This might be in the wrong section of the forum, but I need help

[888alltheway]

Hello. I'm new to the forum, and I know next to nothing about CNC machining.

I have a CAD program (Autodesk 123d) and I'm trying to make a metal yoyo.


Yoyos have changed considerably in the past few years. The wooden toys you guys might remember have changed into high precision, CNC machined (On a lathe), expensive novelty toys that go anywhere from $50 to $250. They are usually made from Aluminum (6061 and 7075) and also Titanium.

The project I have been working on is pretty simple:

1.Use CAD and design a yoyo.
2.Go to a local machinist and have him/her make me a run of about 50-100 yoyos
3.Have them anodized by an anodizer.
4.Sell them to other hobbyists.

Although price varies, I'm aiming for a $100-$150 selling price. I'm most likely going to use 6061 aluminum. Machining tolerances have to be pretty high (0.003mm or maybe a bit less.)

The outer diameter of this yoyo will be anywhere from 50mm to 56mm, which means I'll be using a bar of solid aluminum with a diameter of 2.5 inches to machine this.
The weight will be 64-68grams.

The yoyos are machined one half at a time. Therefore, one yoyo consists of 2 halves, an axle (Usually a grub screw),and a bearing.


This is where the question comes in.

I am aware that lots of factors can change the price, and I need an official quote, but how money would it cost to have it machined? Let's say that I'm going for a run of 100 yoyos, so that's 200 halves. I want it made on a lathe, and not a mill. I don't really care for anodization and other things, but I want just the price for machining+base price for the metal (6061 aluminum). I just want a ballpark estimate of how much that would cost before I go out and bug my local machinist. Tell me what other factors I need to include if needed. Thanks!



Some examples:

one drop yoyos - View topic - *THE WINNER!* Code2 Entry - Rendition Updated 10/8

(There was a contest where you had to design a yoyo.)

http://sphotos.ak.fbcdn.net/hphotos-..._3452858_n.jpg

(A cutaway of an actual yoyo)

http://www.yoyonation.com/product_im...p?imageid=4219

http://www.yoyostorerewind.com/media...gleipnir11.jpg

[DareBee]

.003mm tolerance on a yoyo?
Are you nuts?
Won't get that precision from a lathe.
You better ask about a grand each for them.

[888alltheway]

I should probably lower the tolerances a little then. I just need perfect concentricity. The smallest amount of misshaped metal can induce massive amounts of wobble on a yoyo. I've asked questions to a lot of the other companies, and they said that most of the problems arise when they flip the metal the other way to work on the other side, and things can get misaligned, making the whole run of 100-200 yoyos useless.

[underthetire]

Ya, that tolerance is going to be very expensive. Unless you get a high tolerance bearing, the bearing would have more run out than .003mm (.0001) inch.

[888alltheway]

Yea, I'm hoping that I can make the bearing seat, which secures the bearing, a little smaller, and let the anodize make up for the extra space. I'm not sure what measurements to use though. I have all of the other design elements, but not the bearing seat and the axle threadings.

[RomanLini]

Sorry to sound nitpicky, but those Yoyo designs would perform quite poorly. To make them stable the weight at the outer edge of the flywheels should be narrow so it performs like a single narrow flywheel. The butterfly shape will not be stable and will wobble pretty badly.

If you are interested in any proper Yoyo performance the outer edge of the flyweeks also need to be close to roll down the finger on the initial throw. And the shaft needs to be 1/4" round hardwood, giving enough grip so the user can slectively spin the yoyo at the bottom or yank it to make it grip and bring the yoyo back to the top to end the trick.

The best shape is a disc, with convex sides, and the bulk of the weight at the outer edge.

In case you are wondering my nephew got a yoyo at Christmas and we read the instructions trying to help him get it set up to work well. I'll shut up now.

[Harpye]

THings you would have to specify to get a god result is :

Spin pulse will stabilize the direction of the axis in space

but due to this effect spin pulse needs speed to work and a rather high mass moment of inertia .. you need most of the material on the largest radius from the axis!!! unsymmetrical mass causes wobbeling so you should think about 2 plane fine balancing the fully assembled yoyo.. so if you could get the Alu parts for 30 $ in small amounts per pair, balancing would take another 20 $ dependent on the grade... if you could find someone who takes the job!

[888alltheway]

Originally Posted by RomanLini Sorry to sound nitpicky, but those Yoyo designs would perform quite poorly. To make them stable the weight at the outer edge of the flywheels should be narrow so it performs like a single narrow flywheel. The butterfly shape will not be stable and will wobble pretty badly. If you are interested in any proper Yoyo performance the outer edge of the flyweeks also need to be close to roll down the finger on the initial throw. And the shaft needs to be 1/4" round hardwood, giving enough grip so the user can slectively spin the yoyo at the bottom or yank it to make it grip and bring the yoyo back to the top to end the trick. The best shape is a disc, with convex sides, and the bulk of the weight at the outer edge. In case you are wondering my nephew got a yoyo at Christmas and we read the instructions trying to help him get it set up to work well. I'll shut up now.

The yoyo you have described would make a killer looping "Old school" yoyo. However, what I'm trying to make is a unresponsive, high end metal. These things can spin at the end of a string up to 9 minutes. To execute the high level tricks that are required in competitions nowadays require that the yoyo is wide, and also heavily rim-weighted. Therefore, the wooden axle you recommended will make too much friction. The bearings used in yoyos are much smoother. The narrow shape will make it stable, but making the yoyo heavier and concentration the weight on the outer rims will probably do a sufficient job of keeping it straight.

Here's an example of modern yoyoing.

SHINYA KIDO Promo Video - YouTube

SHINYA KIDO Promo Video - YouTube

[RomanLini]

Thank you very much for the information! My Yoyo knowledge has now been upgraded somewhat.

It looks like they deliberately use a less stable Yoyo design to allow more maneuverability? And then compensate with more total mass at the outer rim to increase spin time and recover some stability. Pretty cool! Best of luck with the project.