How to use this forum
take a look at point 7.

further update on the probe that I had to fix
before leaving eBay feedback I emailed the vendor
very responsive - bottom line got £1.00 refund
I'm happy - the probe works and it (now) only cost me £1.52
the fix was dead easy
here's a picture of the problem/fix

the red circle shows the stainless steel outer after I cut it back
the blue circle is where the outer stopped originally
with the frayed wires shorting out the probe

cheers
Mike

still can't get the b*****s to read it though!

if it's an eStop then remember what the "e" is for
e is for emergency
you want the straightest, simplest, most direct, fool-proof implementation possible
if the cutter has a push to break built-in, just wire the eStop in series with it
the worst that can happen is you break a wire - and the cutter will stop anyway!

adding ethernet and and shut-off widgets introduces far too much that can go wrong
do you want your fingers under the laser while you try and debug the app?

thought not!

enjoy

well it helps as there's no point in telling you to pop to a local store in Sydney if you're in Bangladesh!
country is all I was after, not full address

what electronic projects have you built so far?

good luck
it would help if we knew your approximate location?

you will need more than just a diode to reduce 12 volts (+/- spikes) down to something a 'duino can digest
take a look at voltage regulators ...

Altera an353.pdf

just noticed the attachment in your post
thanks for that

You also need a bit more integral action as evident by the "controlled" deviation at the high temperature.  Integral action is designed to reduce off-set error based upon how long the error exists.  It is evident that you are still applying heat even with the deviation existing.

yup I have upped the Ki value and it has improved
also using the same values thoughout now
simplifies the code - always a bonus

more pretty curves later
cheers
Mike

Code:

int bodyvar=2;  // this variable is global as it is declared outside of any functions

void setup() {
  int setupvar=4;  // this variable is local to setup() as that is where it is declared
}

void loop() {
int loopvar;  // this variable is local to loop() as that is where it is declared

loopvar=bodyvar+setupvar;  // this fails because setupvar doesn't exist here, it only exists in setup()
}

I added some comments to your code
HTH

I suspect you need to activate the internal pullup resistor as well

Code:

digitalWrite(buttonPin, HIGH);

in setup

I have had a number of queries about a CNC gcode system I worked on during 2011/12
(crikey was it that long ago?!?)

it has moved on a bit since then, and I have been remiss in updating the forum
so, to address that...

scope:
I wanted to be able to mill PCBs "direct from EAGLE"
ok maybe a few steps in between, but as brain-free as possible

design:
(hah he uses the word as if he has a clue what it means)

step 1: design the circuit using EAGLE
step 2: run the ULP pcb-gcode
step 3: take the output from step 2 and throw it (in a controlled fashion) to the gcode interpreter
step 4: gcode interpreter takes a single line of gcode and drives steppers, spindle etc.

implementation:
step 1: pure EAGLE
step 2: pure EAGLE
step 3: here is some Delphi software "what I wrote"; it
- opens the file generated by step 2
- manages the interpreter interface
- supports jogging to move the steppers to the right start point
- if the gcode interpreter is offline, it will still read gcode and display what it thinks is happpening on-screen
step4: here is the gcode interpreter; based heavily on RepRap, but with a number of enhancements

warnings:
it is configured the way I work
the code is commented as I find it too embarassing to go back to old code and not have a clue what it does!

caveat emptor: this software is worth exactly what you paid for it!
support will be patchy at best

nevertheless if someone finds it useful ...

cheers
Mike

if you look at your circuit the shunt (that I guess you are using to measure current) is up around 15 volts
I don't know if that contributed to its short life!
can you move current sensing to the low side and have the FET on the high side?

I suspect that this project may be a bit to large for you as a first project
I'd go with something simpler until you can follow the 'scope project instructable

It looks like you have too much thermal mass for your size of heater since there is substantial lag even with the heater fully on..  And you need a method of cooling that mass when ramping down - say a fan blowing ambient air.

guilty as charged!
fan for the cooling stage is next on the list
insulating the oven may help too

oven is 1kW, 9 litres
but I have blanked off the lower 2/3 so effective heated volume is around 3 litres
I also moved all the heating elements to the top as well

Looks pretty good.
How do the hold times compare? They are a little hard to read on my laptop.

time above solder melt point is about 60 seconds; target is 60-150 seconds
I'd like to improve preheat ramp time as it takes 80 seconds to get to 150 degrees
the target was 30 seconds!

Is Ki zero?

Ki is 0.1; do you think I should increase it further?

Is the green line output?

yup!

...
Very nice profile control!  It's matches my default profile that I set up at work for un-profiled boards.  Works great for all but two of our boards.  One is very thin and the other is a 16 layer board with mulitple ground planes.  They require special profiles.

How do you profile your boards if you need to?

er - haven't hit that problem yet!
most of my boards are pretty small 1" by 1" up to 2" by 2"
I guess I would do a dry run with a spare board

what do you do?

cheers
Mike