Alright first actual design post with some pictures.

Z-axis design

- 3kW ATC spindle & Ø100mm spindle bracket. The spindle alone weights about 19kg according to the supplier (RattmMotors).

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- 20x200x500mm aluminium rear plate, onto which spacers, BK12/BF12 bearings and motor bracket are mounted.
- 15x50x500mm aluminium spacers to make room for BK12/BF12 bearings and 1605 ballscrew. Linear rails are mounted to the spacers.
- 20x200x171mm aluminium top plate for HIWIN narrow guide carriages that goes on top of the gantry. Gantry ballscrew nut bracket will be mounted to the same plate.
- 20x200x240mm aluminium front plate, onto which the HIWIN narrow guide carriages and ballscrew nut bracket DSG16H are mounted.
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- About 200mm gantry clearance
- 146mm overhang
- Spindle can be raised about 60mm above gantry
- 1605 ballscrew, 400m long with 25mm F-length end machining for BK12 fixed bearing to allow for pulley. Floating bearing in the other end.
- 20T HTD 5M pulley on the servomotor and 40T HTD 5M pulley on the ballscrew.
- 180W JMC servo motor.
- Motor bracket with oval holes to allow belt tensioning.

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- Moving weight in Z-axis direction, about 26kg - still missing cables, water pipes, proximity switches etc
- Moving weight in X-axis (gantry) direction: 40kg - still missing cables, water pipes, proximity switches etc.

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I am pretty happy with the total weight of the Z-axis. I don't think it'll go over 45-50kg with everything added.

I could still trim down the X-axis direction moving weight, by removing the linear rail spacers and adding machining to the front and rear plates. But I am thinking that I will need that stiffness which the 20mm plates gives me. Would it weaken the structure a lot by adding machining of 7x60mm along the middle of the plates, to allow room for the BK/BF bearings and ballscrew nut bracket?