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Spinning Tops

francist

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#61
Very nice, reminds me of 660 bronze by the colour. Looks like it machines really well too.

-frank
 

kvt

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#62
That is a nice color. a way to inlay some nice bright silver and dark contrast would look good on that.
 

rwm

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#63
Machining is not so great. Leaves a rough finish. A few seconds with a fine sandpaper and it looks much better like in the pictures.
Robert
 

Hal H

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#64
Very impressive tops.
I had know idea they could spin for so long.
What the difference between a 5 minute top and a 7 minute top ?
Perfect balance or is it in the design of the top ?

Hal
 

wildo

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#66
Very impressive tops.
I had know idea they could spin for so long.
What the difference between a 5 minute top and a 7 minute top ?
Perfect balance or is it in the design of the top ?

Hal
5 to 7 min difference? Likely your spin technique. 7 to 15 min difference? Precision machining and design. Ensuring the tip/ball is perfectly on center. Reducing air resistance. Putting the mass at the outer rim and reducing the mass down the top's center line. Tops that stand up just about immediately when released and spin dead smooth/stable- it's a result of the machinist's skill. There's a couple "famous" top makers that are well known for their smooth, long spinning tops (Dan Tochterman, "dt smooth") and then other top makers more well known for their crazy complex designs, but not long spin times (Rich Stadler, Billetspin).
 

rwm

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#67
Not sure about the lead and its effect. I probably only have 3% so I could have added more. It machines betters than Silicon Bronze. I'm gonna use some of this in my next top.
Wildo-After your comments above perhaps I need to abandon the reamer idea and go for a micro boring bar with go nogo gauges?
R
 

intjonmiller

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#68
5 to 7 min difference? Likely your spin technique. 7 to 15 min difference? Precision machining and design. Ensuring the tip/ball is perfectly on center. Reducing air resistance. Putting the mass at the outer rim and reducing the mass down the top's center line. Tops that stand up just about immediately when released and spin dead smooth/stable- it's a result of the machinist's skill. There's a couple "famous" top makers that are well known for their smooth, long spinning tops (Dan Tochterman, "dt smooth") and then other top makers more well known for their crazy complex designs, but not long spin times (Rich Stadler, Billetspin).
To elaborate further, it's largely the relationship between the center of gravity and the center of mass. Center of gravity should be lower, which is what causes the best to stabilize "instantly". This is why the hollow stems are popular and effective. The further you get the mass out from the center the greater the moment of inertia (by definition), so it requires more effort to spin it up but it then better resists changes to its angular momentum and axis of rotation. Then it's up to the precision and materials to minimize wasted energy through vibration, friction, and air resistance. The best materials and machining won't get you there without a good design, and a good design will only get you part way there if using inferior materials and imprecise machining.
 

wildo

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#69
Wildo-After your comments above perhaps I need to abandon the reamer idea and go for a micro boring bar with go nogo gauges?
R
All that I know is that some time ago, I read a post on the FB group that many of the most renowned makers were boring their ball recesses. That said, plenty of them seem to be just find with drilling or reaming (probably more so the latter). For me, I wanted the fun challenge of boring, and really- if I can get it right, then my top would be better for it. I'm sure you're just fine with the reamer. Hell- my very first top was simply drilled and I still got over 10 mins on the spin. Really, dealing with the contact point is likely more for getting the top very stable/smooth when spinning more so than spin times, to be honest. 10 mins is super cool (and I'm proud of that) but the top doesn't spin DEAD SMOOTH. Getting that contact point exactly on center is going to help with the stability and reduce/eliminate hula hooping and fluttering.
 

rwm

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#71
I made a Sherline tool post grinder to modify a reamer:





With the lathe and the diamond wheel running I took .002 off the radius of the end of the reamer for about 1/2".
I reamed a test hole and measured it. I got 0.245". Looks like this will work! I hope .005 is not too much interference for a SiN bearing? If so, I guess I could cut off the tip of the reamer and try again.
Robert
 
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rwm

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#73

This is beefier than the last one.
Wildo- Since you own some professionally made tops and have made your own. What nominal diameter should I shoot for to make the stem? Assume the top is typical size and weight. I am presently thinking about 1/4" is optimal?
Robert
 
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rwm

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#74
Best top yet!







Spins perfectly. This was has a thicker rim with more mass peripherally. The .245 reamer worked perfectly for the bearing hole.
In the end, my cast bronze is pretty nice. I was gratified to find no inclusions or porosity during machining. I have enough left for several more tops.

R
 

rwm

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#75


This particular top spins forever.

R
 
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rwm

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#78
Cool stuff! I thought about making a launcher like that.
R
 

wildo

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#79
Here's one I wrapped up today. Many days in progress... my first milling on a top, first indexing, first three piece, first copper, first cast iron, and first time using a graver. Needless to say- it spins like crap. :(:D But it looks awesome and was really fun to make!

This top is copper over cast iron over a stainless steel stem. It has a ruby bearing.



 

rwm

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#80
That looks great! I find that my tops with a lot of mill work don't spin great. They must be slightly unbalanced.
Have you noticed that your tops spin better over time? Mine seem to. It may be that the bearing wears microscopically and gets more concentric? Otherwise I can't explain it.
I just got a piece of Damascus steel....
Robert
 

Tozguy

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#81
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

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#82
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

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#83
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.

 
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rwm

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#84
Interesting. See if you think it gets better over time. Test my bearing wear-in theory.
R
 

wildo

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#85
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

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#86
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
 

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wildo

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#88
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

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#89
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

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#90
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!!
 
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