Converting a Proxxon MF7. Milling Machine To CNC 3 joebrown. Controlling the MF7. Spindle Speed. Updated 2. April 2. 01. 2 with Eagle Schematic and Printed Circuit Board Design. This post in one in a series. Other posts you may be interested in are as follows Ive already mentioned that Ive attempted to automate as much as is possible, so as to avoid tedium and the inevitable problems with repeatability when human intervention is involved. It would be useful to define required Tool speed alongside the tool definitions, so that when a tool is selected by gcode, the speed suited to the tool and work is automatically selected and implemented. Hardware. The MF7. As a picture is always worth at least a thousand words, Ive included my impression of the MF7. Authors impression of Proxxon MF7. Speed Controller. The circuit is ubiquitous, but Ill glance over the operation. Control over the firing angle of the TRIAC is managed by the 5. K pot, together with the associated capacitors, assisted by the DIAC, hence altering the effective voltage across the bridge rectifier which supplies power to the DC brushed motor. The circuit is popular because it is cheap, and relatively problem free, the only mechanical component being the 5. K pot. Proxxon have marked the dial on the speed control knob in a range from 5. I have not checked this, but indications are that though a little rough, the calibration is adequate, given that the control over speed using a pot in this way is not linear, with greater incremental increases in speed as the knob is rotated clockwise. Given my very healthy respect of mains level voltages, and un isolated ones in particular, I originally intended leaving things exactly as they are, and affixing a geared model control servo motor to the side of the motor casing. Generators are programs that take some sort of input file STL, DXF, BMP, etc. Here are some good GCode generators. Use pcbgcode to generate GCode from Eagle CAD 1. Open your board design in Eagle CAD 2. From the Eagle CAD Control Panel window, rightclick User Language Programs. I subsequently decided that this would end up as a mechanical monstrosity, which was difficult to keep free of metal swarf, and promising myself to be ultra careful, decided on interfacing directly with the electronics of the motor controller itself. I havent played with TRIACS in any serious sense, my experience pre programming days was solely with Thyristors, so some time has been spent reading Application Notes. Not much has changed though, and the simple requisites for phase control are the determining of the zero cross point in the AC supply, and the production of a GATEON signal after a pre determined delay, depending on speed required. Below, the Blue trace shows the zero crossing pulse, note that this occurs every 1. UK, where we have a 5. Hz supply whilst in red the ACTIVE LOW Triac control signal is shown, well delayed until just over 8ms after zero crossing. The reason why the Triac control signal is ACTIVE LOW will become apparent in the next schematic. Phase Control of Proxxon Motor approx 5. Now contrast the above oscillogram with that below taken at a speed of 2. Here, the ACTIVE LOW Triac control signal is triggered at around 5ms after zero crossing, thereby turning the triac on much longer, hence delivering more power to the motor. Phase Control of Proxxon Motor approx 2. As well as controlling the speed of the motor, our additions should cater for turning the spindle motor on and off, as well as allowing for original manual control, and probably most important, shutting off spindle motor power when the BIG RED SWITCH is hit by the user, as mentioned in the 1st post on this subject. JPG' alt='Eagle Pcb Gcode' title='Eagle Pcb Gcode' />Im writing this post while one of the test JeeNode Micros here at JeeLabs is nearing its eighth month of operation on a single coin cell. Last, but most certainly not least, control signals should be isolated from the mains voltages on the existing speed control board. So a shortlist of requirements so far Detection of zero crossing of the AC supply. Generation and provision of the TRIAC gate signal. Emergency shut down. Provision for manual control. Complete isolation of mains connected electronics from controlling electronics. Pcbgcode lets you use your milling machine, router, engraver, etc. Fog Bank Cartoons. You create your design with Eagle. In this first tutorial on CadSoft Eagle, Ill show you how to get the program up and running, how to navigate the interface, how to design your first. How to install the PCBgcode. EagleCad and use it to generate gcode suitable for a CNC mill. EagleCad httpwww. Substrate also called a wafer is a solid usually planar substance onto which a layer of another substance is applied, and to which that second substance adheres. I came up with the following Proxxon MF7. Milling Machine Automated Speed Controller. Dont be put off by the apparent complexity of the above look at each part individually. First, the original speed controller is retained on the right of the diagram, with only 3 small changes 1. The connection between the DIAC and TRIAC has been severed, and flying connections taken to contacts on RELAY 2. A flying lead has been added to A2 of the TRIAC, which connects to resistor R6. A flying lead has been added to A1 of the TRIAC, which connects to capacitor C7. A phase control signal PHASECONTROL supplies ACTIVE LOW pulses to the opto isolated TRIAC MOC3. RELAY 2, to the TRIAC, whenever RELAY 2 is activated. A zero crossing detector circuit comprises R9, BR2, a zener diode, R1. LED2, C7, R1. 1 and a 6. N1. 37. This generates a positive going pulse every 1. ZEROCROSS, which is opto isolated from the mains supply. A spindle motor ONOFF circuit is comprised of Q1, D1 and RELAY 1. An ACTIVE HIGH on MOTORON, will turn on the spindle motor if the ManualAutomatic switch top left of schematic is set to Automatic. Most importantly, the Controlled 5. V supply comes from the 5. Prepaid Meter Keygen there. V supply to motors shown on the BIG RED SWITCH diagram in 1st post of this series. This ensures that when the user hits the PANIC switch, not only will the X, Y and Z stepper motor supplies be cut, but the spindle motor will also be deprived of power. Note Ive shown the relays in their de activated state, which would be so if the ManualAutomatic switch was set to Manual, or the user has hit the PANIC button. In this state, the original Speed controller can be used, switching on the supply using the original and retained switch. A suitable printed circuit design in Eagle is now available. Component foil sides look like this MF7. Spindle Control from PIC Microcontroller Component Side. MF7. 0 Spindle Control from PIC Microcontroller Foil Side. Software. As mentioned above, the relationship in AC control, between time and speed is not linear, and I had no wish to make exact, and complex calculations in software. Instead I decided on allowing the use of the S gcode to select spindle RPM to the nearest 1. The plan is to parse the input speed gcode, then divide this by 1. TMR0 counts, the contents of which could later be tweaked with the use of a tachometer. So the look up table will look similar to this. G code speed parsing like this. GCODES. accept 1. S 1. 00. 0. if temp 0 temp lt 2. INTCONbits. GIEL 0 low priorityperipheral ints. INTCONbits. GIEH 0 enable high priority ints. INTCONbits. GIEL 1 low priorityperipheral ints. INTCONbits. GIEH 1 enable high priority ints. And the interrupt system which processes the zero cross signal and generates the PHASECONTROL signal. Interrupt. Handler. High. if INTCONbits. INT0. IE 1 INTCONbits. INT0. IF 1 test for RB0 edge interrupt ZERO CROSSING. INT0 interrupt flag. INTCONbits. INT0. IF 0. PORTBbits. RB1 1 drive phase control HIGH OFF. TMR0. H tmr. 0reload 8. Interview Questions For A School Bus Driver on this page. TMR0. L tmr. 0reload 0xff reload TMR0. INTCONbits. T0. IF 0 clear TMR0 interrupt flag. INTCONbits. T0. IE 1 enable TMR0 interrupt. TMR0 interrupt. if INTCONbits. TMR0. IE 1 INTCONbits. TMR0. IF 1 test T0 rollover. INTCONbits. TMR0. IF 0 clear TMR0 interrupt flag. INTCONbits. T0. IE 0 disable TMR0 interrupt. PORTBbits. RB1 0 turn phase contol ON. A photo album exists showing my experiments in the development of the prototype speed controller. This can be viewed here http cullercoats.