Custom EUC design.

[Mr A.A]

[Mr A.A]

This is an EUC frame I designed, any suggestions or questions are most welcome. But please keep in mind that I am just an enthusiast who has never even seen EUC in real life, with no engineering background, also I learned Freecad for a few weeks just for this purpose and drew this on a raspberry pi, which is the only computer available to me right now.

 

About the design,. I wanted to use materials which are readily available and could be built in a small workshop, also scalable to bigger or smaller sized rims. This is not a final design nor with accurate dimensions. Mud guard, lights are not drawn in the design

 

The design shown here is based on a 12 inch rim and Tire is 18*3 in, batteries shown in the design are 21700 batteries, If you cram the entire available space on the pedals and frame excluding the control box you can get 120 cells.

The frame consists of flat sided oval tube 2*1 in, which is shown as cut and welded with separate handles on top, but I prefer using a single tube and bending on top to form the handle.

The pedals are designed to include the batteries inside, can use a design without batteries too, also a stand is designed on the pedal itself more on that later.

 

The hub motor is attached to the frame on a metal plate which is welded between the frame tubes, it can also be built with multiple holes for hollow bore motor than single axle. The pedals are secured to the frame using a stud bolt/threaded rod, welded on the frame itself currently, but I prefer welded to a rectangular plate which in turn is welded to the the frame tube. There is also a design with a sleeve over the tube to which the stud bolt is welded which is shown on one of the frame. A hanger is attached with a nut to the stud bolt, the lower part of the hanger has the pivot point used to fold the pedals, the pedals are also supported at the edge of the frame, there are invisible rubber bushes under the frame to avoid metal to metal contact.

 

The electronics control box is just a box with cutouts to accommodate the front frame legs, there is also one design where box is attached to the frame just relying on the frame geometry to keep it in place which is not shown here.

 

The stand design is such that you have to pull it to the side to unlatch the locking mechanism and push it down until it falls into the lock again at the bottom, the spring that keeps the stand in place is not drawn in this version. 

 

I have another version with adjustable pedal height but did not pursue it further as it uses more materials and complicates the design even more.

 

 

Edited June 16, 2023 by Mr A.A
Adding more information

[Funky]

Why don't you just put "everything" into motor. That way you could add really big 28"++ tire and only thing outside of motor itself would be pedals.  I mean literally everything inside the motor.. Can add some kind cover/seat on top of it. 

Wasn't 14" rim a 18x3" tire?

12" rim where 16" tire.

 

Weight in pedals seem kinda good, more weight at bottom = more stable wheel. (Second thought you will have moving wire in pedals closing/opening.. = bad!!! It will break over time. So batteries in pedals = BAD!!!) Also you need to add a mud guard.. Some kind side walls also. Because you will be covered in mud waist down.

 

Just add simple "boxes" at sides for batteries.. You will have covered sides and easy mud guard to attach. I like the frame itself doh - looks strong. Quick tire release also is great.

Also batteries in "frame" itself. How will you pack them "tightly", so they don't move around? (Batteries also have "motherboards" BMS.. More packs - more expensive.) It's the small things that matter the most. Answer me how will you pack them in there..  Also how will you run the wires true frame? Quick disconnects, or you will need to "fish" them true frame each time you remove motor/tire?

 

Give me any design and i will tell you why it will not work in real life.  (Sure any design can work. But do you enjoy headaches?) Not trying to be a "jackass". I'm just saying things that aren't that good. Pedal part alone ticked me the wrong way - because of the moving wire.  Bend any wire enough times and it will break.

Edited June 16, 2023 by Funky

[Mr A.A]

55 minutes ago, Funky said:

Wasn't 14" rim a 18x3" tire?

12" rim where 16" tire.

Veteran Patton 12" rim 18" tire, I just used the dimensions of widely available scooter tires around me

55 minutes ago, Funky said:

 

Weight in pedals seem kinda good, more weight at bottom = more stable wheel. (Second thought you will have moving wire in pedals closing/opening.. = bad!!! It will break over time. So batteries in pedals = BAD!!!) Also you need to add a mud guard.. Some kind side walls also. Because you will be covered in mud waist down.

If you take out the wires through the Pivot point/line there won't be any need to bend or fold the wire by very much. If moving wires are that prone to breaking, all the suspension wheels motor cables going hundreds of times up and down should be changed every week.

I mentioned about not adding the mud guards in this design, one reason being it would be easier to view through everything and second my Single board computer already hangs with all the parts in Freecad.

 

A single pack with snug fitting foam on both sides, battery wires goes through the top into the control box where you can keep the BMS too

 

You have to fish the wires through a hole from the top first time you are installing them, then it goes into the control box where you can disconnect when you need to disable the power

Edited June 16, 2023 by Mr A.A

[Funky]

1 hour ago, Mr A.A said:

If you take out the wires through the Pivot point/line there won't be any need to bend or fold the wire by very much. If moving wires are that prone to breaking, all the suspension wheels motor cables going hundreds of times up and down should be changed every week.

(Suspension.) Long arch for the wires. Or small bend in pivot point. Guess which one will break faster. Same idea as in laptop screens. Most case the screen dies because of broken wires in laptop hinge.

 

[mrelwood]

Interesting. You’ve done a lot of work with this! Unfortunately, to be able to take in consideration the many details that go into a product, the designer really has to be very deeply familiar with the products, how the current wheels are designed, what are their issues, and be fluent in operating the product.

 Patton doesn’t have a 18*3 tire, it has a 3.0-12” motorcycle tire. They call it 18” because they like bigger numbers than the previous ones, and also to confuse people. A 12” rim fits 16” bicycle standard tires, and 12” motorcycle standard tires.

 The problems I see with the design:

- No suspension. This is a disaster market wise today.

- The pedals are not structurally sound. There needs to be a considerable amount of structural material to withstand a 120kg rider jumping on the wheel. And in this case, since a broken pedal would automatically mean a battery short and a fire hazard, you best calculate for a 200kg rider. Or more.

- @Funky was right about the pedal battery cabling. There’s a thin cable for every cell, and two thick ones for every separate group of cells going to the BMS. Suspension EUCs use a very long spring supported cable harness that makes the bend extremely shallow. In your design a bunch of cables would have to turn 90 degrees in a few inches. That’s nowhere near viable.

- Modern pedals are semi-hollow, a honeycomb design. This is very important for riding in the sand, dirt, mud, or snow. Solid non-replaceable pedals would be another market catastrophy.

- Battery replacement is a nightmare. There are battery issues with ALL wheels, and with this design it would practically mean a new wheel.

- A kickstand that would mean an almost certain crash if left down, or when the mechanism wears out. Or if it’s a bit dirty and doesn’t lock in place. Besides it sounded too cumbersome to be operated with a foot.

- There’s no room for a trolley handle.

 

I’m certain that it feels disappointing to hear all these downsides when you’ve put so much time and effort to designing one. But realistically, what did you expect? The current manufacturers have been doing this professionally in big numbers for 8-10 years, and most of them still can’t get stuff right. I’d say that your 20th design would probably be pretty good!

[woke rider]

@Mr A.A I love your design! Do you think the batteries could be easily damaged if they are in the pedals and frame? Would you think a slanted infinity shape for the shell would look good? How would you implement suspension?

[Funky]

I also forgot about honeycomb pedals. I hated the "grip tape" pedals.. Sand/mud/snow/anything would get stuck to them. You would need to clean them almost every ride. 

Having honeycomb pedals now - i never have to clean them. And spikes are much better than "grip tape". So much more grip.

Most people are getting aftermarket pedals anyways. So having batteries there will just hurt overall sales. (Ofc if the plan is to make a mass production.)

Same goes for the side panels - you need to have flat surfaces for power pads.. People like to use aftermarket pads. So having simple flat sides is a must.

Edited June 17, 2023 by Funky