Tuesday, 25 December 2012

Progress on the magnetic milling bed

While i wait to get the last belt for the Y Axis stepper, I want to make some more progress on the mill.

I am going to attempt to make 25 hexagonal coil cups, these are 15mm tall section of 25mm hex bar. I will take a length of hex bar that is 25mm across the flats and cut 25 sections 16mm long. once these are cut i will place each one in the jaws of the dividing head (which will be vertically mounted, that is,  it will turn in the same axis as the cutter turns.

I will then program by hand some Gcode that will lower the tool into the job 12mm deep as it rotates. this will cut a circular slot into the hex face of the job that will allow me to place a sewing machine bobbin into, this bobbin will have wire wound onto the coil, when placed in to the cup onto the center pin and the coil energized any bits of metal will be attracted to the cup and coil, with the coil is set in the cup with epoxy and each of the 25 cups welded into a flat bed i should be able to hold the job with the touch of a button on the UI. the holding force will be adjustable via a slider on the touchscreen.

the code to cut cups :)

%
G21
G90
; starting at 16mm need to get to 3mm, so 13mm of z travel in 0.25mm passes
; 13/0.25 = 52 layers to this program.

; this will mean when i turn the cups upside down get them welded i can then face that off
; to make the flat mounting surface, i then flip and repeat to make my flat working surface
; set the mill to the start position then start.

G1 Z15.75 F100          ; drop the cutter 0.25mm
G1 A360 F300            ; spin the job 360' slowly
G1 Z16 F1000             ; pull the cutter out of the job
G1 A0 F1000              ; spin the job back to the start postion
G1 Z15.75 F1000        ; drop the cutter back down ready for next pass

G1 Z15.5 F100           ; repeat
G1 A360 F300
G1 Z16 F1000
G1 A0 F1000
G1 Z15.5 F1000

G1 Z15.25 F100         ; and repeat some more
G1 A360 F300
G1 Z16 F1000
G1 A0 F1000
G1 Z15.25 F1000
.
.
.
.
.

G1 Z3.25 F100        ; more repeating
G1 A360 F300
G1 Z16 F1000
G1 A0 F1000
G1 Z3.25 F1000

G1 Z3 F100              ; done repeating
G1 A360 F300
G1 Z16 F1000
G1 A0 F1000
G1 Z3 F1000
G1 Z50                   ; job done pull cutter up to allow for next piece . should be able to just hit run between pieces.
%

i ended up using a spreadsheet application open office to write this code i found it easier that way as its repeated 52 times if i need to change a value now i just change the first block then the rest follow to match.

then i take these values and use a concatenate function to join them all for cutting and pasting to a text file.

I really need to find a application that can do this for me. ie write gcode for a dividing head.
i suppose if its not already done i could write something that takes a bunch of parameters and generates the gcode, this would probably result in a module for each type of operation like cut helix, drill hole patterns etc..

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