Finding a Drum for Motor Shaft to Lift 5kg Box

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Discussion Overview

The discussion revolves around finding a suitable drum or mechanism to attach to a gearbox motor for the purpose of lifting a 5kg box. Participants explore various options for drum designs, attachment methods, and considerations for effective operation, including the mechanics of string winding and load management.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested
  • Mathematical reasoning

Main Points Raised

  • One participant seeks advice on suitable drums for a motor shaft to lift a 5kg box and requests suggestions for attachment methods.
  • Another participant suggests a specific drum from McMaster-Carr, recommending modifications for attachment to the motor shaft.
  • There is confusion about how to attach the string to the pulley, with suggestions including using a slot in the shaft or tying the string around the drum with a constrictor knot.
  • A participant emphasizes the importance of a guide mechanism to ensure even winding of the string or cable around the drum to prevent binding.
  • Concerns are raised about the potential stress on the drum due to the weight being lifted, with calculations provided regarding the forces involved in winding the filament.
  • One participant proposes adapting a fishing reel for the project, which is positively received by another participant.
  • Clarification is sought regarding the stall torque of the motor and its implications for drum size.

Areas of Agreement / Disagreement

Participants express various ideas and suggestions, but there is no consensus on a single approach or solution. Multiple competing views on drum design and attachment methods remain unresolved.

Contextual Notes

Participants discuss the mechanical implications of the load on the drum, including potential stresses and the need for a robust design. There are also unresolved questions about the specifics of the motor's stall torque and its effect on the drum's dimensions.

Who May Find This Useful

Individuals interested in mechanical design, robotics, or DIY projects involving motors and lifting mechanisms may find this discussion relevant.

TechTree
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Hello, I'm trying to use this gearbox motor as a winch to lift up a small box (5kg), however it needs to have some sort of drum that's mounted to the motor shaft to wrap the string around. Although I'm unable to find anything suitable that I could use. Is there already something that exists that could work for this, if so how would I go about attaching it to the motor shaft? Here are a few images of the motor:

51sAMEx3wLL._SL1001_.jpg

51QAVdDgx2L._SL1001_.jpg

(Motor Specifications: 12v DC 15 kg.cm)
Any suggestions?

Thanks. :wink:
 

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Maybe something like this?
upload_2018-9-25_19-55-58.png


From McMaster-Carr (www.mcmaster.com). You would need to get one for a 3/16" shaft and drill it out to 5.5 mm. Substitute a socket head cap screw for one of the setscrews, then tie the string to it. McMaster-Carr is a good place to browse around looking for ideas.
 

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Thanks for your reply!
jrmichler said:
Substitute a socket head cap screw for one of the setscrews, then tie the string to it.
I'm just slightly confused, which part of the pulley the string should be attached to? If it's connected to one of the screws how will it warp around the pulley?
Timer_Pulley.jpg


Thanks. :wink:
 

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TechTree said:
Thanks for your reply!

I'm just slightly confused, which part of the pulley the string should be attached to? If it's connected to one of the screws how will it warp around the pulley?

Sometimes the shaft is slotted, so you can stick the end of the string in the slot. Otherwise, I would tie it around the drum with a constrictor knot.
https://en.wikipedia.org/wiki/Constrictor_knot
 
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TechTree said:
it needs to have some sort of drum that's mounted to the motor shaft to wrap the string around.
When wrapping string or cable around a drum, it can be important to have a guide mechanism that moves back and forth to ensure that the wraps are even (to get the most string or cable on the drum that can fit). Without a moving guide, the wraps can become a mess and even bind.

Maybe look at the different kinds of fishing reels to see if you can adapt one of them for what you want to do. You can find relatively inexpensive ones and even used ones. They generally will have a moving guide mechanism, since the fishing line needs to be reeled up neatly time after time without extra effort by the person doing the fishing:

http://www.reeladventurefishing.com/8-types-fishing-reels-most-commonly-used/

0F5KAI9I&Format=_SL250_&ID=AsinImage&MarketPlace=US&ServiceVersion=20070822&WS=1&tag=reelad03-20.jpg
 

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TechTree said:
(Motor Specifications: 12v DC 15 kg.cm)

Is that the stall torque after the gearbox? If so the drum will need to be Les than 3cm radius.
 
berkeman said:
Maybe look at the different kinds of fishing reels to see if you can adapt one of them for what you want to do.
A fishing reel! That's a great idea berkeman thank you for your suggestion! :wink: I'm sure I can adapt one to work for my project.
 
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When you wind a filament onto a winch drum, the filament is wound on with a tension due to the supported load. 5Kg might seem to be very little tension, but call it a force of 5 * 9.8 = 50 Newton. Now wind on 100 turns and you have a combined circumferential hoop stress of 100 * 50 N = 5 kN. That may be sufficient to crush the drum. The wall of the drum is in compression and must be sufficiently thick to oppose that winding stress without collapse.
How many turns of filament can you wind onto your drum?
 
Are you going to use the gearbox motor for fishing reels?
 
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Lynda Jhon said:
Are you going to use the gearbox motor for fishing reels?
Yes, I'm going to try and use the gearbox motor to wrap the line around a fishing reel. Then use a pulley to lift the box. :wink:
 
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