A Rally Car, features steering, suspensions, fake engine and removable optional motorization.

Building a car at mid-scale was a target for me for a while. I didn’t want to make classic supercar with suspensions, steering and gearbox, that is why, I have developed the removable motorization, by using a simple lever this supercar can switch to manual functioning or motorized. This supercar has the following functions :

• Steering with Hand Of God and Steering Wheel
• Suspensions
• All wheel drive Transmission with 3 differentials
• Fake V8 Engine
• Openable Door and roof
• Removable optional motorization

The removable motorization is made with a special translated frame, on which the motors are connected. The two L motors are mounted on this frame, the lever operates a 12-tooth gear on a rack pinion, then the rack moves the frame.  In first position, the motors are not meshed with the transmission, in the second position, the 24-tooth gears on the motors are meshed on the central differential of the transmission which drive the car.

Concerning the steering, it is also removable to enable manual or motorized function. The frame which moves with the motor moves also the servomotor used for the steering. Thanks to a lever and a connecting rod, the servo-motor is moved with the rack. Then a special clutch enables the working of the functioning. This clutch is composed of two pulleys with 3 axles pins which meshed with other 2 pulleys.

Concerning the design I would like to make a 90’s rally car design with angular shaped and tailgate. My inspiration was the Group B Rally Car, for instance Lancia S4, Audi Quatro, Peugeot 205 and Lancia 037. I have worked many hours to get the correct shape, regarding the color, sharpness and homogeneity of the design. I am quite satisfied.

Also, I have made a openable light which is controled in the interior with a lever and a connecting rod. Also the doors and the roof can be opened for displaying the engine at the rear.

You can see here the behind of the car with the transmission, suspensions and motors. Regarding the mid scale and the power functions, there is no more room inside.

The performance are good, not as I expected due to the weight but are nearly correct for moving at correct speed the car. In any case, I didn’t want to sacrify design rather playabily, I want both. I find that this type of hybrid functions are good for supercar, manual functions and motorized when it is needed.

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The video of the Work In Progress chassis, which shows better the functioning or the motorization :

I have of course made the building instructions, you can download it as PDF or by browsing the gallery :

Downloading the high definition PDF building instructions. Lego rally Car By Nico71 – 14 mo, PDF

Want to check before if you can build the Lego Rally Car ? The Rally Car has been indexed to Rebrickable.com, the website which matchs your parts with mocs !

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This type of planimeter was used to calculate area on a mathematical curve, boundary of a country or measure and increase efficiency of machines for instance. There are two type of planimeters, those which work with precisely integrator with a mechanical device, and those which estimate the area with a approximation. The orthogonal planimeter is a first type because it has a real integrator system.

The planimeter is composed of a frame, an axle with wheels linked to the rotating yellow plan, a polar arm which moves the position on the small wheel and two dials to measure the area. The functioning of the mechanism is based on the principle of the wheel/disc integrator, as shown in the figure below.

To obtain the area on the surface, the mechanical device makes an integration of the surface below the curve. To make this integration, the curve is modeled as a standard x,y mathematical curve. On the figure on the top, x is rotation of the yellow wheel disc, also linked to the wheel axle, therefore when the planimeter goes forward, the disc rotates. Y value is the position of the small wheel on the disc, this position is modified on the planimeter by the angular position of the polar arm. And to finish, the product of this two coordinates is obtain on the axle on the disc, the integration process is recovered on the rotation on the small wheel axle equal to ∫y dx / (radius of the disc).

As always, the measure doesn’t depend of the shape neither the orientation of the shape, it works with concave and convex shape and is more accurate than the pritz planimeter. To obtained good accuracy, I have built the planimeter with minimize the deadpoint. For that, I have used gearing with slipping wheels instead of bevel gears which have lot of inversion deadpoint. Therefore the displacement of the planimeter is accurately transmited to the wheel disc which drives after the cursor on the dials. As a consequence, the planimeter is more accurate and have bigger range,  also, it is linear on all range, which is the best enhancement . Here is a small comparison :

• Smallest measure : 5 cm² / pritz : 25 cm²
• Biggest measure : 400 cm² / pritz : 150 cm²
• Accuracy : 2 cm² / pritz : 10cm²
• Linearity : Yes / pritz : No

The best way to understand how does it work is to watch the video :

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I have of course made the building instructions, you can download it as PDF or by browsing the gallery :

Downloading the high definition PDF building instructions. Lego Orthogonal Planimeter Nico71 – 6 mo, PDF

Want to check before if you can build the Lego Orthogonal Planimeter ? The planimeter has been indexed to Rebrickable.com, the website which matchs your parts with mocs !

[View with PicLens]

A planimeter is a device which is used to calculate surface and area from a drawing of the shape. By traveling the boundary of the shape, the measuring instrument integrates the area of the shape which is equal of the surface in the shape. This type of planimeter was used to calculate area on a mathematical curve, boundary of a country or measure and increase efficiency of machines for instance. There are two type of planimeters, those which work with precisely integrator with a mechanical device, and those which estimate the area with a approximation. The Pritz planimeter, also caller Hatchet, is a second type planimeter.

My planimeter is a modified version of a pritz planimeter which is very simple. It is composed of several elements :

• The main rod, which is connected to the wheel and the cursor
• The wheel which can roll but not slide
• A connecting rods system which links the angle of the main rod on a gearing (addition)
• The gearing up (40/8) which increases the angular motion (addition)
• A dial which shows the final measure (addition)

Now how does it works ? With the cursor, you travel the boundaries of the shape, and after comes back to the starting point, the planimeter shows the measure. Mathematically, the planimeter use a tractrix which approximate the derivative necessary to calculate the area and the Green’s theorem which links the line integral around a simple closed curve and a double integral over the plane region. Consequently the area is roughly equal to the difference between the starting and final angular position of the main rod.

To understand more precisely  you can read the description of the planimeter on this website and the maths demonstration and the Green’s theorem.

This device is not very accurate, because the derivative is approximate by a tractrix and because the connecting rod system is not very linear. With low or high value, the non-linearity of the system causes interference with the measure. In any case, it is a simple and very demonstrative of the genius of ancient engineers to measure things with mechanical device.

I have made the building instructions, I encourage you to build it to understand this clever device.

Downloading the high definition PDF building instructions. Pritz Planimeter by Nico71 – 3mo, PDF

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Next to a contest organized at fanabriques 2012 on the theme “build a stage trailer”, the company StageMaster SAS contacted me in September to build a replica of a Folding Stage Trailer SM70. After discussing about bill of specifications, I have started the design process and the quotation. After 4 month of work, the trailer is finished and it has been delivered to the customer.

Bill of specifications

The aim was to have a reproduction of a stage trailer SM70 with following motorized functions :

• 4 pneumatic stabilizers
• Folding right and left panels with a motor
• Folding upper panels with a motor
• raising roof with a motor

Next to that, the following specifications has been introduced regarding the design and deadline :

• color : Black frame, black roof and floor, black panel, gray upper structure
• dimensions : around 60cm long
• can yoke to a truck
• deadline : February, 2013

Design process

The first thing I have done is to build a rough frame to test different types of functions. I have started to build with linear actuators, and pneumatic cylinders but none of them were adequate. The actuators were too big for the scale, and if I have increased the scale, I would have had a very big trailer with lot of weight problem. This scale is a compromise with the functions and the scale. Finally, I have decided to use the internal space of the frame to make the folding functions. That is why I have developed next the system of axle driven. The axle of rotation of each panel are consequently directly driven by a motor and high gear reduction (8/24, 8/24, Worm/24, 20/20 bevel gear). This system enables me to have smaller slider beams.

The second point was to come up with a solution for the raising roof. In dead, on the real model, the main functions were piloted by many hydraulic cylinders. Especially the roof which is elevated by a 3-section telescopic hydraulic cylinder, which is impossible to reproduce in lego. I have therefore tested many systems with 3 sections actuator based on 8421 crane and rack system but none of them were adequate.  Either the clearance was too small, or the stiffness was too low. I have thus developed the final solution : a 2-section slider for the rigidity and a system of winch for the raising force. This solution was very stiff and compact because all driven devices are located in the frame. A M  motor drives a worm screw on a 24-tooth gear which winches two axle with two strings. Then the strings roll on a pulley, reach the top of the slider beam and are attached to the moving parts of the sliders.

The last problem I had to deals with was the weight. The panels are completely recovered of black plate, I had to now the global weight and the consequence on the functioning. That is why I have first of all calculate the mechanical power on the axle of rotation depending of the motor, the gears and the efficiency and compare with the needed force for raising the panels. By applying a safety factor I have modified the gearing to have enough force. I have made the same thing for the elevation of the roof by comparing the force of the winch with the needed force using winchtools.

After that, I have completely modeling the model of SR3D builder, in order to create the bill of material. In total, there are 1575 parts for the trailer and 600 for the truck. After receiving the whole parts from 5 bricklink sellers, I have built the trailer and check the functioning. After 4 months of work, I am satisfied by the result, It adds a success to my industrial references.

Gallery

You can watch the two videos, the first was made with my parts to check the functions and present the concept to the customer. The second is the final version with all the parts.

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The pictures during the building :

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]]> http://www.nico71.fr/folding-stage-trailer/feed/ 3 http://www.nico71.fr/hot-bulb-pneumatic-tractor/ http://www.nico71.fr/hot-bulb-pneumatic-tractor/#comments Sun, 02 Dec 2012 10:09:51 +0000 Nico71 http://www.nico71.fr/?p=1489 Read the Rest...

A lego pneumatic tractor based on a hot bulb engine Lanz tractor. Features drive, single pneumatic engine, adjustable ignition point, steering and suspended seat.

I wanted for a long time to build another tractor to improve the previous and use a single engine with inertia wheel as on my pneumatic machine. The result is here : a pneumatic single engine tractor with a special feature : adjustable ignition timing.

The model is basically composed of a frame which handles the engine, the transmission and the bodywork. The engine is a very simple pneumatic engine with one cylinder. This cylinder drives an axle that is connected to the inertia wheel axle by a gearing of 5:1. On the left side, there is the pneumatic valve that is controlled by a crank connected to the engine rotation through the adjustable ignition timing. On the other side, the axle of the inertia wheel protudes and drives a wheel and a 40-tooth gear which is connected to the fan on the top of the tractor.

The adjustable ignition timing is based on the differential principle. One side of the differential is connected to the engine rotation (input), the other side is connected to the valve rotation (output), the ring gear is locked by a worm gear on it. In nominal rotation, the input rotation crosses over the differential and the angular difference between the  input and the output is null. In set up configuration, the user moves the worm gear, which drives slowly the ring gear, consequently the input is move back and the angular difference between the input and the output is not null. This device makes exactly what an electronic ignition point system makes on a car. It enables to do two things :

• Find easily the starting point of the engine
• In motion, find easily the best functioning which makes the running as smooth as possible

The steering is operated by the steering wheel near the seat, it drives an axle which crosses over the frame on the center and operates the steering with a worm gear on a 8-tooth gear. Then, a lever in rubber operates the steering thanks to its resiliency which also enables to have a good turning radius. To finish concerning the steering, the front axle is also  equiped with a pendular suspension which is an improvement of my previous tractor.

The transmission is quite basic, the rotation of the engine is given to a rear axle thanks to many gearing. At the end of the transmission, I have placed a driving ring which a change over catch to make a basic clutch. Thanks to that, the engine can run and after switching the transmission move the tractor.

To finish, I have placed a suspended seat with a spring under it and the whole bonnet can be opened to see the engine running.

On this video, you can watch more presicely how the engine is built :

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I have of course made the building instructions, you can download it as PDF or by browsing the gallery :

Downloading the high definition PDF building instructions. Lego Pneumatic Tractor Nico71 – 10mo, PDF

Want to check before if you can build the Lego Pneumatic Tractor ? The tractor has been indexed to Rebrickable.com, the website which matchs your parts with mocs !

[View with PicLens]

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After the first attempt to build a mechanical loom, I decided to continue to develop the loom and figure out the problem. Reminder of the problem : sometime, the shuttle doesn’t pass through the threads, induce a blocking of the system. Thus, I have decided to change the system of launched shuttle for a system of pushed shuttle.

The system is very simple, a lever rotates on the primary shaft and makes contact with a cam one time per revolution. When this cam is pushed, it pulls on a rod which operates the main pushed system (green beam). This device allows the system to push the shuttle during the overall crossing through the threads. Even if the slider is a bit smaller, the reed is a bit wrong placed or the threads are a bit not enough tight, the shuttle is forced to pass through. Thanks to that, the system is always in contact with the shuttle, resulting in a significantly increasing of reliability.

After two days of weaving, 70 meters of thread, the result is a 8cm*40cm fabric, not enough for a sock. You can watch it in the video during the fana’briques exhibition :

An French Interview I did on my loom at Fanabriques 2012 :

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The building instructions are NOT planned to be built, the loom is taken apart but I work on a new mechanical loom, smaller and faster.