Commit 2df6ef1d authored by Jake Read's avatar Jake Read

upd8

parent 9543f58c
**.3dmbak
**.rhl
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......@@ -5,12 +5,15 @@
Here I'm using some
- Ballscrews, SFU2005 C7 700mm Long [ebay, $150](https://www.ebay.com/itm/SFU2005-Rolled-Ballscrew-C7-Anti-Backlash-Ballnut-L300-350-400-450-500-600-1000/202274175696?hash=item2f187afad0:m:m2SEqt9q_ykYYkrO5ZM9deA:rk:1:pf:0)
- Nema 23 Motors w/ .25" Shaft
- - x -
- GT2 5mm 12mm Bore Pulley 28T for 15mm Belt 'A 6A55M028DF1512'
- GT2 5mm 12mm Bore Pulley 38T for 15mm Belt 'A 6A55M038NF1512'
- *pick* GT2 5mm 12mm Bore Pulley 48T for 15mm Belt 'A 6A55M048NF1512'
- GT2 5mm 6.35mm Bore Pulley 12T for 15mm Belt 'A 6A55-012DF1508'
- *pick* GT2 5mm 15mm Belt with 55T 'A 6A55M055NF1512'
- GT2 5mm 12mm Bore Pulley 48T for 15mm Belt 'A 6A55M048NF1512'
- GT2 5mm 15mm Belt with 55T 'A 6R55M055150'
- http://shop.sdp-si.com/catalog/product/?id=A_6R55M055150 55T 15mm Closed GT2 Belt
- http://shop.sdp-si.com/catalog/product/?id=A_6A55-012DF1508 12T 0.25" bore Pulley 15mm
- http://shop.sdp-si.com/catalog/product/?id=A_6A55M048NF1512 48T 12mm Bore
- http://shop.sdp-si.com/catalog/product/?id=A_6A55M044NF1512 44T
- http://shop.sdp-si.com/catalog/product/?id=A_6A55M050NF1512 50T
![img](images/uSSM-detail-two.png)
......@@ -18,10 +21,42 @@ End of the line here is (1) to do small-scale material testing, OK. Next step is
I would like to know:
- evaluation: pick: Stiffness and Tensile Strength? some weighted score from both?
- ... no hard yesses, want to be able to pick & make
- so far doing tensile strength and elastic modulus
- to add: poisson ratio with vision and actuation
- inputs: if we are to pick, say, 3 process parameters (to have 3D search space), what are they?
- water, glycerin, agar
- humidity and temperature / during drying time
- heating profile ... how long the cook is
## FEA
I ran a quick simulation to see that this flexure was OK. Here it is loaded in the direction it is meant to be stiff in, with 2.5kN applied vertically. There are two of these members being tested so this would be equivalent to 5kN of force, about where I expect this thing to top out. Displacing about 40uM (I'm looking at the face-to-face distance between the loaded zone and the fixed zone, not that rotation that appears from my non-rigorous fea constraints) with 70MPa stress maximum.
![fea](images/uSSM-v15-beamfea-5kn.png)
![fea](images/uSSM-v15-beamfea-5kn-faceon.png)
And out of plane, with 250N applied, about 20uM displacement. So 1/10th the load and 1/2 of the displacement, it's at least 5x stiffer in one DOF than the other. Is that grounds for a decent flexure?
![fea](images/uSSM-v15-beamfea-500n.png)
![fea](images/uSSM-v15-beamfea-500n-faceon.png)
## The Cutting
0.1mm offset, 0.5mm fillet for test.
## Next Steps
design tasks remaining
- fixturing
- dbner ... in gh
- minor offsets for fits
- measure material carefully
- confirm sdp-si parts fitments
- control box ? psu home ?
- fab this thing
- finish waking up new network, new stepper boards / code
- finish hello-world CV on markers
......@@ -43,9 +78,7 @@ I used [automatakit](https://gitlab.cba.mit.edu/jakeread/automatakit) network co
![gif](video/first-pull.mp4)
Probably the most interesting point is that Sam and I have decided to try using a webcam and some computer vision to track the position of the specimen's endpoints. He's done some prior work, [here](https://gitlab.cba.mit.edu/calischs/subpixel_tracking).
![transform](video/ussm-from-mm-enc.mp4)
We're going to try to track the endpoints with CV, rather than fancy encoders etc. Sam has done some prior work on this, [here](https://gitlab.cba.mit.edu/calischs/subpixel_tracking).
# Microphone Stiffness Testing
......
Jake
JARVIS-THINKPAD
Thursday, January 24, 2019
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