SC/TO Profiles / Q&A / Tips & Tricks

[sea330]

Stevea if you need a GG heating element I have a spare I could throw ya. These things are hard to find any more. I have 3 as back ups so I probably have a life time of extra TOs. This one is from a GG that my Brother dropped, I broke it down for parts, email me if that would help. Rich

[stevea]

Stevea if you need a GG heating element I have a spare I could throw ya. These things are hard to find any more. I have 3 as back ups so I probably have a life time of extra TOs. This one is from a GG that my Brother dropped, I broke it down for parts, email me if that would help. Rich

Sincere thanks sea'.  However I'm now using my virtually new (was a backup) GG-TO.   The old one lost the heating element, arc'ed a hole thru the metal divider, ruined some internal insulation and also the fan motor ceased to work (I didn't try to debug that).   So the old TO was a total loss aside from a  few parts in the bin.  I'd been using it since ... sheesh 2004!, and it looked like it had been through a war.  So "Farewell, Aquarius, and we thank you".

I'm searching for a backup TO unit top and I'll work eBay before I try to raid your stash - but thanks - your generosity is impressive.

===

I've actually tried the "bolt in the socket" idea but the bolt isn't very stable thru the teflon pan hole (which is large).  This old thread has some good ideas, but I think you really need to j-b weld a washer to the pan or something.
http://coffeegeek.com/forums/coffee/homeroast/125259?LastView=1377846314&Page=2

[peter]

I've actually tried the "bolt in the socket" idea but the bolt isn't very stable thru the teflon pan hole (which is large).  This old thread has some good ideas, but I think you really need to j-b weld a washer to the pan or something.
http://coffeegeek.com/forums/coffee/homeroast/125259?LastView=1377846314&Page=2

I forgot about the diameter of the hole being so much larger than the diameter of the bolt; I'm sure it's not a good idea to rely on the pressure of the jam nuts/washers to keep the bolt centered in the hole.  Perhaps there would be some thick-walled, hi-temp nylon or even metal tube that could serve as a spacer in there.

I've often thought about asking my machinist brother to replicate the original shaft on his lathe.  But then I wonder if the original plastic shaft does a better job of not transmitting the heat to the motor.  Now, I'm wondering if I could make something out of hardwood...

[stevea]

Well I took two steps - I used some J-B weld to hold the socket down in -place and this seems to work well.  However I also bought a new SC (Best-Buys, $30) and used washers & 2x nuts & a copper cap.   And that works well too (got 2x roast on each).

I'm currently enjoying a blend of Peter's Burundi + some Harrar longberry.- works well.

Oddly (pix below, mix) I have 2x examples of some VERY unevenly roast beans from the "socket not working" event, and I have to say they taste very good despite (or perhaps b/c) of the uneven roast.   The beans (one a Minas, the other a Sidamo) vary in color for 'toasted peanuts' to oily-dark not-quite-italian tho' most are decent color  and ...   I normally shoot for city+ and the average here is about that, but the gross variation in roasting has produced both good acidity AND deep, vibrant flavors.

I THINK I'll try pulling a little sample early AND late int the next burn-off and see if I can achieve similar results.

[dlofx]

So I just built my SC/TO after acquiring parts and doing research after the recommendation was made here. Thank you for your input thus far! Truthfully, I'm pretty impressed, but there are a few bugs I'm trying to work out still. Mainly, I've had the same inconsistencies as other posters and am trying to dial this thing in. I think two areas could be to blame: Heating and Agitation.

Heating
While I'm absent a thermometer at the moment, my roasts thus far are in the 22-25 minutes to 2nd crack range (12oz of beans). I think this is a bit long. That said, I think I may be losing heat to the chaff ejection I'm using. Not only out the outlet hole, but also where the glass top of the oven meets the ejector. Is this reasonable to suspect? Can pre-heating make a big difference?

Agitation
I think the other issue that may solve some of the inconsistency is the agitation of the beans. Thus far, it seems as though the stock stirrer just pushes the beans in large piles, slowly discarding. I know there are all sorts of mods for these things, but does anyone have good experience with a particular design? I did swap the nylon shaft for the 1/4" socket / bolt combination. While putting plumbers tape stopped some of the rocking, I don't know that this is a long-term solution. I did see a nifty machined one in this very thread I may inquire about. Anyways, any input helps! I put some of the parts below for your reference.

Thanks in advance...glad to be a part of this place!

Resources
I used the socket shaft concoction seen here: http://biobug.org/coffee/turbo-crazy/sc-mod/
I used the woz chaff ejection seen here: http://turbocrazy.atspace.com/index_files/updates.htm
I used the Oyama turbo oven: http://www.amazon.com/Oyama-TRO-110U-Turbo-Convection-Oven/dp/B003XJE60U/ref=sr_1_2?ie=UTF8&qid=1382487794&sr=8-2&keywords=turbo+oven

[peter]

How high is your spacer?  Too high and you move the heat source far away from the beans.

The shaft concoction w/ the wobbly socket and all that is a worthless mod in my opinion.  As is the Woz chaff ejection thing.  The spacer can be made to spring shut, and be propped open only during the times when chaff can be a problem or when you want to modulate the temps.

Usually when the beans are clumping instead of being stirred, the volume of beans is too low.  But I'm afraid to say use more if your roasts are already taking too long.  Is your shaft mod allowing the arms to skim just barely above the surface of the SC?

[dlofx]

How high is your spacer?  Too high and you move the heat source far away from the beans.

The shaft concoction w/ the wobbly socket and all that is a worthless mod in my opinion.  As is the Woz chaff ejection thing.  The spacer can be made to spring shut, and be propped open only during the times when chaff can be a problem or when you want to modulate the temps.

Usually when the beans are clumping instead of being stirred, the volume of beans is too low.  But I'm afraid to say use more if your roasts are already taking too long.  Is your shaft mod allowing the arms to skim just barely above the surface of the SC?

The spacer is 1 1/4" wide aluminum. I did see someone using some sort of wood to wedge the gap open to better control heat and chaff. I may just spring for another $6 at Lowe's and try another one without the screws, which in all honesty was probably the biggest pain assembling for me. As for the shaft, I spent a good amount of time tweaking it to get it at the the same height as the stock one and the plumber's tape seems to do the trick in terms of the wobble, provided you apply it to both the bolt head and the motor. I just worry about how long that will hold is all. If it does end up breaking, should I put the nylon one back in there and do the copper cap deal?

Curious if you are using the stock metal stirrer or have you made any mods to yours? Off your comments thus far, I think my next step is to get myself a thermometer, put some more beans in there and see how it works. I may snap some pictures of everything this weekend if I get the chance.

I will say, that with all the problems of the first roasts, the Rwanda I got from you is fantastic this morning!

[mrjay]

The spacer is 1 1/4" wide aluminum. I did see someone using some sort of wood to wedge the gap open to better control heat and chaff. I may just spring for another $6 at Lowe's and try another one without the screws, which in all honesty was probably the biggest pain assembling for me. As for the shaft, I spent a good amount of time tweaking it to get it at the the same height as the stock one and the plumber's tape seems to do the trick in terms of the wobble, provided you apply it to both the bolt head and the motor. I just worry about how long that will hold is all. If it does end up breaking, should I put the nylon one back in there and do the copper cap deal?

Curious if you are using the stock metal stirrer or have you made any mods to yours? Off your comments thus far, I think my next step is to get myself a thermometer, put some more beans in there and see how it works. I may snap some pictures of everything this weekend if I get the chance.

I will say, that with all the problems of the first roasts, the Rwanda I got from you is fantastic this morning!

I've attached a pic of my SC that shows the spacer and the "inspired by Peter" stir arm.
Since that photo was taken, I've adjusted the chaff chute so it's only about .5" wide - I don't seem to have any issues due to heat loss or problems keeping environment temp stable, but have considered putting a silicone hose on top of the spacer to seal better. 

My SC uses the stock plastic shaft, I cut the threaded stud part off, drilled and tapped it to use a 6mm bolt.  It's been working fine for weekly or twice-weekly roasts since then (June?).  I recently picked up a spare SC and my plan is to similarly drill out the shaft and use a hanger bolt with a wing nut.

I normally roast only 250g of green beans, but have done 350g batches without a significant increase in roast time.  I pre-heat to 350f before pouring the beans in and immediately set the TO to about 400f.  When the beans look and smell like they're dry (4-5 minutes), I turn the TO to about 435f.  Looking at my roast log I see that depending on the beans, 1C is usually at the 10-13 minute mark and 2C starts 3-5 minutes after that.  I monitor both bean temp and environment temp with the thermocouples and ET stays very steady at 500f with the TO set at about 435f.

I'm gonna go out and roast a batch of washed Yirg now...

[dlofx]

I've attached a pic of my SC that shows the spacer and the "inspired by Peter" stir arm.
Since that photo was taken, I've adjusted the chaff chute so it's only about .5" wide - I don't seem to have any issues due to heat loss or problems keeping environment temp stable, but have considered putting a silicone hose on top of the spacer to seal better. 

My SC uses the stock plastic shaft, I cut the threaded stud part off, drilled and tapped it to use a 6mm bolt.  It's been working fine for weekly or twice-weekly roasts since then (June?).  I recently picked up a spare SC and my plan is to similarly drill out the shaft and use a hanger bolt with a wing nut.

I normally roast only 250g of green beans, but have done 350g batches without a significant increase in roast time.  I pre-heat to 350f before pouring the beans in and immediately set the TO to about 400f.  When the beans look and smell like they're dry (4-5 minutes), I turn the TO to about 435f.  Looking at my roast log I see that depending on the beans, 1C is usually at the 10-13 minute mark and 2C starts 3-5 minutes after that.  I monitor both bean temp and environment temp with the thermocouples and ET stays very steady at 500f with the TO set at about 435f.

I'm gonna go out and roast a batch of washed Yirg now...

Very interesting set-up and it is pretty close to what I currently have, so that's encouraging! I got one of the aluminum shafts on the way from Rich and am super excited to see that when it gets here, though said excitement does not resonate with my fiancee.

As for your set-up, I think I'm going to run to Lowe's tonight and grab another piece of aluminum and set my ejector up similar to yours. I'll also try pre-heating on my next roast and see if that does the trick. I have some Columbian from Peter I still got to try out so that will be my excuse.

If you don't mind me asking, how the heck did you concoct the stirrer you are using? It has perked my interest.

[peter]

Nice job on the stirring arm!  Looks just like mine.  Was that a coat hanger in a previous life?

If I ever have to make another spacer it'll look similar to yours, with the exception that there'll only be one screw in the opening, and the outside portion of the spacer will have a keyhole slot, so that the inner overlap can be pushed in and locked open, or the screw/nut can be moved over to allow the overlap to be closed.  You may be able to hold temps with a constantly open chaff slot, but why not keep the heat in if you can?  I like having it closed normally, and then opening it when I want to let some heat out so the temps rise more slowly, or visa versa, having it open to let chaff out and then closing it if I want to keep the heat stable w/o turning the heat back on.

[mrjay]

Yep, former coat hanger and very similar to yours but not a total copycat 

Dlofx, the stir arm is connected pretty much the same way as the stock arm.  I did cut a copper washer and fold down a couple of teeth that hold the arm better.  Coat hanger wire is a little smaller than the stock wire, so the new arm was floppy.  Also a piece of the plastic shaft eventually broke off and the teeth were a necessity at that point.  <edit> when I first read your post I thought it said "connect" and when I looked again I realized you said "concoct"... Creating it was fairly simple.  Step 1, channel your inner Peter and find a coat hanger.  Cut and straighten coat hanger and remove the paint.  Start in the middle and make a bend where the screw will wrap around it - use the stock arm as a guide and slowly work out from the center.  Bend and test fit as you go.  It is tedious, do it when you're bored and have time to kill.

The aluminum shaft sounds great - I didn't know they were still available.

Oh, and the Ethiopian Yirg I just roasted... test batch of 200 grams, 1C at 8 minutes and got quiet at 11, first snap of 2C at 13, pulled beans at 13:30

[peter]

Too funny; I did the same thing w/ a fender washer when part of the shaft busted off too.

What I like about this arm design is that it's great for really small batches.  With the stock arms you get that "angel wings" effect, where two big clumps of greens are just being pushed around w/ no real agitation.  With this arm you get some beans that tumble over, and some that slide under the hoops.  It may limit the upper-end capacity, but it'll do 100g very uniformly.

I actually made a jig out of some hardwood and some pins, thinking I could mass-produce the arm.  The initial bend in the middle would be made and placed in the jig.  Then a pin on either side would be inserted into a couple holes, and the arm bent around those, and so on.  But in the end it was still too much work, and once I had my arm I said screw everyone else.   

[dlofx]

I just got done roasting some Columbian Popayan from Peter following some comments in the last few posts and got what I think are great results! While I didn't really change anything of the set-up, the preheating seemed to really be a good chunk of my problem. Obviously, I still think I have some to gain from swapping the stirring rod and other mods but am really happy with the latest batch.

Can't wait to try it in a few days! This was right before 2nd crack and my roast times were in line with others. I think this appears to be pretty consistent overall. Input always appreciated.

[mrjay]

Looks like a nice, even roast... Good job! 
Curious, what was the roast time to get to dry beans, 1C, etc.?

[dlofx]

Looks like a nice, even roast... Good job! 
Curious, what was the roast time to get to dry beans, 1C, etc.?

Got to say, I was happy with the results! Have not tried this yet, waiting till tomorrow. The first roasts are phenomenal now, despite all my stated shortcomings. The Rwanda Rolindo was fantastic this morning!

As for this particular roast:

• Dry Beans = ~4minutes
• 1st Crack = ~13 minutes

I think 2nd would have been in line with yours. I stopped it just shy, about 2-3 minutes after 1st crack.