Hand-Cranked Marble Lifting Machine with 8 Links Powered by a Worm Gear

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Project by DaleMaley posted 03-30-2021 12:17 PM 1649 views 4 times favorited 10 comments Add to Favorites Watch

I am always looking for ideas for more hand-cranked models. I saw David Rector’s model on Youtube where he used 8 linkage bars to lift a marble 2 times. He powered his model with a 5 RPM electric motor.

Since kids can crank up to 100 RPM, to make this a hand-cranked model, I needed a 20:1 speed reduction ratio, and a worm gear can easily do this. My mating spur gear has 20 teeth, so the ratio is 20:1.

I didn’t think I could make the 8 linkage bars accurately enough in wood, so I went with brass on the mechanism, linked to wood chutes and a wood marble drop tower.

I used a wood fixture for each of the 8 links with the pivot points on 1/4” dowels. I printed out the link in Sketchup, then used that to make the fixture.

I was afraid using a worm gear might shake the mechanism too much and the marble falls off, but it works great.

I made a Youtube video of the model in action. You can see it using this link.

To see my Trials & Tribulations on this project, which were too many to count, see my woodworking web site using this link.


-- Dale, Illinois,

10 comments so far

View 987Ron's profile


2194 posts in 560 days

#1 posted 03-30-2021 01:33 PM

The use of the worm gear exposed. Very nice. Should be fun for all using it.

-- Ron

View woodbutcherbynight's profile


10403 posts in 3653 days

#2 posted 03-30-2021 07:09 PM

Very cool!!!!

-- Live to tell the stories, they sound better that way.

View Redoak49's profile


5391 posts in 3233 days

#3 posted 03-30-2021 08:10 PM

That is an amazing project…I think it is your best.

View DaleMaley's profile


591 posts in 3480 days

#4 posted 03-30-2021 08:27 PM

That is an amazing project…I think it is your best.

- Redoak49


As I think about it, I would have a hard time figuring out my favorite projects :) I still like my hand cranked Ferris Wheel project…......The kids like to crank it so fast that the little people fly out of their seats


-- Dale, Illinois,

View 502flier's profile


62 posts in 3521 days

#5 posted 03-30-2021 11:14 PM

I love those wooden mechanical devices! Nicely done!

-- Kevin - Keep the shiny side up

View Eric's profile


1937 posts in 1117 days

#6 posted 03-31-2021 01:01 AM

Very cool design, and love the video. Ant one would enjoy playing with that. Like the clocks in the background too.

-- Eric, building the dream

View therealSteveN's profile


8878 posts in 1818 days

#7 posted 03-31-2021 04:16 AM

Wood and metal and hours of fun. Another in a great line of wonderful posts.

Thanks Dale.

-- Think safe, be safe

View James E McIntyre's profile

James E McIntyre

1496 posts in 2536 days

#8 posted 03-31-2021 03:56 PM

If your anything your persistent. Wonderful project. Enjoyed your video too. This is what I like about LJ’s the, variety.

-- James E McIntyre

View TopamaxSurvivor's profile


22410 posts in 4920 days

#9 posted 04-01-2021 02:33 AM

Awesome! I love the handoff mechanism ;-)

-- Bob in WW ~ "some old things are lovely, warm still with life ... of the forgotten men who made them." - D.H. Lawrence

View NHdude's profile


68 posts in 962 days

#10 posted 07-04-2021 05:32 AM

Very intricate- nice work!

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