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90 Deg Stepper Motor

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wileel

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#1
As I read through all the CNC build threads I see one thing that keeps standing out to me...big ole motors hanging off the ends of the table and adding extra height to the machines. I've only seen one on here that was belt driven and looked very clean, so got me thinking.

Although it seems like the most efficient method, it looked awkward so got me wondering why one wouldn't use something like a 90 stepper or worm drive transmission.

On the surface (in my mind) it seems feasible but I don't have the actual knowledge/experience. I can see the speed reduction may be an issue but if you gain extra torque couldn't you get away with needing a smaller motor... Also I can see backlash maybe an issue also but looking at some specs is hard to visualize what 20 acr/min would translate into in this application.

Anyone willing to discuss it?
 

Karl_T

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#2
I used toothed belts to my X Y and Knee axis on my CNC mill. its a good way to go as it allows the motor to be tucked under and out of the way.

the Z axis has a right angle drive allowing the servo to be attached horizontal.

So,yes these concepts work just fine.
 

magicniner

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#3
Belt works great because it's cheap and can be near-zero backlash, start messing with gears 90 degree direction change or otherwise and either it gets expensive fast or wear is an issue, it's not done because adding complication, expense and wear/backlash problems (now or later) doesn't make any sense at all.
 

agfrvf

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#4
Worm and wheel is your friend.
 

magicniner

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#5
Worm and wheel is your friend.
For slow speed micro-precision machines it may be, it's useless for decent CNC mills or routers though because the reduction is too high, even for use with fast Ball Screws, and you'd still need to use anti-backlash wheels in order to be able to run without backlash with clearances that don't result in wear and backlash.
There are reasons why some technologies are not used in particular applications, they just aren't really suitable.
 

wileel

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#6
I used toothed belts to my X Y and Knee axis on my CNC mill. its a good way to go as it allows the motor to be tucked under and out of the way.

the Z axis has a right angle drive allowing the servo to be attached horizontal.

So,yes these concepts work just fine.
I really like this idea to save room.

How did you determine pulley sizes and how did you attach the pulleys to the shaft and ball screw?
 

Karl_T

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I really like this idea to save room.

How did you determine pulley sizes and how did you attach the pulleys to the shaft and ball screw?
I went 1:1 with about three inch OD. It was just what fit nice. Put woodruff keys in the shafts and key slot in the pulley.

Its been too long ago, like before this forum, but I had to make a real neat fixture to hold the motor shaft while still in the motor.
 

Silverbullet

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#8
I had pet worms as a kid. Took them swimming and they changed into fish . Wow great friends bought me dinner.
 
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