Ice Ball Maker

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hpcnp
Posts: 6
Joined: Wed Jan 31, 2018 10:59 pm

Ice Ball Maker

Post by hpcnp » Sat Feb 01, 2020 8:37 pm

This is my first post to the projects forum, or any other part of this site, so please be tolerant of mistakes or failures to follow protocol that I’m unaware of today.

The shop work I do, tends to fall into three different categories:
  • building items which are available in the marketplace at what I consider exorbitant prices for what the item is
  • Creating tooling which enhances the usability of my shop
  • Building FRC parts for the robotics teams that I mentor
This project falls into the first category.

Oh, and the first category has something else in common among projects - my hobbies tend to overlap or cross over from time to time.

In this case, I have a penchant for the history and creation of pre-prohibition cocktails - which via friends who enjoy these drinks come around to share from time to time. After reading one of the many cocktail books focused on the craft of the cocktail, something caught my eye. The beauty of the perfectly clear, bubble free ice - typically a sphere (minimum surface to volume) served with scotch or bourbon.

This introduction is already much longer than I planned, so I won’t go into the adventure I had regarding creating bubble free ice blocks. That, so far, has nothing to do with my shop work.

So, a few google searches and I discovered a device which dramatically can turn a large piece of irregularly shaped ice into a beautiful sphere. Much to my dismay - they’re hundreds of dollars. (Simply google search “Aluminum ice sphere maker” - there are some nice YouTube videos showing one of these devices at work as well)

And thus, this project was born.

After measuring the sizes of my old fashioned glasses, I settled on a 2.75” diameter sphere, and a few moments later was looking at 4” 6061 Aluminum stock. Ebay was my friend, and I was able to get the stock I needed for ~$4.50 per pound. No doubt I could have done better, but this price worked out to about $25 per ice ball maker (for materials) which I thought was acceptable.

Some quick Fusion360 CAD and CAM later, and I had an idea about what I wanted to do and the workflow. Alas the first thing I noticed was that to hog out all that aluminum, even using a roughing endmill would have taken almost an hour. So I hatched a plan to turn the stock on the lathe removing a cylindrical plug at the center what would be the spherical cavity which cut down the machining time on the shapeoko by half.

This resulted in my first venture in a non-standard stock shape required for Fusian360 CAM. I used the multi-body capability where the first body was the stock with the cylindrical plug removed, and the second was the finished geometry. (Again, YouTube was my friend here)

Anyone with a sharp eye will notice there is a small hole at the center of the sphere. This hole serves two purposes. The first is to drain water out of the form once the ice makes a seal around the circumference. The second is it allowed me to locate each piece of stock in the same place on the bed of the shapeoko by way of a 1/4” dowel ping which I turned down halfway (after annealing) to fit the .113” hole. Like most folk, I have an aluminum bed with alternating 1/4” holes and 1/4-20 threaded holes which makes holding and locating very convenient.

The workflow was relatively simple:
  • 3D Adaptive roughing
    • 12k RPM[/list=]
    • 30 inch/min
    • 0.020 stock to leave / 0.008 tolerance
    • .002 min step-down / .020 max step-down
    • 6mm carbide single flute endmill
  • 3D Ramp
    • 15k RPM
    • 40 inch/min
    • 0.015 stepdown
    • 0.006 stock to leave
    • 6mm carbide single flute endmill
  • 3D morphed spiral
    • 15k RPM
    • 40 inch/min
    • 1/4” carbide 2 flute ball endmill
  • Spot drilling the guide holes
  • Drilling the guide holes
After this, I put the half back on the lathe to hit the surface of the hemi-sphere with 220, 400 grit sand papers, and then a quick polish with scotch brite. The below is the finished set complete with 3/8 x 6" brass guides along with some ice to test it.

I hope that was useful, helpful, and maybe fun too. Constructive criticism about what I should add, and what was too much is welcome. I have other projects I could post.

I should probably make some comments about my shop and the tools I have access to for anyone considering the project:
Shapeoko XXL with a 2.2 kW water cooled spindle and an air blast / misting system
  • A 9” x 17” Logan lathe circa 1955
  • A Grizzley g3103 milling machine circa 2003
  • Drill press
  • 2 wheel grinder
  • Horizontal and vertical band saws
Attachments
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IMG_9930.jpg
IMG_9930.jpg (514.55 KiB) Viewed 4176 times

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