Monday 6/11.23
Today we quickly explored the possibility that the vacuum pump was too weak. We redid the test with a more advanced vacuum pump.
This did, not surprisingly, result in better and tighter grip. We were thus able to reduce the O-ring size, which was a requirement for continuing the exploring.
However the force proved to be too much for the ham-slice. The slice quickly gave in to the force of the pump.
Considering that a prostate is approximately double the thickness and will be continuously cooled to -20 degrees, so it MAY work, but we have doubts. We await more testing till after prostate drilling.
Later that day we researched freezers, since the freezer at the lab is broken. We wanted to see if we could combine the need for a freezer now with the vision of a standing freezer for our machine after new years.
In preparation we made a box in mdf that would illustrate the size of our CNC-machine, so that we could easily test if it would fit.
We went down to Skousen because very few images online showed whether or not the shelfs were removable. We found out that they are not. No freezer of our required size had removable shelfs. Not at Skousen, not anywhere.
We discussed possible solutions with the person in the store and almost everything failed.
- Bend the cooling on the shelfs to remove the shelfs: No pipes bursts
- Remove the shelfs: No, gas leaks
- Modify a fridge to be colder: No, Too difficult
We ended at a possible solution:
- Modify a box-freezer. Cut out the front and place metal in the bottom to increase cold-capacity.
There is supposedly not cooling wires in the walls of the box freezer, but we are skeptical. Next time we are at Skousen, we ask to plug it in to see where the frost gathers. If we see no sign of cooling wires, we can go to Elkjøp and ask to get one of their broken freezers to cut to pieces and see how it is built.
Friday 10/11.23
Our plan for Friday will be turning on our machine and seeing how it functions at its current state. While it cools we will work on solving the problem of adding cool air to counteract the temperature increase when sucking out air.
We turned on the machine to have it start cooling itself while we worked on finishing the other parts of the machine.
We started the day with quickly crafting some aluminium plates for creating flat test-samples.
We then went on to calibrate the camera and craft a aluminium bed-lid while discussing how we wanted to cool the air going into the box.
While doing that we researched vacuums that were more compact than the one we currently use.
We found that our current vacuum has a volumetric flow of 4000 l/min as max, although we believe our flow to be less as the tube-volume is significantly less going out of the box, than into the vacuum.
This was the best handheld vacuum we could find that had a described volumetric flow.
We also found this which had a higher max power output (watt), but hadn't described its volumetric flow.
We concluded with leaving this be for the time being and focusing on just making this work using our current vacuum, as it had an output.
We will then work on implementing our design described link
Monday 30/10.23
Today both of us were busy doing other course work
Friday 3/11.23
We decided to test the O-ring using a handheld vacuum pump instead of the vacuum we used for our "air-hockey" bed. The reasoning behind using an O-ring was to create an air-tight seal and thus not needing to draw large continuous streams of air.
First we tried using it on the MDF plate (iteration 9) and this didn't work. We saw this was due to the fact that MDF is not air-tight. We fact-checked this by trying to vacuum grip a MEF plate without the silicon protection we have on our plate, and it wasn't able to maintain a pressure.
We then quickly crafted a makeshift bed out of metal, as metal is air-tight, and drilled a hole.
This was tested on many different materials and with many different size O-rings, and the conclusion was that we had to have quite a large O-ring for it to have any effect.
We then moved on to testing on our frozen ham slices and this did not give good results. On the smaller O-ring, the pump did not manage to grip at all. On the larger O-ring, which is already borderline too big, it managed to grip after pumping for quite some time, and the it deformed the slice, by dragging it down.
There are several reasons why it didn't work.
The O-ring could be of the wrong type.
The pump could be too weak.
Monday 23/10.23
Since last Friday's test had to be done without ham, we redid the test today, but this time with ham. We bought some ham from the store and froze it down while squeezed flat as this would make it most resemble the actual prostates.
We developed a new bed lid to test friction. The new bed with metal holes had a little bit more friction. While testing we also discovered a small air-leak between the old bed lid and the rest of the bed. This means that we should be able to grip a little bit harder with a completely air-tight setup. Solving this may be as easy as adding more magnets.
We also designed an adapter for attaching the vacuum to our tube.
The test
Starting the machine: The machine took 2 hours to reach -12°C
Attaching the computer: We had zero complications.
Starting the software: We had zero complications. No calibration had to be done.
Inserting the slice: The insertion of the slice was somewhat difficult, but we had no complications.
Cutting: The cutting went well. It was performed at ~-10°C. The slice was held perfectly still. There was however the problem of spooning, which we know is worse at higher degrees. We also suspect that the drill may have been a little bit dirty, which worsened the quality of the cut.
We then tried to pop out the sample, like you are supposed to do after drilling. This went medium well. A little bit more meat was torn off, so we need to decrease the remaining thickness(drill deeper)
Retrieving the slice: The retrieval of the slice went well. The plate was somewhat stuck, but with some patience it went well.
Conclusion:
The vacuum solution is strong enough to keep a frozen slice of meat fastened to the drill-bed.
Comments:
The vacuum pulled a lot of cold out of the freezer. During the procedure the temperature rose from -10°C to -3°C. We can solve this by simply pumping the air back into the freezer.
The spooning gathered around the cut, which reduced visibility, but had no impact on the quality of the cut.
By sending the video feed to our other pc we managed to get a better view of the drilling during the procedure.
Friday 28/10.23
Today we first had a meeting with our counselor and then with the ARTS team at St.Olavs.
In our first meeting we talked a little bit about our progress and the way forward. Getting answers to the questions we had after these first two months with work.
We concluded that we have approximately 4-5 weeks left until we need to start writing our project thesis.
Going forward we want to focus on improving the gripping method as that is the part of our POC that needs most work. Håvard had a good idea of using a single hole in our drill-bed and have it sealed with an o-ring.
The upside of this is that the seal between the ham and the vacuum would be tighter, thus increasing the gripping force. As no spooning can escape down into the vacuum, no filter solution would be needed. In addition there would be less leakage of cold air, removing the need for an active cooling method during drilling.
The downside of this is that the area covered by the o-ring would then be unavailable for drilling. However if this area is small enough, then if wont be that much of an obstruction.
Håvard also advised us to look at his master thesis to se how a master thesis is structured, so that we know more about how we should think when structuring our thesis.
We have also scheduled a meeting next week where we will get to learn about zotero, which will come in handy when writing our project thesis.
The feedback we got from our ARTS meeting was that they really liked what they saw, but would like to see it done on objects that have properties similar to that of a frozen prostate, only of worse quality. Thus testing the edge cases and further proving that it will work on real prostates.
Examples of this could be:
- freezing ham in a way that induces internal tension in the meat
- Buying a block of meat and cutting it ourselves, of getting people at MENY to cut uneven slices for us.
- Freezing ham on wiggly blocks, so that the surface becomes uneven.
Monday 16/10.23
After testing the 7th iteration vacuum gripper it was decided that it was risky. There was noticeably less suction with that tube. In addition the notch margin of 0.15 mm was too small.
The day was therefore spent testing what the margin should be and looking for better tubes.
We believe the last margin test failed due to the test-prints being to narrow. This time we instead printed the whole width. 6 variations were printed, ranging from 0.20mm to 0.45mm, with a 0.05mm interval. After testing these against our bed lid we found that 0.45mm would probably be the easiest to use while still not so loose that the seal is broken.
In addition we found a tube that was flexible enough that had an internal diameter of 11mm.
Next time our bed hopefully functions properly and we can assemble the whole machine and test it.
Friday 20/10.23
We realized today that we might have prioritized wring the last 2 weeks. A better way of testing the vacuum would have been creating a bed with the largest possible tube and trying to drill, and then reducing the tube size for practical reasons, while maintaining the gripping ability.
This would have been smarter because even though we now know how the different tube-diameters acts relative to each other, we don't know accurately how much force is created by the drill.
The drill and bed was assembled and the suction seems to work well enough for our purpose. Then we calibrated the drill to the achieve the correct drill height and and refined the workspace area, so that the drill wont accidentally cut into the metal frame.
Next we accessed the camera and calibrated it to the bed. It took several tries and small adjustments to make this accurate. Now we have created an alignment method described here.
To our surprise there were no frozen chicken slices in the fridge so we had to resort to testing with a chicken slice.
In the first test the vacuum gripping was not strong enough. It could be caused by several things; too little airflow, a too hard test-material, too low-friction bed-lid, or increased shear forces due to the crooked spindle.
We then hooked the vacuum tube to the lab-vacuum and it worked perfectly.
Monday 09/10.23
Today the newly printed beds were used to test how big diameter we need in order to have a high enough airflow through the bed. The test is elaborated here. The results showed promise and a need to test further with smaller diameters. This will be conducted later this week.
Friday 13/10.23
The print we put on on Monday was not to be found when we returned today. This was too bad as it forces us to delay the testing to Monday. Instead we spent the day preparing for the assembly of the complete prototype on Monday, as well as refining the design of the bed to better fit in the machine. We have also searched the Composite lab for tubes with internal diameters we know work in case Monday's test fails, so that we have a bigger chance of making a working prototype on Monday. We found one promising tube with internal diameter of 6mm, and external diameter of 9mm.
Last test we had to file the gap where the bed top would sit, because the margins were too small. These margins were tested today by 3dprinting and measuring, and correcting the cad if it is too tight or loose. After testing with 3 different prototypes we have concluded that a margin of 0.15 mm is good for a tight, but not too tight fit.
The latest design is being printed to next time. Then we will test if the suction is sufficient, and if it is we will assemble all the parts of the machine and test it.
Monday 02/10.23
Today, we worked on implementing a vacuum gripper on the CNC-machine. We made several small prototypes from lasercut MDF, and tried to find a good way to include a vacuum tube from one of the sides. We will continue to work on this on wednesday.
Wednesday 04/10.23
Today we worked on improving the vacuum attachment to the drill-bed. We did at last find a design we though would work well. We decided to combine the entire drill-bed design into one piece and 3D print it.
Friday 06/10.23
Our next task will be to find out where the tubing for the vacuum will go. One way is to drill through the bottom or preferably into the bottom and out the side. In addition we need to find a way to pump the same air back into the box as to not remove all the cold air from the box.
Before we drill and wire the tubing, we need to figure out how big of a tube we need. We have started manufacturing several beds with different vacuum-hole diameters, so that we can test it on monday. This will hopefully lead to us testing the complete setup at the end of next week.
Monday 25/09.23
Today we started developing the first vacuum gripper prototype.
We tested it both at TrollLabs and down at MR-lab
At the end of the day we had a meeting with the people responsible for the hyperspectral imaging part of the project
Friday 29/09.23
Today, we started with a scrum meeting. Participents were Peter, Øystein, Håvard & Eirik
We developed a quick version of the cam clamp holder, before taking it down to St. Olavs for testing together with the vacuum gripper made on monday. How the test went you can see here: Clamping test 1 (29.09.23).
We will now focus on getting a vacuum gripper on the CNC drill in the freezer. This will be the focus point on monday next week.
Monday 18/09.23
Today we worked out a way for the drill to start spinning before lowering itself onto the slice.
The solution was to include a tiny circle on the edge of the workboard. We will see how this solution holds as the project develops.
We also had a meeting with arts about the project and the plans going forward.
Friday 22/09.23
Scrum with whole lab
Reached the conclusion that we need to measure how much force is needed to hold down the slices.
We have decided to test out a vacuum method because we find it the most flexible solution.
It will not make drilling the sides of the slice a cross-contamination hazard, as many of the other solutions do.
We will use Monday to prototype and test this idea.
Monday 11/09.2023
After many weeks we have finally gotten the basics up and running.
- Three end-stops are attached; one per axis.
- Lightburn software is downloaded on 1 of 2 Laptops
- GRBL is calibrated and oriented
Our next step will be including the lowering and raising of the z-axis in the run-cycles.
Friday 15/09.2023
This week we had the TrollLABS Pecha Kucha along with pizza. Before that we cleaned and fixed stuff in TrollLABS that needed cleaning and fixing.
This week all members of TrollLABS met and got aquainted. Contact information was shared.