INTRODUCING: the "Roto Damper"


 
Wow, this looks awesome and totally beats my current configuration (which involves just stuffing the blower into the intake vent on my kamado and using the slider to hold it in place :) )

I have a 3d printer at work -- are there openSCAD or STL files posted somewhere that I can use?

Thanks for all the great work!
 
Jarom Bodell said:
At 400 degrees the plastic roto-damper will be a puddle before the zinc hits its melting point.
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Sure, but that is only applicable if you've got the roto-damper CLOSE to the intake vent - I'm using a standoff distance of about 6" because with no ceramic insulation on my metal smoker (and pre-roto-damper), I melted the mouth of my blower. That galvanized fitting extends INSIDE the pit a little ways - that's a huge temp differential from what you would see outside and even more a couple of inches away, so in at least my use case, that galvanized fitting would be exposed to a heck of a lot more heat than any of the plastic parts in the system. Not trying to tell anyone what to do or how to rig their system, but I wouldn't be comfortable w/ galvanized fittings inside my own stuff so I thought it was worth bringing up.
 
I think were talking apples and oranges, metal smokers and a BGE or other kamado grills are different animals. Although I went with soldered copper for my grill plate on my FauxMado grill, I'm pretty sure the galvanized part would be fine, 'cause the copper don't get too hot. You definitely want to make sure the tube doesn't extend too far into the grill.

I think most people with metal type smokers are using a dog dish type of mount for their blower, I think the galvanized fitting would be fine on the dog dish as well... What do you think?
 
Mache said:
If you are worried about heat transferring from the intake vent fitting to the roto-damper use stainless steel. Stainless steel has low heat conductivity (around 16 as quoted here) where carbon steel is 43. Stainless steel will effectively stop heat transmission from the smoker to the roto-damper.

-- Mache
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Problem is... getting the parts in stainless. where? and at what cost?

I think at the cost of $1.07 it is worth a try to see if this conduit connector will hold up, on a kamado or a dog dish adapter I think it will....
 
I think most dog dishes are stainless. Most conduit is bendable steel or aluminum alloy (both good thermal conductors). There are a surprising selection of pipe fittings in stainless.

-- Mache
 
I was unaware of any dangers associated with using galvanized pipe. I'll have to let you know if I gain any sort of superpowers or maladies.

As far as thermal conductivity, stainless is great and all but as Ralph said, it doesn't tend to be stocked at the big box stores and if it were I bet it would cost $10, not 87 cents. I still need to do a high heat burn but I'm feeling pretty confident. With Ralph's replaceable cap design though, you're out less than $2 total if it doesn't work for you.

The only issue with the EMT part is that it has that set screw you have to leave in to keep it airtight-ish. I considered making a piece that goes inside the conduit, but I figured that would require me to glue it into the cap which seemed like
emot-effort.gif
 
RalphTrimble said:
I think were talking apples and oranges, metal smokers and a BGE or other kamado grills are different animals. Although I went with soldered copper for my grill plate on my FauxMado grill, I'm pretty sure the galvanized part would be fine, 'cause the copper don't get too hot. You definitely want to make sure the tube doesn't extend too far into the grill.

I think most people with metal type smokers are using a dog dish type of mount for their blower, I think the galvanized fitting would be fine on the dog dish as well... What do you think?
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We might be talking apples vs oranges, but I don't have an orange so I can't comment on whether there is a risk when used on a kamado or other ceramic cooker. I have no data points for temperature in that area on those, but...
I AM one of "most people" with a metal smoker in this case - I use a 1qt stainless dog bowl over the bottom vent on my metal smoker. I don't know what the melt point of the plastic used to make the standard digikey blower fan is, but I definitely exceeded that temperature in use with the dog-bowl when running the temps up for a sear. Getting local temperatures in excess of 400F seems very likely with my setup at least.
 
Tom Kole said:
if you don't need to take the risk, why do it?
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If there's no risk at all, then what does it matter? In order to get zinc vapor into your lungs, it first needs to be vapor. It can't be vapor below 900C. If zinc delaminates at the intermetallic boundary, it will flake off, not atomize. I think it's silly to believe there's any health risk at all involved. That's like not eating with a plastic spork because if you ingest too much plastic you could have health issues! :)

If you're really paranoid you could toss the conduit onto hot coals then go inside and wait an hour and go fish it out. Any zinc that is going to vaporize will be safely gone by then.
 
I agree with you that I don't think there is any health risk unless someone starts trying to forge steel in their smoker. My point though was that it shouldn't even be an issue because you don't have to use galvanized steel for this. There are many other materials available that are just as inexpensive.

Edit: you must also remember that it's not just the vaporized metal that is dangerous. The aerosolized particulates are also likely to be dangerous and can be inhaled at much lower temps. Again, the concentration of them in this application is likely to be very low.
 
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I am on the same page, I doubt that anyones grill plate is going to reach 900C, however, if there is a possible safety risk it seems a no-brainer to use a different material that poses no risk if available and affordable....

Which brings me to ask the question, what parts are just as inexpensive and convenient to use for this application that do not contain zinc? I did't see much stainless steel at HomeDepot, and many of the parts in the plumbing section were much more expensive than these conduit connectors.
 
For anybody wanting heat resistance people could really print or make something out of ceramic due to it's high heat handling. Ralph, I'm wondering how your awesomely designed roto damper would do with a ceramic print.
 
Brandon N said:
For anybody wanting heat resistance people could really print or make something out of ceramic due to it's high heat handling. Ralph, I'm wondering how your awesomely designed roto damper would do with a ceramic print.
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Well, in general the Roto-Damper doesn't need to be heat resistant because it is offset from the heat source far enough in most applications. I have mine attached to a short copper pipe which is soldered to a copper plate which is placed in my my grills vent. With this setup none of the parts get hot enough to worry about, the solder hasn't melted and the Roto-Damper stays plenty cool, so no worries.... I guess it is the thin walled metal smokers that are a bigger concern, although most of them have an outer shell and seperate inner burn pan, so I was guessing a pipe connected to a dog dish style mount on the outer shell wouldn't get too hot either? IDK 'cause I don't have a grill with this setup...

However, I am sure a ceramic printed Roto-Damper would be really cool! A ceramic printed grill plate adapter would be more useful though. I'm not hip to the ceramic printer but I know my printer can't print ceramic.....
 
RalphTrimble said:
Well, in general the Roto-Damper doesn't need to be heat resistant because it is offset from the heat source far enough in most applications. I have mine attached to a short copper pipe which is soldered to a copper plate which is placed in my my grills vent. With this setup none of the parts get hot enough to worry about, the solder hasn't melted and the Roto-Damper stays plenty cool, so no worries.... I guess it is the thin walled metal smokers that are a bigger concern, although most of them have an outer shell and seperate inner burn pan, so I was guessing a pipe connected to a dog dish style mount on the outer shell wouldn't get too hot either? IDK 'cause I don't have a grill with this setup...

However, I am sure a ceramic printed Roto-Damper would be really cool! A ceramic printed grill plate adapter would be more useful though. I'm not hip to the ceramic printer but I know my printer can't print ceramic.....
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Your printer does a great job and I myself am not worried about the plastic melting (owning Darth Damper and such) but for the people who really care it's a thought. Shapeways will print ceramic and it's the cheapest of the materials they have. Plastic is ungodly expensive.
 
Brandon N said:
Shapeways will print ceramic and it's the cheapest of the materials they have. Plastic is ungodly expensive.
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Wow, I wasn't expecting to hear that!

I guess maybe I could design a grill adapter for the Roto-Damper that could be sent to Shapeways to be printed in ceramic if it is actually affordable. I would have to learn a bit about the capabilities of the ceramic printer before I set out to design something to be printed in ceramic. If I were to have a ceramic printed version of the conduit fitting discussed above the next question would be "what metal is the nut made out of?"... I guess there could be a ceramic nut like on older light fixtures but I'm not sure how durable or printable that would be, or how well that would seal. Or a compete grill adapter could be printed, plate and all, no nut needed... but I would think that would be costly....

I'll put looking into the ceramic printer on my to-do list, if it seems feasible I'll design the adapter(s)...
 
RalphTrimble said:
Which brings me to ask the question, what parts are just as inexpensive and convenient to use for this application that do not contain zinc? I did't see much stainless steel at HomeDepot, and many of the parts in the plumbing section were much more expensive than these conduit connectors.
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I would look into parts like these. It will still allow you to punch a hole in a sheet of metal (or dog bowl) to fit whatever smoker you desire and then you can just use two nuts to secure from both sides.

As far as the shapeways ceramic, I would be wary. A little over a yr ago someone on this forum submitted the case to them for a print in sandstone and it was a disaster. I realize they are very different materials but I would maybe start with a small test piece that contains some similar geometry and maybe a flat surface find out if they can achieve what you desire.
 
Well, at $8.57 for a single stainless steel elbow it'll end up a little pricey after you get all the fittings to put the thing together. To each their own I guess, I know my grill doesn't get hot enough at the vent to cause an issue with any type of metal...
 
So i have a weird issue i noticed last night.... i turned on the heater meter with attached roto damper and the pit probe would go from detected to "no pit probe" this was with ambient temp around 34 degrees.... once the pit heated then it seemed to operate normally.... i was also able to duplicate this plugged directly into the heater meter with no roto-damper attached any thoughts.... ? I also just brought the HM in to the house and the issue has not happened could this be related to the low temp?
 
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