Intake-side servo damper for BBQ Guru Blower


 
S

SteffenL

New member
Hi,

I recently built a HM 4.2.4 with thermocouple and it works really well on my Primo L. Initially, I had started my journey into BBQ temperature control with a BBQ Guru CyberQ and I already had their 10cfm blower and adapter plate. The CyberQ works quite well, but one of the main limitations is the rather low maximum temperature of the pit probe, it's certainly not usable for high-temp cooks. On the HM I'm now using an Auber TC for the pit and the ChefAlarm probes for food. The HM is a great design, thanks a lot!

Since I still had to adjust the top vent and/or the manual damper built into the BBQ Guru blower, I decided to add a 3d-printed servo-controlled damper. In order to keep it away from the hot end of things, I made a very simple direct-drive design that controls the air intake side of the blower. The servo is a MG90S, the parts are PLA. Here a few photos of the setup:







The damper is quite tight, when fully closed and the fan is running at 100% there is no air flow out of the blower pipe. It also doesn't seem to unduly limit the airflow into the fan when fully open.

Last night I tried it out on the grill for the first time, using the damper in open/close mode:



The long flat top is an actual cook (whole chicken) and I opened the lid a few times, after that I started playing around, using the controller to try some high-temp settings just for fun. During the heat up to high temp I removed the center divider, added some charcoal and spread it out. I still didn't have enough charcoal in the grill to hold the temp at 700F, but keeping the temperature constant at 600F was no problem. At the end, the damper managed to shut down the fire (I closed the top vent some time later though).

If there is interest in the STL files for the damper, I'd be happy to post. It might also be interesting to combine the concept of intake air control with the standard blower.

Update: Here the link to the STL files: http://www.thingiverse.com/thing:431849


Steffen
 
Last edited:
That Is awesome! I would definitely be interested. I have the BBQ Guru Blower as well. How do you find it works with the HM 4.2? I have issues using with my 4.0 board at any speed below 50%.

Cheers
 
The fan works fine for me from 1% to 100%, no problems. I'll post a link to the STL files as soon as possible. Will probably post the OpenSCAD source, too, once I've cleaned it up a bit for public consumption ;-)

Steffen
 
Awesome, I'm new here but have all the parts for a HM 4.2.4 ready to go. My main purpose at this time is low temp cooks - 175-300 or so for smoking. I'm using a Primo XL and considering starting with simply a servo based intake control. Have you tested using just a vent control with no fan on a Primo? I'd be interested to see how it performs.
 
I haven't tried just using vent control on my Primo. I did a low-temp cook (tri-tip roast) at 225F tonight:



Looking at how much of the time the fan is off and the damper fully closed (blue graph at the bottom), I think a damper-only control could work fine, but maybe not with the additional resistance of the (stopped) blower. Certainly worth a try.

Steffen
 
SteffenL said:
Looking at how much of the time the fan is off and the damper fully closed (blue graph at the bottom), I think a damper-only control could work fine, but maybe not with the additional resistance of the (stopped) blower. Certainly worth a try.
Click to expand...

I gave this a very quick try while the grill was still hot: With the blower disabled and the damper fully open, my configuration is not able maintain 225F (temp falls quite rapidly). For damper-only operation you'll need something that doesn't restrict the airflow as much. I think there have been various discussions in this forum.

Steffen
 
SteffenL said:
I gave this a very quick try while the grill was still hot: With the blower disabled and the damper fully open, my configuration is not able maintain 225F (temp falls quite rapidly). For damper-only operation you'll need something that doesn't restrict the airflow as much. I think there have been various discussions in this forum.

Steffen
Click to expand...

Cool, thanks for giving it a try, somewhat surprising as for me to be at 225 the vents on my Primo are barely open at all. My current thought is a somewhat modular design basically allowing me to use any setup, just vent control, just fan control or both. Perhaps I'll skip that and just do a fully integrated setup with both vent & fan control, that will certainly be more compact overall than a modular setup.
 
That's really fantastic! I love seeing new designs to tackle different requirements. What a great looking grill station you've got there too.

I'm also interested to learn that even with the 31mm ID tube and this large vent area it isn't able to maintain 225F. I keep feeling like a damper-only solution would be great for sub-300F cooking but all my designs have fallen short of being able to deliver enough natural airflow if you leave the blower attached. I've even tried some larger designs with printed venturi (venturis?) to allow more natural draft but those just ended up having a hard time keeping the temperature down.

I got a little off topic there but great job on the design!
 
Bryan Mayland said:
That's really fantastic! I love seeing new designs to tackle different requirements. What a great looking grill station you've got there too.

I'm also interested to learn that even with the 31mm ID tube and this large vent area it isn't able to maintain 225F. I keep feeling like a damper-only solution would be great for sub-300F cooking but all my designs have fallen short of being able to deliver enough natural airflow if you leave the blower attached. I've even tried some larger designs with printed venturi (venturis?) to allow more natural draft but those just ended up having a hard time keeping the temperature down.

I got a little off topic there but great job on the design!
Click to expand...

Bryan, I saw this on different site. Yet another way of controlling temps: http://vimeo.com/90480641
 
Yeah I've seen that too, and you can do it with a HeaterMeter as well. I don't have the ability to make one of those though because I fail at metalwork every. dang. time.
 
Bryan Mayland said:
That's really fantastic! I love seeing new designs to tackle different requirements. What a great looking grill station you've got there too.

I'm also interested to learn that even with the 31mm ID tube and this large vent area it isn't able to maintain 225F. I keep feeling like a damper-only solution would be great for sub-300F cooking but all my designs have fallen short of being able to deliver enough natural airflow if you leave the blower attached. I've even tried some larger designs with printed venturi (venturis?) to allow more natural draft but those just ended up having a hard time keeping the temperature down.

I got a little off topic there but great job on the design!
Click to expand...

Is this what your looking for maybe? Here is a 250 degree Rib cook and a 350 degree Brisket cook (best brisket I ever made by the way!). The fan never ran after heat up, fan on at 100% only, so it was vent only for entire cooks. This is on a XL BGE.






I've posted pictures of my control on other threads. It is a 3 1/2 inch PVC pipe with servo vent on inlet and a muffin fan in middle. I step down top and bottom of pvc pipe to fit BGE. End up with 2 1/4 inch square opening to cooker. Somebody could make a real nice looking one with a printer. FWIW. Dan
 
Last edited:
OK, I uploaded the two STL files to Thingiverse.com and edited the original post to add the link. This should be really easy to print as there are only two overhang areas (inside the two posts with the mounting bolt holes). The hex nut hole is sized for an M3 nut. I've attached the damper box to the fan cage using 2 M3x45mm bolts. The center hole of the rotating disk should more or less fit on the servo axis without using the horns, but might need a little widening.

Steffen
 
Would love to see a picture of your setup in this thread or a new thread!

Aubrey

Dan Francis said:
Is this what your looking for maybe? Here is a 250 degree Rib cook and a 350 degree Brisket cook (best brisket I ever made by the way!). The fan never ran after heat up, fan on at 100% only, so it was vent only for entire cooks. This is on a XL BGE.






I've posted pictures of my control on other threads. It is a 3 1/2 inch PVC pipe with servo vent on inlet and a muffin fan in middle. I step down top and bottom of pvc pipe to fit BGE. End up with 2 1/4 inch square opening to cooker. Somebody could make a real nice looking one with a printer. FWIW. Dan
Click to expand...
 
You must log in or register to reply here.

 

Back
Top