Posted Sat Nov 12, 2005, 11:22am Subject: Re: Z&D Update
Thanks for the comments.
Sometime back while I was ordering a chaff screen or something from Lisa at Z&D I mentioned this string and recomended that she check it out. I think at the time I just had the thermocuple probe installed and the roaster leads coming out of the case. It was primitive, but it worked and the concept of a higher power roast heater and temp probe in the roast chamber were there. I don't know if she checked it out or not.
It could be that their liability lawyers saw it and went into spin-dry.
I believe that if they were to put a temperature probe into the roast chamber and replace the 400 watt roast heater with a 700 watt heater controlled with a phase control lamp dimmer, they would have a machine which Coffee Geeks would be lineing up to buy and it wouldn't cost them much.
Wow Phil those are some extensive mods! Have you considered sharing your ideas with Z&D for their someday next generation roaster?
Thanks a lot for sharing your ideas and hard work!
Posted Thu Jun 21, 2012, 1:57pm Subject: Re: Z&D Update
This is the latest update to my Z&D. Since I started with this thing I have been boosting the voltage to the roast heater to get a faster temperature vs. time ramp. With my variable transformer I can get to 150 volts which raises the power of the roast heater to ~ 625 Watts from the OEM 400 Watts. This of coarse has rendered the roast heater a consumable. Z&D and now Nesco would not hear of selling me roast heaters. I have been getting by through the generosity of CoffeeGeeks who have sold or given me their dead machine to harvest heaters from.
Since I was on my last OEM heater and it looked pretty decrepit I have been pushed into doing what I've been talking of since 2004. I have installed a more powerful heater into the machine.
The Doner nichrome coil came from the corn popper heater shown below:
Posted Thu Jun 21, 2012, 2:04pm Subject: Re: Z&D Update
The image below shows the "new" coil and the remains of an old OEM coil. Note the string inside the coil. I would like to know what the material is. I did untie it successfully but looking at it with little fibers dropping off I have to wonder if it should be used near something which I plan to ingest. I elected to not use it.
Posted Thu Jun 21, 2012, 2:34pm Subject: Re: Z&D Update
Since I elected to not use the questionable string the coils looked as they could expand and touch the mounting screws. I have used a three wire cord and grounded the exposed metal parts so there is no hazard except to the coffee in the even of the roast getting interrupted by a short. I crammed some mica sheet between the screws and the coil and secured it with RTV.
I am regarding this as a prototype as I want to get rid of the mica altogether. The mica does stand the heat however it does deteriorate.
Ultimately I want just Nichrome and ceramic but this will give me an idea how a high power heater controlled by a phase control dimmer works compared to the OEM heater powered via the variable transformer.
So far I think I am going to like it although I had to go easy on the heat to avoid smoke from the not fully cured RTV. One thing I did notice is that the EMI from the router controller effected the electronics in the machine as when I changed the power the speed of the motor would change. It is not a problem except when speed changes in a Z&D one worries that the auger bearing is about to seize.
Below is a picture of the variable transformer which I used with the old heater next to the Harbor Freight router controller which I now use.
Posted Tue Jun 26, 2012, 12:01am Subject: Re: Z&D Update
So far I am liking this configuration. The RTV smoke has subsided so I can run it full power (~800 Watts). This is a bit more margin over the old configuration. I no longer have to worry about room ambient temperature. For the next iteration I may go for ~ 1000 Watts.
Posted Tue Jun 26, 2012, 2:53pm Subject: Re: Z&D Update
The new coil is mounted on the form of a failed roast heater.
I'd like that heater which you are showing in there. I have thought of extending the bottom of the machine and supporting the auger drive shaft on two bearings spaced farther from the roast heater and having room for a heater which you are showing.
What my next iteration will probably look like is a bunch of ceramic stand-offs mounted to the roast chamber metal and the heater supported on the standoffs with no mica. I am looking at the ceramic parts which you gave me.
I hope to have this completed before the present configuration fails.
You should be able to easily handle 500 gram loads with 1KW.
btw - That 'new coil' mica photo looks like the 'after-burner', not the heater, correct?
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