(Topic ID: 252468)

Rocky and Bullwinkle Nell Motor Fix!

By scottacus

2 years ago

Topic Stats

  • 9 posts
  • 6 Pinsiders participating
  • Latest reply 1 year ago by trueno92
  • Topic is favorited by 8 Pinsiders


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#1 2 years ago

Hello Poetry Pals! If your Rocky and Bullwinkle machine is like mine, there are issues with your Nell motor.

The Data East designers chose to use an AC asynchronous motor that was geared down to 4RPM to drive the log and saw blade. Asynchronous motors (like the kind in your microwave turntable) will run either clockwise or counterclockwise depending on the starting position. This means that about half the time the motor will run the wrong way and put stress on the reduction gears which eventually fail.

I tried fixing my motor but a previous owner had already already attempted this to no avail so I bought a replacement motor from Marco for $64. Unfortunately this motor didn’t have enough torque to drive Nell with the original return spring so sometimes Nell moved towards the saw blade and sometimes Nell moved away from it because it is an asynchronous AC motor!

I was frustrated with this because the Nell toy is one of the coolest parts of the machine so I decided to design a direct drop in replacement to fix this. My requirements were that the Nell toy unit that would:
1) always run the correct direction
2) reverse at the end of travel (save Nell or “It’s Curtains!”)
3) not run past the end of travel so that no undue stress is put onto the mechanism.
4) not require any rewiring or other complex electronic work, just plug and play!

To use this new system, the old Nell motor is removed and a new one is put in its place using the holes that mounted the old motor. The original gear and pulley are replaced with a new 3D printed version that can be mounted on the shorter shaft of the new motor. A new driver board with all of the onboard electronics is screwed to the bottom of the playfield in place of the original board and plugged into the native driver board plug (no rewiring). Nell needs to be slid to the far end away from the saw blade and you are ready to go!

Design, testing and manufacturing (Eagle design, custom etching, CNC drill pattern etc) has taken a lot of time so I made three boards since I was set up for production. One is in my machine and has been working great for a few weeks and the other two I’m offering up for sale to the first two Pinsiders who reach out to me via a message on Pinside. The cost for the board and 3D printed parts is $80 and I’ll ship via USPS Priority mail which is $8 for the small flat rate box for the continental US, I'm not sure about Hawaii or Alaska (Total of $88).

I've included photos down below of:

-The driver board mounted under the playfield.
-The motor with mount and printed gear/pulley unit.
-The two units that are for sale and ready to ship.

Here is a youtube video of the unit in action! First I show what happens when Nell is not rescued, note that the log moves at exactly the right speed to just reach the saw blade when "It's Curtains!" Second I show a Nell save. In each case the log moves quickly and smoothly back to it's starting point.

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4 weeks later
#2 2 years ago

I've redesigned the board so that it now has a much more robust Buck Converter that displays the voltage and amperage so that the user can tell if there are issues with any variation from specs. The buck converter is also visible from the coin door.

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8 months later
#3 1 year ago

Wow, very impressive! Are they for sale?

4 weeks later
#4 1 year ago

Yes they are, please contact me at [email protected] for more information. Sorry I don't check in at Pinside very often so I missed your post.

#5 1 year ago

Nice work! My Nell motor is working well enough for my standards (after recently replacing the belt that drives the saw blade), but if it ever gives out, I'd prefer your replacement.

1 week later
#6 1 year ago

Thanks for the hookup. Looking forward to seeing the new mechanism in action!

#7 1 year ago
Quoted from King_Jelly:

Thanks for the hookup. Looking forward to seeing the new mechanism in action!

Your welcome!

1 month later
#8 1 year ago

I was contacted by a Pinsider about making them a Nell Driver unit and from the photos he sent we figured out that he was missing the saw blade and the entire metal housing that supports the motor and saw blade. Because these parts are not available I took my RaB apart and measured up the parts and made a two piece model in F360 that I was able to 3D print for him.

I used my CNC machine to make a replacement saw blade plastic and used photoshop to make artwork for the saw. The DecalPro system was used to print the saw blade graphic and this was applied to the plastic. Here are photos of the housing and blade with replacement motor and gear/pulley from the Nell driver along with a video of the entire Nell board driver and the replacement parts driving Nell on my saw mill.

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1 month later
#9 1 year ago

This is pretty sweet.

Is there a test menu in the game to test this in diag?

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