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Alernative to Eject Solenoid
NoTan2
Hi All,

Has anyone found a practical alternative to the eject solenoid?

Every six months or so, my solenoid jams in the closed position. I always keep a heatproof glove handy and it's just a matter of removing the front door and the beans will spill out into the cooling tray.

However, I then need to pull the machine apart, clean the pin which slides into the solenoid and reassemble. It's only an hour's work but eventually the threads on the screws and self tappers are going to get stripped.

I'm half inclined to try to replace the solenoid and pin with one of my spare model aircraft servos but I don't know if it would survive in such a harsh environment.

Has anyone gone through this exercise and found a suitable solution?

Thanks,
Paul.
Randy G
Have you also cleaned the bore of the solenoid coil?

Life's too short to drink bad coffee.
RedAce
I don´t know the Hottop internals very much, but I am also a RC modeller and I would not use regular RC servo in a roaster. Maybe some robust servo with metal case and gears would work in such environment but I wouldn´t consider it a big upgrade in reliability. Maybe a stepped motor for 3D printer would be a good alternative if you want to mod the original setup...
renatoa
Maybe a retract servo for landing gear, or winch servo, for navy, these are special build servos, using a worm gear instead regular gear, capable of outstanding torque, and shock resistance.
Randy G
If you find a replacement that runs on AC line voltage and can take the heat, smoke, oils, water condensation, and particulate matter, you will also need to use an additional relay and likely a power convertor as well as the room to mount it all safely.

Hottop starting using drip shields over the solenoid and I think that they pretty much eliminated early failure of the solenoids. If you change the stock solenoid be sure to also get and install the drip shield. You will need to drill and tap two holes for it (or use self-tapping screws for metal).

Life's too short to drink bad coffee.
NoTan2

Quote

Randy G wrote:

Have you also cleaned the bore of the solenoid coil?


Actually no, I didn't and I certainly should have thought of that.
That's an excellent suggestion for next time.

Thanks Randy.
NoTan2

Quote

RedAce wrote:

I don´t know the Hottop internals very much, but I am also a RC modeller and I would not use regular RC servo in a roaster. Maybe some robust servo with metal case and gears would work in such environment but I wouldn´t consider it a big upgrade in reliability. Maybe a stepped motor for 3D printer would be a good alternative if you want to mod the original setup...

Yep, the more I think about it, I can't imagine the internal grease or either plastic or Karbonite gears lasting very long.

I've got a draw full of stepper motors that I've been playing around with for my robotics and astronomy hobbies. They're el-Cheapo brand so they'd probably melt as well.

Quote

renatoa wrote:

Maybe a retract servo for landing gear, or winch servo, for navy, these are special build servos, using a worm gear instead regular gear, capable of outstanding torque, and shock resistance.

I've been looking at the Hitec website to see if they had any "extreme heat" servos. Couldn't see any but there are certainly a significantly greater variety than last time I looked.
NoTan2

Quote

Randy G wrote:

If you find a replacement that runs on AC line voltage and can take the heat, smoke, oils, water condensation, and particulate matter, you will also need to use an additional relay and likely a power convertor as well as the room to mount it all safely.

Hottop starting using drip shields over the solenoid and I think that they pretty much eliminated early failure of the solenoids. If you change the stock solenoid be sure to also get and install the drip shield. You will need to drill and tap two holes for it (or use self-tapping screws for metal).

I agree - I don't think I could reasonably improve on the existing solenoid as it works well until it gets gummed up.

But a drip shield - that certainly bears thinking about. I wasn't aware that Hottop was fitting them in later models.
NoTan2
Thanks to everyone for your good advice.

I'll definitely put some thought into Randy's drip shield suggestion. That seems to be straightforward.

I'd be happy to open the door manually each time if I could fabricate a subset of the UK100 kit. It's no great burden to hit the Eject button and then pull on a knob to hold the door open until all the beans are out of the roast chamber.

In the meantime, I'll remember to clean the inside of the solenoid and if I strip any threads, I'll deal with it at the time.

Many Thanks.
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