Spinning Tops

[Tozguy]

Any ideas about where the imbalance comes from and how to avoid it during fabrication?
Can it be corrected by using the ruby as a centre and turning the o.d. ?

 

[rwm]

Using the bearing as a center is a good idea. You need to be very careful in drilling that hole first. Ideally it would be bored and then reamed slightly under size. My .245 reamer works great for this.
The problem I see is that any time you mill you take off slightly greater or lesser material making the disc asymmetric.
Robert

 

[wildo]

I'm not sure why this one is unbalanced. Actually to be honest it seems very balanced, which is to say that it doesn't wobble at all when spinning. However it does "walk" and doesn't seem to want to stay settled down. The milling *shouldn't* have affected the balance as the slits are indexed every 40 degrees. The pieces were all bored to fit and the fits were to .001" interface. I snuck up on all the bores taking only .001" of the diameter at most hoping to produce the best possible hole. Honestly, I'm really not sure what I could have done differently in order to get more stable spins. This is a little disheartening because I really felt like I took great care to ensure (to the best of my ability) proper alignment and balance. Not giving up, but also probably not attempting any more three piece tops for a while!

[EDIT]- I made a video of the spin. It actually spins a bit better than I thought, but still there is plenty of room for improvement. I'm also kind of surprised by the low spin time, though all that movement uses up a lot of energy. Still... I've been machining for two months total. I'm not too disappointed.

 

[rwm]

Interesting. See if you think it gets better over time. Test my bearing wear-in theory.
R

 

[wildo]

Interesting. See if you think it gets better over time. Test my bearing wear-in theory.
R

As it were, it actually spun quite a bit better today. I did gain a full minute on the spin time, topping out at 6:27. There might be something to do with a little bit of bearing wear, or maybe just seating itself a little better perhaps.

 

[scwhite]

Great pics! Looks like the bar has been raised quite a bit here. We should have a vote for the best shop made top at some point.

Robert

I made these tops for my son years ago
I made them out of Black walnut wood
With a metal tip .
They are the old traditional style tops
And they are big

 

[rwm]

R

 

[wildo]

How does it spin? I'm really enjoying incorporating my milling machine into top making! I planned on doing something here shortly like what you've done. Are you a member of the "German Spinning Tops Rule" facebook group? If not, you're really missing out. Of course- their designs are very unique and almost trademarked so to speak. It would be hard to come up with something like this without feeling like I was copying what they've done. But great work! I'm really curious how you managed the setup. I totally get how to so the milling orthogonal to the top body, but at an angle like that... I'm not sure if you rotated the mill head, or maybe used a rotating dividing head. Great work!

 

[rwm]

It does not spin well! I think the milling is a problem due to minor imbalance. I first machined the top surface of the wheel on the lathe with an elevated ridge. Then I tilted the mill head and used a rotary table.
R

 

[wildo]

Then I tilted the mill head and used a rotary table.
R

Cool! If you wouldn't mind sharing, can you post a picture of your rotary table setup? I have a small import rotary table that my dad gave me, but I honestly don't understand how to affix work to it. It doesn't really have a center taper, and the table doesn't appear to be made to hold a chuck. I don't really get it. This is the only picture I have on hand at the moment. I think it's probably a 4" table or so.

Also- did you see the video above of my milled top spinning? Pretty freakin' proud of that one!!