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README.md

 # Roller Coaster Gantries
 
+ - kinematic mounts are three button head cap screws on 20mm grid w/ reciprocal / wherever-u-like mount ins 
+ - all axis have scroll-along top plate w/ connection to motor plate, final scroll kinematic triangle 
+ - all axis have scroll-along bottom beam plate w/ 20mm grid w/ last scroll kinematic triangles 
+
+## BOM
+
+### Hardware 
+
+Type | Size | QTY | Where Used | McMaster PN
+--- | --- | --- | --- | --- 
+SHCS | M3 | 2.5mm Hex | 91292A110 
+SHCS | M4 | 3mm Hex | 91292A116 
+SHCS | M5 | 4mm Hex | 91292A124 
+
+Type | Meaning
+--- | --- 
+SHCS | Socket Head Cap Screw: machine screws with hex heads in a 'socket' - i.e. the head is the socket, not the driver. 
+FHCS | Flat Head Cap Screw: similar to SHCS but have triangular heads, used when making fastener surfaces flush.
+BHCS | Button Head Cap Screw: rounded head socket heads !
+PLSTCF | Plastic Thread-Forming Screws: have triangular lobed threads and torx drive caps, wonderful in plastics as the beefy threads mean no inserts required. 
+
+
+``` OLD DOC: move this to /kunits/README.md and /kunits/images ```
+
 Scratch / Landing page for the roller-bearings and 2d-sheet-stock axis system.
 
 With RCT, we break axis into individual kinematic elements - and roll those elements into machine designs. 
@@ -71,6 +95,22 @@ This set assumes you're building with 3/8" HDPE or similar, Nema 23 Motors with
 ! to add here
  - hardware stackups, BOM, tuning note 
 
+## Notes for Jake
+
+ - RCT Mod
+  - tabs on rail supports still no bueno 
+  - std. order side-wall taps / wall-to-surface -
+  - of course the belt tensioning needs help ... fold-over or something ? glue it down? single track? 
+  - belt tender assy - 3dp walls, bearings to hold-down, m4 screws on to carriage at edges ?  
+  - motor rotational tensioning: pin one 
+
+  - and make tools for drill, tap 3dp 
+   - also drill / tap m6 / m4 verticals 
+   - m4.3 or similar nice for m4 thru on motor 
+
+
+  - order up tiny clampz 
+
 ## BOM
 
  - [N17 Bearings](https://www.amazon.com/5x11x4mm-Replacement-Precision-Bearings-MR115-2RSBU/dp/B00Y5W3JYS/)

kunits/README.md

+``` OLD DOC: move this to /kunits/README.md and /kunits/images ```
+
+Scratch / Landing page for the roller-bearings and 2d-sheet-stock axis system.
+
+With RCT, we break axis into individual kinematic elements - and roll those elements into machine designs. 
+
+![gantries](images/one-two-three.gif)
+
+A reasonable system for beginners, and easy to manufacture (with another CNC mill). Particularely, this system begets the [Madison Park Vocational Machine](https://gitlab.cba.mit.edu/jakeread/mpvm)
+
+![mill](images/mpvm-v03.jpg)
+
+## Building Axis and Machines from 'Kinematic Elements'
+
+Machines are made of degrees of freedom, and those degrees can be assembled from 'Kinematic Elements' i.e. here I have one Motor / Pulley Unit, as well as Lateral (into the gantry) and Cross (across the gantry) supports. I'm doing a mediocre job of explaining this, but here are some images:
+
+To scratch a machine together, I pull elements into Rhino as .step files, and lay them out into axis - here's one linear degree of freedom:
+
+![basically](images/kunits-basic.png)
+
+Then I assemble those axis together, keeping track of where I'll be adding plates of material:
+
+![units xz](images/kunits-before-form.png)
+
+Then I go about filling in detail design, adding tabs etc to bring beams and chassis together.
+
+![one](images/kunits-one.png)
+
+![two](images/kunits-two.png)
+
+![three](images/kunits-three.png)
+
+![four](images/kunits-four.png)
+
+## Fabricating Axis 
+
+I then mill these axis on our shopbot, or any CNC mill you like - the N17 size elements can likely be laser-cut with acrylic or similar (delrin would be nice, but is expensive and a bit toxic to cut, so goes the lore). 
+
+![cam](images/mpvm-rhino-cam.png)
+
+I do CAM in Fusion with a .step I export (after flat-packing) from Rhino.
+
+![mill](images/mill.jpg)
+
+## Assembling Axis
+
+I typically assemble machines one axis at a time. That's not saying much, but here's an image to get a sense of how the hardware goes together:
+
+![one](images/rct-one-rob.jpg)
+
+The 'adjustable' elements use a captured nut to pre-load bearings against gantries. TODO is better documentation of this, but here's an image of the flexure in simulation to get a sense for what I mean:
+
+![sim](images/preload-sim.png)
+
+# CAD for You
+
+### RCT Elements NEMA17 Size 
+
+CAD For these elements is available in the repo [cad/elements/rctElementsN17](cad/elements/rctElementsN17)
+
+This set assumes you're building with 1/4" HDPE or similar, Nema 17 Motors with GT2 Pulleys of 6mm width, and have access to a set of M3 Socket Head Hardware and 'MR115' or '5116' trade names or similar, 5x11x4mm. Lots of those.
+
+### RCT Elements for NEMA23 Size
+
+CAD For these elements is available in the repo [cad/elements/rctElementsN23](cad/elements/rctElementsN23)
+
+This set assumes you're building with 3/8" HDPE or similar, Nema 23 Motors with GT2 Pulleys of 9mm width, and have access to a set of M5 Socket Head Hardware and 'skate bearings' - 608ZZ or similar, 8x22x7mm. Lots of those.
+
+# Machines using RCT Gantries (v1)
+
+![mill](images/mpvm-v03.jpg)
+[Madison Park Vocational Machine](https://gitlab.cba.mit.edu/jakeread/mpvmachine)
+
+![smallgantry](images/smallgantries-fab.jpg)
+[Small Gantries Workshop Machine](https://gitlab.cba.mit.edu/jakeread/smallgantries)
\ No newline at end of file

cad/elements/rctElementsN17/RCT Elements 17 Belt Tension Static v8.step → kunits/cad/elements/rctElementsN17/RCT Elements 17 Belt Tension Static v8.step

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+'D:/Dropbox (Personal)/CBA/projects/machines/rctgantries/cad/elements/
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cad/elements/rctElementsN17/RCT Elements 17 Bushing v1.step → kunits/cad/elements/rctElementsN17/RCT Elements 17 Bushing v2.step

@@ -10,9 +10,9 @@ FILE_DESCRIPTION(
 
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