Making your own pcb's.

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zmemw16
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Re: Making your own pcb's.

Post by zmemw16 » Thu Oct 19, 2017 10:16 pm

@roger
i meant use the circulation fan out of one, not using a fan oven :lol:
srp

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RogerClark
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Re: Making your own pcb's.

Post by RogerClark » Thu Oct 19, 2017 10:35 pm

zmemw16 wrote:
Thu Oct 19, 2017 10:16 pm
@roger
i meant use the circulation fan out of one, not using a fan oven :lol:
srp
OK

I tried to get hold of a cooker fan, but they were not easy to source.

I see Amazon in the US has them for $11 USD, but I can't find a local supplier in Australia.

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Slammer
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Re: Making your own pcb's.

Post by Slammer » Fri Oct 20, 2017 12:32 am

Andy Brown is using common halogen oven with STM32 based controller.
Take a look : http://andybrown.me.uk/2014/05/11/awreflow

zmemw16
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Re: Making your own pcb's.

Post by zmemw16 » Fri Oct 20, 2017 2:15 am

as usual with Andy Brown's stuff, very comprehensive :!:
srp

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Slammer
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Re: Making your own pcb's.

Post by Slammer » Sat Oct 21, 2017 4:28 pm

My concern about halogen ovens is about stability (eg. vibration) of rack inside oven and how this affects the pcb. For reflow I have used an Electic Crepe Maker (hot plate actually) with very good results. Crepe Makers have acceptable flatness and temperature distribution.
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victor_pv
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Re: Making your own pcb's.

Post by victor_pv » Sat Oct 21, 2017 8:30 pm

Well, yesterday after an hour placing little bits of solder and components in the board, I tried the skillet method. This is a large board, 100x140mm.
The solder went fine, but overheated in the center, because the skillet was not totally flat, and burnt the botton of the board.
Amazingly enough, all the copper contacts were still fine except for a small ground area, so I broke that off, applied a bit of nail polish to protect the solve, and completed the board.

If it doesn't work, I have another 9 more to fine tune my skills ;)
Next try I need to 3d print a stencil because applying the solder by hand was a pin in the but. Also I used a lot of 0603 components, big mistake since I have enough space to have used 0805 for all of them, but well, that will go to rev 2 of the board.

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RogerClark
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Re: Making your own pcb's.

Post by RogerClark » Sat Oct 21, 2017 8:57 pm

Your 3D printer must be a lot better than mine ;-)
Min layer size is probably going to be too thick e.g. .2 or .4mm
Edges are messy.
Positional accuracy is perhaps 0.5mm at best on my Mendlemax 1.5

victor_pv
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Re: Making your own pcb's.

Post by victor_pv » Sun Oct 22, 2017 2:04 pm

0.2mm is the thinnest I can print, but metal stencils seems to be around that thickness too.
Will have to test and see what happens...

Woud you say the T-962 is not worth it even with the open source firmware and cold junction modification?
I have been reading on modifying a toaster oven, and seems like a lot is needed to make it reliable. i.e. insulation, sealing, add a controller, add/replace heating elements... at the end of the day after all that is a lot of time and perhaps the same cost as a t-962 in ebay.

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RogerClark
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Re: Making your own pcb's.

Post by RogerClark » Sun Oct 22, 2017 8:41 pm

I bought the T962 because I thought it would end up being cheaper and more effective than modifying a toaster oven.

However, I never had any success with it, even when running the open source firmware.

The readings I got on the 2 temperature probes, were more than 20 deg C different from each other, so I bought new probes, however that didnt help
I bought 5 new probes, and tried them, but the results were the same, i.e I cant get an accurate temperature reading.

I put an additional probe on the tray, but it didnt help as that probe showed a differnt temperature to the other two ( which are in the top of the oven)

I tried to solder a few test boards, just with cheap components e.g resistors, but the resukts were very inconsistent. Often the solder had not melted.

I think the issue is that effectively this is not a hot air reflow oven, its the 2 radiant heat elements in the top of the oven, which heat by radiation as much as by convection.

Perhaps some people made these work, but I have yet to see a youtube video of someone showing consistent results, except of they made a lot of modifications e.g. fitting a convection fan

racemaniac
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Re: Making your own pcb's.

Post by racemaniac » Mon Oct 23, 2017 7:58 am

I think i already mentioned it here, but for stencils i bought a silhouette portrait cutter, and it's amazing :). i cut stencils from overhead slides, and it has no problem going down to 0.4mm pitch pins, and creates great stencils :).
the machine only costed 150€ new, and i use it with a free python script that converts a gerber to instructions for the printer :).

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