish of the material may be a little rough. Obviously some components of our camper will need to be fiberglass like the fold over bed (everyone else does it this way too) so some knowledge of these construction methods will have to be employed.

Steel

Steel – permanent and would be very easy to weld up a frame out of mild steel. The concern here is likely the weight factor.

 

 

 

Aluminium

Aluminium – rust proof and lightweight. One of the most popular materials to use on Slide On campers here in Australia and anything Ute based (tool boxes, canopies, etc, etc). It’s tried and tested. But can I weld aluminium? That’s a no. Can I learn? Short answer is also a no, not in the time frames I want be-able to accomplish the project.

Aluminium has really appealed to me of late because of the lightweight & strength properties – even the ease of working with a material softer than steel (easier cutting, grinding, etc, etc) but I don’t want to outsource the framework to a welder.

A quick search into building with aluminium actually showed a lot of problems in welding it, not only can welds fatigue and crack (especially on corrugations) but the only real way to test for a good weld is to x-ray them.

So what do others do? Well aluminium ute trays are very often bolted & riveted together rather than welded because it takes the vibrations better and lasts a lot longer.

Gussets & Rivets on Light Aircraft

So that’s where I started. Maybe I could build the entire framework with bolts or rivets? Lightweight aircraft actually use gussets and rivets in their fuselage construction, maybe that would work?

Sketch of Gusset Plates [+]

Here’s a very rough sketch of how a gusset & rivet based framework might work. There is still quite a bit of work involved in riveting the entire structure, so the search is still on as to other methods.

Stay tuned..

A closer look at construction: #2

This camper is pretty impressive and definitely warranted a closer look.

Sketchup

It was one of the first Ute campers I had come across and wondered whether it would be a good base on which to design my custom camper. I took to Sketchup (3d design software) and came up with some very basic/rough ideas (note the cantilever bed for the Dual Cabs).

This camper is one of the lightest ute campers at around 370kg. Somehow they’ve managed to keep the weight way down but still using the usual materials (aluminium, fibreglass, wood, etc).

The construction is very similar to the Wedgetail, aluminium frame, fibreglass lid/bed, etc, etc.

I recently made a game-changing discovery about how these are built and will write up a post about this soon!

Project: Roll out awning

This one was a few years ago now. I couldn’t find the original write up I used to make this one, but the idea is pretty simple.

Roll Out Awning [+]

I wanted an awning a bit bigger than the commercial ones typically available (usually 2.5m long). So I decided to make my own 2.5m x 4m long awning.

To build the awning, I used 100mm PVC pipe and bought a couple end caps. I cut a slot along the length of the pipe for the opening. The internal rod (10mm pipe from memory) spans the length of the tube and pokes out both ends through the caps (this allows it to spin freely).

I got a cheap tarp off eBay for starters just to try it all out. The tarp is cable tied and duct taped to the internal rod then slid inside the unit. I had to add a few features like a locking bolt & velcro straps to stop it spinning and unravelling while driving.

To roll it up – I have a hex bolt head welded to the end of the rod, so all I have to do is put a socket wrench on there and wind it in.

It works really well and we definitely couldn’t do without it while camping now. If I had to do it again, I would try to get much a stronger PVC pipe (maybe even aluminium pipe) to help prevent flexing, this may not be a problem though depending where your mount points are.