Hi Everyone,
Sorry for the long delay in updating the thread, but I have been busy (work, life, Fluxer stuff - you name it). Back this afternoon with some updates.
Power relay and MOSFET issues: I'm still receiving reports of bad power relays MOSFET failures. You will know if you are affected by this, unfortunately, as your heater will stop working. If this happens, you will need to send your heater back to me for repair.
The 14mm coil heaters with top mount temp controls have experienced more failures than the other models.
So far I have identified a few factors that contribute to this type of failure: inconsistent chip quality in the MOSFETs used in the power replays; excess resistance in the temp control circuit (due to an error on my part); and a lower-than-ideal solder temp for the heater MOSFETs (I switched to a higher temperature solder, and it has some different heating requirements). There may be more causes, too, but those are the ones I've identified so far.
If you are affected by this issue, please send me an email and I will send you the instructions for sending it back. The turnaround time for the repair is quick.
Thanks for your patience, and sorry for the rough edges...
14mm coil vs 15mm coil:
Some 14mm coils run very hot. Some merely run hot.
As was mentioned up-thread, the 14mm + Ti tip combo can be especially unforgiving if the heater over-performs just a little bit. The temp control doesn't always do much to reduce temps in this situation, as the very close coupling afforded by the tight work coil "wins" over the lower power you send to the heater - the material near the edges of the chamber may still char due to the longer heating time, even of the heat is a bit lower overall.
If you got a heater with a 14mm coil and find you hate it, I will be happy to change it. Send me an email, we'll work it out.
The 15mm coil is also a nice size. It seems to respond better to the temp control than the 14mm. (And a shout out to
@affirmative_dave__ a friend IRL, for that great 15mm coil user report!
) I think people will like the 15mm coil a lot once they try it.
One thing I have learned while working with these various coil sizes is the importance of winding a tight coil. I think my earliest 16mm coils weren't wound as tightly as they could have been, and this made some 16mm coils perform like 17mm coils. This can be fixed with a new coil, BTW.
Additional thermal fuse:
Starting immediately, I am adding a second thermal fuse to the circuit. It tucks in against the front side of the coil:
This will protect against runaway heaters issues while on the mains power adapter. I need to do some more testing to be sure, but this may also make it possible to operate the heater from a mains power adapter with the batteries removed.
The new fuse will be 115°C, will be normally open, and should be transparent unless/until tripped. If tripped, it will short the positive and negative paths of the circuit, tripping the power fuse and immediately stopping the heater from operating. Once the heater cools down, the power can be cycled and the heater circuit will be restored to regular operation.
This is intended to serve as a secondary safety check and an absolute kill switch for excess heat/runaway heater situation.
I will also be adding this to units that come back to my bench for repair, or any Fluxer heater that wants one.
Lists, progress, waiting times:
The list is long, my progress is slow, and some folks feel like they have been waiting forever.
Thanks for your patience. I had more delays in February than expected, plus the shop was offline for a week, so...not a lot of progress to point to, especially when coupled with the power relay failures that require repair. Thanks to everyone who still wants a heater.
One ray of hope here is that some schedules have changed lately, and as a result I may be able to squeeze a bit more shop time into the week. Since I am the bottleneck, that has to help, lol. Thanks for your patience.
I will wrap this up for the moment, as I need to run some heaters over the the post office before it closes. Thanks for all the kind words and the feedback, which is especially welcome in light of these damn power relay issues some of us have been contending with. If you are a customer and were affected by this - thank you!
Cheers,