You’re finally going to be putting your LongMill together! We hope that you’re excited to start making new and interesting things as this CNC router becomes yet another tool you can reach for on your tool-belt.
The LongMill Benchtop CNC is a machine design that we’re very proud of: a good balance between performance and affordability, simplicity and rigidity. As more LongMills continue to ship around the globe from our office, we’re always keen to hear customer feedback since it helps us to make our benchtop CNC even better. This is why after shipping over 2500 LongMills since it’s conception, we’ve still further introduced some small quality of life updates to the design of the LongMill; newly designated ‘Version 4b’.
Versions
Implementing these improvements batch-by-batch means that there are small variations in the assembly process depending on when you receive your LongMill:
- Version 1: shipped from October 2019 to March 2020
- Version 2: shipped from March 2020 to August 14th, 2020
- Version 3: shipped from August 14th, 2020 to January 11th, 2021
- Version 4: shipped from January 11th, 2021 to August 2nd, 2021
- Version 4b: current version*
*Version 4b has a slightly different set of hardware for assembly compared to previous versions. Kits that have this change will have a sticker on their hardware bag to indicate “Batch 5.” Revisions will be noted in the online and PDF assembly instructions as you put your machine together.
This section of the Resources will always have the assembly instructions for our most recent LongMill version, but a PDF form of both the current version and all previous versions can also be downloaded below if needed:
There is also an impromptu, follow-along, assembly video series available for the LongMill Version 2 that Chris put together if you’d prefer to assemble your machine while following along with a video rather than reading the instructions. The video series also works for Version 3. For Versions 4 and later, there will be minor changes that are not included in the videos, please refer to the PDF or online assembly instructions for clarification.
LongMill V2 Assembly Video Series
Tooling up
Here is a list of tools you should have on hand for assembly. Most people will have these tools in their shop:
- Metric Allen keys or a drill and Allen driver bits
- A small flat head screwdriver
- Rubber mallet (optional)
We designed the assembly instructions in a way that you unpack the machine as you go; this helps you to become more familiar with the parts that make up your LongMill. If at any point you’re having difficulty finding a part, you can always come back to this page or refer to the Appendices of the PDF manual to see the packing layout of your machine. If you are missing parts or need technical help, please contact us here: https://sienci.com/contact-us/technical-help/
Use the bottom buttons to navigate step-by-step or use the sidebar to quickly travel to a desired page. Remember to stay safe during assembly and while being around your machine so that you can enjoy it while getting the most out of it.
Packing Layouts
V1
The LongMill comes with a lot of parts, but we’ve organized them to make it as easy as possible to find and put everything together; each kit comes with several cartons. For the complete BOM, visit: https://docs.google.com/spreadsheets/d/1MqOwPg3VSUTMtn3ff6rXjfvliAWnFqg8ez2eZasJLCE/edit#gid=0
Top Carton #1
When you first open the top carton #1 it should look like this:

This box includes:
- A welcome page with safety guidelines on the back
- Some assorted stickers, including long ones for the LongMill and some with Louis on the machine, Andy’s dog and our unofficial mascot and CEO
- Parts for the dust shoe (if you ordered it) including two hardware bags (one for assembling the dust shoe and one for mounting it), a backing plate, and 2 aluminum extrusions.
- The touch plate in the yellow padded envelope (if you ordered it)
- The end mill add on pack (if you ordered your machine through Kickstarter)
- Aluminum router mount (in the size you requested)
- Hardware bag #1 which contains:
- M8-25 (x12)
- M8 hex nut (x12)
- M5-25 (x35)
- M5-12 (x5)
- M5 nylock nut (x35)
- M5 washer (x14)
- M4-16 (x10)
- M4 hex nut (x10)
- Hardware bag #2 which contains:
- V-wheel (x12)
- 608zz flange bearing (x8)
- Delrin block nut (x4)
- Pulleys and belts (x2)
- ACME locking nut with M3 set screw (x4)
- 1/4″ to 8mm coupler (x3)
- Hardware bag #3 which contains:
- M8-16 (x30)
- M8 washer (x4)
- M5-50 (x12)
- Aluminum standoff (x12)
- 1.25”, 1.5”, and 2” board screws (x10 each)
- Eccentric nut (x6)
- Three un-threaded motors (X & Y-axis) and one threaded motor (Z-axis)
- The power brick with its AC power cable inside a white cardboard box
- A bagged USB cable (type A to type B)
- The electronic control box protected by grey padded foam (the three orange components won’t be there for most machines)
Top Carton #2
When you open the top carton #2 it should look like this:

This box includes:
- The whole range of 3D printed parts, listed from left-to-right and top-to-bottom:
- Back feet pair
- Front feet pair
- Drag chain mount
- Shoulder brackets (x2)
- Middle feet (x3 for the 30×30 and x1 otherwise)
- Drag chain foot
- Z-axis mount
- XZ-gantry sub-assembly protected within a padded envelope
- Z motor plate, a piece of 1/8″ thick steel protected by paper wrapping
- Two Y-axis gantries, both pieces of 1/4″ thick steel protected by paper wrapping
Top Carton #3
If you ordered a Makita Router with your LongMill it can be found here, if not this box will remain empty to help keep top cartons #1 and #2 secure during shipping.

V2
The LongMill comes with a lot of parts, but we’ve organized them to make it as easy as possible to find and put everything together; each kit comes with several cartons. For the complete BOM, visit: https://docs.google.com/spreadsheets/d/1MqOwPg3VSUTMtn3ff6rXjfvliAWnFqg8ez2eZasJLCE/edit#gid=1012984008
Please note that the carton layout may vary. Carton #2 is a bubble mailer.

Top Carton #1
Our first carton comes with stickers and a welcome letter with links to resources and safety information. If you ordered your machine with end mills or other parts, you may find them in here.

Top Carton #2
Our second carton holds our steel gantries and XZ gantry assembly. Inside you will find the XZ gantry assembly and Y-axis gantries.


Top Carton #3
Our third carton holds several different items, including router mount and the LongMill’s controller. If you ordered your machine with any add-ons, such as the dust shoe, end mill add-on pack, or touch plate, you should find them here.


Top carton #4
Our fourth carton will hold your Makita router if you ordered one. If not, it will be empty.

NEMA 23 Motors
Under carton #1 and #2, you will find a box containing the motors and wires.

Bottom Carton #1
Working our way through to the bottom cartons, our first carton holds all of the rails, lead screws, and drag chains.


Bottom Carton #2
In Bottom Carton #2, you will find your power supply and AC cable, USB cable, Z-axis motor mount plate, as well as bags holding all the fasteners and smaller components for your LongMill.


Bottom carton #3
In our final carton, you will find all of your 3D printed parts.


V3
The LongMill comes with a lot of parts, but we’ve organized them to make it as easy as possible to find and put everything together; each kit comes with several cartons. For the complete BOM, visit: https://docs.google.com/spreadsheets/d/1MqOwPg3VSUTMtn3ff6rXjfvliAWnFqg8ez2eZasJLCE/edit#gid=1433071683

Top Carton #1
Our first carton comes with stickers and a welcome letter with links to resources and safety information. If you ordered your machine with end mills or other parts, you may find them in here.

Top Carton #2
Our second carton holds our steel gantries and XZ gantry assembly. Inside you will find the XZ gantry assembly and Y-axis gantries.

Top Carton #3
Our third carton holds several different items, including router mount and the LongMill’s controller. If you ordered your machine with any add-ons, such as the dust shoe, end mill add-on pack, or touch plate, you should find them here.


Top carton #4
Our fourth carton will hold your Makita router if you ordered one. If not, it will be empty.

NEMA 23 Motors
Under carton #1 and #2, you will find a box containing the motors and wires.

Bottom Carton #1
Working our way through to the bottom cartons, our first carton holds all of the rails, lead screws, and drag chains.


Bottom Carton #2
In Bottom Carton #2, you will find your power supply and AC cable, USB cable, Z-axis motor mount plate, as well as bags holding all the fasteners and smaller components for your LongMill.


Bottom carton #3
In our final carton, you will find all of your 3D printed parts.


V4
The LongMill comes with a lot of parts, but we’ve organized them to make it as easy as possible to find and put everything together; each kit comes with several cartons. For the complete BOM, visit: https://docs.google.com/spreadsheets/d/1MqOwPg3VSUTMtn3ff6rXjfvliAWnFqg8ez2eZasJLCE/edit#gid=1110761832

Our first carton comes with stickers and a welcome letter with links to resources and safety information. If you ordered your machine with end mills or other parts, you may find them in here.

Top Carton #2
Our second carton holds our steel gantries and XZ gantry assembly. Inside you will find the XZ gantry assembly and Y-axis gantries.

Top Carton #3
Our third carton holds several different items, including router mount and the LongMill’s controller. If you ordered your machine with any add-ons, such as the dust shoe, end mill add-on pack, or touch plate, you should find them here.


Top carton #4
Our fourth carton will hold your Makita router if you ordered one. If not, it will be empty.

NEMA 23 Motors
Under carton #1 and #2, you will find a box containing the motors and wires.

Bottom Carton #1
Working our way through to the bottom cartons, our first carton holds all of the rails, lead screws, and drag chains.


Bottom Carton #2
In Bottom Carton #2, you will find your power supply and AC cable, USB cable, Z-axis motor mount plate, as well as bags holding all the fasteners and smaller components for your LongMill.


Bottom carton #3
In our final carton, you will find all of your 3D printed parts as well as the galvanized steel brackets for mounting the drag chain and x-axis.

