Finding a freezer

Writing about what to look for in a freezer.

When we were looking for a freezer, there were three main requirements it had to meet.

Firstly, it had to be big enough for us to be able to fit a CNC and our other hardware into, but not so big that it would be unpractical to have stationed at a lab. Utdyp 

Secondly, the freezer had to be modular. To ensure a maximized use of space, the freezer could not have cooling rods in-between the different freezer drawers. This would make it impossible to find a big enough CNC. Vis med bilder 

Thirdly, the freezer had to be able to reach low temperatures. Since freezers are made for storing food, not drilling prostates, they usually did not go below -18*C. However, more modern freezers often come with a super cooling function, meant for cooling the freezer more than usual after if had been opened, to help protect the food. This can often take them down to -30*C. Vis 

Finding a CNC

Writing about what to look for in a CNC.

When we were looking for a CNC we had several requirements it had to meet. 

Firstly, it had to be big enough, but not too big. Milling prostate slices would require a minimum bed size of approximately ... mm X ... mm. But the CNC also has to fit inside the freezer. Here you have two options. Measure the size of your freezer and order a CNC that fits within the specifications, or buy a CNC that is modifiable and can be cut down to fit in the freezer. Utdyp om hva som gjør at den kan bli kuttet ned 

Secondly, since the components are to be operating in a -30*C environment, it is important that they can withstand it. How can this be checked/What components are most important to check 

Modifying the CNC

Writing about what changes must be made for the CNC to be compatible with the freezer.

The CNC needed some modifying in order to fit into the freezer, and to mill in the way we want it to mill.

The first thing we did was cut the profiles and leadscrews so that the CNC would fit together.

Since the axes came pre-built with stepper motors and end-plates, we first had to dismantle it. To ensure that the right motors would be assembled with the right profiles, all pieces were marked with tape. Every piece from the first y-axis was marked with white tape, every piece from the second y-axis was marked with white tape, and every piece from the x-axis was marked with blue tape.

We measured the freezer and found that the freezer was ... cm wide and ... cm deep. We then measured up that distance on the x-axes, starting from the end of the stepper motors. We added an extra 0,5 cm for the end plate and and extra 0,5 as a safety margin.

We marked the distance with several rulers, and a square tool, and the areas to be removed were marked with tape. For the Y-axis profiles, the part where the steppermotor was mounted was kept, whereas the other end of the profile was removed.

We then measured how much material was to be removed from each of the profiles and marked the same length of material on the leadscrews. 

The components were then sent to the workshop to be cut. The profiles were cut with a ... (Kappsag?) and the leadscrews were cut with a (vinkelsliper?).

Next the newly cut edges on the leadscrews and profiles had to be made similar to their other ends.

 - The leadscrews were rounded using a drill and a (Båndsliper).

 - The profiles were filed using had files

 - New holes were tapped in the profiles using M5x0.8 tapping tools.

The y-profiles were then reassembled with their end-plates and stepper motors.

Next the x- axis was attached to the y axes and its stepper motor too.

After all the axes had been connected, the CNC was placed inside the freezer to double check if it would fit.

• New Base-plate
  • Use Baseplate.dxf file to create component. The baseplate used made for this CNC was made using a platecutter and an 5mm aluminium plate. After the plate was cut, the 4 mounting holes showed in the DXF-file was drilled out using a pillar drilling machine, and a 5mm drillbit. Lastly, the rough edges around the hole was removed using a 6.3mm countersink bit.
  • The plate was mounted to the CNC machine using soe existing threaded holes in the bottom of the y-axis beams. They were mounted through the rubber feet that came with the CNC kit, and four M5x25mm bolts were used. 

After the axes had been assembled, some components from the original design needed replacing. The original design contained a base plate and a frame to stiffen the machine. The designs of these components were slightly changed to better fit our purpose.

The first component to be made was the base plate.

This component can be created by downloading the "Baseplate.dxf" file. This file contains the nescessary measurements for the design. It can therefore be made in MDF using a lasercutter, and used as a drilling guide. The core material is a 5mm thick aluminium plate, which was cut to size using a platecutter. However, a thickness of 3 or 4 mm should also do the job. Next, drill out the 4 holes in the aluminium plate and a pilar drilling rig. (The holes are cut 10mm from each side, and 30 & 40mm from the top/bottom edge). This is shown in the picture below.

To mount the baseplate to the CNC, 4 M5x__mm bolts were used. As the rubber legs are made for M4-bolts, the hole in them needs to be widened. This was done using a handheld drill and a 5mm drillbit. Carefully remove the required material. Then, thread the M5-bolts through the rubber feet, and screw them into the existing threaded holes at the bottom of the frame. When completed, it should look like the picture below:

Building the CNC

Writing about how the instructions were followed to assemble the CNC.

Download and create the clamping attachment. This will be the backbone of the CNC movement. It can be machined or 3D printed.

Image of the attachment (perhaps as a CAD)? 

The clamping attachment can be fastened to the x-axis using 4*M5x15 screws.

Next, attach the end stops.

y-axis end-stop:

Attach the two y-axis end-stop on the same side of the CNC as the x-axis stepper motor.

The rear end-stop is fastened with 1*M5x10 screw in the center of the profile at the back of the CNC.

This profile will have to be tapped.

The front end-stop is fastened using the same 1*M5x10 screw, but is mounted using a T-slot, not a screw hole.

The front end-stop is mounted ... mm away from the rear edge of the CNC. The easiest way to accurately place your end-stop is to slowly run the bed x-axis towards the mill, and then stop it at ... mm, then fasten the end-stop flush against the y-axis plate.

x-axis end-stop:

The end-stop is screwed into the clamping attachment from the back using 2*M4x10 Screws.

Two bracked are fastened on the udnerside of the x-axis to provide the counterpart to the endstop.

Use 1*x-axis endstop bracket, 1*M4x5 screw, 1*T-slot per end-stop bracket.

The brackets are to be fastened ... mm away from the y-axis plates.

When you are done, it should look like this:

Since we have modified the size and how the CNC functions, the optimal routing of wires will be different.
The first step is therefore to remove the wire-guide and wire-socks.
The wire-guides easily click open at every limb.
The wire-socks will have to be cut open.

Start by opening all the wire-guide clips.

Once all wire clips are open on the first half of the wire, the guide can easliy be removed.

The second wire-guide comes with attachments that are difficult to remove and cannot be opened.

One of the attachments can be disconnected, the rest is best to simply let be, and thread the wire through the gaps to free it from the guide.

You are then left with the guides and one attachment, and semi-loose wires.

The next step is to cut open the wire-socks. We recommend scissors.

You are then left with a loose bundle of wires.

Next the wires can be connected to their respective motors/end-stops. Each wire is marked to simplify the process.

The clamping mechanism

Writing about how to produce and attach the clamping mechanism

The clamping mechanism design can be found in the file: ...

The clamping mechanism is designed in such a way that is it easy to sterilize between procedures and therefore comes in several components.

Start by assembling the clamping mechanism

When the mechanism is assembled, connect it to the clamping attachment using ....

The z-axis

Writing about how to produce and attach the z-axis with the spindle

Here we will begin writing...

The Z-axis part of the CNC, containing the spindle motor, will have it's own frame and setup. The development process of this is described here.

 The frame of the Z-axis is made from leftover material from the downsizing of the CNC, as well as beams meant for use in the frame. This was done so that as much material and parts as possible comes from the CNC building kit.

The main beam was cut from what remained of the X-axis beam from the downsizing process. It was then cut to a length of 242mm using a kappsag. After that, the holes on the edges were threaded with an M5x0.80mm threading tool. The rough edges from the cut was also lightly filed to remove the sharpest edges.

Bilde

The next part of the frame is the legs. This was made from the bottom crossbeam 1 in the CNC building kit. To make them sequal in apperance, they were cut from each end of the crossbeam. They were cut to a length of L=154mm using the Kappsag. Next, the rough edges from the cut was filed down. The next part was to drill holes for the mounting screws. 4 holes were drilled out in each beam, at the center of each slots: 10mm and 70mm from the top of each leg. See the picture below. The drillbit used was Ø5mm thick. 

With the holes drilled out, the legs were connected to the main beam using 8 M5x30mm bolts. The picture below shows this assembly.

The Next part is to assemble the spindle to the Z-axis assembly. For this, follow the guide in the instruction manual page 23. When finished, it should look like this:

Bilde

After this, it is time to mount the Z-axis assembly to the main beam. This can be done in several ways, including T-slots and brackets, as well as using the predrilled holes in the Z-axis assembly. This last option was the one we went for. As the holes needed for connecting the is slightly off-centre and therefore difficult to accurately drill, a drilling guide was made. This can be found as "Z-axis backplate-dxf". This was lasercut using 6mm mdf, before being mounted to the beam as shown below. To make the backplate easier to mount, one leg was removed. Make sure that the 4 parallell holes are mounted to the lower part of the beam. It also needs to be mounted perfectly in the centre for each edge. To calculate the distance from the edge, the following fomrula was used: (L_beam - W_backplate)/2 = (242mm-90mm)/2 = 76 mm. This ensures that the holes will be drilled into the beam so that the Z-axis assembly is mounted in the centre of the beam. The holes are then drilled using a 5mm drillbit and a pilar drill setup. 

After drilling the holes, the backplate can be removed, and the leg mounted back onto the beam. Then, the Z-axis assembly can be mounted to the beam using 4 M5x60mm bolts with discs and locktite nuts. To do this, unscrew the leadscrew from the Z-stepper motor, and slide the spindle all the way down to reveal the higher mounting holes. Push two bolts through, and use a "8mm fastnøkkel" and "skralle" to properly tighten the bolts. Then, turn the leadscrew so that the spindle is all the way to the top, and re-attach the leadscrew to the steppermotor. Then, the two bottom mounting holes should be visible. Repeat the same operation as for the top mounting holes. The z-axis should now be attached to the beam properly and in the centre.

Lastly, the whole beam and Z-axis assembly is ready to be mounted to the CNC. This is done with 8 T-slots and 4 brackets, as well as 8 M4x6mm bolts. Mount two brackets to the bottom of each leg as shown in the picture below. Then, place the whole assembly onto the CNC as shown in the other picture (all the way at the front of the CNC), make sure everything is leveled and flush, before properly tightening every bolt. The z-axis should now successfully be mounted to the CNC.

The camera

Writing about how to produce the mount and attach the camera

The camera will be attached on the left side, above the x and y axis. This will maximize the how much of the bed we will see. It will be attached to the z axis frame, pointing first to the left, and then another beam pointing backwards (Like an L).

The camera is mounted ... 

The camera mount design file can be found...

Cable management

Writing about how to produce and attach the z-axis with the spindle

As each stepper motor and end-stop, as well as the spindle motor has it's own set of wires, there is a need for a good cable management.

For the Y-axis stepper motor, as well as the rear Y-axis endstop, the cables will be run through the lower frame of the CNC. This requires some minor modifications to the Backbeam. 

Start with disconnecting the stepper motor wires from the motors, as well as unscrewing the endstop from the backbeam. On the backbeam, mark where the slots from the y-profiles meets the backbeam with a marking tool, as well as where the edge of the stepper motor plate meets the backbeam. This will be the area which will be removed to make place for the cables. Then unscrew the 4 bolts holding the backbeam in place. Remove the backbeam from the CNC.

Then, using a dremmel with a cutting disc, cut out a large enough area inside the markings with the dremmel, as shown in the picture below. When the cutting is done, make sue to thoroughly clean the beam to remove all aluminium particles.  Also, use a file or a sanding tool from the dremmel to remove the sharp edges left behind from the cut.

The next step is to mount the Backbeam back onto the CNC. When mounted, also mount the endstop where it belongs. Then, the cables needs to be organised inside the slots. The two cables from the stepper motors should go into the slots closest to the middle of the CNC. The endstop cable should go to the other slots. This is because the bolts mounting the Bottomplate to the CNC needs to be bolted into the threaded holes in the outer slot. The endstop cable is small and flexible enough to go around the bolt, whereas the stepper motor cables take up the whole slot. Make sure that no cable goes out from the slot, or is in danger of being clamped between the frame and the bottom plate.

The next step is to remount the bottom plate. Make sure that the cables are not sqeezed between the frame and bottom plate, and that the Bottom plate sits flush with the frame.  When the bottomplate is mounted, the wires can be reconnected to the motors and the endstop.

The Lightburn tutorial

Writing about how to boot and connect with Lightburn

Setting up Lightburn

Start by connecting your computer to the CNC by using the cable.

When you first open the program, it will display as shown in this image:

To add the machine to Lightburn, start by pressing "Devices":

Next press "Find my Laser" to let the computer automatically detect what you have connected to your computer.

Once it is done scanning it should display a GRBL. Select it and choose "Add Device".

Name the device after your choosing and select axes of length (X=100mm, Y=100mm) and press "Next"

Next select "Rear Right" as the origin of your laser, and turn off "Auto home your laser on startup".
Click Next.

Your CNC is now added to Lightburn and the front page should look like this.
Next the CNC device has to be calibrated against Lightburn so that the machine will run effectively and safely.

Calibrating Lightburn

Lightburn comes with several settings that can be modified for our benefit.

Included below is the Lightburn settings pdf, which provides the default value of each setting and a description of what the setting controls.

GRBL_Settings_Pocket_Guide_Rev_B.pdf