DIY industrial CNC router

enclosed reduction drive

enclosed reduction drive

ist table in position

ist table in position

tilting motor mount

tilting motor mount

Just think; if you had a CNC router you could start on the Original Twist 3-wheeler, make some furniture, maybe even earn a good living with contract work. Time to join a mass of DIY enthusiasts and knock one up yourself?
Youtube reveals some totally heroic machines made in plastic and MDF with frames in off-the-shelf extruded aluminium beams. Cheap computers and software have brought CNC machining within range of the DIY brigade. I’d like to continue in this spirit but head towards something much bigger and heavier without increasing the cost to anywhere as much as that of a professionally made router.
Size: In order to machine round the outside of an 8’x4’ sheet we’ll need a long and strong X axis. A 14 foot long steel RSJ will make the heart of our CNC router. It’s long enough to overhang the ends of the support posts so that tension ties can counteract even the smallest tendency to sag under the weight of two 4.5kW router motors and two drills. The neat thing about an RSJ is that it is not only cheap but the ‘I’ section enables us to put drive gears and the drive rack neatly inside the web.
Torsional rigidity is not a strong point but is easily enhanced by welding a heavy tube or two inside one of the webs. Unlike cast iron, steel can pick up vibration so filling a tube with heavy chain and oil will make a cheap but effective damper. You only get really smooth finishes on a machine that is well damped.
Z axis: You could buy an off the shelf Z slide and hang that off the X axis for a conventional and simple layout but the logic of that is debatable. When machining flat boards etc there is very little Z movement so it would be better to put the Z under the Y table so that the two major movements are as light as possible. The Z frame is raised like a garage car lift with 4 chassis mounted screw posts rotating to drive ball nuts on the frame. Unlike the continuous chain of the garage hoist there would be a single timing belt for each screw sharing one of a pair of drive spindles which are both driven by a fairly short belt and the stepper motor. This way we get reduced belt stretch and a built in reduction drive. This layout enables a much bigger Z travel – 3D modellers note – and makes a fast and responsive machine with a tidy uncluttered look. Air balancing means there would be no heavy lifting for the Z stepper motor despite having to lift the entire Y table plus the job on top.
Y axis: This is the table going forward and back and a conventional 2 belt and shaft drive will be fine and neatly out of site at the rear of the machine.
As it’s a long machine it could be worth having a pair of tables rather than one big one. Production is greatly increased when one side can be reloaded while the other works and the 2 can be worked together to make one big table. As is common practice one makes the Y axis table tops out of Tufnol self machined to skim true and make the vacuum rubber channels.

Tooling mount: This the neatest twist and the basis is a wrap around box of thick aluminium plates enclosing a 1ft length of the beam.
Each of the 4 plates has a unique function. The top and bottom plates are for the slideways; Turcite blocks for the heavy downward loads and vibration damping, ball bearing rollers only for lateral location.
The drive sideplate supports the entire drive mechanism – see picture – the drive motor sits over the top of the aluminium box and drives the big pulley on the outside. All the rest is inside the web of the RSJ ending up with the toothed belt driving onto the rack with a sort of caterpillar to give more tooth contact. This plate is at the back of the machine and also supports a pair of Desoutter AFDK drills. These lovely drills just need a pulse from a 4mm air pipe to set them off on an automatic drilling excursion.
The front plate supports a swinging plate that holds a pair of angled router motors that are alternately selected with a push from an air cylinder; the cheapest alternative to a tool changer you’ll ever see.
The tool changer: The top pivot point is in line with each router motor axis so that they both swing into exactly the same position. The pneumatic pusher cylinder is mounted inside the box and pushes a peg that goes through a slot – neat huh? Between the motors a round steel plug is pressed into the plate and one of a pair of electromagnets pulls this to lock the plates together (better solutions in comments please).

So there we have a heavy duty industrial quality router with 2 tools and 2 drills; about £20,000 worth if you had to buy one. One could earn a comfortable living with one of these. Not a lightweight project but still DIYable especially if some of the complex parts are tested in MDF first and then self machined in aluminium or Tufnol to finish. Don’t get bogged down with cutting, welding and drilling heavy frames; the steel suppliers have all that kit and will make to your drawings in no time.
Levelling the beam: There must be a few ways to do this other than sending it away for precision grinding. Once fitted in place with some representative weights clamped on, the tension stays can be tightened to get close to straightness. A small steel block with a laser on it will show a dot moving up and down a target to reveal the bumps which will respond to a light touch of an engineers scraper.
When the beam is true the finally added hardened steel guide bars will provide the perfect flat finish.
Panels: Professional machines come with expensive steel panels. As the central box chassis needs to be stiff and straight use MDF panels bolted to the steel to make it neat and strong too. Hammerite paint on MDF is remarkably durable and will keep it all looking very tidy.
Bellows: With a rectangular box sliding on the RSJ there will be no problem in adding bellows to make the machine the ultimate in tidiness and this will be no bad thing for the unlubricated Turcite slides.
For further reading try following -a fount of CNC knowledge- and please criticise or add ideas for improvements in comments.

Honda GX200 in the Original Twist 3-wheeler

A 200cc engine in a car! Surely we jest?

Honda GX270 - even smaller without the tank

Honda GX270 – even smaller without the tank

Well first let’s see what the engine is required to do. Remember the car is a light, range extended plug-in electric car with everything minimalised to save weight. Even the electric range is cut back to 20 miles to halve the usual battery pack; half the weight and half the cost. In normal use the car would do the school run or a shopping trip on battery power alone but with no range anxiety thanks to petrol back up. Most electric cars boast longer range but for the majority of journeys they have carried around a heavy stack of surplus batteries. It follows that for most of our short journeys we are also lugging round the petrol engine so weight is going to be a major consideration.
The main use for the petrol engine might come from a weekend run in the country with some fast roads thrown in. With the 20-40bhp electric motor for brisk acceleration and overtaking the 9bhp petrol motor is really just for cruising at up to 50mph. Bear in mind that the engine is charging the batteries when the car is stationary, at the lights say, so the available, combined power when on the move is higher than one might imagine.
The Honda GX engine range actually gives us the choice to go for a bit more power but with weight penalties. Thanks to the go-kart scene they can all be tuned for more revs and more power. The rev limiter is always removed and a stronger flywheel added.
The GX200 only weighs 35lbs and can produce a useful 9bhp. The Loncin Chinese clone version only costs around £250 and makes a good starting point.
Next up is the GX270. Weighing in at 55lbs this might turn out to be the sweet spot between power and weight. With the usual modifications and the bigger carburettor from the GX390 this engine will give a good 12bhp.
The GX390 is good for up to 20 bhp but weighs a back straining 69lbs. Only testing will tell if that is departing too much from the light and minimalist idea but it would certainly be good for breaking the speed limit on the motorway. One should bear in mind that the engine and the electric motor are mounted just ahead of the rear wheel and the aim is to keep the overall weight distribution just slightly front heavy.
The engine mounting plate on the Original Twist hybrid 3-wheeler will be pre-drilled to mount all 3 engines so the choice is there. We can also consider the Briggs and Stratton racing engine with all the right bits built in at the factory – it’s called the ‘Animal’.
No doubt some inveterate tinkerers will have a spare engine for tuning experiments and, who knows, in time there might even be a racing series.
It is the intention that the engine will be pretty much clipped on and able to be changed in a couple of minutes so concepts like service exchange engines, rented engines etc are feasible. With that in mind the little 35lb GX200 that fits in a shopping bag looks attractive.

Plug-OUT Hybrid car

Plug-in Hybrid? Yes but what about a Plug-OUT Hybrid?

The Original Twist Plug-in Hybrid featured on this site has some useful components in it which can be used for many other purposes:-

9bhp petrol motor
20bhp electric motor battery pack
Power shaft close to the rear luggage rack

We’re looking at such a hugely versatile mobile power house that it’s hard to imagine all the potential uses. I’ll leave that to you but here’s my first selection:-

Domestic UPS
A small inverter connected to the batteries will provide 240V a.c. which can power a house for hours. This feature will augment the battery pack that off-grid P.V. systems will have anyway.

Grid balancing
When electric cars go mainstream the grid will bid for their stored power via smart meters. A parallel hybrid will always be able to sell power when the price is right and still make the next journey.

Electric generator
The batteries can be kept topped up by the 9bhp petrol motor charging via the electric motor on the other end of the power shaft. Extended power cuts won’t be a problem.

Mobile power supply
The vehicle can deliver d.c. and a.c. power wherever it goes. The range of power tools that can be driven is endless and this will empower trades people and farmers alike.

Power shaft
It just takes an extra pulley on the power shaft to provide drive to anything bolted to the rear luggage rack. The picture here shows a compressor but it could be a lathe, a potters’ wheel, a wood chipper, a water pump ….. etc etc.
A rear p.t.o. is also easily arranged for light duty mowing, for example.

No problems with lighting and cooking when you go camping in a Plug-OUT Hybrid.

The Honda GX petrol motor takes just minutes to refit into a go-kart and it’s already modified with racing parts to suit.

If ever there was an automotive Swiss Army Knife this is it.

Swiss Army Knife?

Swiss Army Knife?

Original Twist hybrid electric 3-wheeler

Original Twist 3-Wheeler

Original Twist 3-Wheeler

OK – so the next automotive era has arrived and all car makers now offer some variation of an electric car. However, despite thousands of people with free home-brewed solar electricity just itching to go electric there is nothing economically viable on offer. Here then is an attempt to define what would be a workable, even desirable, alternative.
Anyone paying the London congestion charge could be paying an additional £2,000 a year. That alone, with negligible other costs, is worth at least £10,000 to give a return of 20% on capital.
Let’s set a price target of £10,000 – £15,000 and define what sort of attributes most users would want:
Safety – very strong with above average crash sustainability.
Seating – for 2 adults and a rear parcel-shelf seat for occasional use, children and baggage.
Range – a normal daily commute of a 20 mile round trip entirely on battery power.
Range – a small combustion engine to give unlimited extended mileage.
Parallel hybrid – both power sources used at once if extra power is needed.
Plug in hybrid – batteries charged at home or by range extender engine.
Performance – equal to or faster than normal traffic.
Luggage – similar capacity as any other small car and much better than a microcar.

The key to economical motoring is lightness so from the start let’s begin with a 3-wheeler with two wheels in front and one behind. At a stroke this dispenses with some heavy things like a differential, axle, and one back wheel with suspension, brakes and associated bodywork.
With some heavy batteries mounted low down between the front wheels there will be no stability issues.
The power train couldn’t be simpler. The rear wheel spindle is mounted in an ‘H’ shaped swing arm, just like a motorcycle, with a chain drive to a sprocket that spins on the same inboard spindle that the swing arm pivots on. This sprocket spins alongside 2 others whose chains run up to the main power shaft where dog clutches engage either one to give high and low ratio drives. The power shaft has a push on drive coupling on each end to connect an electric motor on one end and a small single cylinder petrol engine on the other – it’s that simple.
The permanent magnet Lynch electric motor produces maximum torque from a standstill so there is no need for a clutch. It also doubles as the starter motor for the engine, a regenerative braking charger and can run backwards to provide reverse gear. Dispensing with a starter motor, alternator, gearbox, clutch and reverse gear puts more in the ‘saved weight’ account. Electric power is a useful 20bhp with 40bhp available in 5 second bursts. By comparison the original 850 Mini had 33bhp but weighed 70% more than our target of 7cwt.
The electric motor and the battery pack is sufficient for general short trips of up to 20 miles and perfect for city traffic creeping while the combined power sources produce lively performance up to 60 mph progressively dropping to 30 mph if the batteries pass a low threshold.
The slightly modified Honda 200cc GX petrol engine only weighs 35lbs and produces 9bhp; adequate for performance boosting, charging, range extending and even as a limp home device. It can be replaced for well under £500 (clones are £200) and after 5 minutes of unclipping could be left behind for servicing.
Maximum combined power is 49bhp to give a power to weight ratio of 150bhp/ton; it will be nippy.
Of course the design could have substituted extra batteries and an extra electric motor for the petrol powered assistance but the logic is that some petrol power enables the driver to set out on any journey with confidence.
With an Indian made Agni electric motor (very similar to the Lynch pancake motor) this car would make great third world transport with India to start with. Tata this is your new super-cheap world car!
A £100 programmable logic controller is used to control gear selection via the clutches and the potentiometer throttle pedal. Regenerative braking is controlled but limited if the rear wheel tries to lock up. The same idea also provides optional launch control and safer driving by restricting wheelspin.

3 power modes are selected by a dash mounted knob;
Engine +
The ‘Range’ mode uses ‘engine +’ to drive as normal but whenever the car stops, the engine revs up and starts charging the battery ready for the next burst of power. At the first touch of the throttle the engine disengages and the electric motor stops the power shaft to select first gear.

At the front end of the car a simple subframe makes a battery box with incorporated suspension mounts. A lightweight rack and pinion and unassisted brakes take care of steering and stopping; all very simple but maybe the biggest weight and cost savings will come from the novel bodywork or indeed from the lack of it.
Central to the strength of the car is the passenger cell made from 2 CNC machined aluminium sheet and plywood bulkheads all connected with 3 fat aluminium torque tubes and further panels in the same aluminium and wood sandwich. The complex bulkheads enable the suspension loads to be fed into the extremely rigid passenger cell as well as mounting dozens of other components. Design like this not only saves weight, cost and assembly time but the bare aluminium looks so good that there is no need to paint it.
A smaller stressed panel incorporates the dashboard where a matt carbon fibre like laminate sets off the Stack instrument panel and the selector knobs for power and varying the regenerative braking.
Behind the passenger cell there is no bodywork as such; a horizontal tubular hoop supports motorcycle panniers on each side of the back wheel and a top box over the top.
At the front a one piece moulding covers the battery box with a pair of wings over the wheels and partially down the side panels.
The narrow central roof panel is supported by two longitudinal roll cage bars which also provide hinge points for the gull wing window/doors. Similar to a Mini Moke (and the Mercedes SLS) there are no doors as such, just side pontoons.
To cut out the cost of regulations, crash tests etc the car will be sold as a kit car so customers will be expected to fit the engine and the wheels, perhaps with 10 minutes of help at the point of sale.
Can the price target be met? By raiding the parts bins for existing components and keeping it all minimal and simple the answer is yes. The result would be a characterful and useful eco-runabout with almost negligible running costs and at half the price of a Morgan 3-wheeler (with sales of over 1,000).
The Renault Twizy costs just £8,000 but battery hire costs £55 a month and it is hardly a useful all-rounder, and anyway similar mass production would make our car much cheaper.
This is just a sketch to hint at the full design. If you want to make one just let me know.

Tech notes: front suspension – wishbones but none sourced yet. MX5? Usual Cortina geometry from kit car uprights.
Rear swing arm – nice specials available for drag bikes at reasonable prices, just need a wide mounting to take side loads. .. easily made anyway.
Wheels etc .. 155×13” tyres at front … cheap and plentiful. 165×14” at rear.
Electric clutches … magnetic or dog clutches .. either would work … drag race air shifters?
A lock-up centrifugal clutch needed for the engine to provide limp home mode.
Roll cage; usual wide front and rear hoops connected by a close pair of tubes running from top of screen to rear and then down the rear bulkhead to pick up the engine/transmission plates. The rear frame extension is a loop of same width as the roof bars and provides a rear grab handle as well as support for top box etc.
The aluminium engine/transmission plates also provide swing-arm mounts, rear frame bracing and pickup lugs for the rear coil shock absorber units – a nice CNC machining exercise.
For a low car like this, gas-strut balanced self raising seats would be a nice touch to make getting in and out easier and the side pontoon height could then be higher for better strength and protection.
Rear corners of the passenger cell are fitted with sprung skateboard wheels to counteract any inadvertent tipping without damaging the bodywork. The Morgan F4 used to scrape the exhaust to the same effect (only after C of G was raised with back seat passengers)

Rotary PV solar garage

PV rotary garage

If you are a bit of an eco-warrior you might fancy an electric car, some photovoltaic panels to charge it with and a garage to keep it in. Here is a concept sketch for all those things in one neat package

Photovoltaic arrays perform some 20% better if they track the sun so the 24 panels on this rotary sun tracking garage perform as well as 28 static ones. 4 extra panels would cost £1,000 so tracking is worthwhile and of course adds to the FITs return. In addition to tracking the sun, the front and rear sections also tip up or down to get the most of morning and evening sunlight. The front set can tip up out of the way whenever the sliding garage door is open; alternatively they rotate out of the way to a preset parking angle.
A conventional array would have problems with the varying inputs across the panels but here each panel has its own micro-inverter which also enhances reliability and the performance reporting via wi-fi is fabulous.
The 250W panels together make a 6kWp array which is pretty punchy for domestic purposes and would leave a good surplus after charging the car inside.
The garage shown here has a diameter of 5 metres.
An elegant alternative to the rotary roof is to mount the garage on a car turntable so you would find your car all charged up and pointing down the drive ready to go. There would have to be 2 doors of course.
The price for the rotary roof garage should come in at around £16,000; not bad for a free petrol pump in the garden and subsidised electricity for the next 20 years.

If this seems a bit too much to add to the heavy price of an electric car, just watch this space. The Original Twist affordable plug in hybrid will be arriving on the site soon.

260mph in a 3 wheeler!

It’s in the pub car park, still hot and ticking slightly as it cools. It has a pair of wheels visible under some cowls outside at the front of what looks like a glider fuselage, so it must be a vehicle of sorts, but the rear tail wing and the pair of jet engine cowls blending into the rear bodywork make it look like a combination of a glider and a Lockheed A-10 Thunderbolt alias the Tankbuster or the Warthog. Unlike most cars this looks very military with matt grey paintwork and stenciled labels such as ‘Keep 2m clear when motors running’, ‘no handhold’. I just had to have a word with the owner.

Q: This looks more like a glider fuselage with two wheel pods on the front. Is it some sort of jet car?
A: It’s a very slippery and light 3-wheeler and yes the detachable canopy is from a glider.

Q: Does it have a jet engine then?
A: No it has a front mounted 600hp turbocharged Subaru 2.5 litre engine driving all three wheels through an automatic gearbox. The things like jet pods at the back are air intakes for the entrained exhaust powered water cooling. The brake lights are incorporated which gives the illusion of exhaust flare and sometimes the exhaust does proper flares too.

Q: I guess you could keep up with a Bugatti Veyron then?
A: It’s a close thing and really a battle for traction. Acceleration is about the same up to 120 mph with all 3 tyres trying to smoke but up to 160mph the computer controlled rear wing gives exactly enough traction to get the edge. After that we can flatten the wing and carry on to 260mph with the Veyron in our mirrors. We don’t need to compare ourselves this way though – it’s easier just to say that this is a match for the supercars but the quickest 3 wheeler ever.

Q: What about braking?
A: Backing off from 260mph gives 600bhp worth of drag. Slamming up the wing gives drag and downforce so we can pull 3G on the brakes – only a good idea with a full harness on though and it’s hard to hold your head up. In some ways the brakes are too good as there is always a danger of collecting all the cars behind you whenever you stop.

Q: Why isn’t the rear wing on straight?
A: The wing is computer controlled for downforce as well as lateral force. We literally fly round corners. It sounds silly but we park the wing sloping to stop people putting their drinks on it at the pub. The car always has a crowd round it and it was fun when the start up routine tipped all the drinks off the back but we thought glass on the road was a bad idea.

Q: So what made you build it then?
A: I heard about some Australian guys who had built a successful drag Subaru WRX and it struck me that the drive to the rear could just power one rear wheel and that would enable a streamlined plane-like body to be used. They were getting 600hp and the thought of that in something light and aerodynamic was too much to resist.

Q: So it’s a road car?
A: Yes it is used daily on the road and is easy to drive slowly. What really freaks people out is when we play a loud jet engine soundtrack on the stereo and the best bit about that is playing the sound of a turbine spooling down after parking the car. The main problem though is talking to people about it all the time.

Q: Oh – that’s me too I guess. Well thanks for the chat; will we be seeing any more of these on the road?
A: We hope someone will take up the design and produce the car albeit with a bit less power. The Thunderbolt was a spectacularly beautiful plane and its character should live on in a car.

Security equipment update

Aeon Labs door sensor

Aeon Labs door sensor

Aeon Labs multisensor

Aeon Labs multisensor

Vera Lite Controller

Vera Lite Controller

Security equipment news
Time for a quick review of some components to flesh out my last note on Z-Wave home security solutions.
First a quick recap to emphasise how the simple radio meshed network of Z-Wave components has come to dominate home security systems in America, displacing the old ways of doing the job.
The old way is where ‘the experts’ arrive at your house and for €2,000 fix lots of wires and a control box and then reappear every year for a €600 check to see that it is still working.
The new way? You connect a Z-Wave home controller such as Vera Lite to your router, buy a few sensors, most of which run on batteries, and then decide (via your PC) which configuration would suit you with regard to email, i-pad or phone alerts. You can play with ideas such as having the lights flash a couple of times when guests arrive and any other variations you can dream up. The system self diagnoses all the time so there is never a need for a scheduled check up. All that for a third of the price and no further expense.

Anyway – about the new kit
Fibaro are becoming a leading force in the sector and have fought back against the inexpensive Vera Light controller with HomeController Lite, a cheaper version of their main controller for £250. It includes Geo fencing which is a supported phone app where you designate physical boundaries for your smart phone which if crossed generate reports or activities. For example if you leave the perimeter of your house with your phone you might want all the alarms to be set, or you might want to be able to track your teenage kids or maybe just find out where you lost your phone. Fibaro tend to release kit a bit ahead of market readiness so for choice I’d still go for the more proven and cheaper Vera Lite (£129) and the same sentiments go for the amazing Fibaro multisensor where I’d stick with the Aeon Labs version pro-tem. Fibaro do some excellent little Z-Wave relays that can switch up to 3kW of mains power and these have been tried and tested for a long time. They are small enough to be tucked into a deep pattress box behind a standard light switch so existing lights can be controlled by Z-Wave.
The interface on your PC, phone or tablet is an easy way to check and adjust any element of your home automation. Once the security side is set up you won’t be able to resist adding more elements like flood sensors, light switches and remote door locks. Try asking the old security company if their system will turn down the heating when you leave the building or if it can turn on the immersion heater from the airport? is the place to go to buy most of these parts and they go to great lengths to ensure components are compatible with each other.

For outside motion detecting I’m taken with the Aeon Labs water resistant multisensor for £45 which enables you to extend your security perimeter well outside the house. Multi layered security is a useful concept where a movement outside the house invokes a mild alert and a house intrusion escalates that to a full alert. This sensor also detects temperature, humidity and light levels.
Aeon Labs have also brought out a £52 door and window sensor that is so small it fits in a drilled hole in the frame so there is no need for any ugly blocks screwed to the outside. The sensor is Z-Wave compatible and tells your controller when the battery needs changing.

You’ll need to see what’s going on and the world of cameras opens a potential can of worms of the technical type; ip addresses, data storage, wiring etc; all tricky for the uninitiated.
Y-Cam makes this a little easier with their HomeMonitor system. In a nutshell you buy indoor cameras for £150 and outdoors for £250 and plug them into your router and a power supply. Setting up is pretty much automatic. After that, whenever activated, the cameras send content out to a remote server where it is stored free for 7 days. A clever twist is that when an event occurs the previous few seconds are front loaded onto the recording so you can see the baddies coming before the motion sensors do and even if they destroy the cameras you still have the footage. Of course your phone or pad can look in on the cameras whenever you like. The cameras only transmit triggered events or viewing requests so your internet bandwidth should not be compromised.

Getting started
One could start off with a controller, 2 sensors and a camera for £369 and then build that up over the ensuing years. The era of affordable home security has arrived.
There is little doubt that such equipment will become pervasive over the next decade and then burglary will become a problem of the past.