Introduction: My High School CNC Projects
My CNC endeavor started with a 9th grade science fair project. Since then (currently in 11th, 16 years old) it has grown into my hobby and favorite pastime, this is my CNC story.
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Step 1: My First CNC, Science Project
In 9th grade my friend and I took on a challenge, develop an alternative method of making channels in nero-regenerative scaffolding(used to assist in the regeneration of damaged nerves). The current method being used involved painstaking and time consuming molding, we decided to test an alternative method,a CNC mill. We built a small, high precision desktop mill. This machine needed to be accurate to +/- 5 microns, we achieved +/- 3, 10,000 RPM spindle, and have an area where the Scaffold material could be frozen into a solid machinable state.
This was the result, Parker Dedal XY table, and a high precision cross roller bearing Z axis with a 10,00 RPM spindle. The frame for the machine is 8020 extruded aluminum. To achieve a "clean room" capable machine, all aluminum parts are anodized and the base of the machine is a composite counter top material.
Above pictured is the CNC, machining scaffolds with dry ice, the motor controller unit, and the spaghetti and scaffolds after machining, the holes are 300 microns in diameter. Yes that is 5 holes lengthwise down a piece of spaghetti (photos taken with stereo microscope). Finally a completed scaffold (transparent), the two large holes are the smallest possible with the molding technique, and the 7 have been CNCed and are 300 microns in diameter.
We tried to make some more practical things with this machine but it was decided that it was worth more for it's parts than if functionality and quickly replaced it, although i now have interest in retooling it for making PCBs.
Step 2: Bigger 3 Axis CNC Mill/Router
Over my brother's college winter break (my 10th grade year) he took the liberty of throwing together the linear stages of a 3 axis CNC. I proceeded to convert some of the small desktop electronics to the bigger mill. I used the CNC to make any new electronics enclosures as well as the dust boot, upgraded the spindle motor etc. The result is a 16x16x10 inch work area, .00002 inch resolution (verified with micrometer) and a 6,000 RPM ER16 spindle and collet. The XY table is a Aerotech with cross roller bearing and zero backlash ground ball screws.
Although i still need to replace the temporary wooded mounting base this machine is competed and runs beautifully
Above are pictures of the CNC, converted electronics, and dust boot. The machine is typically used for fun projects, learning, and parts for the High School's FRC robotics team (i'm a mechanical lead, and responsible for ensuring that all parts on the robot get manufactured,More info here)
Step 3: 4 Axis Desktop CNC Mill
Designed for small components, Sonic Screwdrivers, and carbon fiber rocket parts, this machine is a larger 4 axis clone of the the CNC made for the Science project. With +/- 3 micron resolution and a precision A axis gear reducer this machine has a 4x4x10 work area with 360 degrees of moment in to A axis (+/- .0001 degrees).
In an effort to be professional as possible I had the electrical enclosure's panels printed. The enclosure allows for Machining hazardous material in a controlled environment (example carbon fiber). A micro-particle filtering system is in place to filter out all dangerous carbon dust (can be harmful and will fry electronics). The machines operations (starting, stopping, ventilation control, etc) change the LED,s, Flashing red, yellow and green to indicate machine changes as warnings and alerts to the user.
This machine took a few months of on and off work to compleate and i'm really happy with the result and I can't wait to start using it! The first thing that i want to make is the 11th doctors sonic screwdrive r.
Note: This machine was originally designed and built (by me) to make multiple coats of indicators on iridium tipped needles used in an ophthalmology based medical research program. It was latter rebuilt as a the CNC seen above.
Step 4: 2 Axis CNC Lathe Overhaul
For the longest time my school's engineering department has had a small CNC lathe but i'd never seen it get used. when looking into why I found out that the control system was buggy and outdated. After consulting the department chair and showing him my previous projects, we decided that I had a $1000 dollar budget to rebuild the lathe. I decided to replace all the electronics,the old cheap servo motors with more powerful steppers, new digital stepper drivers, CNC USB MK2/4 controller, and use the current 3 phase motor controller inverter. After many weeks of working during lunch and open hour here was the result. As to this date the machine has been moved from it's temporary work environment and we are struggling to find a breaker that can supply enough current to the Lathe for more than a few minuets. Other than the power issue, the lathe is nice to have back for students, robotics, and science clubs to have at their disposal.
This was a really fun project and I learned a lot about working around preexisting problems, Now I want one of my own!
Step 5: One Last Hurrah, a 5 Axis Mill.
All of my previous projects have been building up to one last CNC build before leaving for college in fall of 2016, building a 5 axis Mill. Serving as a Independent study in advanced CAD and CAM manufacturing with Autodesk® Inventor Professional® and Autodesk HSM®, to date all aspects of the machine have been CADed and I am beginning stress testing and computer simulations as well as getting some of the unique manufacturing aspects contracted. (My dad gave me a $1000 budget to build this machine excluding anything we already have).
The machine will have a 18x15x15 inch work area with 150, and 360 degrees of freedom in the respective A and B rotational axis. I'm using the same Aerotech ground ball screws on the 3 axis mill for the Y and Z, and purchasing a similar ball screw for the X axis. All of the linear rails are THK HSR or HR 25, or 20mm rails.For the A and B, I have two 61:1 Alpha gear reducers with 4 point contact ball bearing gear heads(less than 3 arm minuets, +/- .0001 degrees of backlash). I'm purchasing a CNC USB MK3 Ethernet/USB controller for the control system and using 5 parker PDS-13 Stepper drivers. For the spindle I have a 10,000 RPM spindle with ER25 collet and a 5000 RPM closed loop servo geared up 2:1 to power it (the closed loop feedback servo allows for taping holes with taps and making threads with other similar tools). I'm using a brushed servo controller and servo AMP to power the spindle motor. I've also decided to invest in a full blown coolant and misting system, water proofing and and at a minimum water resistance will be added to all components in the machining area. Polycarbonate shielding and coolant collection systems enclose the machine.
A unique problem arose, how to build a accurate, stiff, low cost machine, without using cast iron as most mills use. After considering of filling aluminum boxes with concrete, sand, cat liter, etc; or using steel tubing with similar fillings, I decided to go out of the box. The 3 largest parts of the machine will be granite, the A table, and the vertical supports on the Z axis, respectively 3 and 4 inches thick. These will be CNC water jet cut by a local granite shop on their 5 axis CNC, typically used for counter tops. Above are photos of the machine's CAD models and many of it's main mechanical attributes with text captions.
Thank you for your time, I look forward to any and all comments, suggestions, or questions you have. Hope you get inspiration for your own projects from this and keep inventing and please vote in the CNC Challenge and the Tools contest !