Hello everyone,
I'm posting here today because I am currently in the middle of a segway project, and am looking for advice or ideas for one or two of its components.
In the pictures below is the segway this far. It was designed and built by a senior design team at my university I go to (I will be returning for my sophomore year studying electrical engineering this fall) around 6 years ago. I expressed my interest in building a homemade DIY segway to one of my professors I am pretty close with, and to my surprise he told me of these left over parts and how they were getting ready to be thrown out. Thus, I was given all the parts.
This is the segway in pictures from the design project. It has two NPC T-64 motors, controlled by two OSMC motor controllers, and in their version it was controlled by an atmega32 chip. I may end up using the same chip, or use an Arduino Uno I have lying around. The steering mechanism on the scooter is custom machines twist handle located on the right side of the handle bar.
Wheels:
I plan on using many of the components that were used in the original build. However, one thing I know I want to replace are the wheels and tires, as they have deteriorated over the past five or six years.
The wheels originally on there were 12". I want to have bigger diameter wheels on the segway because the larger the wheel the faster it will be.
Ideas:
I want to have large diameter, thin wheels. Basically, this narrows my options down to bicycle wheels.
I plan to have either 16" or 20" wheels, this will make the speed of the segway substantially higher than it with the 12" wheels.
The problem I come to with this idea, is the mechanical and construction side of implementing this.
The motors have the mounting hole configuration shown in the picture below.
As you can see, a custom machined hub of some sort will be needed to be used, I assume.
When considering bike wheels, I have been considering just getting a regular bike wheel, then have a hub made, then lacing/stringing the spokes between that hub and tire. This is what Trevor Blackwell described he did with his 2nd version of his segway. http://tlb.org/#scooter2 From what I can tell this is a condensed version of his project webpage compared to back when he did it. This hub he made used to have a CAD drawing available for download, however unfortunately isn't the case anymore.So what I am asking is does anyone have any tips or information to give concerning making a hub like described, or have any design of their own, or an archived copy of Mr. Blackwells?
My other option at this point comes from a design by a senior design team from Purdue doing a segway.https://engineering.purdue.edu/ece477/Webs/S08-Grp12/pictures.html They use the plastic rimmed Skyway bike/BMX wheel, and attached them directly to the motors (which are the same as mine). While the drawings for these are posted, they would be easy to replicate.
https://engineering.purdue.edu/ece477/Webs/S08-Grp12/documents.html
The one question I have about this design, that complicates things is how the key hub that is apart of the wheel is made and fit into it. By looking at this picture, it looks as if it is press fitted in, but I am not sure.
I would be starting from a hub similar to the one above on the white wheel.
My last question, is how much would it cost getting either of these hubs machined approximately?
Ultimately, it would be much cheaper I think to just go the regular bike wheel route and "spoke" it. However, this may be a little hard, and with my inexperience would result in a wobbly wheel. While the Skyway wheel looks better and may be easier, it is going to be a lot more expensive I believe. I appreciate any feedback and suggestions regarding types of wheels, mounting techniques/designs, etc.
Thanks, Logan.
I will offer a less expensive alternative to bike rims.
Go to a place like Big R or TSC (Farm supply stores). Head to their section for lawn mowers. You should see a fair number of pre-assembled wheels; plastic wheels, bearinged wheels, etc. You might find something more affordable there vs paying for bike rims. Also, respoking a rim, as I understand it, is a job even for pros.
Thanks for the suggestion.
Thanks for the suggestion. Honestly though, I think once I get this thing fully operational (still waiting for the batteries and IMU to come in) I will find that the old wheels will still be usable.
The main reason I want these larger diameter wheels is because they look tons more aesthetic, and I am expecting around a 25-35% speed increase bumping the wheel size up six inches, assuming the motors can take it.
Concerning spoking the rims, my plan is/was to custom machine the hub then take it to a local bike shop and see if they could do the dirty work. Any google search pertaining to what I’m trying to do only yeilds info on adding a ‘hub motor’ to the wheel itself on a bike, which actually brings up many tutorials on how to lace such custom hubs and motors.
What is most frustrating about this is that it seems almost impossible to be able to get a Skyway wheel without the bike axle/hub crap, and with a keyed hub I need. (Skyway actually makes them, but cant buy directly from factory)
The even more frustrating part about spoking/lacing the wheel is that there used to be a drawing/CAD file availalbe for Trevor Blackwells wheel hub that he used for the exact same thing I am wanting to do. However, he has condensed his site and project info sometime in the past few years and all that data is not reachable anymore.
Does anybody else have any other suggestions in getting some beefier wheels on this thing? Also if you have any questions about the segway itself feel free to ask. Thanks!
Machining the hubs
Maybe see if there is a model engineering club near you, might machine it for a beer 
Machining Shop
One of my brother’s very good friends actually works at a machine shop, although I have yet to talk to him about it I bet I could get the hubs machined for almost nothing at all.
I’m just not really sure about the design of a custom hub. I emailed a local bike shop to see if the owner had any advice and if I could pay him to lace the wheel if I did go that route.
I searched the Internet Archive.
I found no CAD files of the hub you were talking about. They have snapshots of the website back to when he started posting his updated scooter. Honestly, there is very little difference between what he has today vs what he had 7 years ago. The only real differences were some HTML formating. Drawing up the hub you need shouldn’t be too difficult for you. There are a number of free CAD programs available to you.
I did a search for hubs for the motors you have. I got a link to a similar(?) motor. http://www.robotmarketplace.com/products/NPC-PH448.html
I tried searching the
I tried searching the internet for several hours for the drawings too with no success. I know there used to be some available because it is discussed in this thread. http://www.chiefdelphi.com/forums/showthread.php?t=67562
Also, Trevor used the same design for his motored unicycle he made, and he links to the hub on another page of his website. However, you get a ‘Not Found’ error when you click on the link.
While searching for anything regarding the topic I did find a better picture that shows the wheels and hub a little,
I have access to very good CAD software at my internship (Creo Parametrics 2), and don't doubt my ability to draft a drawing of a hub. However, the area I am not sure on is concerning what diameter to make it/flange size/etc. I may throw something together sometime soon and then upload it for comments and suggestions. I just don't want to get something custom machined then it end up cracking, warping, or breaking due to bad design.
Since I am at the desk now I may try to throw something together.
Thanks,
Effect on torque.
Having larger wheels is going to cause your motors/controllers to draw more current at startup. You need to make sure you will not exceed the maximum ratings.
I was poking around …
I was poking around and decided to read this thread, then went to another thread that linked to a LMR page that might be of use to you with your wheel attachment issue. The link is https://www.robotshop.com/letsmakerobots/node/13769 and the second video shows/explains his wheel setup which is similar but smaller than what you want but still might apply. Instead of a custom hub insert maybe you could run bolts through the area just outside the center hole of the wheel. Anyhow it might trigger an idea so check it out.
I m trying to make clone segwaybut the frame just keep toppling aroung axle. Can’t maintain it’s balance. any suggestions???