The Adapt-a-Damper - Open Source Project


 
Bryan Mayland said:
Have you considered making the holes in the top slightly smaller? It looks like the way it is right now, there is virtually no overlap of the edges of the holes in the top versus the shutoff area in the body. 50% of active area of the cap is hole and 50% is solid. It makes it so you have to be dead on with the servo adjustment and movement to fully close the damper. The radius of the hole could remain the same, but they would "sweep" a couple of percent less to create a small overlapping area, like 48% of the top plate will be hole and 52% will be solid. Something like that?

My testing shows that even with the damper fully closed, and the blower at 1%, it is still putting out close to 10% of the fully on/open airflow. Making the holes in the top slightly smaller would allow a better seal at 0% with a little more room for error, as well as being able to provide a small transition area where the blower is on but the damper is still effectively closed (but leaking air due to the blower vacuum).

I know it makes the effective input area 2% smaller at wide open, but I think the tradeoff of 0% being really solidly closed is worth it because at fully open there is plenty of cross sectional area to support the full airflow.
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The holes are actually 1 degree smaller on each end, so a total angle of 88 degrees, as opposed to the disc which is 90 degrees. You are correct, though. They should be re-designed a bit smaller. A quick 5 minute fix when I get time.

Thanks for the heads up, Bryan

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SteveCK said:
Come on Begg! Amateur mistake!
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Drrrrrrrrrr!
 
Yeah I was looking at it last night as I took it off the egg and came to the conclusion that there was some amount of overlap for sure. I was having a hard time initially setting it up and getting my servo parameters just right without going too far that it went to the slightly open position on the other side. The design is good though and all the pieces snapped together quite securely, so good work!
 
I've added a new option for the top case and damper disc to accept the more reliable Tower Pro SG90 servo after a few failed MG90 servos that I assume is due to cheap imitations, and finding that other users are having similar experiences.

I've also added a bit more overlap to ensure proper full closure of the damper, although maybe a bit more could be added. In addition, there are also now screw holes to properly mount the servo, and a much tighter fit of the horn to the disc.

As usual, I've added it here ... http://www.thingiverse.com/thing:1194140
 
WBegg said:
I've added a new option for the top case and damper disc to accept the more reliable Tower Pro SG90 servo after a few failed MG90 servos that I assume is due to cheap imitations, and finding that other users are having similar experiences.

I've also added a bit more overlap to ensure proper full closure of the damper, although maybe a bit more could be added. In addition, there are also now screw holes to properly mount the servo, and a much tighter fit of the horn to the disc.

As usual, I've added it here ... http://www.thingiverse.com/thing:1194140
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Will, do you mind making one for the 15cfm as well? If I can get one printed in time, I might use it for our competition. The superglue mod I performed definitely helps, as well as dialing in the servo range at the very start of a cook (versus keeping it the same all the time).
 
NickMV said:
Will, do you mind making one for the 15cfm as well? If I can get one printed in time, I might use it for our competition. The superglue mod I performed definitely helps, as well as dialing in the servo range at the very start of a cook (versus keeping it the same all the time).
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No worries. Will you still be using the MG90? If so, I'll send you an STL (and post) of just the disc, modified for a better horn fit and greater overlap (if you plan on printing locally). Or I could print it here and send it to you.
 
Are the current files you posted on ThingVerse setup for the MG90 servo or do I need one or several different files to accommodate that specific servo?
 
Mache said:
Are the current files you posted on ThingVerse setup for the MG90 servo or do I need one or several different files to accommodate that specific servo?
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I assume when you say "MG90" you mean "MG90S"? The MG90 is the digital version of the MG90S, and I'm not totally sureit has the same form factor as the MG90S.

If using the MG90S then use the files I mentioned to you earlier in this thread. The newest files added will only work with the SG90, thus the subscript "SG90" in the file name.

TopCase_2Hole, TopDisc_2hole, BottomCase_V2, BottomCaseBox_V2, and Adapter. If you want to use the Delta "official" fan, then replace BottomCase_V2 with BottomCase_V2_Delta.
 
As a complete air flow and heatermeter newbie I have a question regarding dampers. What are they really used for? I have been reading up on the blower design which (from my reading) seems to be designed to move a certain air mass with a constant speed. This air mass is controlled by the heatermeter by regulating the fan speed 0-100%. So why would one want a second air regular (damper)?
 
Because if the fuel is driving the temperature too high you need to cut the air flow by turning off the blower and by preventing normal air flow from the lower vent. On my Primo grill, if the lower vent is open ¼" the pit will go to 250° on its own. The damper can choke that down by preventing natural air venting. For me, the damper is much more important than the blower/fan.
 
Ken B said:
Because if the fuel is driving the temperature too high you need to cut the air flow by turning off the blower and by preventing normal air flow from the lower vent. On my Primo grill, if the lower vent is open ¼" the pit will go to 250° on its own. The damper can choke that down by preventing natural air venting. For me, the damper is much more important than the blower/fan.
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I see. I didn't think of the natural air flow. Allright so I understand the need of shutting the air flow off completely but how does that work with the damper designs that are not either fully closed or fully opened. If you have a damper that are using the PID to calculate how much air to let in I assume you then instead set the Fan speed to a constant. For example always 30% when run.
 
Rikard Vinkvist said:
I see. I didn't think of the natural air flow. Allright so I understand the need of shutting the air flow off completely but how does that work with the damper designs that are not either fully closed or fully opened. If you have a damper that are using the PID to calculate how much air to let in I assume you then instead set the Fan speed to a constant. For example always 30% when run.
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Not really. The addition of a damper control gives you many more options. Many people with efficient smokers, such as Kamado style ceremic grills, will run the damper control only, and only have the fan turn on if additional air is needed. The PID is controlling the servo damper as well, so it's up to how you define it's settings as to how it operates.
 
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