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I make concrete flower pots. I had a drill mounted directly to a shaft that I used to turn the table when I made smaller pots. I now make much bigger pots, about 2' high by 44" at the top rim and 22" at the base. I use five 80 lbs bags of mortar on each pot. The mold is basically sand in the shape of the pot. This takes about thirteen 5-gallon buckets. The table is around 75 lbs. It is mounted on a frame with a 2-way 12" Industrial Grade DIY Lazy Susan Turntable Swivel Base. One side mounted to the stand and the other to a 2' square plywood the table sits on.

With the full weight of the sand and mortar I can turn the table using one hand to spin the table but it is not easy as when I wore a younger mans clothes. I burnt out the drill I had mounted to the base once I attempted to make the first pot of this size. My guess is the total weight is close to the 1500 lbs mark (sand 75 * 13 buckets - mortar 5 80lbs bags water). The table needs to spin very slowly.

I have been doing some research how to get the correct size electric motor and type. It seems like it is all about the torque needed to start it to turn and the torque needed to keep it rotating. I can find many articles on lifting but not much on turning a tabletop. Any help would be appreciated.

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    $\begingroup$ First thing is to figure out the torque required to turn it. Find a luggage scale or fishing scale. Attach it to the edge of the turntable, pull tangentially and note the maximum reading. The torque required will be the radius x the reading - inch-lbs or foot-lbs in your units. $\endgroup$
    – Transistor
    Oct 6, 2022 at 21:40
  • $\begingroup$ Thank you for your comment. I will try that once I get the next pot built on the table. $\endgroup$
    – Phil
    Oct 6, 2022 at 21:55
  • $\begingroup$ Just finished making the next pot. With the table loaded sand/concrete I used an old hook type scale that goes up to 336 LBS or 150 kilos. I used vice grip type clamp on the outside edge of the table. I then put the hook on the scale to the vice clamp and pulled until the table started moving. Pulled many times. The scale showed between 12 to 20 lbs. Basically the more I tried to turn the table the less it took. $\endgroup$
    – Phil
    Oct 17, 2022 at 20:23
  • $\begingroup$ Good work. Measure the radius and multiply by the force and you've got the torque. Then calculate the speed you want (RPM) and start looking at motor gearboxes. The motor torque will be low but speed will be high. When stepped down you get trade speed for torque so you'll have high torque at low speed. Put in a safety factor of at least 2 for unexpected friction, etc. $\endgroup$
    – Transistor
    Oct 17, 2022 at 21:15
  • $\begingroup$ First thank you for your help. The table is a 48 inch table so the radius would be 24". I would take 20 lbs x 24 and that would give me 480 is what I would need for torque? I would only want the table to turn about 1 rotation per minute, 2 at the most. If I understand what your saying about lower speed gives you more torque then I should be looking for something with very high speed? $\endgroup$
    – Phil
    Oct 17, 2022 at 21:44

1 Answer 1

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If you don't need it to be fast another drill motor should do fine. Just use a large gear reduction. For example put a 12in diameter pulley on the lazy susan, and a 1in diam pulley on the power drill, that gives you 12x the torque.

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  • $\begingroup$ I was looking at putting a motor at the center of the table. I currently have a shaft that comes down that I had the other drill attached to. My version of direct drive. Maybe this requires to much power and will have to use a belt type set of pulleys. $\endgroup$
    – Phil
    Oct 17, 2022 at 20:27
  • $\begingroup$ Well there are gearboxes suitable for direct drive, such as planetary gear sets, but a pulley and belts is much simpler if you can make it fit. $\endgroup$
    – Drew
    Oct 18, 2022 at 18:12

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