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Show"N"Tell ( Your Machines) / Re: Conect 121 lathe retro
« on: August 20, 2011, 06:15:55 AM »
Hood,
Welcome to the world of small and you will certainly have fun with it.
I put bearings on both sides of the Z and X axis on mine with one side able to adjust preload of both bearings.
The problem on having the X motor mounted to the back side is that there is not much to grab onto for mounting. I made a bracket
and things worked out. Another pain is ball screw size on the X axis since it's small in size ( small and accurate means expensive you will find ).
My x axis screw has a rather fine lead and didn't need any reduction / stepper is directly attached. Actualy it's a positioning ball screw and i was
after accuracy. Both of the screws have backlash adjustment for the nuts....so post tweaking the bearing preload i could then refine the nut preload.
For the x ball screw a tapped hole in the top of the carriage provides for getting to the nut adjustment. With both ends of the ball screw anchored / rigidly supported allignment becomes trial and error. Not much problem for the Z, but the x axis is very short and no give .......have gibbed x axis slide ...so the bearing mounting plates can be shifted some to provide for gib adjustment. In the end all this paid off.
I use a 1/2 HP motor on mine and when using the back gearing get plenty of torque and no spindle slow down when threading. Draw back
here is spindle speed though. But with CNC you can always use a fine feedrate to get surface finish.
A small accurate CNC lathe is just a joy to use,
RICH
Welcome to the world of small and you will certainly have fun with it.
I put bearings on both sides of the Z and X axis on mine with one side able to adjust preload of both bearings.
The problem on having the X motor mounted to the back side is that there is not much to grab onto for mounting. I made a bracket
and things worked out. Another pain is ball screw size on the X axis since it's small in size ( small and accurate means expensive you will find ).
My x axis screw has a rather fine lead and didn't need any reduction / stepper is directly attached. Actualy it's a positioning ball screw and i was
after accuracy. Both of the screws have backlash adjustment for the nuts....so post tweaking the bearing preload i could then refine the nut preload.
For the x ball screw a tapped hole in the top of the carriage provides for getting to the nut adjustment. With both ends of the ball screw anchored / rigidly supported allignment becomes trial and error. Not much problem for the Z, but the x axis is very short and no give .......have gibbed x axis slide ...so the bearing mounting plates can be shifted some to provide for gib adjustment. In the end all this paid off.
I use a 1/2 HP motor on mine and when using the back gearing get plenty of torque and no spindle slow down when threading. Draw back
here is spindle speed though. But with CNC you can always use a fine feedrate to get surface finish.
A small accurate CNC lathe is just a joy to use,
RICH
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