Friday, 23 September 2011

Progress Update 4

Last night i was at my mates workshop to build something to connect the belts to the tension springs without the belts wearing. these were really simple they are made from 3mm aluminuim, with a hole for the spring and a slot that the belt can go through. the belt is then bent back and ties off with some cable ties. 

I Also  made some brackets for the X carriage to hold the springs and anchor the belts, these are now installed and ready to go.

I had to add a spacer between the angle and the anchor to raise it above the bearing bolts.

I just visited jaycar and left with lots of goodies, i bought some multi core cable to extend the stepper motor wires, and a whole stack of various connectors and heat shrink, I have been tossing up on weather to upgrade my electronics or not, so i thought i will do some thinking and see what i need from my electronics.

so i want to have 3 nozzles, this will require 6 pins 3 analog inputs and 3 pwm outputs, i will need to control the heated bed this will take another analog input and 1 digital output, could be pwm but it doesn't need to be. i need 1 digital pin for the fan. 12-15 pins for 5 stepper controllers. and 6 pins for the endstops.

6   +    Heater + Sensors
2   +    Heated Bed + Sensor
1   +    Fan
15 +    Steppers ( S,D,E x 5)
6         Endstops

that be a total of 30 pins, that's just what the ATMega644 has exposed on the Gen3 motherboard, yes i will have to use a USB - TTL converter but that's easy. I made one from a pic18f14K50 chip and crystal, used the sample firmware provided by microchip (there is a cdc emulator that is perfect for this no mods needed).

 X carriage you can see  the belts anchored on the left and attached to springs on the right, this keeps the belts nice and tight, the anchors for the belts should help prevent them wearing, if they fail i will get the corrugated plates made for anchors.

 The Y Axis belt attaching to the springs. i bent the belt back again just to keep the excess from interfering when the carriage goes all the way to the end, the excess would jam the pulley.

 just a couple of shots showing me the measurements so i could make the brackets the right size.

 I have started to layout the track board RAMPS type carrier for my nice new shiny stepper motor controllers they are pololus without the 5 volt regulator. that's no problem i will add one its easy.

i am planning on soldering the gen3 motherboard to the track board and run wires to the bit on the under side, this will be much neater than the previous setup. as you can see there is 4 pololu stepper controllers there, these are fro X Y and 2 for Z, I could use one driver for Z but my motors are Larger Nema23's so i will use one for each. i will then reuse 2 of my MB2.3 stepper controllers to drive the two stepper motors on the extruder. one is for selecting the filament and the other feeds the selected filament. i am thinking of re-designing the extruder, and i may change the filament selection stepper for a smaller one with a much much higher gear ratio, the camshaft doesn't need to go really fast so i can use a smaller one and save weight, i might even switch to a smaller stepper driver to suit. I have a stack of PM14 and PM20 stepper motors and some 1amp driver chips to suit, i have drawn up a control board for them, yet to get them etched, i will one day soon, if anyone wants to look let me know and i will post the schematic and pcb files, i have used a pic to convert the SDE signals to grey code that the stepper driver wants, the pcb is really small, i have drawn the board up to take 5 of these but can be separated. the plan is for a micro printer one day, will be slow but very very accurate, a friend of a friend is a jewellery setter and  can drill me some micro nozzles, this micro printer would have a 50mm^3 print area designed for wax casting.

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