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[JMauk]

Hi Top-Spinning Gang!

I want to bring you up to date on Giant Top 2.0.  We spent most of the last half of 2019 planning, designing and having the frame (or shell) manufactured.  We took delivery in December and began some initial tests.  Have hit a couple of snags but the main problem is the Philippines is in Covid lockdown since March 15.  All three of our conference centers (re-creationcenters.com) are shut down and virtually all staff laid off.  We hope we can start re-opening by July but it's a big challenge with no income for such a long time.  Also, the center where Ruth and I live now (CCF Mt. Makiling Re-Creation Center) is near the Taal volcano that erupted January 14.  No one came to us for a month after that.  Then we had about three weeks of good operations before the Covid shut down kicked in!  But at least I have time to catch up with all of you and get you caught up on how far we got with giant top 2.0 before the shutdown.

Also, just wanted to brag a bit, so forgive me, in January 2020 I surpassed a total of 6,000 tops shows since my first one in Australia in 1975.  God has been very gracious to me and, as you know, my tops shows are designed to teach about God through the tops.  Glad I reached that milestone at the start of the year since I haven't had a tops show since mid-March. Usually do 3 or 4 shows a week on average.

I'm going to start searching my photos file and posting pics of the Giant Top 2.0 history up to present.  Will put them as replies to this post.
As we go through them I look forward to your input on the project.
Thanks,

Joe Mauk

[JMauk]

We began last March 2019 by dismantling Giant Top 1.0.  It had a blowout in August 2018 and we spent some time trying to figure out whether to repair or rebuild.  When time, funds and opportunity came together we decided to build a new one.  We took down 1.0 before we even had a complete design for 2.0.  Tends to get one motivated!

[JMauk]

I have a friend my age who owns a large manufacturing plant of heavy machinery (they build paper mills!).  He (finally!) took an interest in my project and set one of his sharp young engineers on the design.  They had a complete design by June 2019 and started manufacturing in July. Here are some pics I took in August.  Note the sharp super hard point in the last pic.  It became a problem as you'll see later.

[JMauk]

We took delivery early early morning September 10,2019.  Less traffic for wide load (4M diameter center ring)

[JMauk]

It took all day to get the parts together, upright and ready to go.  At this time we had the framework complete but were not yet sure how we wanted to cover it.  Wanted to do some testing before deciding.

[JMauk]

A little fun after assembly

[JMauk]

The nice sharp and hard point drilled holes in the hardened steel plate!  The middle hole was when we first tested it on day of assembly.  Three days later we did a Bumblebee pull.  It pulled the point to the side of the bottom bearing holder and it drilled there. Will post that video next. A few days later we hoisted it up to prove what I suspected.  It wasn't moving to center because it drilled a hole at the side!










image hosting free

[JMauk]

Here's the video with the point shaft stuck to the side at the end

[JMauk]

So we put in a stainless steel plate that was twice as hard.  It drilled a hole half as big!

[JMauk]

So back to the engineer and manufacturer.  They proposed fabricating a pressure bearing to take the weight.  The point shaft would then sit in and on the bearing and the tip of the point would not be touching anything.  Will post some videos of the not so successful tests.

[JMauk]

Here is the manual pull test of the pressure bearing.  Everything went fine but was concerned that the top slowed faster than before after release.

[JMauk]

Here is the Bumblebee pull test of the pressure bearing.  Sorry for the poor quality video. Borrowed phone!
There is a slippage as Bumblebee pulls.  I believe this is because the plate where the point is set rests on the top of the pressure bearing.  We assumed it would not slip as the frame already weighs 800K without a skin yet.  Apparently it does and probably needs to be fastened.  The other thing is the quick slow down of the spin after release.  Should keep its momentum much better than that.

[ta0]

OMG! (can I say that?) Wow! Over-the-Top! 
I doubt anybody will ever challenge you for the biggest top in the world! 
I was wondering what had happened with your project, but I see you were still going full steam ahead!
You should have posted updates during the construction: it would have been as interesting as watching the progress of SpaceX Starships south from here, in Boca Chica, Texas.

800 kg? It looks even heavier than that! I'm not surprised that it drills on the base. Perhaps Iacopo on this forum can give you some advice on material matching between the tip and the base (for a fixed tip) as he has carefully studied this on his much smaller tops.
The bearing idea you are trying is intriguing. Let me think about it.

I believe the main limiting factor on your previous top was air drag. I think you should be able to get much better spinning times with the open frame once you fix the tip issue. I suggest getting the Guinness Record before putting a skin cover.

I'm really impressed!

PS: You got the wrong video for the manual pull test.

[JMauk]

This is a more specific view of the top spinning with the Bumblebee pull.  The amount of slow down is quite dramatic.  It appears the pressure bearing creates too much drag.  That is where we are at the moment since we've been shutdown since mid-March.  I intend to send the bearing back to manufacturer to see if they can reduce any unnecessary friction. Hoping things open up soon.

[JMauk]

PS: You got the wrong video for the manual pull test.

Thanks for the heads up. It should be the right one now.  Yes, I should have been posting all along but I was hoping to have the whole thing ready for the new year and do it all at once.  Hindsight is 2020 in 2020!