>
> The URL for the oven I was looking at is
> <http://www.johnlewis.com/stores/product.asp?sku=230196563>. #79.50.
>
> What I would like is a service manual for the Maxi Oven. I want to replace
> the thermostat with a thermocouple, a PIC and a really beefy triac or
> relay.
> Why? Because the thermostat in the oven is most likely designed to be
> accurate over a 30 minute period - for soldering it needs to be accurate
> over
> a much shorter timespan, with a better temperature slope.
> I think it's time for a "PIClist Group Project", don't you? :)
>

> > What I would like is a service manual for the Maxi Oven. I want to replace
> > the thermostat with a thermocouple, a PIC and a really beefy triac or
> > relay.
> > Why? Because the thermostat in the oven is most likely designed to be
> > accurate over a 30 minute period - for soldering it needs to be accurate
> > over
> > a much shorter timespan, with a better temperature slope.
> > I think it's time for a "PIClist Group Project", don't you? :)
> >
>
> You've got me interested.

> As far as temperature control goes, you'd need to override the oven's
> onboard
> thermostat. If the oven was out of warranty, I'd rip the cover off and
> replace the thermostat with a solid-state relay or a triac. Otherwise, the
> best option (AFAICT) would be to lock the oven thermostat at maximum, then
> let a PIC based circuit control the power externally. It also saves
> tracing
> out wiring and the messy business of voiding warranties. I doubt any
> reputable manufacturer would still offer a warranty on a toster oven that
> had
> been used for SMD reflow, though :)
>

>------------------------------
>
>Date:    Sun, 4 Jul 2004 03:45:28 -0000
>From:    Martin Klingensmith <KILLspammartinKILLspamNNYTECH.NET>
>Subject: Re: [OT:] SMT soldering oven was: Death ..
>
>
>
>>In message <4794.24.58.201.94.1088884436.squirrel@24.58.201.94>
>>          Martin Klingensmith <RemoveMEmartinTakeThisOuTNNYTECH.NET> wrote:
>>
>>
>>
>>>Add some Kaowool [fibrous high temp insulation] and it will reliably go
>>>up
>>>to this temperature quicker.
>>>
>>>
>>Hmm. Never heard of that stuff - I'll have a look online later.
>>
>>
>>
>
><infoarchive.net/sgroup/hobbicast/?keywords=kaowool+sources>
>ITC-100 is another thing to look for. They're just different types of
>insulation. ITC-100 I believe is colloidal zirconia and reflects almost
>all infrared.
>
>
>
>
>
>>I found a similar mini-oven in the Argos catalogue for about #50, so
>>that's
>>probably a slightly better option. I don't feel like spending #80 on a
>>toaster oven, just to solder up a few boards, especially when my soldering
>>station only cost #65 :)
>>
>>
>
>You could even take a metal box, but some suitable insulation or fire
>bricks in it, and buy some nichrome wire to make your own. It should cost
>less and be better for the relatively high temperature.
>
>
>
>>As far as temperature control goes, you'd need to override the oven's
>>onboard
>>thermostat. If the oven was out of warranty, I'd rip the cover off and
>>replace the thermostat with a solid-state relay or a triac. Otherwise, the
>>best option (AFAICT) would be to lock the oven thermostat at maximum, then
>>let a PIC based circuit control the power externally. It also saves
>>tracing
>>out wiring and the messy business of voiding warranties. I doubt any
>>reputable manufacturer would still offer a warranty on a toster oven that
>>had
>>been used for SMD reflow, though :)
>>
>>
>>
>
>I wouldn't ever buy a new toaster oven to solder boards in anyway :)
>A J or K thermocouple circut with a very simple microcontroller would work
>well for this.
>--
>Martin Klingensmith
>
>

> Well, this little guy gets up to
> 300C in 7 minutes flat.  It's actually just a little slow getting
> from ambient to 100C, but I'm thinking that's not going to matter too
> much.   I'm just going to do a little controller with a thermocouple,
> PIC and a triac; putz with the temp profile after I settle on what
> kind of solder paste I'm going to use, and just see what kind of
> result I get. This whole approach appeals a lot to me, since my
> eyesight isn't what it used to be, and the idea of hand soldering
> fine-pitch stuff just seems likely to cause a lot of frustration. So,
> I'm on the experimental path!   I'll post my results soon!

>
> Hi,
>
> > Ok, what?  The lead doesn't vaporize.  Not at all, at the temperatures
> > we're talking about for correct reflow; it's just barely MELTED, and
> > that only because of the alloying with the tin.
>
>     I can agree with that but I would never try myself ;-)
>
> > The rosin or similar compounds shows up in assorted herbs and liquers;
> > If there's enough in food to hurt you, you'll taste it...
>
>     The no clean flux on solder paste is quite "strong" and not natural
> stuff at all. Not much of "herbs" and "liquers" in it. It is very different
> from the resin that we see in regular solder wires. It can be quite a good
> stuff to help someone build cancer or other diseases... Any residual amounts
> can be quite bad for health if eaten. You should take a look at the papers
> that come with the solder paste.
>
> > It's not a good idea to reuse the oven for food, but I doubt that it's
> > likely to cause serious problems, either.
>
>     I think it would be a VERY bad idea to try it... And maybe even a worse
> idea to say it is not dangerous to a list with 2000 people....
>
> Best regards,
> Alexandre Guimaraes

> On Sun, 4 Jul 2004 18:30:53 -0700, Jim Tellier wrote:
> > FWIW, *me too*!  I happened to go into FRYS this afternoon, and by
> > chance wandered down the "toaster oven" aisle (!)... I saw an el-
> > cheapo "Maxi-Matic" 650W, 2-element job on sale for $18 (!).. so I
> > said, hey.. if it ain't up to snuff for SMT reflow, I can always use
> > it to toast my bagels in the morning!!
>
> ***** PLEASE ***** Don't EVER use your toaster oven for food after it's
> been used to solder SMT assemblies. There are very bad things in the
> solder paste mixture you don't want to ingest and once they have been
> vaporized inside the oven you can't get rid of them!!!
>

>
> On Jul 4, 2004, at 9:17 PM, Matt Pobursky wrote:
> >
> > ***** PLEASE ***** Don't EVER use your toaster oven for food after it's
> > been used to solder SMT assemblies. There are very bad things in the
> > solder paste mixture you don't want to ingest and once they have been
> > vaporized inside the oven you can't get rid of them!!!
>
> Ok, what?  The lead doesn't vaporize.  Not at all, at the temperatures
> we're talking about for correct reflow; it's just barely MELTED, and
> that only because of the alloying with the tin.

>
> As suggested earlier, use Kaowool or other brand of ceramic fiber
> insultation, it handles pretty much like fiberglass but it's a bit more
> brittle (wear gloves!). I use it for very hot things like kilns and
> forges. Your local pottery supply store should have some or know where
> to get it.
>
> Make sure to coat the inside with collodial silica (rigidizer) so you
> don't get the particulates all over the place. It's not good for your
> lungs and probably wouldn't be good for the boards either. Coating the
> inside with ITC-100 after that would probably be $$$ overkill.

>
> The whole lead-in-solder-smoke thing was researched on this list about a
> year ago.  Basically, lead is not present in solder smoke in sufficient
> quantities to bother you.  it is the REST of the components of solder
> smoke that are bad!  My policy is to have a smoke absorber handy at all
> times when soldering, and make efforts to use it.  The chief risk is
> occupational asthma, the rosin smoke apparently does some kind of lung
> damage and leaves you wheezing after chronic exposure.
>
> You can buy a nice fan from Hakko, or you can hack one together out of an
> old muffin fan.  A filter is good, to pick up the particles, but gettting
> the stuff away from your face is the big issue.