This build was my first attempt at a 3 Axis CNC and at the time i knew very little about them and because of this i made lots of mistakes. The biggest mistake was that the Astrosyn y129-5 12v 0.16A Nema 17 stepper motors where really under powered but i still managed to get the machine to engrave the road runner that came with mach 3 CNC software.
The Stepper controller is the Tachus42 3 Channel Discrete Unipolar from PMINMO.com which i built using the instructions on the site and only cost £12 for the parts. The Tachus42 it a good simple controller to start with and because of its simplicity if you let the magic smoke out it can be fairly easy to fix. As with many simple things they lack the more advanced features such as micro stepping and current control, so if you wanted to increase the voltage to the motors above their rated voltage you had to use resistors to dump the extra power which is very wasteful and also very quickly needed very high wattage resistors or build the additional chopper board but this has been known to come with its own set of problems that can be difficult for beginners like my self at the time.
The wood i used was from an old TV cabinet that my next door neighbour was chucking out and i purchased a few drawer slides from ebay i also purchase some 6mm all thread rod from ebay which was another mistake, threaded rod that small just really sucks for a make shift lead screw. i used a cheap dremel type rotary tool as the spindle which worked well when the machine wanted to work.
I learnt a lot from building this machine and although it did not work very well it only fuelled my thirst for a well built CNC so i set about reading everything i could about CNC Machines and started planing my next build Big Red
Big Red 2.0 with perspex sides, MDF Spoilboard and full aluminium construction with the Y Axis linear bearings upgraded to fully supported rails.
The beginning of a quick test of the machine using a pencil to draw Sweet Dreams with a heart ether side which i plan to engrave in some perspex and side light with a few RGB LEDS.
End of test
I`ll add descriptions to the pics soon but basically the little black block is a 1.4w 445nm laser diode that can be pulse at 2w and i have added a vacuum system and the thing with the copper wire wrapped round next to the router is a small camera to help with alignment of the tool. i still need to get the aluminium plate for the front, back, part of the Y- Axis and all the parts for the Z-Axis milled but for now the Big Red has no problem cutting wood and plastic.
i am currently running the motors at 24v 4A but i have still to fit a couple of boost converts to kick the voltage up to the max the drivers can comfortably handle of 40v 4A which will help increase the speed. i have already had the Y Axis running at 3500 mm/sec which is about 137 IPM but for testing i have been running at between 500-1000 mm/sec 19-39 IPM to make sure i dont kill it with one wrong move.
Isometeric view of CAD model with the perspex sides and MDF spoil board
Right view of CAD model
Isometeric view of CAD model
Front view of CAD model
Back view of CAD model
45×45 Extrusion Gantry on Big Red V1 for scale.
45×45 Extrusion Gantry on Big Red V1 from the front for scale.
960w 24v PSU worth over £500 that i picked up for £30 on ebay int the small hours of the morning
I have now added fans and covers to keep the driver cool
USB keypad used to control the machine until i build something better
i placed some magnets on the back to allow me to stick it to stuff
1.4W 445nm Laser which can be mounted to enable laser etching and cutting of thin materials
dust guard and vacuum system
the copper was temp holder while i aligned the camera
An old bagless hoover is being used for dust collection for now but i will be making a cyclone dust seperator at some point.
An old TV bracket with a shower rail bolted on so the vacuum pipe can move with the CNC
The Super PID router speed controller is now mounted in a nice abs case and all the cables are now run to allow control of it from mach3
Here is a little about what i plan to accomplish with this machine. I am hoping to end up with a 5 Axis CNC machine that i can change the head to a 3d printer head and have a cutting area of about 1300mm x 1000mm x 240mm.
i will first build a 3 Axis Gantry CNC with hand cut 18mm MDF and then use that machine to cut better quality parts in the hope that a can start to machine aluminium. Then if all goes to plan start making aluminium frame work and build it up to a 5 Axis CNC.
One that is phase is complete i will move onto building the stand along control panel and motion controller using a combo of AVR, Ardunio and TI Stellaris Arm Micro controllers which i hope to use to make a closed loop system using some AS5048A magnetic rotary encoders on each stepper motor shaft. From there i will start work on accessories like auto tool changers, 3D digitizers and all the other fun stuff.
i am still looking for any other parts people could donate like sheets of Plastics ie delrin, hdpe or aluminium that would be great even old machines that i can salvage buttons, electrical and mechanical parts from would be great.
The geek will inherit the earth. 🙂
All the electrical and mechanical parts 2x 1320mm LG Hiwin 20mm rails and blocks for the X axis, 2x 240mm EG Hiwin 25mm rails and blocks for the Z axis, 2x 1000mm round carbon steel rails bearing and clamps for the Y axis and 4x 16×4 trapezoidal lead screw 2x 1450mm 1x 1150mm 1x 500mm.
i`m using an old AMD sempron 2800+ board with 1GB ram and 2nd PCI Parallel port for extra I/O`s
4 heavy duty limit switches for the X Y axis i will need some more for the Z but i might use some micro switches, hall sensors or IR interrupters because i will need things to be compact to make it easier to up grade to 5 Axis
4 TB6600 drivers i have removed them from the heat sinks and join all the sinks using aluminium tape and added fans for extra cooling because they will be running at 24v 4A which is close to their 5A max
Top of heatsinks
i`m going to remove the trim potentiometer use for controling the current limiter and the dip switches used for setting the micro stepping and replace them with a AD5206 digital Potentiometer and digital switches controlled by an arduino so that later on i can if needed via the motion controller i am building using a Stellaris LMF4 120XL ARM controller
I got this vicor 3x 24v 8.3A 200w PSU for a steal on ebay it sells new for £300 i got it for £30 delivered. Because it has load sense on each output i am going to parallel the outputs to give me 1 24v 24.9A 600w rail which should power all four 4A stepper motors and maybe the 2 smaller motors i will use for the 4th and 5th axis i plan to add later.
These dual shaft stepper motors are 200 step beasts with holding torque of 4NM / 566 ozin i will be using 2 for the gantry X axis to make sure there is plenty of power for cutting the big jobs.
i got 2 different break out boards just to see which is better and i found a problem with the one on the left for some reason the opto isolators dropped the voltage to low for the driver board to see a logic high it could be possible that this happens because the drivers also have isolators on but i will look into that later.
The 400w ATX PSU will supply the mainboard, all the 3.3v, 5v logic power and also the 12v fans. the 160GB harddisk is a bit over kill for linux cnc but its all i had spare.
it was going to cost £9 for each lead screw nut and i was going to need at least 4 but i really wanted to use 6 so i bought a length of Delrin and a 16×4 Tap to make my own for £45 which was a bargin.
The smaller Hiwin rails are perfect for the z axis
Tap and matching leadscrew 16×4
cant wait to get these installed
maybe i will get 2 extra blocks for the x axis when i can afford them
PC PSU and shaft couplers
Motherboard and vicor PSU
Motor Drivers and Fans
A new TB6600 Stepper Motor Driver
First modification i have done is to de-solder the connectors and refit them vertically so i can mount them side by side i still need to replace the pot and dip switches but that will be done after the machine is built
All 4 drivers mounted on the heat sink with some nice new Arctic Ceramique 2 thermal compound in stead of the nasty cheap silicon paste that is used by the manufacturer.
i will be adding 2 or 3 LM35 sensors to the heat sinks and using the built in tachometers i should be able to use PID to keep things cool but for now i will just run them at 75% power to keep everything nice and cool
Side view of motor drivers
all 4 heat sinks joined using aluminium tape which is surprisingly strong. i might at some point try some epoxy to join them or if the heat transfer of the epoxy is low maybe try brazing them together.
i`ve add mounts for the motors, 2 clamps for the spindle motor and a matrix of boxes on the cutting bed to add strength and for mounting a sacrificial MDF sheet. also i have managed to get the shaft supports and other things to show in the rendering with a nice science lab background to give some idea of scale
Front of machine
Side of machine
Rear of machine
i`ve lengthened the cutting bed so it over hangs to compensate for the distance the spindle is from the center of the gantry.
My new Bosch POF 500 A Router that i picked up second hand for a tenner and its had very little use. It will be a great starting milling head for the machine. All i need to build for it is a PID Pulse Width Modulation speed controller because the 27,000RPM it runs at is far to fast for most materials other than wood.
Getting ready to glue the printouts of Z Axis parts to the MDF
First ruff cuts
end of a bloody hot day but one step closer to my machine coming to life. 🙂
Almost finished the Z-Axis it still need a bit of sanding to make sure every thing fits flush but it only needs to good enough so that the machine will be able to cut more accurate parts for the final build.
The sides slot into the back plate and hold together even without glue or screws. I plan on making all parts slot together for the final build to help add to the overall machine rigidity.
Pillar drills are an essential tool for any workshop, with out mine all these holes would have been a total nightmare to get straight.
i`m starting to get an idea of the overall size of the machine and i got the Z-Axis attached to the Y-Axis today once i fit the Z bearings the rest of the machine will be plain sailing until i have to add all the electrics.
I`m thinking of adding some plastic sheathing to the rails to protect them from sawdust getting into the bearings or bicycle inner tube.
Nice and close
Finally all the wooden parts have been cut and well ahead of schedule the only problem is it has turned out a little bigger than i pictured in my head.
Y Axis Gantry
Still need to cut holes
The Z Axis is the most complex part of the machine.
The 25mm Hiwin bearings work a treat they are only preloaded to Z0 but you can see no movement.
A quick test of the 20mm steel shafts and kinear bearings, they are slightly misaligined but stil work well.
Lots of hot glue to hold the delrin nut in place
i had fun grinding the screw down so it would fit in the coupling.
the screws with hot glue on will be use for the limit switches
1 complete Z Axis it is strong enough for my daughter to stand on while it moves.
Because it is much bigger than a normal case i can install all the electronics in the one case
This is an old PC case i found in a skip about 6 years ago i knew i would find a use for it
its hard to see from this pic but the vicor power supply for the motors is install on the side of the drive bay.
i have managed to tuck the Hard drive out the way in the back of the case
Many lesser women would murder their husband if their front room looked like this. Love you my beautiful lady.
This all happened due to the fact that the first motherboard i was using thought it would funny to crap out once i fitted most of the electronics in the case. Fault finding is so much fun, it also turned out that one
4 Ammeters 1 for each of the motors so i can keep track of each axis power usage with out having to break out the multi meter.
4 screw in 8 pin sockets for the motor cables
Every thing back in the case i still need to play about with wire routing so data and power cable do not cross but everything seams to be working ok for now.
Ammeters all powered up and testing 1 axis at half power. i still need to add a power switch for the vicor power supply and the motor drivers fans plus lots of indication leds.
Quick and dirty router clamps
Finally got the Z-Axis Mounted and the Y-Axis leadscrews fitted
Quick picture with my 13 year old son next to the machine to give some sense of scale.
All of the motors are now fitted
Just need to fit the limit and home switches, then route the cables to prevent strain on them when the machine is moving.
I have finally got round to start building the rest of the tools needed for my electronics workshop. I built this Resistor Substitution Box using 6 x 12 Pole Rotary Switches, 6 x Chicken Head Knobs, 1% 1 Watt Metal Film Resistors, 2 x Banana Sockets and some old thick coax cable for connecting the switches together because of its low resistance. Total Cost £7.19 Total Resistance at 0 = 0.3 ohms all the the way up to 999,999 ohms in 1 ohm increments. I am thinking of building another one and a module to connect them together as a potential divider but i might just add a 10k ohm 10 turn potentiometer and and extra socket to the box for that function.