Ossum Racer, Part 2: Motor and Gearbox

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One day we will be able to 3D print functioning combustion engines in 1:10 scale, but for now the car will have to be driven by regular old electric motor, it’s sad but true, I know!

Why Reduction Is Needed

Small electric motors spin incredibly fast, but don’t generate much torque. In order to make them useful we need to gear them down appropriately.

Most RC cars get the majority of the reduction done in the first step, using a very small pinion on the motor, and a very large spur gear, but this is not really suitable for a realistically shaped gearbox, so I will use multiple stages of gears to achieve the desired reduction.

Design Goals

I have the following design goals for this reduction box.

  1. Motor must be low (for centre of gravity)
  2. Fully printable (without support wherever possible)
  3. Strong gears, big teeth, easy to print
  4. All gears to be hidden in a (semi) realistic enclosure
  5. Minimize unique parts

Selecting a Ratio

Although you can get a lot of power out of the “540” sized motors commonly used in RC cars, they still need a lot of gearing down, so it’s time to design a reduction gearbox.

I have done some rough “back of the napkin” calculations which show that a final drive ratio of about 8.5 will be decent starting point. The glory of printing is that we can experiment and revise once the car is working

Theoretical Max Speed Calculation
Example 1 Example 2 Example 3
Motor RPM 17000.00 22000.00 22000.00
Brushless Motor kV equivalent (2S) 2297 2973 2973
Brushless Motor kV equivalent (3S) 1532 1982 1982
Final Drive Ratio 8.50 11.00 8.50
Rear Wheel Diameter (mm) 95.00 95.00 105.00
Distance in One Wheel Revolution (mm) 298.45 298.45 329.87
Distance in One Motor Revolution (mm) 35.11 27.13 38.81
Speed (km/hr) 35.81 35.81 51.23

Gear Design

Although I did not use this tool to generate the gear profiles, I find it very useful for visualising a complete setup, you can follow this link to mess around with it yourself (link).

Gear Generator Screenshot

I decided on a stackable gearbox design, which consists of repeats of the same section, each one accounting for a 11/17 reduction in final drive ratio, resulting in a 5.7:1 ratio at the output.

This leaves room for a further reduction at rear axle (13/21, for example, would result in a final drive of 9.2:1)

Engine Model

Just because we are forced to use an electric motor doesn’t mean we have to look at one, so I began the design of a Merlin V12, scaled to 1:10. This engine will go over the electric motor, and given it’s size, probably also hide some electronics or the steering servo.

There are of course many details to go, but having the rough shape helps me work out the car’s final dimensions.

Gearbox Location

The gearbox can be orientated horizontally or vertically, which I am not yet decided on. I prefer the vertical orientation for aesthetic reasons, but horizontal may be more practical.

Either way, the motor stays at the lowest point, and the output is roughly in line with the rear axle input shaft.

 

Up Next

The next most pressing issue is probably to design the rear axle, and the telescoping driveshaft that will connect it to the gearbox, so stay tuned. In the meantime, I am curious to hear your thoughts!

Ossum Racer, Part 1: Developing the Concept

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In the last post I introduced myself, in this post I’d like to introduce the project.
I have a real soft spot for the raw nature of roughly 1930’s era, often single seat, open cockpit race cars. The crazier the better. I don’t really consider myself a “car guy” but I love cars that evoke an emotional response, and to me there is nothing quite like a set of wheels strapped to a Merlin V12 to get the pulse racing.

As it happens, there really aren’t (m)any RC cars in this category, and as far as I know, no 3D printable ones. I aim to correct this travesty! My goal is not to build a specific replica, but a believable and functional model, built around component designs that we will be able to reuse in future models. Since many of the real cars like this were one-off builds, such as Jay Leno’s ridiculous(ly awesome) 1917 Botafogo Special,  this seems totally reasonable.

As with a real car of this nature I will let the functionality direct the form to some extent, and so I begin the process with sketches.
First I decide on some rough dimensions, and do a side view and top view sketch on graphing paper, before scanning those and importing them into Fusion 360 at the correct scale. While I plan to design all the parts, including wheels and drive-train, for printing, I want to keep them to a size where standard RC parts can easily be swapped in too.

Next I make a simple pose-able mock-up of a human figure at 1:10 scale and pull in RC components that I designed for my 1:10 rat rod build, this allows me to check that the scale is feasible.

Things look ok, but a rough body shape shows a bit of a problem, these narrow bodies don’t have nearly enough space for a regular-sized battery, which I would really prefer to use, so it may need to grow a little.

Raising the motor slightly is undesirable from a center-of-gravity point of view, but might be a solution, alternatively, does our driver really need legs, he has a sweet car to get around in anyway…

Before spending too much time of these problems I will start with design work on the mechanical components: transmission, front and rear axles especially, because they will dictate everything else. Tune in next time and keep an eye on Ossum in the meantime for behind-the-scenes posts!

You can follow along here if you like:

Ossum Facebook

Ossum Instagram

Ossum Youtube

 

BLOG 1: Jason “Ossum” Suter Introduction

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This is the first of what is going to be a series of blog posts in exciting collaboration between myself, Jason Suter (known as “Ossum” around the web), and CEL-UK, the creators of the Robox project.

Before I get stuck into what we are planning to do I feel it would be best to introduce myself. I am an electrical engineer in the telecoms field for my day job but apparently have never quite grown up, because I still dream of being a toy designer or building props for movies. I have been designing projects in CAD for 10 years now but it is been over the last 2 years when I when I got access to a 3D printer that I was really able to start making those dreams come to life, at least in my spare time!

I am passionate about designing things that “do something” with a mechanical or electronic element, so I seem to have naturally fallen in with the RC crowd, but really my projects and interests are diverse, you never know what might happen next.

My first major printing project was a 1/10 scale RC rat rod, which I designed in Fusion 360, had the body printed via Shapeways and the chassis laser cut from aluminium. The design files I released won me a 3D printer, which really got the ball rolling.

I diverted into some mechantronic interior design, if there is such a thing, with a blooming flower night light which was featured in make magazine. This was a challenge to build something that would have been completely impossible for me to do without CAD and a 3D printer.

I went back to my roots with an RC 1/10 scale Willys MB Jeep and M416 trailer, which has been extremely popular. I get a real kick out of seeing my designs being built around the world, it helps me justify the hours that I spend working on them if I know they will be amortized over many builds!

 

There are some other weird projects in the middle like my giant LEGO skeleton where I flipped the scale and went 10/1, he ended up being 40cm tall!

Besides designing and building myself, I really enjoy getting others interested in tackling it themselves, I have really enjoyed the vibrant community that has sprung up around my designs. Here you can find the facebook page and group.

I have had the idea for a fully printable RC single-seater vintage racer brewing in my head for a while now, and in collaboration with CEL-ROBOX I will finally be bringing it to fruition, and sharing it with the world.

Over the course of the next few months I hope to bring you along on my journey through the design process, and with any luck, inspire you to tackle some things of your own. I’ll be posting fortnightly updates here and on my pages. In the next post I’ll be going into my design goals and how I get started on a project like this.

If you want to discuss any aspect of the project with me, I now have a forum section for this project which you can find here.

 

Inspiring students at King Edward VI Community College

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“Our Robox 3D printers and the CEL UK-based support team have been superb. Students of all ages, from our primary school partners to Post-16 students, have all been able to access and use the Robox software and hardware systems effectively. They have inspired students and led to numerous STEM Big Bang competition wins. Further to this, our work as a community Fab Lab has allowed organisations and individuals to develop ideas on a personal level or commercially.

“The Robox technical support team are second to none and offer excellent training materials to ensure systems are kept up and running. CEL are always keen to support users with emerging applications of their machines and illustrate their forward and positive principles.

“I would recommend Robox to any educational establishment looking at purchasing additive manufacturing systems. ”

KEVICCDavid Irish
Head of Design and Technology
King Edward VI Community College

RoboxPRO launches at Bett 2018

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CEL is the manufacturer of a range of low-cost power tools and the hugely successful POWER8 Workshop, an award-winning cordless benchtop power tool innovation originally featured on the BBC’s Dragons’ Den. As a manufacturer, we did all the CAD work but, like most, would outsource the manufacturing of the prototypes to 3D printing service bureaus or contract manufacturers.

After growing increasingly frustrated with the high costs and delays experienced with outsourcing, we made the decision to bring prototype manufacturing in-house by developing our own 3D printer with help from open-source RepRap designs from the University of Bath. We developed and added new technologies and features to work with these designs, sourced the highest quality components, and, after many design iterations, we decided to bring the 3D printer we developed to market as a new product itself: Robox.

As a small, resource-limited manufacturer, we certainly didn’t want to develop a 3D printer that was time-consuming to start, operate or maintain. To us, a 3D printer isn’t a gadget, novelty or toy; it is a manufacturing tool whose sole purpose is to bring virtual designs into physical reality. Since deciding to bring the 3D printer we initially developed for ourselves to market, we’ve spent a great deal of time and effort streamlining the software workflow and developing automatic hardware calibrations in our efforts to make the 3D printing process as simple and fast as possible (Robox 3D printers have won several awards for their user-friendliness).

We’ve benefited hugely from taking the decision to bring both the design and manufacture of our prototypes in-house. 3D printing technology has dramatically reduced our costs while improving our rate of innovation and, ultimately, the quality of our products. With Robox, we wanted to show other manufacturers that they too can take full control of prototyping and reap these same benefits.

Beyond business, we have a stake in British education as a British manufacturer. We can use the Robox brand to help the next generation become world leaders in design and manufacturing, by empowering young people to think creatively and not be afraid to make mistakes through the iterative design process. Anticipating Robox being used in education, we included an interlocking mechanism in the door as a safety feature in the original Robox model. Astonishingly, Robox 3D printers are still the only desktop 3D printers that include this critical safety feature.

We use Robox 3D printers in our work with the James Dyson Foundation and partner schools around the country to help improve learning outcomes in STEM. We want to do what we can to play our part in helping Britain grow as a world-leading source of innovation and inspiration for young people.

Since launching the original Robox model, we released an upgraded dual extrusion version, RoboxDual, in early 2017. RoboxDual can print with two colours or materials at the same time while still running on the same award-winning hardware and software platforms. We’re now excited to be launching a new, ground-breaking 3D printer, RoboxPRO, at Bett that offers considerably more advanced capabilities. We look forward to showcasing RoboxPRO and the other 3D printers in the Robox family at Bett 2018 and invite visitors to come to stand B470 to learn more. The show takes place in ExCeL London between 24-27 January and is free to attend. Visit our exhibitor page to find out more:

We’re taking pre-orders now for units from our first production batch, so get in touch if you’d like to be among the first to get your hands on this new Robox 3D printer.

SingleX™ – Robox development and experimentation head.

By | HeadLock, Materials, News | 6 Comments

Material development is constantly expanding upon and often stretching the capabilities of 3D printers. Robox features an open material system which gives users the choice of using filament from any source.

We have always advised against using “filled materials” mainly due to the abrasive nature of these materials. We maintain this advice with all of the heads available to fit the HeadLock™ system.

This SingleX™ head is an exception, this head is designed for experimentation. To combat wear this head comes with the very well known Olsson Ruby Nozzle with 0.6mm aperture. The SingleX™ heater block has a M6x1mm thread.

We have removed the needle valve in the SingleX™ head, so if you want to send gcode from another slicing engine you are free to do so. Dribble and ooze are now your responsibility 😀 as is any harm caused by code produced outside of the typical AutoMaker environment. This head provides freedom to use the Robox platform in new ways.

Remaining in place are many of the features which Robox pioneered in 3D printing. Surface mapped bed levelling, SmartReel material recognition and simple 3 click operation. The extruder provides feedback during a print to ensure material is not jamming or has run out, pause and resume at will.

A word of warning…When using abrasive materials, abrasion is not limited to the nozzle. Our testing has shown little wear on filament drive gears and other parts within the filament path after over 3kg of Carbon and Glass filled Nylon, ABS, PETG and other  filled filaments but these parts are still considered to be consumable.

I want it!
Link here

The Olsson Ruby
Six reasons to get the Olsson Ruby

One nozzle

The Olsson Ruby will work with a huge range of materials.
PLA, ABS, CPE/PET, Nylon, and composites with abrasive additives such as Carbon fibre, Steel, Wood, Boron Carbide, Tungsten and Phosphorescent pigment, are some of the materials sucessfully tested so far.

Highly wear resistant

The ruby mounted at the tip makes sure that even the toughest materials will be printable. It was originally designed for printing with Boron Carbide (B4C), the third hardest known material in the world.

Excellent heat conductivity

Since most of the Olsson Ruby is made from brass, with its excellent heat conductivity, performance and throughput is first-class.

Verified performance

People all over the world have been testing different iterations of the ruby nozzle since early 2016. We are very happy to have received only good printing results from this community.

Speed

By using the 0.6, 0.8mm and High Output versions it is possible to reach a higher throughput and speed than ever before for abrasive materials, while retaining wear-resistance and reliability.

Manufacturing quality

The Olsson Ruby is manufactured, assembled and tested in a high-quality facility in Sweden. This is why 3DVerkstan guarantees the very best quality and tolerances.

Wear resistance compared

Brass, 0.3kg carbon fiber filled filament printed.
Stainless steel, 1kg carbon fiber filled filament printed.
Hardened steel, 4kg carbon fiber filled filament printed.

Robox is a tool, not a hobby.

By | Design, Education, News | No Comments

Robox is designed to be Plug and Print. We are designers, we created Robox to allow us to spend more time designing, testing and refining our prototypes. Doing our jobs basically. As designers we did not want to spend time levelling or preparing a build plate, looking up or testing settings or tweaking profiles. We wanted a 3D printer which makes printing easy. Robox has won best of Plug’n’Print 2 years running. It is also the only printer which is safe for use in education at all levels.
Learn more here http://www.cel-robox.com/technical/

3D printer software development

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CEL produces Robox which is a class leading 3D printer with global reach based in Portishead near Bristol, UK.

Our success and innovation in the additive manufacturing (AM) field has led to funding for new developments in similar technologies. There are two stages to this which follow very similar paths and promise several years of very rewarding work which will become a very high value product. This development will further expand the use of additive manufacturing in industry by enabling automation and streamlining of currently impossible tasks or tasks which are cost prohibitive using available methods.

CEL-UK have an opportunity for a creative software developer to join our team of mechanical engineers and firmware specialists to develop the next generation of AM here in the UK leading to intellectual property and new machinery which will be sold around the world. The role/s could be filled by a person who can plan and lead a project, growing a team around themselves and/or someone who can do the leg work and work to a plan which is defined for them.

The role of software in this project is vital and, as this is a new project, is completely open to the creativity and ingenuity of a capable developer to shape into a valuable manufacturing tool.

The new projects have links to our existing work but will require a higher level of control and processing of three dimensional models into code to control machinery. G-Code has been used in CNC machining and robotics for a long time and is almost identical to that commonly used by most 3D printers.

The software application created during this project will have the ability to import one or more digital 3D models. Rules will be applied which generate toolpaths based on these 3D shapes for use by embedded firmware and electronics which will be developed alongside the software. Hardware such as stepper motors and valves will be controlled via the electronics. The resulting movements will produce physical objects with the features and dimensions of the original digital model.

There are existing tools and applications which can produce machine code close to what we need. It is possible that the final application will be combination or rework of existing code or a totally new application written from the ground up.

C++, Java, other… The programming language used will be that which best suits the planned project and the team.

The final application will include a user interface and is likely to receive regular or live status reports from the firmware. This interface may be independent or possibly built into an existing application as a plugin or extension. To satisfy the initial brief this interface can be very basic.

Initial features of the software will allow the user to alter settings which tune the output of the machine to ensure the best possible quality and reliable, repeatable results. Building on this we intend to add features which focus on user experience and production efficiency.

There is significant separation from our existing software, AutoMaker, but the projects may converge as development progresses and there is likely to be some crossover which benefits both of these projects. AutoMaker is a user interface for the commercial 3D printer hardware which is Robox. It allows a user to monitor Robox hardware and to lay out a print job and choose settings, these are sent to an open source slicing engine called Cura and then the resulting code is altered before being sent to the Robox hardware where it is stored and accessed by efficient and bespoke firmware and electronics. AutoMaker was developed using JDK 1.8 and JavaFX along with typical development tools, Git, Jenkins, Jira and Netbeans IDE.

The perfect person for this position could be either; someone with experience in leading a project or; someone who can do the leg work and work independently to a plan which is defined for them. Most importantly this person will be excited and passionate about the project.

This person/team will probably have:

  • An excellent mathematical understanding of three dimensional spaces. Computational geometry.
  • The ability to plan and prioritise to ensure realistic goals are met and features are completed.
  • Strong communication skills to work with the team and achieve the best outcomes.
  • Excellent project management to ensure resources and code are efficient and easy to maintain.
  • Strong debugging and test abilities.

Relevant experience will include:

  • Application development from start to finish. Systems to UI.
  • Manipulation of 3D spaces and models and rendering, generation, control or processing of this type of data.
  • Robotics, Machine code, 3D printing or CNC control.
  • Project planning including user experience planning and improvement.
  • Integration of software and hardware functions.

CEL is a friendly and casual workplace with a great team of talented and inventive people. Our core business is product design so there are always exciting technology projects running. We are about to expand into a very new and exciting venture and we would love the right person to be part of it and grow with us.

Full time, Salary negotiable.

Please apply using this contact form:

http://www.cel-robox.com/job-application-form/

Pinshape 3D Printer Guide 2017

By | News, Press | One Comment

Check out the guide here!

A perfect result in the Pinshape 3D printer guide for 2017.

5/5 across the board and some really nice reviews.

5/5 PRINT QUALITY
5/5 EASE OF USE
5/5 VALUE
5/5 EASE OF USE

Excellent printer compact design and easy to use. Support from CEL is second to none and easy to contact with a lot of Q/A available online. Regular software & firmware updates, models are very good with little or no clean up. I am very satisfied with this printer and would recommend it to anyone thinking of purchasing one, the price is good to.

TAZIEExcellent Printer

A fantastic printer, was printing with in 20mins of opening the box, very easy to use with many automated features such as bed levelling taking the chore of setting up away from the user and letting you get on with designing and printing. would highly recommend to anyone wanting a no hassle printer .

jamestoogoodLove My Robox

Incredible Printer ... from the first moment perfectly printed, makes the process simple and effective, and you have to just worry about your design

jjnm5 PERFECT!!!!!