Metal CNC Machine
| This machine was designed to
address the problems with the
trial machine. The X rails were placed near the gantry beam to reduce gantry end-plate flex. The under table leadscrew was removed, and racks and pinions were used on the ends of the gantry to prevent racking. The X and Y rails were supported, and the Z axis used fixed bearings with moving rails. The rails and racks were placed above the work surface so the chips would fall away from the mechanical components. ......................
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| The gantry is made
of aluminum tube,
angle and flat bar. |
The Y leadscrew is supported by a pair of bearings that are spaced a few inches apart. This greatly reduces leadscrew whip. |
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| The table bed just welded. The bed is a discrete unit which is connected to the chassis with adjustable mounts. These allow the bed to be leveled relative to the router's travel. | The gantry on the X chassis. The gantry weighs 80 lbs and rolls easily. The bearings are adjustable and allow proper tensioning. |
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| Though the rack is already installed, this shows how the rack was aligned when butt-jointed. A short piece of rack was clamped into the two meeting pieces. This made the job manageable and the results are accurate. | The rack ends before the rail does; if the limits fail the pinions freewheel. The rack was placed upside-down above the pinion so the dust would fall away from it. |
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| The pinion is pulled upward into
the rack with a spring loaded bearing block. The rod coupler adjusts
the spring's tension. The rack/leadscrew version in the plans eliminates this complexity with a much simpler system. |
Gearing on X axis. Servos turn much faster than steppers and require a more complex gearing system for the pinions. The compound pulley system shown above gives a ratio of 13.8 motor turns per inch of gantry movement. The steppers in the rack/leadscrew and belt drive tables do not require this level of complexity. |
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| The servo's belt is adjusted by
a moving plate. The rack/leadscrew
table uses a simpler system that permits a fixed motor. |
The bearings for the X and Y
axes are based on the system derived
earlier. This is overkill on the gantry. The tables in the plans use simpler systems that are just as stable and are more easily adjusted. |
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| The X bearings from the trial
table were recycled into the Z axis. The system
in the plans is greatly simplified and does not require welding. |
The Z carriage on the gantry.
The moving pipe with fixed bearing system has served well. |
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| The table moved to its own room.
Stock can be moved directly from the truck to the table. The control box can be seen on the back of the computer cabinet. |
The tee slots from the trial
table were reused. The slotted table can be removed for deeper stock. Hold down clamps slide in the slots. The table was lined with tempered hardboard on the sides and MDF on the bed. This contains the chips. |
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| The router mount can be removed from the spindle plate by loosening a few nuts. This permits other tools to be used such as the circular saw shown below. | An adapter for the Dremel fits
into the router clamp and vac system. It also allows access to the shaft lock for bit removal. It is made of copper fittings and DWV plumbing pipe. |
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| A bracket for an old circular
saw was welded together. This made the table handy for cuts that would
be difficult to do with a table saw or by hand. |
The saw body cannot swivel so
cuts can only be made in the X direction. Z's height and Y's positioning are still functional, so rabbets and dadoes are possible. |