Overview

The Maus V0.03 XY Flexure Table is a 3D printable stage that can move freely by up to 8mm in the X and Y axes without moving significantly - even on the micron scale - in the Z axis. The mechanism's essentials are four pairs of rectangular complementary flexures, and a stack of perforated plates which form the Stage on which micron-scale parts are eventually printed. Two long, thin flexures are attached to this Stage, and these will connect the Stage to the Axis Drivers during final assembly.

Note: The XY Flexure Table flexures have been redesigned in V0.04 and their use is highly recommended.

The 3D printed parts for the Maus XY Table are all on one 3D print sheet (maus_complementary_plate_A.stl), though there are some slotted brackets on the sheet that will be used later.

Component Choices

The Stage holds a UV LED in its central Light Well. A diffuse UV source is preferred to a point focused one, and USB UV LED lighting strips are an inexpensive source of UV LED modules (though if you have an SMT UV LED and know what do to, feel free to improvise) . Choose one that can have the LEDs cut off individually - some have a minimum cut size and are not suitable.

The LED used by this particular prototype runs off 5V, and the CNC Controller supplies 12V. Therefore a 680 Ohm resistor is needed in series, not shown in these instructions. Otherwise, choose an appropriate combination for your CNC Controller.

Part Preparation

A UV LED needs to be wired on flexible leads and mounted. A grounding probe for the CNC Z Touch function needs to be fabricated from solid coper wire and a piece of flat PET soda bottle.

Wire Up The UV LED

Where to cut the UV LED Strip

Take a length of 8mm LED UV strip light, and hold it up to the underside of the Stage Top. Cut off one segment long enough to ensure the LED therein will sit in the UV LED Trough in the centre of the Light Well.

Take each of the wires that will connect the UV LED to the CNC Controller and wind them closely 10 times around a small screwdriver shaft, leaving about 50mm of unwound excess at one end. Apply heat with flame or heat gun, and allow to cool for 30 second before slipping the wire off the shaft. They should maintain a coil. Using this coiled wire will place minimal force on the Stage when it moves.

Heating the coiled UV LED attachment wire

Finished coiled wire

Strip the short ends of the wires and solder them to the UV LED strip's positive and negative contact pads to complete the UV LED Wiring.

Make the Ground Probe Wire

Forming the Ground Probe Wire's loop

The words are tricky, suggest looking at the pictures above to see how easy it is, but here we go: Make an 8mm diameter loop in the end of a piece of bare solid copper wire at least 60mm long, with the live end going an extra half way around the loop. Place an M3 screw in the loop. Flatten the loop, and put the screw closest to the dead end. Twist the excess of the loop and the live end together. You should end up with a lump of twisted wire, a screw caught in a tight loop, and a long length of wire poking out. You can remove the screw.

Completed Ground Probe Wire

Tightly coil the wire four times around a former 1-2mm in diameter, and cut off the end leaving 5mm of straight wire. Solder a Dupont pin to the twisted segment. The Ground Probe Wire is complete.

Make the Ground Probe Spring

Finished Ground Probe Spring

Cut a flat strip of PET from a soda bottle approximately 9mm wide with scissors. Using a 3mm drill or awl (an awl is probably neater), put a hole in the centre of one end. Round off the two corners near the hole and trim the strip to 20mm long. Starting from the square corners, taper the edges by about 3mm. This plastic spring will press the Ground Probe Wire into contact with the workpiece when using the μRepRap in Z Touch mode as the copper wire is not very elastic.

Captive Nuts

Note: There is an upgrade for this section. Details here.

Table Frame captive nut locations

Insert four M3 nuts into the matching cavities on the two smaller Table Frames.

Flexure Table Assembly

Joining a Table Frame to an Outer Frame with two M3 x12 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 12mm screws and nuts, finger tight. Ensure the frames are square on. The protrusions on the Table Frame point in towards the centre of the Outer Frame. 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 12mm 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.

The underside of the Flexured Stage has several nut cavities in it. These nut cavities do not need normally to be populated as they are for attaching test articles to the stage.

Installed Ground Wire Probe

Locate the octagonal screw head cavity on the underside of the Stage Top that is furthest from the Wired UV LED Trough and insert an M3 x 12mm screw. Secure the screw firmly with an M3 washer and nut. Onto the protruding screw put the Ground Probe Wire (oriented with the free wire end pointing at the stage), the Ground Probe Spring, and a loosely-fastened M3 nut.

UV LED installed with a little hot glue

Install the Wired UV LED into the UV LED Trough so that the LED points into the centre of the Light Well. If it is a little loose, add a small quantity of adhesive but take care that nothing protrudes above the surface of the Stage Top or it will not sit level. It may be easiest to hold it in place with paper tape, apply the glue, and remove the tape.

The inverted, stacked Stage. Orange 4 hole Metriccano Strips used for clarity

Turn the Stage Top over and insert four M3 x 30mm screws into the centre two holes in each narrow end and stand it on the bench with the screw threads pointing up. Orient with the wires pointing towards you. We will now add the components with X and Y flexures on. These will both be placed with the X and Y legends facing down.

Place the Flexured Stage onto the screws with the flexure extending to the left.

Onto the back pair of screws stack a flat 4 hole Metriccano Strip and the Y Axis Flexure Block. On the front pair stack a flat 4 hole Metriccano Strip and a 4 hole Square Metriccano Strip.

Carefully manoeuvre this into the assembled frame and loosely screw it into the pairs of captive nuts. Ensure the Stage is square with the XY Flexure frame and tighten the screws.

The Stage Top has two rectangular cavities in it. Press a 30mm x 10mm x 3mm magnet into each cavity - remember not to stress the flexures. If they do not lock firmly in place, add a little hot melt adhesive. Do not leave any excess adhesive above the top surface of the part. Do not use a powerful adhesive such as epoxy as it may be necessary to remove the magnets for repairs or modifications.

The assembly process is now complete.

Testing

With the frame flat on the bench, place one hand on the two outer parts of the frame and hold them down. Move each of the tabs marked "X" and "Y" back and forth by 10mm. The stage should move without the long flexures kinking, and there should be no sound of contact between any parts of the flexures and framework.

Temporarily connect the UV LED to the output on the CNC Controller, and check that it can illuminate the LED.

The XY Flexure Stage is now ready to be integrated with the Axis Drivers.