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Messages - Stonemull

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1
Mini CNC / Re: Corexy plasma cutter
« on: July 10, 2018, 07:44:06 AM »
1 step closer, added the holder for the Y carriage pulleys and X carriage beams.

1 step backwards, shattered one of my idler mounts trying to move it on the beams with a wooden hammer.

Photo of both..

2
Mini CNC / Re: Corexy plasma cutter
« on: July 07, 2018, 12:03:39 PM »
Yeh, already own that .. a 50A pilot arc plasma cutter. I forget the brand, bro bought a 60A Cut-60 (older model) and the thing only lasted a few days though it got a hammering by one of his employees, blew one of its 6 pairs of mosfets, I replaced them and they blew instantly, so ended up just removing them so he now has a 50A one as well I guess :)

I bought a sheet of 1.2mm steel a while back so thats been the goto, set to around 20A its a hot knife through butter, I need to keep a tiny gap though if possible as it does get tacky to the steel if you dragcut, which means its shorting the plasma to the cutting tip internally which stuffs the tips.
I have tested it with some larger stuff, like 10mm rebar. I have an old landcruiser that needs gutter replacement and thought this would be good to chop out suitable size sheets the right shape.


3
Mini CNC / Corexy plasma cutter
« on: July 07, 2018, 06:39:14 AM »
Not sure if right forum area, seemed suitable though..

Hoping to get some advice here on some of the experts, I am sure I will need it, I just uploaded the files/photos/stls to thingiverse at https://www.thingiverse.com/thing:2993546

current build state is as posted, so I still have to cut the horizontal steel, mount the thing, make a main carriage for the plasma tool, add a carrier for X axis, not sure whether to do a single or 2 rows of steel for the axis, idlers, belt clamps etc  .. then all the electronics and find a functional grbl that works with SD cards etc (I have a mega board with LCD, sd card holder etc, just no code for it)




4
T2 Engraving / Re: Gerber confused
« on: May 16, 2018, 07:18:27 AM »
just tried it and it works, import gbr then autotrace with T2.







5
T2 Engraving / Minor bug on exit
« on: April 25, 2018, 09:49:35 AM »
Not sure if it has been mentioned, got me twice so far .. "are you sure you want to exit without saving" .. traditionally hitting "cancel" takes you back to the software, not exits :)

I just did a perfect PCB, forgot to save the profile or note the settings, doh!



6
Trouble Shooting / Re: Wireless Engraving?
« on: April 24, 2018, 08:43:45 AM »
I have run mine wirelessly by programming an ESP8266 with ESP-Link and plugging it into the laser bluetooth connector, then you need to install com2TCP on your computer and connect it to the ESP and give yourself a virtual com port, then just print via that comport, works ok.

You should also be able to do it using a bluetooth-ttl serial adapter like http://www.ebay.com/bhp/bluetooth-ttl as long as you have a bluetooth dongle on your PC and a driver capable of bluetooth serial profile, old blue soleil should do it.


..and it was perfectly safe, it is only like 8 feet away, more reliable than a long USB cable, I would claim its safer cause you have less chance of glancing at the thing. Pretty sure I would know if it caught fire from the crackling sounds.


 

7
Projects / Re: PCB solder mask
« on: April 24, 2018, 08:33:06 AM »
Finally some success, no luck at all using the laser to expose it but I can sure nuke it, so there are probably better masks out there like high temperature paint maybe since the UV cure side of things is useless (unless you want to make a film and expose it under a UV source as designed that is).

So I ended up with 0.05mm resolution, unidirectional, 400mm/min, laser 200

First image is straight from the laser, second after giving it a brush down with steel wool and the third after attacking it with solder.
Solder is still a bit hesitant on the surface, so some residue remaining still but not a great deal.
It also took 15 minutes to burn .. and thats just a 12mmx 12mm region so doing the entire pcb like this would be a pain, I dont need a mask on the entire pcb though, it is just for those annoying little 0.5mm pitch things and SOIC devices like this (pads mostly underneath) that need solder paste.
Question now is that the mask layer is larger than the pads, so if I lasered this over the top of an IC would it burn the fibreglass all around the pad.
Might need more tuning yet.



8
T2 Engraving / Re: Gerber confused
« on: April 24, 2018, 06:53:12 AM »
heh, I just dropped by to say that I think the scale is 10X out :)
It is reporting a size of 69.7 x 48.1 when it is more likely 7mm x 4mm, the "pcb" size is actually 10mm x 13mm but I am plotting that layer with the edge cuts turned off.

Ok, I will try it with a larger format, add a second copy and see what happens.

ok, if I leave the edge cuts on and have the board >10mm on both axes I can get a working import. will give it a go, trying to burn through etch resist now.






9
T2 Engraving / Re: Gerber confused
« on: April 24, 2018, 05:07:56 AM »
No easy way with flatcam, just not laser friendly, ended up importing as a .plt file, tried putting tape on glass and then on copper and burning the vector pattern.
It seems to cut the tape easily enough but leaves the glue layer behind, trying to peel the tape off usually tears it, even if you lightly press it down I think the heat sets the glue hard.
image shows the scale of what I an trying to do against a matchhead and the land pattern for the type of chip in question. That bit of tape I did peel off and move hence the tear in it.
This was at speed 600 and laser 200 I think.


10
T2 Engraving / Gerber confused
« on: April 24, 2018, 02:45:28 AM »
Sorry guys, been a bit busy working and stuff and not had much time to play.

I know its not big on your todo list, just trying to make sense of the gerber import, was trying to blast some kapton tape with a solder mask, just a generic SOIC powerpad chip by itself and I end with tiny dots for mask/paste and copper layers.
Attached is the gerbview plot for the mask (green) and either paste or copper layers (white, they are identical) and the T2 import of the gerber.
Also attached the gerber of the mask layer, I figured it doesnt come much simpler than a single square padded device, is there a workaround maybe?

Anyway, I will see if I can get Flatcam to process it for me, just MUCH prefer T2 for these jobs :)






11
Projects / Re: PCB solder mask
« on: February 27, 2018, 03:58:09 AM »
I finally got around to assembling the board from a few days ago and this mask stuff is sooo unforgiving!
It needs a far more thorough stripping than I gave or the 'clean' copper is basically unsolderable. It looked clean but it must have had microscopic film or blobs of resist and about the only thing that helped was scratching away with a stanley knife.
That means the resist has to be exposed well to allow a good cleanup, something that will be impossible with the 2 wavelengths I have tried so far.
Maybe it would be possible if the laser had no side flare, as it is off when travelling over the areas to be unexposed, however it still partly exposes, enough to be the major issue. So it must just be speckle off the lens surface .. perhaps dropping the lens down really low ? I need a point source .. might be worth finding a more precision lens.
The other thing that might help is just using a much thinner layer of mask, clutching at straws here :(

12
Projects / Re: PCB solder mask
« on: February 24, 2018, 06:19:07 PM »
I have tried kapton to use as a solder paste stencil and the 2.5W does cut it, it had some issues that I can't remember off hand, being orange it absorbs the energy just fine. I think I needed to do more research, are nuked polyamide fumes dangerous ?
I was doing it in situ though on the pcb and the power needed burnt the fibreglass too, I then found that black insulation tape gave better performance with cleaner edges .. apart from being vinyl with nasty fumes.
I might revisit it with a mask in mind.
The main issue is that masks are larger than the pads, stencils are same size or smaller, so you often end up with only a few microns of material between pads on the mask with smaller pitch devices.
I will update after more researching..


13
Projects / Re: PCB solder mask
« on: February 24, 2018, 07:14:13 AM »
Solder mask, would help with 0.5mm pitch components.
Etched a board last night and spent the last few hours trying to get it right, no luck so far.
Mainly due to lining up the mask with the pcb on the laser, you have to add some lines on the mask layer at 0,0 and the diagonal corner to assist in alignment as T2 will trim the gerber to the pad extents if you dont, the 0,0 is no longer where you expect it to be.
Despite the misalignment I still let it expose and "developed" it, I got it partially right only once.
I think the issue is that the laser is on most of time and scattering from the lens is enough to partially set the resist.
My first attempts were at 0.05mm resolution, at 6000 mm/min the resist falls off, at 5000 mm/min .. none of it comes off unless you use acetone, then it all comes off.
Dropped to 0.1mm resolution to reduce the time spent over the board, still nogo, photo shows the best i managed it so far, simply not enough setting of the UV resist, I think I need a different wavelength, all I can find so far is it should be 350-400nm.
UV sunlamp set the resist hard in a few minutes though, I may have to use a film technique which I do not want to do or I might as well use it for the whole method.

Only a protype design so I did not really want resist on this one as it will have wires tacked all over it, also big pitch an no need for it, but good to experiment on, now I am depressed :(


14
Projects / Re: PCB solder mask
« on: February 23, 2018, 07:14:07 AM »
will zap it with extra UV afterwards, either leave it in the sun or hit it with my mercury lamp. just been wiping it off and trying again so far, I did have to use a paint scraper at one point, even steel wool wasnt getting it off.
The laser is not fully hardening it, however the pads were not clearing if I zap it more.
It says to use petroleum or petroleum based solvent to use to wipe it off, hence trying isopropyl, dry cleaning fluid and acetone so far..
Some people use thinners.
Still experimenting a bit. its only a little over $2 delivered for a tube of this stuff so worth an effort.


15
Projects / PCB solder mask
« on: February 23, 2018, 02:33:02 AM »
UV curable solder mask, dab a little on the pcb, squish with transparent film and smooth out with a bearing. Use T2, import solder mask gerber and then invert, need a negative.
Tried a few exposures using my plotter with the 405nm 50mW laser and the 2.5W laser.
Speeds down to 1000mm/min and power 100 on the higher powered laser, no curing occured.
On the 405nm at full power, 5000mm/min left me darker patches over the pads (where there shoukd be no mask) however even acetone would not remove resist, increased to 10000mm/min and had first success, excess removed with isopropyl alcohol, acetone still too violent and removed exposed material easily.
So somewhere between 5000-10000 mm/min at 50mW 405nm will be the magic spot.
Will toughen it up with further exposure to UV later.


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