Support And Enclosure Components

This section describes how to connect the Axis Drivers, XY Flexure Stage, and Z Axis Probe in a rigid structure that also supports two USB microscopes and a base board. Two base boards may optionally be stacked to give a space in which to put the CNC Controller electronics. You will need to have already assembled two plain Axis Drivers and the Z Axis Probe.

The most of 3D printed parts are on one print sheet (maus_complementary_plate_B.stl).

You will also need these Adjustable Brackets from Plate A,

and the Z Tower from maus_z_tower.stl.

Assembling X And Y axis Components

X And Y Axis Support

Maus C uses customised Metriccano-based parts to create a framework for mounting the X and Y Axis Drivers, and the Microscope Clamps.

NOTE: When attaching parts to the XY Flexure Frame, be very careful not to damage the long, thin, fragile flexures.

Inserting Captive Nuts

Insert eight M3 nuts into the cavities in the X Axis Mount as shown above.

Insert three M3 nuts into the Y Motor Mount as shown above.

Assembly

Top and Bottom Pole Arm fixed to the X Axis Mount

Using four M23 x 20mm screws with nuts and washers, loosely fasten the Top Pole Arm and the Bottom Pole Arm to the closed end of the X Axis Mount. The loops on the Pole Arms should face in the opposite direction to the hooked ends of the X Axis Mount. Note that the top and bottom Pole Arms are different. Their position will be adjusted later in construction. If you have larger M3 washers available this will make repositioning easier.

X Axis Mount fitted to the XY Flexure Stage

Using four M3 x 20mm screws fitted with spring washers and flat washers, and four M3 nuts attach the X Axis Mount to the top of the side of the XY Flexure Stage, on the face with the wires hanging out of it. The clips on the Pole Arms should face away from the Flexure Stage. There should be a gap of a couple of mm between the protrusions on the X Axis Mount and the Flexure frame.

Note that the spring washers are there to space the ends of the screws away from the flexures. You can instead use a thicker stack of ordinary washers.

Y Axis Mount secured to the flexure frame

Turn the assembled frame around so that the Y flexure is pointed towards you. Fit the Y Axis Mount to the left edge of the front of the frame with two M3 x 12mm screws and nuts. These go through the thinner parts of the mount. Note that the Y Axis Mount is positioned one hole down from the top hole in the frame

Y Axis Driver attachment to Y Axis Mount

We do the Y first because nut access is a bit tricky. Take a plain Axis Driver and insert two M3 x 25mm screws into the second holes back from the platform. Use these to secure the Axis Driver to the last holes in the left side of the Y Axis Mount with two M3 nuts. This should anchor the driver and mount to the flexure frame. Note that this is easier to do if the assembly is resting on the Axis Drive motor as you can then reach through the underside of the flexure frame.

Further secure the Axis Driver to the Y Motor Mount with two M3 x 20mm screws and two nuts through the adjacent holes.

Screws holding X Axis Driver to X Motor Mount

Turn the assembly around so that the Y flexure is pointing away from you. Take the remaining plain Axis Driver and secure it to the two sets of captive nuts in the ends of the X Axis Mount. Use the same two pairs of holes as per Y axis but with two M3 x 25mm screws in the inner holes, and two M3 x 15 screws in the end holes.

Testing X And Y Axis Driver Movement

After attaching the X and Y Axis Drivers, move the Stage around manually 8mm in both directions on both the X and Y axes. Ensure that there are no screws protruding that will contact the flexures. If you find one and do not have a suitable shorter screw, put a washer or three under the head of the screw until the screw no longer protrudes into the flexures.

Attaching X and Y Axis Drivers to Drive Flexures

IMPORTANT: First make sure the X and Y Axis Drivers are set so that the Drive Screw Holder is in the middle of the Drive Screw

To attach the axes drivers to the drive flexures, angled slotted brackets are used. These allow drivers to be changed while prototyping and still achieve alignment. If you have used a later driver revision, you may need to change the anchor locations but the principle is the same.

Connecting the X Axis Driver to the X Drive Flexure

Secure an Adjustable Bracket by two slots to the rear of the X Axis Driver's plate such that the single slot overlaps with the slot in the tab on the X Drive Flexure. Use two M3 x 12mm screws and two M3 nuts with M3 washers under the nuts. For now, leave the screws loose enough that the bracket can be repositioned.

Raise the bracket until it touches the axis flexure's tab and is perfectly parallel. The parts should only make light contact. Carefully secure the two screws without altering this alignment (it helps to first fasten one screw a little bit, then the other, and alternate until they seem sufficiently tight).

Take an M3 x 15mm screw and put an M3 washer on it insert it into the flexure tab's slot such that it passes through the slot in the Adjustable Bracket. Wind on an M3 nut. Check that the drive flexure is still in a neutral position, and carefully tighten the screw without torquing or shifting the flexure. It helps to pull down slightly on the nut as you tighten the screw.

Connecting the Y Axis Driver to the Y Drive Flexure

Connecting the Y Axis Driver to the Y flexure is similar, except that the Adjustable Bracket is mounted on the inside of the driver's plate and points the other way. Again, lightly fasten the bracket to the plate with two M3 x 12mm screws and M3 nuts, with a washer under each nut.

However, the Y axis illustrates an issue to look out for: If the flexure tab is bolted directly to the bracket, the flexure will rub on the top of the bracket and this will cause errors in movement. Therefore, put an M3 washer between the tab and the bracket before aligning them. Then fasten them all with an M3 x 15 screw with a washer under the head and M3 nut.

From this point on, do not attempt to move the stage around by hand or you may damage one (possibly all) of the flexures.

Mounting The Z Axis Probe Driver

The Z axis support structure, while reasonably sturdy, requires the Base Board to be fitted for full stability, so don't panic if it feels a bit wobbly.

Inserting Captive Nuts

Take four M3 nuts and insert them into the nut slots in the sides of the four pillars on the Z Tower as shown above.

Screw cavity hidden underneath the Z Tower

Secure the base of the Z Tower to the lower corner of the Y Motor Mount with an M3 x 20mm screw through the hole in the bottom of its base plate.

Attaching side of Z Tower to the Y Motor Mount

With two more M3 x 20mm screws, secure the twisted pillar of the Z Tower to the captive nuts in the Y Motor Mount.

Securing Z Axis Probe Driver to Z Tower

The Z Axis Probe assembly can now be secured to the top of the Z Tower with four M3 x 15mm screws, driven into the captive nuts on the tops of its pillars.

Spacers used on Z Tower due to particularly large body of this NEMA17

As the motor here is quite large and would otherwise collide with the base of the Z Motor Tower, 3-hole Metriccano Strips are being used as spacers between the probe assembly and tower, secured with 20mm screws.

Note: V0.04 no longer needs these spacers.

... and I'll continue writing in the morning.

Microscope Clamp Assembly

The microscopes are attached to a 220mm length of pipe 16mm in diameter. If this is not available, 3D print an octagonal bar 14.6mm wide laid flat on the print bed. This will give maximum strength and print without support.

16mm is a common size of pole for USB microscope stands. If your microscope already comes with a convenient adjustable mount that fits the pole, you can use its pole and mount. The Pole Arms may be adjusted to suit different lengths of mount.

Maus C requires two poseable clamp assemblies, each holding a USB microscope. Two different clamp sizes are provided to hold microscopes with with a cylindrical body 30mm-32mm and 32-34mm in diameter.

Insert Captive Nuts

Insert four M3 nuts into the set of parts for each Microscope Clamp as shown in the image above.

Assemble Thumbwheels

Assembled Thumbwheels showing alternative double-stacked method for M3 x 30mm screws

Each clamp assembly requires four Thumbwheels. Three of these are made with M3 x 20mm screw, and one with an M3 x 25mm screw. As M3 x 25 are not common, you can use an M3 x 30 and stack two Thumbwheels on the same shaft to effectively shorten the screw (there are spares on the print sheets).

Assemble the Thumbwheel by inserting the screw so that the screw head is in the octagonal cavity. Tighten an M3 nut on the other side.

Connect Clamp Arm Segments

Take four M3 washers and put one on the shaft of each Thumbscrew to prevent them from digging into the plastic when tightened. Larger washers are better for this purpose, but not essential.

Take the longest Thumbscrew and use it to secure the hinge to the segment with the smallest split clamp as shown above.

Split clamp fitted with Thumbscrew

Fit a Thumbscrew to the small split clamp. This does not need to exert very much force to be clamped - do not over-tighten.

Microscope Clamp fitted to the Hinge

Attach the Microscope Clamp to the Hinge using the captive screw in the Microscope Clamp's shaft.

Fit a Thumbscrew to the captive nut in the split end of the Microscope Clamp. This should allow the clamping of most cylindrical USB microscopes with a barrel of 32-30mm. For other sizes, pass the value of the microscope radius to microscope_clamp() in maus_complementary.scad .

Repeat the process for the second Clamp Arm.

Take the 16mm diameter pole and insert it into the Pole Arms mounted to the Flexure Frame. The position of these may be adjusted depending on the size and focal length of the microscopes used, but they should secure the pole vertically. When you are satisfied with their position, tighten the four screws on the Pole Arms into their captive nuts.

Slacken the Thumbscrews on the small split clamps and push the two Clamp Arms onto the pole. The microscopes can now be fitted and posed. By rotating the pole, both microscopes can be moved clear of the stage simultaneously for easy access.

Base Board

Two Baseboards stacked with mounts

The Base Board is required for structural stability, both to the XY Flexure Frame and the Z Tower. It can be made on a laser cutter, cut from a section of 10mm pitch perforated board, or manually constructed. Using M3 screws to suit the thickness of the board and nuts (typically 20mm), secure two locations on the Z Tower, and two locations on each side of the Flexure Frame to the Base Board. Shown here one Baseboard is made from acrylic allowing a view into the circuitry below, and the lower one is made from cheaper MDF.

Optionally, two Baseboads can be used as pictured above, separated with four sets of Baseboard Mounts from maus_baseboard_mounts.stl . Each end of the pillars holds three M3 nuts captive. These hold the top Baseboard, and feet are provided for the lower Baseboad to prevent screw heads from scratching the bench.

Mechanical assembly of the μRepRap is now complete. It now needs to be calibrated and tested.