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J-Rail Roller Blocks

Started by sagrada737, July 18, 2021, 04:08:02 AM

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sagrada737

July 18, 2021, 04:08:02 AM Last Edit: July 18, 2021, 05:57:24 AM by sagrada737
Hello All,

For my Weber Seats, I wanted to buy a Boeing J-Rail system (roller blocks and rails), but it seems that they are rare, and almost impossible to find -- not to mention very expensive.
 
That being the case, I decided to design and build my own J-Rail replica system for my Weber Seats, following the design from FSC.  I used a dual J-Rail design with conveyor rollers inverted to provide the required "sliding movement".  This approach works, but it not as smooth as I wanted.  This is mainly due to the fact that the conveyor rollers simply do not work as well when inverted.  They tend to get stuck and make excessive noise.  Also, since I constructed this J-Rail system using steel plate, it is quite heavy.

"If at first you don't succeed, try, try again!"

Needing a better solution, I recently decided to re-design the J-Rail system, following the form and function of the real Boeing J-Rail components.  See photo...   A friend of Scott loaned me one of his Boeing J-Rail Blocks so I could better understand its design.  The original Boeing J-Rail parts are built like a tank -- like everything else in the 737... :)

I decided to use 3D printing as a way to build and construct a similar Roller Block assembly.  Although I could easily use my CNC milling machines to make these parts out of aluminum, the idea of using 3D printing intrigued me.  At this stage, I am prototyping the design, which looks promising.  Below is a photo of my Creality 3D Printer -- I use two of these.

For 3D printing filament material, I chose PETG, as it is very tough, easy to print, dimensionally stable, and allows for post-machining, eg. tapping holes, etc.  I am using 4 layers for top, bottom, and wall thickness, with 40% in-fill.   This all results in a very strong part.

The original Boeing J-Rail roller blocks use a system of 5 bearings, which allow for smooth movement, constrained along the J-Rail.  In effect, I am using 5 bearings to accomplish the same result.  One bearing is for pivotal rotation as the seat moves fore/aft and rotates to the side.  Another set of bearings manage the combined vertical load of the pilot/seat divided  by 4.  The other 3 bearings manage the lateral constraint as the Roller Block moves along the J-Rail.

The photos show the prototype in its early stages of design.  I have gone through several iterations of design to date, and I am close to finalizing the design for initial testing with the Weber Seat.  I hope to test my new J-Rail Roller Blocks in a couple of weeks.

One point that I think is important... For our full-scale Sims, we don't necessarily need original (Boeing or other) parts to accomplish the needed function.  In the case of the J-Rail system, all we need is a system that will handle the weight, and one that provides smooth operation.

Making our own "stuff" is part of the fun in building our Sims.   3D printing is one such tool that helps to make that possible.

On another note...  The astro-image below is for you Trevor...  It is a color narrowband image of "The Pelican Nebula", which I imaged a few days ago with my 24" telescope from our Sagrada Observatory.  Thanks again for all you have done for this Forum.  Enjoy!

Clear Skies,
Mike
Full-scale 737-800 Sim; P3d v4.5x with Sim-Avionics (two computers), FDS MIP,  FlightIllusion hardware.  3-Optoma ZH406ST Laser HD projectors, with 4K inputs from a single Nvidia RTX-3090 GPU, resulting in a 210 deg wrap-around display.  6dof Motion Platform using BFF 6dof motion software, driven by a Thanos Servo Controller to 6.2 KW Servos, Lever type actuators.

navymustang

Mike, great idea and glad to see additional 3-D printing going into our sims. How do you keep the block on the rail and keep the seat from tilting if one lifts or pushes out of balance? That is, there doesn't seems to be any part of your rail block that goes under the rail to keep it from lifting.
Thanks for sharing.
My 737-800 full-scale cockpit has been sold. Now onto my full-size military helicopter project. An AOPA member and LifeTime member of National Association of Flight Instructors. Please note that I am a self-employed professional cockpit builder that provides consulting to defense contractors and civilian schools and airlines.

sagrada737

yep...   3D printing has been a very useful process with both my 737 Sim Project, and the telescope stuff I work on. 

As I mentioned in the initial post, The photos are early prototypes of "some" of the parts.

You are quite observant to discern that there is a need for Lower Brackets to keep the Seat from rising off the J-Rail.   The Boeing J-Rail roller blocks have these parts.  In my design, I am also incorporating these Lower brackets, which allow for about 1/16" vertical clearance for the Roller Block to move on the J-Rail.

Typically, when the Seat is moved, the pilot raises a bit to reduce the load on the seat.  But when the pilot moves back in the Seat, it's common for the front end of the seat to rise up.  Hence the need for the Lower Restraining Brackets.  Thank you for pointing that out...  I'll post more photos when I finish making all the parts.

Below is a photo of my current J-Rail seat system.

Mike
Full-scale 737-800 Sim; P3d v4.5x with Sim-Avionics (two computers), FDS MIP,  FlightIllusion hardware.  3-Optoma ZH406ST Laser HD projectors, with 4K inputs from a single Nvidia RTX-3090 GPU, resulting in a 210 deg wrap-around display.  6dof Motion Platform using BFF 6dof motion software, driven by a Thanos Servo Controller to 6.2 KW Servos, Lever type actuators.

sagrada737

July 26, 2021, 03:53:34 PM #3 Last Edit: July 26, 2021, 03:57:09 PM by sagrada737
Hello All,

I am making good progress on my 737 J-Rail Roller Blocks and Rails system.  The photos below represent a 5th generation design, to essentially duplicate the functionality of the Boeing J-Rail roller block system.  Static testing demonstrates this design to be very strong and having smooth operation.

I ended up using a combination of PETG 3D Printed material for the main part of the block and the upper Pivot Block.  I used steel plate to help distribute the vertical load, and aluminum brackets to provide vertical constraint on the lower part of the roller block.

This design incorporates the same size bearings as the Boeing roller block assembly to handle the vertical load as the Seat moves back and forth.  Boeing uses a Delrin type of roller combined with a sloped steel roller bushing for lateral guidance along the rail.  In my design, I simply used 3 roller bearings to accomplish the same function.

Below are photos show Top and Bottom views of the Roller Block assembly with its Pivot Block as it will ride on the "J-Rail".  For initial testing of this Roller Block Assembly with my Weber Seat, I will modify one of my existing J-Rail sets.  The final J-Rail will be a Plasma cut weldment with Base, made into a set of four rails, much like the Boeing setup.

Also is a photo of my 3D Printer working to produce a set of Blocks.  I am using a 40% Infill for these parts to add strength.

Next post will be to report on the J-Rail test results as installed with the Weber Seats.  At that point, I will be better be able to design a Seat Locking mechanism, which will have a similar design to the IPECO handle type setup.

Lastly...  Below is a recent Astro-Photo of the galaxy M33 "The Triangulum Galaxy".  Enjoy...

Regards,
Mike
Full-scale 737-800 Sim; P3d v4.5x with Sim-Avionics (two computers), FDS MIP,  FlightIllusion hardware.  3-Optoma ZH406ST Laser HD projectors, with 4K inputs from a single Nvidia RTX-3090 GPU, resulting in a 210 deg wrap-around display.  6dof Motion Platform using BFF 6dof motion software, driven by a Thanos Servo Controller to 6.2 KW Servos, Lever type actuators.

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