Add direct drive mod for 2.1/2.2 (#51)

* Direct drive mod for 2.1 and 2.2.

* Add example image to direct drive mod readme.md

* Add assembly instructions to direct drive mod readme.md

* Fix m2.5-m2 assembly instructions bug in direct drive mod readme.md

* Add v6 direct drive mount.

E3d v6 is reported to be 1.1mm taller than the mosquito all mounted up.
This change should retain the nozzle elevation to help keep inductive
  probes working if someone mounts a v6 to the BMG mount plate.

* direct drive model improvements

* make room for extra belt
* add 0.32mm seats for back side nuts
* Fix support arm model bug in v6
* drop the fan nozzle outlet as low as I dare

* add known issue

* Add 2.2 openbuilds chain mod

* added example render image to 2.2 openbuilds drag chain mod

* add taller x carriage mount for drag chain mod

* update openbuilds xy bridge

* pull back cable chain mount 3mm +x
* modify tube profile
  * add 1mm mouth height
  * add 1mm span width to curves

mods/README.md

@@ -328,9 +328,15 @@ Also covers the Z-belt hole for improved aesthetics.
 
 ## warriorofwire
 
-[Openbuilds Drag Chain](../mods/warriorofwire/openbuilds_drag_chain)
+Openbuilds Drag Chain
 
-- Collection of models for using an off-the-shelf, cheap, snap opening drag chain for gantry wiring and protecting wires down to the deck.
+- Off-the-shelf, cheap, snap opening drag chain for gantry wiring and protecting wires down to the deck.
+  - [2.2 printers](../mods/warriorofwire/openbuilds_drag_chain_2.2)
+  - [2.1 printers](../mods/warriorofwire/openbuilds_drag_chain_2.1)
+
+[Direct Drive BMG-m mount](../mods/warriorofwire/bmg_direct_drive)
+
+- Bondtech BMG-m and Mosquito direct drive combo.  Partial support for e3d v6.
 
 ## wile.e.coyote  
 

mods/warriorofwire/bmg_direct_drive/README.md

@@ -0,0 +1,49 @@
+# Direct Drive Mount for BMG-M on 2.1 and 2.2
+![example image](https://user-images.githubusercontent.com/3454741/67543958-79ce1b80-f6a8-11e9-998e-90cd94887999.png)
+
+Note:
+* Tested with 300mm 2.1 build only.
+* 1.6 looks plausible too, ymmv.
+
+## Why
+* Direct drive is easy to print with.
+* It looks sick.
+* I couldn't get my bowden extruder to bridge well.  Pressure advance only gets you so far.
+
+## BOM
+* 5x m3x8 Socket head screws
+* 1x m3x6 Socket head screw
+* 2x m2x 6-10 socket head screw
+* 4x m3 nuts
+* [Bondtech BMG-m](https://www.bondtech.se/en/product/bmg-m-extruder/)
+* [Bondtech BMG mount plate](https://www.bondtech.se/en/product/bmg-alu-mount/)
+* [OMC 20mm pancake stepper](https://www.omc-stepperonline.com/nema-17-stepper-motor/nema-17-bipolare-1-8deg-13ncm-18-4oz-in-1a-3-5v-42x42x20mm-4-fili.html) but use it at like 0.6 amps instead.
+* [Slice Mosquito](https://www.sliceengineering.com/collections/hotends/products/the-mosquito-hotend%E2%84%A2)
+* Slice fan.  Use their fan or you're way on your own!
+* Same neat little 40mm blower from the Voron BOM.
+
+
+## STLs
+File | Note
+---- | ----
+gumby_mount_mosquito.stl | Print solid.  No supports.  Print the v6 one if you're of the e3d persuasion.
+fan_mount.stl | Print with vent face down.  No supports.
+
+## Assembly
+1. Hold the ALU plate to the plastic plate, mark your spot where the left carriage bolt head will be and drill your ALU plate.  Should be about 6mm diameter.  Size here is not critical, it just needs to clear your socket head bolt.  A stepped drill bit is awesome for this.
+2. Bolt the ALU plate to the gumby_mount.  Your m3x6 goes on the bottom left hole.  That location has to be flush with the back or it interferes with the carriage.
+3. If you have an M3 tap, tap the bottom holes on your hotend fan.
+4. Bolt the plate to your carriage.  Sorry, the m3 nuts don't stay put very well and the space is too small for your fingers.
+5. In whatever order you like, bolt the BMG-m to the stepper through the ALU plate, bolt the Mosquito to the BMG-m, bolt the hotend fan to the Mosquito under the BMG-m.
+6. Bolt the fan_mount to the hotend fan. (m3x8)  Yo dawg I heard you liked fans...
+7. Bolt the 40mm blower to the fan_mount. (m2's)
+8. Wire to taste.
+9. Set esteps to 415 per Bondtech, reset the X/Y location of your touch probe.
+10. Print!
+
+## Known Issues
+* No doors.  They add weight and aid nothing.  You're on your own if you want them!
+* This will offset your nozzle 15.4mm to the left.  You can move your bed over.
+* Putting it together is a nuisance.
+* You have to drill a hole in your Bondtech aluminum plate for the left Voron mount screw.  Just do it; it's only aluminum.
+* It's DD so the tool head is a little heavier than the stock bowden.  The mass is distributed differently, so it's not a straightforward comparison but generally you'll want somewhat lower acceleration & jerk settings.  You can still print at high speeds but you need to consider mass direction changes.

mods/warriorofwire/openbuilds_drag_chain_2.2/README.md

@@ -0,0 +1,29 @@
+# Off The Shelf Drag Chains for 2.2
+Note: Printed but untested.  If you try this, tell me what worked and what didn't on Discord.  I'll use it soon enough.
+
+![Render because I do not have a 2.2 yet](https://user-images.githubusercontent.com/3454741/68000301-c66fa480-fc1c-11e9-9096-63312416205e.png)
+
+## Why
+* Drag chains with a snap open side are a joy to work on.
+* It looks awesome.
+* I hate printing chains for myself and these are _cheap_.
+
+## BOM
+* Some M3 screws
+* Some M3 nuts
+* A few M5 screws that are a couple millimeters longer than the M5's on the gantry.  You'll figure it out.
+* [3x Openbuilds 10x15mm 18mm radius Drag Chains](https://openbuildspartstore.com/drag-chain-cable-carrier/)
+
+## STLs
+File | Note
+---- | ----
+x_carriage_mount | You screw your drag chain's floppy end to this side.
+xy_bridge | You screw your drag chain's floppy end to this side.  Wires go through it and up into the Y chain.
+a_corner_tube | Keeps your wires from touching the rail, frame, side covers and belt.
+upper_z_mount | You screw your drag chain's floppy end to this side.  This holds a_corner_tube
+lower_z_mount | Mounts to the rear lower frame.  You'll need to cut an L shaped slot into your bottom panel.  Also a great spot to run your bed and heater wires down through.  Move this on the rail until you get a little tension on your Z chain.  That'll keep it tight and it will look awesome.
+
+Orient the models for supportless printing.
+
+## Known Issues
+* your issues here.