3D Printed Barrel Servo/Fan

Tom Kole

TVWBB Pro
I can't really tell from the photos Tom, but what is the slot for next to the RJ11 slot where the servo goes? I'm assuming it has something to do with the servos?
Are you talking about the small slit next to the rj11 jack? If so, it is for one of the servo mounts...I made my BGE connector last night so I should get a chance to test it out tonight.
 

Tom Kole

TVWBB Pro
I did a quick test yesterday. The graph is on the first page and the results speak for themselves. I have a couple of minor things I am going to adjust for convenience. Unfortunately I won't be able to play with this for another week.
 

s fortin

New member
What is the size of the outside square portion of your holder. It looks like it might be able to slide into a 2" piece of square tubing, which would be perfect for my smoker.
 
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Joel Peterson

TVWBB Member
Yeah, I want the whole kit for my large Big Green Egg. Will you be selling the adapter that fits the fan to the Big Green Egg air intake?
 

Tom Kole

TVWBB Pro
Yes, I have been using it when I have time to bbq, which unfortunately, I have not had a lot of time for lately. That said, I don't have any plans to start selling these at this time because I don't have any data on how they fair in other peoples hands yet (coming soon), and I really don't have time to add another thing to my 3d print tasks. My main concern is servo wear during repeated use. I simply have not had enough time to run it over and over. If you know someone with a 3d printer and want to try it out, the files are on the first page.

The mount is extremely simple to make and is described in a post in this thread. You just need some sheet aluminum, 1" square aluminum tubing, a 1" chisel, hammer, metal snips, JB weld, and a drill.

1. Cut out a 77 mm square from the sheet metal
2. Draw an "H" in the middle with dimensions of 1"x 1"
3. Use chisel to pierce through metal along the borders of the "H"
4. Use hammer to bend back the newly formed tabs at 90 degree angles
5. Insert and 2" piece of 1" square aluminum tube in between the 2 tabs and slightly (1 mm or so) through the opening in the sheet metal
6. Use 1/8" drill bit to drill a single hole through the tabs and metal tube
7. Use an M3 or 1/8" screw to fasten together
8. Place JB weld along the edge of the tube that is protruding through the sheet metal to form a nice airtight seal
 

Tom Kole

TVWBB Pro
Those are the latest files. I basically got rid of the cover rear screw hole because it was interfering with the valve.

No welding required.
 

Steve_M

TVWBB Guru
My buddy over at Autodesk is going to print up this design for me. He said their 3D printer guys are working on some new support ideas and the barrel will give them a chance to see how it works out. This of course all hinges on their makerbot printers actually working, as he says they are often needing repairs!
 

T Hayes

New member
How is the housing secured to the 1" aluminum tubing? Is there a screw that secures it, or is it simply a "snug fit"?
 

Tom Kole

TVWBB Pro
You'll see that there is a hole in the housing and body that you drill through the 1" tubing using a 1/8" bit and then pass a 3mm or 1/8" bolt through the whole thing.
 

T Hayes

New member
I got this printed and assembled, and I'm about to give it a try. How far open do you keep your top vent, now that the servo damper is severely restricting the airflow? Previously when running with a fan only, I had to shut the top vent to almost completely closed. I assume I want to set it much more open with the servo?
 

Tom Kole

TVWBB Pro
I got this printed and assembled, and I'm about to give it a try. How far open do you keep your top vent, now that the servo damper is severely restricting the airflow? Previously when running with a fan only, I had to shut the top vent to almost completely closed. I assume I want to set it much more open with the servo?
On my large BGE I always keep the top so that the radial pattern of holes is about half closed. I haven't really tried it any other way. I don't think that just because there is a servo that you can open the top much wider. I had an egg way before a heatermeter and when I used to bbq the old fashioned way (by manually adjusting the intake slider), I had to keep the top fairly closed. A servo is not going to perform any better than that, it just adds automatic control.

Also, I use the servo in fan and servo mode and have limited my max fan to 40%. I plan on running a test overnight with running the fan with the servo in on/off mode only. I'm interested in seeing how it behaves acting as an electronic auber-like damper.

Also, I have 2 of these out in the wild being tested by other people. One user has reported that his servo began acting up after about 12 hours of cook time. I'm not sure if the servo ended up burning out or what but he's going to get back to me later in the week. Servo wear is definitely something I worry about with these. To that end, I got a couple of the metal component ebay servos that people on the board have used. In comparison to the plastic amazon ones that I list on the first page, they have about 50% more torque and should probably be more durable. The only issue is that they are a slightly different size than the original servos so I had to mod the body of the unit a little. I'll post my results of the on/off test tomorrow.
 

RalphTrimble

TVWBB Diamond Member
I got this printed and assembled, and I'm about to give it a try. How far open do you keep your top vent, now that the servo damper is severely restricting the airflow? Previously when running with a fan only, I had to shut the top vent to almost completely closed. I assume I want to set it much more open with the servo?
I don't have a BGE and am using my own servo damper design, but it has been my experience that when you are using the blower to regulate the pit you need to clamp down the top vent quite a bit, when you use a servo damper you can open the top vent up much more like you would when running the pit without the HM attached, which is preferred IMHO.
 

M Hoskins

TVWBB Member
Ralph, any chance of getting that barrel design for testing? I agree with your design philosophy and would love to get my hands on a prototype to test out.
 

DarrenE

TVWBB Member
I don't have a BGE and am using my own servo damper design, but it has been my experience that when you are using the blower to regulate the pit you need to clamp down the top vent quite a bit, when you use a servo damper you can open the top vent up much more like you would when running the pit without the HM attached, which is preferred IMHO.
Did you find that to be the case even with your fan + damper? I'm using a fan only with a flapper as a damper, no servo. It's not super air tight but I can close the top vent about halfway on my BGE like Tom. I have been curious to know how moving to a servo could help. I'm under the impression that the top should be as open as it can and still maintain temp.
 

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