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building my 1st roaster
sfloyd
Top  #1 Print Post
Posted on 12/16/2024 9:02 PM
So I've decided to attempt building my first roaster. After researching I am going off this ever popular one. But I plan on making the framing more rectangular, picture more like a box. Here is that link https://www.home-...32095.html Luckily where I work there's a ton of scrap metal from a plant build out so almost all of my metal is free. I have some questions:

For my drum
1) it is 8 inches diameter by 18 inches long SS 20 qauge solid, I am getting some perforated SS for the back of it. This is the sheet I am getting https://www.amazo...0&th=1 my calculations show as about 1.6 Kilo of beans by using the volume/15 method (rounding down to 1.5 kg). Issue here?
2) for the shaft supporting the drum Should it go completely through the drum or just to a support inside the drum?
3) How far back should I place the support?
4) Vanes.... typical questions... still wrapping my head around that. But i am thinking I will do 3 sets of 3. How far back should the 1st set be?
5) should each set of vanes should be off set from the previous, so that they are not in a straight line?
6) How tall and thick should the vanes be?

For the framing
1) I will be using 1/4" reg steel for the face. Is that too thick? Same for the back?
2) I will be leaving 2" of space around the sides and top of the drum, 1" of which will have insulation. Too little or too much?
3) I calculate the box dimensions to be 12" wide, 18" tall and 20" deep. With the insulation taking up 1" on the back side of the drum, will 1" of space between the insulation and the back of the drum be enough for pulling the exhaust through?

For the burner
1) I am looking at using this one https://www.amazo...ca_id_hp_d directly in the middle of the base with a piezo to ignite it. Should this work?
2) The drum will be 5 inches from the top of the burner. Too high or too low? should I use a diffuser? If so any suggestions?
3) The burner is totally enclosed in the system. With exhaust also coming out through the face, some sort of make-up air is required. How would I accomplish this? Cut slits in the bottom or side?

I am sure I will have many mor questions to come....
Edited by sfloyd on 12/16/2024 9:17 PM
 
sfloyd
Top  #2 Print Post
Posted on 12/17/2024 1:09 PM
update. I decided to go 22 inches deep on the setup instead of 20
 
sfloyd
Top  #3 Print Post
Posted on 12/17/2024 6:24 PM
some pics of the beginnings

side wall layout
sfloyd attached the following image:
sidewalllayout.jpg
 
sfloyd
Top  #4 Print Post
Posted on 12/17/2024 6:25 PM
the drum
sfloyd attached the following image:
drum1_3.jpg
Edited by sfloyd on 12/18/2024 8:53 AM
 
sfloyd
Top  #5 Print Post
Posted on 12/17/2024 6:27 PM
for some reason its not letting me add additional pics of the drum
Edited by sfloyd on 12/17/2024 6:33 PM
 
oldgrumpus
Top  #6 Print Post
Posted on 12/17/2024 11:08 PM
I just saw this and I'm happy to see someone here diving in. Glad to see you stepping up! I had a blast building my roaster. I'm almost sorry it's done and working since I love the process of thinking through all the parts and pieces. I'd love to give you my $0.02 on some of the questions you're posing but this old man is just getting to bed here on the west coast. I'm looking forward to following you're build! I'll be back soon...
Clever Coffee Dripper
Grinder: Macap M4
Roaster: Completed drum roaster project photos shown here:
Photos https://goo.gl/ph...Da6K4wfqw5
Videos https://www.youtu...Bd1NrdpSUH
Build thread https://homeroast...post_38189
 
sfloyd
Top  #7 Print Post
Posted on 12/18/2024 8:52 AM

Quote

oldgrumpus wrote:

I just saw this and I'm happy to see someone here diving in. Glad to see you stepping up! I had a blast building my roaster. I'm almost sorry it's done and working since I love the process of thinking through all the parts and pieces. I'd love to give you my $0.02 on some of the questions you're posing but this old man is just getting to bed here on the west coast. I'm looking forward to following you're build! I'll be back soon...


Thank you, I have been wanting to make one for a while ever since I owned a coffee shop years ago but finally getting around to it. Any and all ideas are helpful. I am headed out of town for a few days and may or may not be able to come online
 
oldgrumpus
Top  #8 Print Post
Posted on 12/18/2024 10:45 AM
1. Your dimensions are in the ballpark not much different from my roaster. I also think your choice of perforated metal is just fine. I am not sure there is any advantage to using stainless steel for a drum. Stainless does not distribute heat quite as well as mild steel. Regarding upsizing or downsizing from a calculated volume is not a big deal. I wouldn't straight too much, but I don't think it is a hard and fast rule.
2. Yes, the shaft should go all the way through the drum to assure alignment on both ends where the shaft is supported by the ball bearings.
3. The placement of the support inside the drum should be at a distance back from the front plate to accommodate your tryer and bean temperature probe. You may also have return vanes that come forward a bit of the support which could also interfere with either the temperature probe or the tryer.
4. Vanes... forward enough to not interfere with probes or tryer. Here is a photo of my completed drum. https://photos.ap...YewcVjRpr9
They are flat. I mimic the layout of a Diedrich roaster.
5. Just my opinion but offset or not is not important. You are essentially making a cement mixer. Mixing may improve by a better design somewhat but I wouldn't get too bogged down over thinking things and stressing out about it.
6. Mine are 1/8 of an inch thick. I used that thickness only because it was easy. They just need to be thick enough that they won't bend. They've also got to be easy to attach to the drum wall. I silver braised mine in place, which was a real pain. But as a fabricator you probably know how difficult it is to weld or braze anything where the two pieces are very different in size and mass.

More later...
Clever Coffee Dripper
Grinder: Macap M4
Roaster: Completed drum roaster project photos shown here:
Photos https://goo.gl/ph...Da6K4wfqw5
Videos https://www.youtu...Bd1NrdpSUH
Build thread https://homeroast...post_38189
 
oldgrumpus
Top  #9 Print Post
Posted on 12/18/2024 1:31 PM
eBay and Amazon have bearings at very reasonable prices but fractional bearings are quite a bit more expensive. I used a 3/4 inch shaft and when I looked for bearings I was shocked at the price. I chose to use metric bearings and fill in the gap with shims. It wasn't easy and I admit it wasn't the smartest thing to do. So you may want to do some research on fitting those parts together before you move ahead with either purchase.

Now for the next batch of answers:

"For the framing
1) I will be using 1/4" reg steel for the face. Is that too thick? Same for the back?"
IMO yes, it's too thick. Mine is 1/8 and it's just-right.

"2) I will be leaving 2" of space around the sides and top of the drum, 1" of which will have insulation. Too little or too much?
I think it's OK, but don't go any tighter. This is how I did mine." https://photos.ap...SefD3kyFh9


"3) I calculate the box dimensions to be 12" wide, 18" tall and 20" deep. With the insulation taking up 1" on the back side of the drum, will 1" of space between the insulation and the back of the drum be enough for pulling the exhaust through?
I'd be inclined to increase the space behind a bit, maybe to 1-1/2 or 2 inches."
Clever Coffee Dripper
Grinder: Macap M4
Roaster: Completed drum roaster project photos shown here:
Photos https://goo.gl/ph...Da6K4wfqw5
Videos https://www.youtu...Bd1NrdpSUH
Build thread https://homeroast...post_38189
 
Yasu
Top  #10 Print Post
Posted on 12/18/2024 5:41 PM
Nice to meet you, I'm YASU.
I am looking forward to seeing your roasting machine, and I will be looking forward to your progress each time you introduce it to us.
As you mentioned about the material of the drum, I think stainless steel has about 1.5 times higher thermal expansion than common carbon steel.
　This difference in coefficient means that the clearance between the front of the drum and the front panel will be even larger when the drum is cold than when it is hot during the roasting process.
 
sfloyd
Top  #11 Print Post
Posted on 12/18/2024 10:32 PM

Quote

oldgrumpus wrote:

eBay and Amazon have bearings at very reasonable prices but fractional bearings are quite a bit more expensive. I used a 3/4 inch shaft and when I looked for bearings I was shocked at the price. I chose to use metric bearings and fill in the gap with shims. It wasn't easy and I admit it wasn't the smartest thing to do. So you may want to do some research on fitting those parts together before you move ahead with either purchase.

Now for the next batch of answers:

"For the framing
1) I will be using 1/4" reg steel for the face. Is that too thick? Same for the back?"
IMO yes, it's too thick. Mine is 1/8 and it's just-right.

"2) I will be leaving 2" of space around the sides and top of the drum, 1" of which will have insulation. Too little or too much?
I think it's OK, but don't go any tighter. This is how I did mine." https://photos.ap...SefD3kyFh9


"3) I calculate the box dimensions to be 12" wide, 18" tall and 20" deep. With the insulation taking up 1" on the back side of the drum, will 1" of space between the insulation and the back of the drum be enough for pulling the exhaust through?
I'd be inclined to increase the space behind a bit, maybe to 1-1/2 or 2 inches."


Thank you grumpus for the response. I am planning on an additional 2" on the back side and i will also switch over to 1/8 plate. What size did you use for the exhaust pipe and fan?

I've been looking on ebay, amazon and mcmaster as well as work scrap for the parts.
 
sfloyd
Top  #12 Print Post
Posted on 12/18/2024 10:38 PM

Quote

Yasu wrote:

Nice to meet you, I'm YASU.
I am looking forward to seeing your roasting machine, and I will be looking forward to your progress each time you introduce it to us.
As you mentioned about the material of the drum, I think stainless steel has about 1.5 times higher thermal expansion than common carbon steel.
　This difference in coefficient means that the clearance between the front of the drum and the front panel will be even larger when the drum is cold than when it is hot during the roasting process.


Hi YASU,
Thanks for the heads up on the heating coefficient. I think i will space it about 2 mm from the face., then test it by heating up the roaster and spinning the shaft by hand. Any suggestions on how hot to test it at?
 
Yasu
Top  #13 Print Post
Posted on 12/19/2024 2:07 AM
I have an infrared thermometer on my drum.
The temperature of the drum circumference varies depending on the conditions, so this is just a reference value.
Condition 1
The distance between the gas burner and the outer circumference of the drum is about 10 inches.
(Single drum)

Condition 2
The heat source is a gas burner (10kw) and a hot air generator (3kw) (electric heater).
Hot air is directly applied to the beans from the back of the drum, not to the drum circumference.

Under these conditions, the drum outer circumference temperature is about 200℃~230℃.（392F～446F）
 
renatoa
Top  #14 Print Post
Posted on 12/19/2024 3:56 AM
On the opposite side of the burner? Or what measurement location ?
 
Yasu
Top  #15 Print Post
Posted on 12/19/2024 4:27 AM
The sensor measurement site is on the opposite side of the burner, although it is not opposite either, as the rotating drum surface temperature
is continuously measured without contact using an infrared sensor
 
Yasu
Top  #16 Print Post
Posted on 12/19/2024 4:58 AM
The sensor we are using is a Keyence FT-30.
https://www.keyen...ls/ft-h30/
 
allenb
Top  #17 Print Post
Posted on 12/20/2024 11:22 AM
Hey Sfloyd and welcome to HRO! I agree with oldgrumpus that this sounds like a real fun project! Just so you know, you've got two of the premier high-end drum roaster builders with oldgrumpus and Yasu helping you!

On your question on drum gap to keep it from rubbing, you might check this out from Probat to see what they recommend. As Yasu stated, stainless may require a bit more than Probat is mentioning.

https://www.youtu...irTWOFUNjc
Edited by allenb on 12/20/2024 11:28 AM
1/2 lb and 1 lb drum, Siemens Sirocco fluidbed, presspot, chemex, cajun biggin brewer from the backwoods of Louisiana
 
Yasu
Top  #18 Print Post
Posted on 12/20/2024 11:46 AM
The 1.5 times expansion due to heat means that there is a gap problem, but it is also necessary to accept that the force of expansion on the bearing is also 1.5 times greater.
My roasting machine has a sliding bearing on the drive side, so there is no stress.
 
allenb
Top  #19 Print Post
Posted on 12/20/2024 12:21 PM
If I may add another 2 cents worth on the drum front to front plate gap concern. As Yasu stated, the best scenario is to have the shaft fixed to the front bearing and for the rear bearing to float. By fixing the front end, you have the least variance in front gap due to expansion. The only caveat is that you want enough friction between rear bearing and shaft so that the shaft doesn't spin inside of the bearings inner race and wear grooves into the shaft.
1/2 lb and 1 lb drum, Siemens Sirocco fluidbed, presspot, chemex, cajun biggin brewer from the backwoods of Louisiana
 
oldgrumpus
Top  #20 Print Post
Posted on 12/20/2024 2:37 PM
I did a vary rough calculation on an 18 inch stainless steel being heated 400 degrees F and the expansion for the whole length would be approximately .0025 inches. So yes, do let the rear bearing float and adjust the drum back far enough to not rub on the front plate, and call it good. 2-1/2 thousandths of an inch doesn't seem like much to worry about, and either way, with stainless or ordinary mild steel, expansion must be accounted-for.
Clever Coffee Dripper
Grinder: Macap M4
Roaster: Completed drum roaster project photos shown here:
Photos https://goo.gl/ph...Da6K4wfqw5
Videos https://www.youtu...Bd1NrdpSUH
Build thread https://homeroast...post_38189
 
Yasu
Top  #21 Print Post
Posted on 12/20/2024 3:52 PM
The expansion seems to be about 0.062in for stainless steel and 0.043in for carbon steel.

I may have made a mistake with Fahrenheit and Celsius, mm and inches, and English translations, but, again, I will do the calculations tomorrow.
Edited by Yasu on 12/20/2024 3:59 PM
 
sfloyd
Top  #22 Print Post
Posted on 12/22/2024 11:22 AM
Hi Guys,
Sorry I haven't responded I have been away for the last few days without my computer.

Thanks for all the help, I did a quick calculation on this site https://utausa.co...alculator/ and found the calculated expansion to be .07344 inches converted to 1.865376 mm so I'm thinking of going with a 2mm gap between drum and front of plate. I like the dark roast/Espresso so I went with a temperature of 450F

Yasu - I am familiar with Keyence as I've used them with other machine builds/retro's. That is a very nice product, unfortunately it is out of my price range for this, plus I am gonna keep it old school with the dial thermometer, looking at this one here https://www.amazo...M&th=1
 
sfloyd
Top  #23 Print Post
Posted on 12/22/2024 5:23 PM
Bearings and shaft

I am looking at using this for the back sude of the roaster to allow for the thermal expansion. I will need to pop it on the lathe and machine the shaft down slightly to fit https://www.amazo...P&th=1

This one on the front for the fixed positioning https://www.amazo...9&th=1

and this rod as the shaft https://www.amazo...w&th=1

Thoughts on this?
 
oldgrumpus
Top  #24 Print Post
Posted on 12/22/2024 10:55 PM
I may be misunderstanding how you're using the linear bearings with the square flange... a linear bearing is designed to slide on a shaft back and forth.

The pillow block bearings look OK, but they are sealed and greased. I used similar bearings, removed the seals and the grease, which enabled them to be subjected to heat.

The SS shaft looks good too.
 
sfloyd
Top  #25 Print Post
Posted on 12/25/2024 1:54 PM
Hi Grumpus,

I just looked through your pictures... Did you find direct drive to be better than belt and pulley? I was thinking of doing the same
 
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