Rather than update the V0.03 build documentation for every alteration, changes will be listed here and the documentation update done en masse.

The main change is the fixing of a bug in the XY Flexure Table. The Y Flexure on the Stage is due for replacement, allowing a simplified Stage design. In turn, this requires a Y Transfer Bar to replace the Y Stage Flexure.

The Axis Driver NEMA17 parts have been overhauled so that tightening screws does not distort them, and additional securing holes have been added to increase rigidity of the Axis Driver mounting on the X and Z axis.

The Z Tower has been modified to avoid collisions with the enlarged complementary X Flexure. It has also been made slightly taller so that boosters/spacers are not needed to fit large NEAM17 motors underneath it.

XY Flexure Update

Issues

The V0.03 has an issue with the complementary flexures, largely due to developer experience. The pairs of flexures were of different lengths, resulting in approximately a 40μm height variation over the total range of movement.

The attachment points for the Axis Drivers require fasteners which intrude into the frame. These are inconvenient to assemble and may possibly restrict movement at the extremes of travel.

Resolution

The flexures are now supported by integral blocks to adjust them to the same height.

Captive nut recesses have been added to the frame, allowing shorter screws to be used when securing the Axis Drivers. This improves flexure clearance.

XY Flexure Table Construction

The V0.04 assembly is compatible with the V0.03 components, though the height is increased by approximately 1mm so drive flexure attachments will need to be adjusted

Part Preparation

Print two of each of the outer_frame_unit() and table_frame_unit() from the maus_complementary.scad file. Ensure the flexures have printed cleanly and none of the screw holes in the frames have collapsed.

Captive Nuts

Table Frame captive nut locations

Insert four M3 nuts into the matching cavities on the two smaller Table Frames. Take care not to stress the flexures.

Outer Frame captive nut locations

Insert eight M3 nuts into the Outer Frames. Note that these nuts are not all on the same level. These will be used later to attach the Axis Driver supports.

Flexure Table Assembly

Joining a Table Frame to an Outer Frame with two M3 x 16mm screws and nuts

Secure the outer two holes on a Table Frame to the two end holes on the flexure beam of a larger Outer Frame using two M3 x 16mm screws and nuts, finger tight. Ensure the frames are square on. The protrusions on the Table Frame point away from the centre of the Outer Frame. Ensure these protrusions do not rub on the Outer Frame when the flexures move.

Try not to place stress on the flexures within the frames. Connect the second Table Frame to the second Outer Frame in exactly the same way.

The assembled XY Flexures

Connect the two pairs of assembled frames and join them into a cubic structure with four M3 x 16mm screws and nuts. If it is truly square you should be able to stand the frame on its sides on a flat surface with no wobble. Fully tighten all eight screws.

Y Transfer Bar

Issues

The V0.03 X and Y Stage flexures allow the stage to be moved in both axes simultaneously. This causes movement on the X axis to cause small deviations in the Y axis and vice versa. The deviations are in the order of 1%-2% over the original working area, but are cumulative.

Resolution

The Y Axis can be moved by attaching the Outer Flexures on the XY Table directly to the Y Axis driver with a new part, the Y Transfer Bar. This prevents the X movement from directly displacing the Y axis, though it does not prevent the reverse (which may be remedied by a later upgrade).

The existing Y Flexure may be trimmed off, or an updated Stage Assembly can be fitted.

The part is in active development.

X Transfer Bar And Stage

Issues

As per the previous section, V0.03 X Stage flexure results in movement on the X axis causing small deviations in the Y axis and vice versa.

Resolution

As the stage is moved in the Y axis first, and then in the X axis, the simple flexible linkage for the X axis has been replaced with a complementary flexure. This allows free movement on the Y axis while the X axis is independently driven. This flexure is now part of the Stage, so many of the Stage components have now been reduced to a single printed part.

Stage with integrated X flexure

Stage Assembly

The Flexured Stage is now assembled without supporting Metriccano blocks and Y Flexure. These have been removed from the printable sheets.

The assembly of the Stage Top is identical for V0.04, except that it has narrow, tubular integral support material in two of the screw head holes. This will need to be removed.

Part Preparation

Do not attempt to remove loose filament from the flexures as damage is likely.

Captive Nuts

Place eight M3 nuts into the Flexured Stage captive nut cavities as shown.

Be aware that not all these nuts will be used in the default configuration, but the locations are hard to access and it is best to fit them now.

Captive nuts in Flexured Stage

Place the Flexured Stage on the XY Flexure Table Assembly such that the Y Transfer Bar is at the 12 o'clock position, and the X Complementary Stage Flexure is at 3 o'clock. Place the Stage Top on top with the UV LED wires coming out at the 6 o'clock position. Put four M3 x 30mm screws through the pairs of recessed holes in the Stage Top, and screw them into the captive nuts in the Table Assembly. Ensure the Stage parts are all square before fully tightening the screws, and take care not to stress the flexures.

XY Flexure Stage Assembly awaiting magnets

The part is in active development.

Axis Driver NEMA17 Parts

Issue

If the M3 x 50mm screws used to secure the flexure components to the Motor Pillar Assembly are slightly too long, they can protrude into the NEMA17 Plate and displace the axial alignment of the motor.

The Pivot Arm hits the Limit Switch too early.

If an M3 x 50mm Drive Screw or a NEMA17 motor shaft is too short, the Drive Screw may not correctly engage with the Bearing Block above.

Vibration and torsion by the NEMA17 motor can cause unwanted flexing of the motor mount.

Resolution

The NEMA17 Plate has holes that will allow the M3 x 50mm screws to over-extend slightly.

The Limit Switch and support have been lowered slightly.

The pillar height has been dropped by 1mm to allow the Drive Screw to reach the Bearing Block.

Additional mounting holes have been added to the face of the Limit Switch support to allow extra anchoring to the frame.

X Axis Driver

Issue

Some flexing of the X Axis Driver was observed. This may or may not have a practical impact but frankly didn't look good.

Resolution

Additional mounting holes in the Motor Pillar Assembly provide another fixing point between the X Axis Driver and the XY Table frame, with the space between them taken up by two 2-unit Metriccano square strips.

Z Tower

Issues

Large NEMA17 motors do not fit between the Z Axis Driver and the base of the Z Tower.

The X Flexure has been made complementary to allow independent movement of the X and Y axes, which has increased its size. It is now very close to colliding with the Z Tower in range of motion exceeds 4mm.

High speed movement of the Z Axis results in excessive torque and vibration of the Z Axis Driver and consequently the probe.

Resolution

The Z Tower is now one Metriccano unit taller. This allows large NEMA17 motors to be fitted, and removes the need for spacers to lift them.

Mounting holes in the Motor Pillar Assembly allow the Assembly to be fixed to the Z Tower, improving rigidity.

Undocumented Assembly Steps

Several of the parts here have not been tested in the fully assembled state and construction details have therefore not been written yet. Should you wish clarification, please do ask directly on Github, the RepRap Blog, or on the Printables RepRapMicron page.