CNC Machine (2020 onwards)
Problem: ask me about it.
Solution: this project, consisting of the following parts:
1. Cyclone dust collector
Parts Overview
Can you tell that the dust collector will be antistatic and fire-proof? The milk can has a volume of approximately 35 liter. I expect it to accomodate at least 20 liter of dust before having to empty it.
Adapter between collecting tray and cycloneDecember 14, 2020
The cover is a simple disc that covers the milk can and holds the cyclone. The emergency valve is a passive mechanical construction. It consists of a wooden plate that is held in place by a spring during normal operation. In the event of interrupted air intake, a vacuum may form inside the tray (aka milk can). The plate is then pulled inwards to let air flow through the holes and into the tray.
Preliminary assembly, screws still missing:
Final assembly and testDecember 24, 2020
What can I say... it works like a charm. The transparent tube has a diameter of 50mm and is antistatic. The red sponge rubber on the bottom of the lid seals the vacuum fairly well.
I tuned the emergency valve such that it opens shortly after the intake is blocked. The threshold is set by the force of the spring that holds the emergency valve and can be adjusted by turning the screw nut, cf. pictures on December 14, 2020.
For a first test of operation, I emptied the vacuum cleaner bag onto the floor and cleaned the mess up using the cyclone dust collector. As you can see, the wood chips and dust end up in the milk can as expected.
The dust collector has its place next to the table that is dedicated to the CNC machine. The transparent tube will be hooked up to the machine head. The original gray tube with a diameter of 35mm is available for miscellaneous cleaning around the workshop.
2. WorkBee CNC machine kit by Ooznest
Parts OverviewNovember 20, 2020 & January 7, 2021
St. Nicholas came early this year: Ooznest delivered the WorkBee CNC machine kit two weeks early, staying ahead of Brexit. In the background: the Makita router that will serve as milling spindle.
Ooznest provides an online knowledge base with extensive documentation for assembly and operation of the CNC machine at https://learn.ooznest.co.uk/. You may download the latest resources as pdf to print them for ease of reading.
Meanwhile, the boxes abound with parts. Everything is well sorted. This is a picture of the contents of the brackets and spacers box.
Mechanical Assembly: 1. WheelsJanuary 7, 2021
The instructions for the assembly are well-thought-out and contain just enough details to make them easy to follow. Clear and professional illustrations give further guidance. The pictures were taken before and after the first step of assembling 30 wheels. If anything, one could ask for a dedicated list of required parts. As is, one has to carefully read and understand the text (something you should be doing in any case) to determine which parts are relevant. A dedicated list of parts may tempt people to skip the reading the instructions.
Did I mention that the bags contain spare parts? Just in case anything goes awry or you need to repair the machine at a later time.
Mechanical Assembly: 2. Y-PlatesJanuary 8, 2021
Mechanical Assembly: 3. X-CarriageJanuary 9, 2021
The z-limit switch should be put in place prior to assembling the X-carriage. I have read of someone else's experience, mounting it at a later time. He did not seem to enjoy it too much... The latest assembly instructions point this out, so there is no more way of overlooking this aspect.
Back to the mechanics: the lead screw nuts were tilted by 0.5mm along a length of approximately 25mm. I did not want to stress the screw nuts more than necessary. After a couple of attempts, I managed to keep the offset below 0.1mm. I have not tested the squareness of the lead screw nuts, but I assume the 3D print and tapping at Ooznest is similarly accurate.
Another special to consider in between: I ordered a XYZ Touchprobe for ease of calibration. Some parts are mounted directly underneath the stepper motor.
The next step continues with the regular assembly kit. It is concerned with the Z-axis lead screw.
One of the 8mm-Lock-Collar needed some rework. After removing left over cuttings from tapping inside the collar, the collar fit perfectly onto the lead screw. I do not consider this a big deal. Rather, I mention this to highlight how well Ooznest prepared the entire kit, for this minor aspect to stand out from among all the flawless parts.
Mechanical Assembly: 4. X-GantryJanuary 9, 2021
Mechanical Assembly: 5. Base (Part 1 of 2)January 9, 2021
All extrusions line up to a squared base frame. This photograph shows one of the four corners prior to connecting the profiles with an end plate.
Impressions of the frame. The stepper motors and ACME screws of the Y-axis are still missing.
Mechanical Assembly: 6. Spoiler Board Support ExtrusionsJanuary 10, 2021
Angle corners are available to reinforce the frame as a first measure.
Second, extrusion profiles are used to strengthen the base of the frame further. To ensure an exact alignment of brackets on either side of the frame, I use a slightly modified piece of paper as a template.
Here is my second minor criticism (if there is anything worth mentioning after all): one of the extrusion profiles was tapped out of square. Luckily, the the wrong measure meant a shorter profile, so that I was able to mount it without further adjustment.
Here is a view of the fully assembled frame. Turns out the surface of the second-hand desk that I am using as a foundation is not 100% even... I will deal with this circumstance later.
Mechanical Assembly: 5. Base (Part 2 of 2)January 10, 2021
January 14, 2021
January 16, 2021
Mounting the Y-axis stepper motors was straightforward, connecting them to the Y-axes screws turned out to be a little bit more effort. I put the lead screws aside after assembling the X-gantry when I should have left them im place. Because of this, I had to loosen and readjust the guides on the gantry to feed the scews through them. Mounting the X-gantry without the hassle of dealing with overhanging lead screw was rather pleasant, so I would consider assembling gantry, frame, and scews in this way again.
I mount the CNC machine on 18mm multiplex beechwood so that it rests on an evenly flat and sturdy platform. With this, the machine can even be moved around, if necessary. Do not let the pictures fool you, though. The machine weighs approximately 20kg and the beechwood plate adds another 10-15kg.
The construction is clamped to the table with 6mm cork underneath to attenuate vibrations. Moreover, this set up compensates for the uneven surface of the desk underneath.
Mechanical Assembly: 7. Router MountJanuary 10, 2021
Not following the assmebly instructions helps with horizontally aligning the router mount: I assembled only the bottom two corner angles, adjusted the alignment, and then added the upper two angles. The third picture shows the final check that the router mount is perpenticular to the Z-axis.
Trying out the router mount adaptors:
- the 66mm adaptor from Ooznest holds the Makita router in place, and
- an additional, custom-made 20mm adaptor to hold the Proxxon IBS/E.
Mechanical Assembly: 8. Installation of SpoilerboardJanuary 14, 2021 & February 13, 2021
I am using a 12mm MDF spoilerboard. Three M5 screws hold it in place at the front and at the back, respectively.
To get started, I made some clamps from scrap beech wood. They are tightened using M6 screws that attach to insert nuts at the bottom of the spoilboard.
Electronics Assembly: 1. Y-Axis Drag ChainJanuary 15, 2021
Mounting the drag chains turned out to be adventuresome. For the Y-drag chain, you have to tighten a screw in a place that is so hidden and dark, that you cannot even see it on the photograph.. I recommend to mount this part of the drag chain prior to assembling the X-gantry.
Coming up next: feeding cables through the drag chain and then hooking the drag chain up to the frame. The assembly manual actually states that it "will take some force to click it into the Drag-Chain-Fixed-End." After a few failed attempts, I unmounted the drag chain fixed ends, hooked them up to the drag chain, and then mounted them to the frame. I strongly suggest you do the same.
Electronics Assembly: 2. X-Axis Drag ChainJanuary 16, 2021
Knowing about the issues with hooking up the drag chain to the fixed ends, I assembled chain and fixed ends before mounting anything to the frame. I am not sure how much faster I was able to complete this step in comparison to the Y-drag chain, but it was significantly easier.
Pictures below show the assembled fixed ends and the fully mounted drag chain atop the X-gantry.
Electronics Assembly: 3. Power SupplyJanuary 16, 2021
The power supply has an adjustable output. The manual does not ask for it at this time, but I wanted to make sure the voltage is right before connecting it to the controller. Expected output voltage is 24V, so this seems just about right to me.
Electronics Assembly: 4. Limit SwitchesJanuary 16, 2021
Placing the limit switches is straightforward - given, that you have only the X- and the Y-axis limit switches left to mount at this time. The Z-axis switch should have been mounted when putting the X-carriage together. The assembly manual does contain a respective note, so there are no surprises to be expected here.
Electronics Assembly: 5. Wire RoutingJanuary 30, 2021
The end switch wires are quite thin. To avoid damage from the zip ties, I wrapped heat shrinking tube around them. Any other type of rubber will do as well. The result is not particularly beautiful, but it is very practical. Black tubes may blend in better next time.
The second picture shows the overall result with all cables fixed at the ends of the drag chains, respectively.
Electronics Assembly: 6. Duet ControllerJanuary 30, 2021
First of all, Ooznest thought of a clear wire management. Small tags are attached to all motor and end switch cables, are color-coded and labeled with numbers. The assembly manual helps matching cables to the pin headers on the controller board through pictures and text. This is solved very elegantly.
On the other hand, the original mount places the controller out in the open. I am not too happy with this design, since it lacks protection of the electronics.
Furthermore, the fans blow onto the top of the circuit board. Note that the Duet3D developers specifically state:
The PCB is designed to transfer heat from the stepper drivers and power mosfets to the underside of the board. Therefore your mounting method should encourage good airflow underneath the board.
If you mount the board vertically, make sure that cool air can enter at the bottom of the board, flow upwards behind the board, and escape at the top. Convection cooling will usually be sufficient, but if you are using high stepper motor currents then you may wish to add a fan below the board to encourage the upward flow of air.
Source: https://duet3d.dozuki.com/Wiki/Hardware_Overview#Section_Dimensions
In other words, the effectiveness of mounting the fans as proposed is questionable. For this reason, I designed a case that is inspired by
- Duet 2 Ethernet / Wifi Case for Workbee CNC by ChrisGilletti available from https://www.thingiverse.com/thing:3721923 and
- Duet Wifi Case by YogiG available from https://www.thingiverse.com/thing:2812765
At this time of writing, the draft is yet to be printed. These are virtual impressions from FreeCAD, which is a powerful tool once you get the hang of it. Thanks to elaborate and picturesque documentation and tutorials, the essentials are quickly understood. This is my first time using it.
The lid will be made from transparent plexiglas with a thickness of 2mm.
Update March 12th, 2021: First attempt to print the housing is a success. The fans fit in perfectly. The picture on the right was taken during assembly with one of the fans half way in place.
Back to hardware: my cable management is rather practical at this time, since my only goal was to make sure nothing gets into the way of moving parts. I will replace the mount by the case before too long.
Connecting and Start of OperationJanuary 31, 2021
Ooznest deliveres preassembled cables. However, the cable between power supply and Duet controller is not terminated properly near the controller. To avoid risk of short-circuit or even fire, cut off the soldered ends and use the bootlace ferrules that come with the Duet Controller to crimp the ends of the power supply cable.
Booting up the controller for the first time is as simple as turning the power on. No unexpected movements, no smoke, ... just the hum of the fans.
In order to check the firmware and initialize the network connection, I recommend the original documentation at https://duet3d.dozuki.com/Guide/1.)+Getting+Connected+to+your+Duet/7.
Ooznest's documents are rather brief and not complete at this time (January 2021).
Nevertheless, remember to follow Ooznest's documents regarding connecting, updating, and configuring the WorkBee. They provide a custom firmware and guide you through the process well. I did not run into any issues, but I hear that Ooznest's support is quick to respond, too.
Testing of operation is a three step process and worked like a charm:
- Temporarily disable the requirement of homing prior to being able to jog axes. Then, move a few millimeters along each axis to check that the polarity of the stepper motors is correct.
- Check that the three end switches for X-, Y-, Z-axis are recognized by the controller.
- Home the CNC machine in the top right corner using the "Home" command.
Done!
Extension: Emergency (Soft) StopFebruary 14, 2021
You can use the end stop inputs of the Duet controller to iniate G-code commands. I connected and configured a software emergency stop to do just this. Note that this only stops faulty G-code execution and brings the stepper motors to an immediate halt. With the current setup, it does not stop the spindle motor. However, hitting this button is more intuitive and accessible than clicking the respective button in the web interface.
Test Operation: Plotting and MillingFebruary 6, 2021 & February 16, 2021
Getting to know G-code and machine controls with a pencil. Better be safe (and cheap) than sorry in case of faulty positioning.
Second test: use a small spindle motor to manufacture a cog wheel from 4mm plywood. This is the first try. I am pleased by the good quality of the edges.
This is the result after minor sanding and applying linseed oil.
To be continued... Further steps include:
- Controller case
Note to self: Set 5V_EN jumper for 5V fans https://duet3d.dozuki.com/Wiki/Power_Wiring
3. Enclosure for noise and dust protection
More to follow...