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## 2021 02 03
NEXT REV: you've mounted the hotend static, and the motor floating post-loadcell. However, loadcell deflection is really minimal, and you could fix the motor / mount the hotend on loadcells. This would let you touch-probe the bed w/ the nozzle itself, for zero calibration etc.
## 2021 02 27
I have this together and, though some network struggles still exist, am able to capture data from the hotend.
This was calibrated with 50g -> 1kg, in 50g increments, but I think there is some hysteresis as there is a PTFE tube in the filament load path...
I've gathered [two](2021-02-26_extruderTestData_1.json) [datasets](2021-02-26_extruderTestData_2.json), running filament at 100, 200, 300, and 400 mm / min. The datasets are time-series and include extruder feedrate (in mm/sec), loadcell readings (in netwons) and temperature readings. The time steps / readings should be synced to about ~ 2ms.


## 2021 01 24
This part works, new toolchanger feels good also.



## 2020 12 27
Revisioning this to bring it up to speed with toolchanger deltas, also found a new loadcell to suit the smaller toolchanger design, that's UXCell PN `a15110200ux0247`.
So I've to revision to tighten this up, but it should be pretty straightforward. I think I do this, then fab it all, and can bring loadcell probes in to the mix once I have two of these swapping pretty well... would love to have i.e. an 0.8mm infill tool and 0.4mm perimeter tool.
- adjustment for smaller loadcell,
- adjustment to hotend pinching clamshell
- rm interference between hotend / bowden top and loadcell
- more-better planar constraint on hotend / coolside / front-of-hotend clamshell
Great, this is done, so I'll fab and then bring heaters & loadcells online.

## 2020 12 10
Assembled one of these, have some hardware bugs but will continue to bring this online instead of revisioning:
- could use a third thru-bolt to get the planar constraint w/ the second half of the hotend-pinching clamshell
- loadcell to bowden connector does not clear (visible in CAD: move out or move up)
- m4 head-thru on top of loadcell on hotend not wide enough
- more pusher-part (extruder / top half) clearance to plate, notice misalignment / out of squareness at loadcell mount
## 2020 12 06
Did a bunch of development for this thing offline.

It's E3D hotend compatible, I'm using a Dragon hotend. Has a loadcell inline to measure extrusion force, hotend fan but no part cooling fan yet, etc.