CNC solder paster dispenser - how do I approach this.

[HankMcSpank]

Lateral thought... would it work to make all the pads on the PCB the same size?

Alas, that can't work a SOT23 device is significantly smaller with much smaller pitch vs say an SMD LED(there's not be sufficient space)....often the pads need to beof a certain size for heat disappation etc.

Jonathan, thanks for the input....food for thought there. I'm trialing cambam which is very good for cam, so there may be some mileage there. (I asked on their forum....http://www.cambam.co.uk/forum/index....5.msg13159#new )

Re USB CNC & brains...no not yet, he mentions that there's a scripting ability that has just need introduced. (I think if I went the way of USB CNC, I'd make sure I have the ability to fallback to mach3 quickly! I really like his product & it looks like by & large it'll fit my needs well - for example I asked about Z transformation & he's onto it already, he calls it warp - http://www.youtube.com/watch?v=r-l7I...1&feature=plcp , but there's clearly not the depth of support & features if you want to go off piste. )

[JAZZCNC]

I could write a quick program to do that, but find and replace will be fine. I use that all the time to edit the code when I accidentally put the wrong feedrates/retract height in.

Yes I do that as well if I have too. Now i'm now expert on find-replace but dont think the standard find-replace would work because it would only repalce A with B.

This would need to find the T# then replace the P# of the G4 command. The code should really only put one T# for each tool (or pad in this case) so there will be lots of proceding lines with no T# untill next pad change or T#. So just finding the T# and replacing the whole line won't work Unless everyline starts with a T# which hisn't very effficient.

The Script would need to look for the T# then replace any proceding G4 P### time values with a stored value matching that T# then repeat untill it find another different T# so on n so forth.
I don't know how to do this with the standard find-replace without using some kind of script which defeats the purpose so may as well just use the script straight off.
Jonathan If you know how then I'd be interested because like you I do use it to change code on the fly and being able to target one value and change another select value would be good info.!

[HankMcSpank]

Bit of a result here.

I started wading through the threacle that is Eagle user ulps....and found one written in 2001, with the obtuse name of dose-pro.ulp!

Anyway, when I run it within eagle on my pcb layout, it creates two files

1. A list of SMD pad surface areas and the pretend tool that it has married for that size of pad...

Tool Pad-X Pad-Y Square mm^2
T01 X000055 Y000120 | 000.66
T02 X000060 Y000060 | 000.36
T03 X000060 Y000220 | 001.32
T04 X000079 Y000089 | 000.70
T05 X000100 Y000140 | 001.40
T06 X000114 Y000185 | 002.12
T07 X000120 Y000120 | 001.44
T08 X000140 Y000140 | 001.96
T09 X000160 Y000160 | 002.56
T10 X000160 Y000180 | 002.88
T11 X000160 Y000180 | 002.88

and just as importantly...

2. a file containing all the SMD pad coords and auto-grouped by tool size, for example....

T01
X000790Y-00460
X000790Y-00270
X001050Y-00460
X001050Y-00365
X001050Y-00270
T02
X-00146Y000683
T03
X-00262Y-00238
X-00262Y-00111
X-00262Y000016
X-00262Y000143
X-00262Y000270
X-00262Y000397
X-00262Y000524
X000258Y-00238


This latter file actually opens up just fine as a drill NC file in USB CNC (so I now have all the points the solder dispenser needs to go to)....so all I need now is for the USB CNC software to raise a output pin signal of somekind at say Z +.0.2mm (start the dispense), then dwell (pause) depending on tool number, then release the pin signal (stop the dispense).....and then I'm done!

[Jonathan]

Brilliant ... that thing you've found is in C, so we can edit it to output exactly what you want!


It's here:

http://dale.chatham.org/Interests/El...p/dose-pro.ulp

It looks like you've outputted the pad co-ordinates not in mm, however there's a selection thing at the beginning of the code so that shouldn't be a problem. I think you'll want the format something like this, but with the right units:

T01
G0 Z5
G0 X000790Y-00460
G0 Z0.2
M8
Px
M9

(so instead of the program outputting just X000790Y-00460, it outputs that with all the above appended)

...for each line. Where M8 macro (looking at mach3, use whatever it is for diycnc) is the coolant pin which you can connect to the dispenser, M9 switches it off. Px, x is the time for the delay using the pad area from the other file multiplied by some constant which you need to work out to get the right time.

I think that should do it?