When: 2 July 2019
Members present: All
Update Meeting #3
We got interrupted ๐ … With compliments! The slides can be viewed here.
| Alexis |
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| Claudia |
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| Carissa |
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| Vanessa |
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Overall, we are confident that we have our MVP, and will be able to spend the next few weeks fine-tuning it. Dr Ho mentioned that one question which many will have for us would be viability of our product when it comes to printing patterns with different colours. We’re currently thinking of ways to overcome this issue and it would serve as a good enhancement to our current printer that can currently only print one colour at a time. A possible solution would be to first separate the object/picture to different parts, grouping them based on their colour. The files can then be saved at one go, and the files can be run consecutively one after the next, changing the colour of the yarn required for each run.
Dr Ho also said that he would like us to present the progress of our project to students from Mayflower Secondary School tomorrow! We’re very honoured and excited, we hope they will like our project (lol).
Product Design
To prepare for the presentation, Alexis prepared the following diagram to better show how all our different parts come together.
Afternoon Progress
The afternoon was mainly spent tinkering the Cura code that would automatically run at the start of every print.
Our current issue is the fragility of the needle. The moment it stays stuck in the styrofoam and is dragged along, the needle is broken. Just focusing on the start of the print job, there are two ways to mend this:
- Retract the needle before every print job. But this is proving difficult due to the nature of the motor used as a stepper rather than a servo motor. It’s difficult to programme.
- Have the entire Yarn Feeder and Main Body lifted upย before reaching the initial X, Y coordinates for the print job. Afterwards, the entire yarn feeder and main body moves down to the correct Z axis for the print job.
Although it is possible for us to manually retract the needle before starting the print job, by rotating the linear actuator, it is not user-friendly. Our product should be able to be easily accessible, so we decided to try option 2 instead.
Hard-forcing Software
And that resulted in a few hours of straight-up troubleshooting. This is the code we were trying to run:
[1] ; Ender 3 Custom Start G-code [2] G1 Z40 F3000 ; From where the Sewing Module (SM) is, move vertically upwards 40 mm [3] G28 X Y ; Re-home X & Y axes [4] G1 Z40 F3000 ; SM moves 40 mm vertically upwards [5] ; End of Custom Start G-code
The comments following ; in each line designate the start of comments that explain what that line encodes.
This all works out fine and dandy, except after the end of the custom start code, the SM moves directly along the X, Y and Z axes to jab into the first position (where it would normally print from had it still been an ordinary, non-SM, extruder piece). We couldn’t have this because during the Z movement, we risk the needle being inserted into the styrofoam too early, and hence breaking. Vanessa and Guo Yao was busy trying to figure out what went wrong but we were kind of stuck (while Tony was stuck assessing for the Update Meeting #3 of the afternoon batch).
After a long time spent tinkering with the above code, we decided to try this:
[1] ; Ender 3 Custom Start G-code [2] G1 Z40.0 F3000 ; From where SM is, move vertically upwards 40 mm to (x,y,40) [3] G28 X Y ; Re-home X & Y axes [4] G1 X70 Y70 Z40.0 F3000 ; SM moves to (70,70,40) [5] G1 Z0.5 ; SM moves to (70,70,0.5) [6] G92 X0 Y0 Z0 ; Sets the current position (70,70,0.5) as the new origin (0,0,0) [7] ; End of custom start G-code
The addition of line 6 causes the printer to think that the point at (70,70,0.5) is already the base layer, so it would not move any further down (otherwise, it would think it would be moving through the ‘ground’ layer). But this would mean that we would have to reset the printing area every time, for every design. This is even more troublesome and precision-sensitive than Option 1.
Back to Square One…?
Our final resolution: We managed to code the LA to move at an incredibly high speed, one that should be fast enough for the stabbing motion. If we can sufficiently slow down the X/Y movement, we can avoid needle breakage. We will continue using the unmodified Start Cura G-code.
(Oh well, there goes our efforts for the mid-afternoon ๐ป …)
We placed an order for a much faster stepper motor yesterday. It has better heat sinks, so it also won’t heat up as fast too. Here’s hoping it arrives asap!
Yarn Feeder Mk V
The current suggestion is to have the base be made of clear acrylic, so we can see what is being embroidered. This means that our yarn feeder would now be split into 3 different parts: The backing, the acrylic base, and the needle/yarn Y-tubes.
Fusion360 model of the new backing piece of the Yarn Feeder Mk V.