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[ta0]

After making a lot of things spin including dragonfly shapes, butterfly shapes, etc. I'm going out on a limb and say that all except 1 and 12 will spin at least a bit.

I like your confidence, Don, on being able to spin almost anything. But here you cannot select your spinning axes, they are a given. Also, these are not flat figures. No, I am not referring to air drag: although it affects the spin of these tops, I think the classification between spinners and non-spinners would remain the same on the moon (unfortunately, I don't have a vacuum bell to try it  ).

As this starts a second page, I will repeat the photo for easy reference:

[ta0]

Mmm, seems many are afraid of guessing wrong Why? I would have guessed pretty badly, myself.

Well, somebody will win at least a Turbo, for sure. I'll post the solution late tonight.

[the Earl of Whirl]

I, too, like Don's confidence in spinning things.

I would be making more guesses, if it were allowed.  Actually, no one said I couldn't make more.  If I were more of a person who would stretch the rules (ha ha) then I might make many more guesses and totally dominate the results.  But, as it is, I will try to refrain myself from such unsightly behavior.

Now that I am back from our district track meet I will count the hours and minutes until the result is announced.  I have to toot my own horn a bit and tell everyone about the pole vaulters I coached tonight who did a pretty good job.  One was fifth and the other won the championship.  The winner will now go on to the regionals and might have a shot at making it to the state meet.  This vaulting news might not be too top worthy but there is a solid connection.  They both have held some spinning tops in their hands at practice this season!
 

[John Buechele]

I think 17 spin and 8 do not.
Column 1 Rows 1,4,5
Column 2 Rows 2,3
Column 3 Rows 2,5
Column 5 Row 2

[the Earl of Whirl]

It is now 11:30 our time.  I am starting to get sleepy......but I dearly want to hear the results!  I will try to hang on a little longer.

[MatiasStuntMan]

ohh master Ta0 you really know how to keep the tension high, I dont have any more nails to bite, this wait and suspense is killing me

[ta0]

Ha, I am having a little trouble uploading the pictures, but so that Mike can go to bed  the answer is:

8 do not spin!
17 do spin (but one barely)

Now, for the bonus question, nobody was even close.
Much more in a little while.

[ta0]

Ok, that makes John B's last minute entry the winner. I feel bad for Greaves504 because he answered in the first 5 minutes with almost the right answer. In fact, the top that is a marginal spinner spins for not more than a second. I may have to give him some prize.

Well, I could disclose the complete solution but let's give you guys (and gals if you dare  ) another chance to win the Turbo 2nd gen plus Jumbo. You have 22 more hours (so Mike can go to bed early) to name all the non-spinners. You already know they are 8, but this time I don't accept any errors. If there are several winners I will spin a dice top to decide 

[Spinningray]

How many did Chris get to spin?

[the Earl of Whirl]

Dagnabbit John Buechele!!!

You and your last minute entries.  Argh!

[Neff]

How many did Chris get to spin?

I got a different result.  I'll PM ta0 my results to compare.  There may be an explanation, the stem is broken off one of mine, one that I assumed would spin, but maybe not...

[ta0]

Yep, that is exactly right. The one you have with the broken stem does not spin, and it is one of the most surprising results. The rest of your list is the same as mine.

I feel torn about the marginal spinner. For any practical purposes it should be listed as non-spinner. I believe the reason it spins so little is similar to the reason why the non-spinners do not spin at all. On the other hand, the other not-so-good spinners (but still much better) are bad for different reasons.

[Dick Stohr]

If 8 is the magic number then:  1,3,7,8,12,15,16,21 do not spin.

[MatiasStuntMan]

Ok, with the hint of 8 I will add the two displaced semi-circles to my original list.
Here is my original list:
Doesn’t Spin:
The banana (but that doesnt count)
Column 1, row 1: Half circle (worst)
Column 3, Row 2: Triangle with uncentered peg
Column 1, Row 4: Pizza Slice
Column 2, Row 4: Parallelogram
Column 1, Row 5: Kite shape with uncentered peg

Plus the displaced semi circles:
Column 3, row 1, and
Column 5, row 3

[ta0]

(I have a juggling club meeting tonight so I am ending the contest a couple of hours early)

I'll follow the numbering proposed by Rob, from top left to bottom right.

These are the spinners:



No surprise for most of them, except on row 4: the pizza piece (quadrant, #16) and the trapezoid (#17) are surprising as the stem is not an axle of symmetry. The trapezoid spins pretty well and my guess is because the unbalance is small. On the other hand the quadrant dances in circles pushed by the off-center weight, but it still spins surprisingly well. The one that almost did not make it was the diamond (rhombus, #19) also in row 4 (more on that one later).

The non-spinners are:



Some big surprises here.

The semicircle (#1), triangle (#8), banana (#12) and kite (#21) were not that surprising to me as the stem is off-center (but after what I said before it is not that obvious for 8 and 21).

The rest have radial symmetry, that is same mass distribution to both sides of the axle, so I expected them to spin well, except perhaps because of air drag. But that is not the case: they refuse to spin on the stem!  The most surprising is the big X (#24): it stumped everybody!

A clue of why this happens is the diamond (#19): after spinning for under a second it falls and tries to spin on one of the vertexes.

I need to go now, but this top made by Philippe Dyon is a great demonstration of what is going on here:



It refuses to spin on the dark axis but spins well on the other two, even though the three are axis of radial symmetry. Philippe makes the dark axis of a heavier wood.