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Posted

Thanks for the post and picture. But your axle is nowhere a 11l knuckle to knuckle axle, but a 13stud. This is why you have room to place the servo like that and you can use 5l suspensions arm without problem.

Attention, the use you do of the suspension knuckle 6571 on  the geared hub is problematic as this piece lack a bevel on a side, so it collides against the geared hub and make it force when steered. It is better to use the new 3l suspensions arm or the 5l in your case. Also, to me you can not use the daytona differential on your axle, but I can miss judge, let me know if this is correct as you stated it works.

Have a look to the my axles on rebrickable, https://rebrickable.com/users/Nico71/mocs/ The constructions is different because of the constrain of 11l width, that is why I have waited to get the news 3l suspensions arm from the Bronco.

If you want a similar axle as yours in 13l width, have a look to my Kodiak axle here : https://rebrickable.com/mocs/MOC-155168/Nico71/chevrolet-kodiak-c70-control-version/#details

Posted (edited)

I know it is a bit wider...but stud lower...it is a problem to fit if servo is in up position...perhaps I'll make kind of swinging servo...

...i have used this 6571 part because new 3 studs suspension arms were on the way at the moment...

...and I use CLAAS tires on that axle...so there are some differences

Edited by 1gor
Posted (edited)
19 hours ago, nico71 said:

 

If you want a similar axle as yours in 13l width, have a look to my Kodiak axle here : https://rebrickable.com/mocs/MOC-155168/Nico71/chevrolet-kodiak-c70-control-version/#details

I saw your Kodiak a while ago, but I also need 11L gearrack length based steering...

My initial plan was to use 7 x 7 suspension arm from McLaren, but I had to reinforce it because it bending under weight...

My problem is that I need 3 studs wide part of chassis / axle so CLAAS tires will not hit anything to have decent steering angle

Edited by 1gor
  • 4 weeks later...
Posted

New instructions for a 14-year old model, the Integraph ! If you are allergic to maths, run ! 

A LEGO Technic replica of an Integraph, a mathematics instrument created in 19th century by Abdank-Abakanowicz, for plotting the integral of a graphically defined function.

lego-integraph-1.jpg

lego-integraph-6.jpg

Original model (Coradi edition) :

1000x588.jpg

How it works :

The grey chassis with wheels move in x axis, the input stylus along the y axis. The stylus is placed on a sliding sub chassis with a slot. On this slot come the carrier which is connected to the main orientation arm, so when the stylus move, the orientation of this main arm change.

On this main arm, there is a sliding mechanism which hold the red carrier. This red carrier is build in a parallelogram way, in order the orientation of the two beams remains parallel. And on the extremity of this red device, the rotating beam is connected the contact wheel. So when the stylus input moves, the main arm rotates, and the orientation of this main arm is transferred to the contact wheel. The contact wheel is mounted on a carrier which can freely slide left right in y axis, and hold also the pencil with rubber band, plotting the output graph.

integraph-functioning-1.jpg

The trick is that the contact wheel acts as a tangent wheel where its orientation will defined where it goes by acting on the carrier, being free of moving on the chassis. When the tangent wheel is aligned with y axis, the carrier does not move. When it is angled, the tangent wheel forces to displace laterally the carrier, and as its orientation depends of the y value, it moved along the differential curve and plotting the output graph.

But why its integrate ? Because by definition, the inclination of the tangent of the integral curve -the slope or gradient- is equal to the ordinate of the initial curve to integrate (differential curve). If you look the machine in the reverse order, and follow a curve using the tangent wheel, the orientation of the tangent wheel define the gradient of the curve and so its derivative on each point which is the Y value.

integration_principle-600x479.jpg

All the mechanical complication around are just to transform translation into rotation movement, and decouple each movement to be independent and not dependent of their position with the different slide and carrier.

The applications of the integraph was numerous, calculate or divide areas, determine centres of gravity, calculate moments of inertia or stability, load and resistance, and solve algebrical equations like simple differential equation. Compared to a planimeter which gives the area result under the curve, the integraph give the representation of the function (primitive) so further calculus can be done. Therefore it was use in applied mathematics and physics, civil engineering with earth transport and bridge design, electricity with electromagnetism, shipbuilding, irons constructions, optics and ballistics with displacement and velocity determination for instance.

Example of result ( f(x)=x and x²+y²=r²)

integraph_result_annoted.jpg

These types of machines reached their peak with the mechanical differential analyser and balistic calculator in the twentieth century and then decreased in popularity with the advent of the computer.

Video :
 


Some additional resource :
 

 

Instructions : https://www.nico71.fr/product/integraph/

Bill of material : https://rebrickable.com/mocs/MOC-237895/Nico71/maths-instrument-integraph/#parts

 

For the model, I used a quite rare boat weight ref 73090. You can replace by any heavy part of about 50gr or use the alternate LEGO weight setup below (remove boat weight, add the displayed partlist, use the weightreplacement pdf).

weight_replacement_bom.png

How to use it :
 

  • Fix the paper, ideally A3 for both input and output, on the support with tape
  • Place the integraph parallel to x axis, and the stylus on the smaller value in y.
  • Place the tangent wheel carrier on the middle of its travel.
  • Displace the integraph along the x value (horizontal left to right) while following the curve with the stylus (vertical y value)
  • You can help the yellow sub chassis to move, as wheel as the tangent wheel carrier if it get stuck
  • It is easier to be two to operate the machine (on for the x axis by holding the wheeled chassis traight, one for the y axis to follow the curve with the stylus)
  • Ensure the surface is plane and the pencil touch it without too much force (do not lift the tangent wheel)
  • If a part of the curve is missing, you can draw by hand if you have integrated a continuous functions
  • 3 weeks later...
Posted

When you need a compact fake engine, without metapieces like 2×2 cylinder or new cam and piston , this is not easy to create. You have to make a functional model, without being blocky and if possible nice to see, top of the cake if it is easily removable and not part of the structure.

During my works on different cars and trucks, I have designed several compact fake engines in different configuration and building style. Today I propose them for free in a collection of instructions and 3D model.

free_engine_collection_16-9_1.jpg

Feel free to build it, look how it is made and reuse it. Each engine has its particularity :

  • Nissan 4 Inline (based on LZ20BT, used in my Nissan Skyline KDR30) : longitudinal, rear wheel driven, 2l axle piston, beam to hold them, brick-built crankshaft, easily extendable to 6 inline
  • Cummins 6 inline (based on X15, used in my Western Star 6900 Twinsteer) : longitudinal, 2l axle piston, stacked 3l connector to hold them, liftarm-built crankshaft, easily extendable
  • Citroen FWD 4 Inline, (based on 11D, used in my Citroen Traction), longitudinal, front driven (gearing on the front), 2l axle piston, stacked 2l connector to hold them (when the 3l connector is too expensive), brick built crankshaft, with half stud connector for the chassis mounted if you want to place as low as possible with a 12t/12t spur gearing
  • CAT V8 (based on CAT3208, used in my 6×6 Offraod Truck and Kodiak), longitudinal, 2l axle piston, angled stacked 3l connector to hold them, liftarm-built crankshaft, easily extendable
  • Honda 4 transverse inline (based on B16, used in my Honda CR-X Del Sol), transverse mounting, gear inside the liftarm-built crankshaft for front wheel driven car, 1/2 pin piston on 1/2 beam, extendable to 5 cyl, no more

free_engine_collection_16-9_2.jpg

Instructions and 3D models : https://rebrickable.com/mocs/MOC-238705/Nico71/free-engine-collection/#details

😀

 

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