LinuxCNC is working nicely

I'm using HeeksCNC to calculate the toolpath and LinuxCNC to drive the Bridgeport Series 1.

With some help from John.

We unplugged my "Heeksatrol" computer from the Bridgeport Series 1 and replaced it with a PC running LinuxCNC. In less than a day we had it moving the 3 axes, with very little work by us.
We copied some code to make LinuxCNC ask us to press a button to continue on a tool change:

 loadusr -W hal_manualtoolchange
 net tool-change iocontrol.0.tool-change => hal_manualtoolchange.change
 net tool-changed iocontrol.0.tool-changed <= hal_manualtoolchange.changed
 net tool-number iocontrol.0.tool-prep-number => hal_manualtoolchange.number
 net tool-prepare-loopback iocontrol.0.tool-prepare => iocontrol.0.tool-prepared

But we didn't work out how to make it retract up to our limit switch on a tool change, yet. 

The stamp we made was used today. The resulting piece of silver looks good. They put it through the rollers on a too tight setting, though, and squished the stamp. So we'll have to make another.

 

Sodium Chloride solution 2.2V 5A, 2 hours, Mild Steel. 106mm x 55mm
John and I used a bigger tank for our electro etching. We also had a fish tank pump making bubbles of air come up from the bottom. ( We made some holes in a plastic pipe and  blocked the end )

We also tried writing on a stainless steel spoon with a CD marker and doing it for 20mins.

Engraving mild steel

I bought some new mild steel sheet yesterday. It was 1.5mm thick. It was much newer than the other steel I got. It sanded clean very easily and was not pitted with rust. I engraved this with a 3mm slot drill, a 1mm slot drill and my engraving tool; nominally 27.5 degrees half angle, 0.1mm cutting diameter at the tip.

I was pleased with the result, although I had to tidy it up with my pen-knife and sand and polish it to get shiny ridge tops. Also, the fine detail pass at 0.05mm depth left a step on the ridges.

Etching

Having had trouble with engraving steel; it was probably hardened steel though, me and my assistant went to see a chemical etching expert on the Welsh border, last Monday. After getting some advice, we bought some supplies from Maplin in Hereford. We tried cleaning up our steel sample pieces, applying the Press N Peel transfers and putting them in the Ferric Chloride solution at about 30 degrees C. It only removed about 0.01mm of the steel in an hour. We left it over night, but it had only taken off about 0.05mm.

In the picture, we were trying electro etching using salt solution; John's idea. It took off enough material, but was not a good surface finish.

We need to try it while agitating the liquid, because some of the areas between the lines were not etched at all. We had to remove a layer of crust from the metal. So, we've bought a pump.

Gear checking

Before I make a test rig for my customer's injection moulded gears ( the gears which I made the solid models for ), I checked some of the gears, by rotating them on a spindle under a dial indicator. I am quite pleased with the way I displayed my results to him. The paper data was written down by my assistant, as I spoke the values. I then wrote a Python program, which made a text file. The file contents were copied and pasted into HeeksCAD, making points, which I could then create spline curves through. I wonder if I could automate this using an arduino, a stepper motor, and a dial indicator with a serial interface? something like this http://www.arduino.cc/cgi-bin/yabb2/YaBB.pl?num=1288396532

Python program to make HeeksCAD points:

import math

fout = open("points.txt", "w")
fout.write('\n')
gears = [
[17, 17, 16, 17, 17, 17, 16, 16, 15, 14, 13, 13, 13, 13, 13, 15, 16, 17, 18, 20, 22, 26, 29, 32, 37, 43, 41, 36, 32, 29, 23, 19, 12, 10, 9, 8, 7, 3, 2, 1, 0, 1, 2, 2, 5, 8, 10, 13, 13, 14, 15, 15],
[10, 10, 11, 11, 11, 11, 11, 11, 12, 11, 11, 12, 11, 12, 10, 10, 11, 10, 10, 12, 15, 18, 22, 28, 33, 36, 41, 42, 37, 31, 26, 22,  18, 14, 9, 5, 5, 5, 4, 4, 4, 3, 3, 4, 5, 6, 7, 8, 9, 9, 9, 9],
[15, 15, 16, 17, 17, 17, 17, 15, 14, 13, 12, 12, 13, 13, 13, 15, 17, 20, 21, 21, 24, 27, 31, 34, 39, 44, 43, 37, 34, 29, 21, 17, 13, 11, 10, 8, 6, 4, 3, 1, 1, 2, 3, 4, 6, 10, 13, 14, 14, 13, 15, 14],
]

id = 1
for gear in gears:
    i = 0
    for p in gear:
        angle = (float(360)/len(gear) * i) * math.pi / 180
        r = float(1.0) + 0.4 * float(p) / 40.0
        y = r * math.sin(angle)
        x = r * math.cos(angle)
        fout.write('\n')
        i += 1
        id += 1