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This is a simple spindle for simple milling machines, that we can make with a 3D Printer and some off-the-shelf parts.
It uses a 'collet holder' (which can be found on ebay) with two simple roller bearings on either end. To drive the spindle, we use a hobby brushless motor and a GT2 Pulley.
At the moment, the CAD in this repo is for a spinldle that will easly mount to a faceplate of one ['rct' gantry](https://gitlab.cba.mit.edu/jakeread/rctgantries) but it can easily be remodeled to suit another machine.
## To Build
To put this thing together, get the parts listed below together, and a 3D Printer. Go to the ```cam``` folder in this repository, and download either the .step or .stl files (the .stl files do not include bits required for an encoder mount - but that's outside of the project scope for the time being).
Print the ```simplespindle-body.stl``` file, and if you can't source a 40T / 12mm Bore Collet Holder, also print ```gt2-40t-12mmbore.stl```. I print these things pretty much solid with infill.
I'm hoping assembly is straightforward: push the bearings into the obvious holes. They should press in with only a bit of force, if you need to use an arbor press that's OK, but **don't** hammer them in unless you like noisy machines. The collet holder should slide into the bearings without much resistance: just take care to line it up.
The belleville washers (disk springs) included in the BOM should be mounted between the collet-holder collet-holding end and the inner race of the bottom bearing. The 40T pulley w/ respective set-screws holds the collet holder into the bearing / body assembly - as you tighten those screws, try to compress those belleville washers. This way the bearings are a little bit preloaded, which helps them run smooth / for a long time / quitely. S/O to [Ilan Moyer](http://web.mit.edu/imoyer/www/index.html) for this tip.
From there, I zip-tie the ESC somewhere handy, and mount the BreadBoardBoard nearby. Here's what that looks like:
## Runout
I measured a runout at the collet holder of ~ 1 thousandths, and at the tip of a 1/8" tool around ~ 3 thousandths. That's OK for $150 in parts, and a plastic housing.
## Controlling the Spindle
This thing dreams of [atkbldcdrivers](https://gitlab.cba.mit.edu/jakeread/atkbldcdriver) but in the meantime, we use a [breadboard board](https://gitlab.cba.mit.edu/jakeread/atkbreadboardboard) to send a servo signal to an off-the-shelf ESC.
What | Spec | QTY | Where Used | Link
--- | --- | --- | --- | ---
ESC | 40A 6S | 1 | Driving Motor | [Hobbyking](https://hobbyking.com/en_us/yep-40a-2-6s-sbec-brushless-speed-controller.html)
Motor | 35-36 1800kV | 1 | Motor | [Hobbyking](https://hobbyking.com/en_us/propdrive-v2-3536a-1800kv-brushless-outrunner-motor.html)
Collet Set | ER16 | 1 | Tool Holding | [Amazon](https://www.amazon.com/Engraving-Machine-Milling-Beauty-Star/dp/B0749FW9D5)
Collet Holder | ER16x100L | 1 | Bedrock | [Amazon](https://www.amazon.com/a15060800ux0208-C12-ER11A-100L-Straight-Milling-Extension/dp/B012T6DQGM/) or [Ebay](https://www.ebay.com/itm/US-Stock-C12-ER16A-100L-Collet-Chuck-Holder-Straight-Shank-for-CNC-Milling/401225965058?hash=item5d6aee5e02:rk:5:pf:0)
Spindle Pulley | GT2 40T 12mm Bore | 1 | Transmission | [Amazon](https://www.amazon.com/Orish-Alumium-Timing-Pulley-Synchronous/dp/B01H94CLCY/)
Motor Pulley | GT2 20T 5mm Bore | 1 | Transmission | [Amazon](https://www.amazon.com/Qunqi-Aluminum-Timing-Pulley-Printer/dp/B01IMR6OR0/)
Timing Belt | GT2 10mm Wide 75T / 150mm Loop | 1 | Transmission | [Amazon](https://www.amazon.com/RobotDigg-150-2gt-6-Endless-Length-Synchronous/dp/B07B5YK7J9/) or [Robotdigg](https://www.robotdigg.com/category/28/GT2-Endless-Belt)
6001 Bearings | 12x28x8mm 2RS or ZZ | 2 | Spinning | [VXB](https://www.vxb.com/6001-2RS-Bearing-Deep-Groove-6001-2RS-p/6001-2rsbearing.htm)
Belleville Disc Springs | 12.3x21.8x0.75 | 2-4 | Preload | [McMaster](https://www.mcmaster.com/94065k42)
# V0.2
I'm working through an update to this, adding some CAD now. This time I'm going for [crowned pulleys](https://woodgears.ca/bandsaw/crowned_pulleys.html) using the back-side of a 100T GT2 closed-loop pulley. I've added some fancy / fun tapered-screw-shaft-pinching setups for the pulleys.
This is also going to hook up to the [hotplate](https://gitlab.cba.mit.edu/jakeread/hotplate)
## V0.2 TODO:
- assemble, check, rev
- BOM, drawing
- belt tensioning / tracking ok?
- bldc programming, power testing etc
- belt testing slip / at high speed?
- what is failure mode ?
## BOM V0.2
What | Spec | QTY | Where Used | Link
--- | --- | --- | --- | ---
FHCS M2.5x6 | 18-8 or Black Oxide | 3 | Encoder Manget Mount -> Motor | McMaster (?)
Timing Belt | GT2 6mm Wide 100T / 200mm Loop | 1 | Transmission V2 | [Amazon](https://www.amazon.com/BIQU-Printer-Timing-200-2GT-6-Closed/dp/B01FNT093A/)