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Old 06-23-2021, 12:53 PM
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Reliable Spinner Balancing

Recently I have been doing PM on all of my planes and went and balanced the props and spinners. What I came up with was that the way I was balancing could make the situation worse.

The issue is that none of my balancing equipment is rigid enough or center the spinner properly to not induce a wobble and an out of balance situation. This wobble would make one balance a potentially good spinner and back plate.

So, like the engineer that I am, I went and modified the equipment.

I purchased a new true turn spinner and back plate and checked the balance on my new design. As advertised, the true turn was good to go out of the package. I did not even have to mark the location to match the backplate with the spinner.

A 1/4 inch aluminum scrap plate was used to drill and tap (8-32) four holes. The posts and bearings from an old Dubro fixture was transferred to the plate. Several size hardened ground shafts were evaluated from 1/8" to .250. The 3/16" diameter shaft seemed the best for all sizes. I did not like the 1/8" as it is susceptible to bending.

I manufactured and shrunk a mandrel onto the shaft and machined the tip ..394 to fit the inside of the back plate. 3/16 rod was used in that it is closest to 5mm which is the standard size bolt used to secure the spinner to the prop spindle. A cone was turned to hold the tip of the spinner on center.

While the true turn was balanced with the new shaft and fittings, it showed that it was out of balance using the rubber cones and 1/8" rod.

I will post a video shortly.
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Old 06-23-2021, 03:19 PM
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Here is the video.


Spinner Balancing (8 min 4 sec)
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Old 06-23-2021, 05:31 PM
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Thanks for doing the Video . It's nice to know the the True-Turn Spinners are that Good.
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Old 06-23-2021, 06:44 PM
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They're get'n lower mate.....
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A T-Turn may cost a bit more ....... their quality is excellent
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Old 06-30-2021, 02:53 PM
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Mag-Lev Balance Fixture

The top flite magnetic balancer gave me an idea for a magnetically levitated shaft. I took some scrap aluminum and build the frame and attached the magnets which has a 5mm hole in the center.

I will work on the shaft in the morning. I know it is a bit out there, but I love to work on stuff like this.

I think the modified Dubro beam and thicker shaft works just fine, but I wanted to experiment.

The downside to this is that the magnets are super brittle and powerful. I had a couple crack due to the force of the impact as one slipped out of my hand. As you can see by the white box in the background, these magnets come with a warning!

If you are wondering why i have three sets of magnets in a triangle format on the right it is because all of the forces will be pushing the shaft to the left leaving the right side to bounce. By surrounding the shaft magnetically, the shaft bounce and oscillation should be reduced....I hope!!!
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Old 06-30-2021, 02:58 PM
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Mag-Lev Balance Fixture

Sorry for the double post!!
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Old 07-02-2021, 04:30 PM
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Mag-Lev Spinner Balancing- Version 1

I have completed the mag-lev balancer and it still needs some work.

I need to center the magnets better as the magnet holes are .204 and my screws are .187. I should have gone to 5mm screws but did not think of it until it was too late. I used 10-24 screws instead.

I also need a sharp tip and additional magnets to stop the shaft from bouncing.

Mag Lev Spinner Balancing (3 min 31 sec)
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Last edited by ChemE; 07-02-2021 at 04:46 PM.
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Old 07-03-2021, 05:59 AM
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Great work!
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Old 07-03-2021, 07:45 PM
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Quote:
Originally Posted by ghoffman View Post
Great work!
Thanks for the compliment.

What else is there to do on a stinky New England weekend?

In any case I made some modifications to the fixture and we are making vast improvements. I still have to redesign the shaft tips, but we are getting agreement with the Dubro balancing method.

The Tru-Turn spinner is an excellent product. The only problem I have is that I dropped and slammed it against the frame and table so many times that I am amazed that I didn't put a dent in the spinner.

Mag Lev Spinner Balancer version 2 (2 min 46 sec)
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