Server Rack Smoker ***UPDATED with Q-view***

[siegelscott]

Hey all, I've been visiting this site for some time, but this is my first time posting something.  I just completed retrofitting an old server cabinet into a smoker.  When I was sketching out the plans, I saw a similar design already posted here from a while ago, but I hope that you can look this over and give me your thoughts.




First off, thanks for checking out this post.  I have been making beef jerky on a Char-grill smoker for around a year now, and it has become very popular with my friends and even my coworkers.  I find myself making 50 lbs of flank steak into jerky at a time, and to smoke that much meat sliced into strips the size of bacon takes me around 4 hour per 6 lbs of raw meat.  It goes through a ton of charcoal and wood and is very labor intensive to keep the temperature right so it doesnt actually cook the meat instead of drying it out.



I've been toying with a lot of custom ideas on a homemade smoker, and when a buddy of mine located a computer surplus warehouse for another project he was working on, I realized that the steel cabinet that is used for a server would be a great idea.  I sketched out a plan and did some research here and on other sites, and hopefully you will all be proud of the build.



I'll post the highlights below (photos and give a little background), but I also have literally every last step detailed on a blog I've been keeping that my coworkers read each morning (http://www.ssiegel.com) 



-Scott

 

[siegelscott]

Starting with the final view of the server smoker, this is the outside of the behemoth.  It is around 6-1/2 feet tall, 18" wide and 24" deep.  I am using a propane burner (right) to keep the smoker around 150-160 degrees (for jerky), and using (for the first time ever) a Bradley Smoke generator (left) to impart the appropriate amount of mesquite or hickory.

The case is wrapped in a welder's blanket as I had a hard time getting the un-insulated version to stay at temperature, even with some bricks inside to help regulate the temp.

 

[diggingdogfarm]

Interesting build.
I've always been under the impression that a welding blanket is more a spark/flame guard than an insulator.
Does it really offer much insulation?


~Martin

 

[siegelscott]

This is a side view of the interior. I managed to find premade grill grates that were nearly exactly the correct dimensions.  My case can handle 24" x 17-3/4" and these are 23.5" x 17.5".  I ordered 8 of them giving me around 3400 square inches of smoking space.

The whole smoker, parts and all, cost me around $400 to build... the shelves were half of the cost, running me $200.  I tried to find expanded metal to use but either the gauge was too thin or the cost was too high.  

Below is a view from the front looking into the smoker.  The side panel is off in the picture, but will obviously be screwed back in during use:

You might notice some silver on the doors or side panels.  This is aluminum foil tape.  I found it at Harbor Freight.  I like it cause the tape is blocking off some of the many vents in the sheet metal without having to grind and weld panels over it.  I hope the tape is okay - it is rated for high heat and my smoker should never really get up over 220 degrees.  In my early tests, it holds up great.  The adhesive is outward facing to protect the food inside the smoker from being exposed to the glues.

 

[siegelscott]

About a foot below the lowest shelf is a 15000 BTU propane burner. It is cast iron with a brass nozzle located on the outside of the case.

On the left is the vent coming from the Bradley smoker.  I'm sure most are familiar with this. I used to use chopped up hunks of wood, but I thought to give this thing a try to see if its any good.  I ran a few tests and was pretty impressed with it, even if it feels like cheating, using a machine to burn wood pellets.

Above the burner is a steel shelf and 8 regular clay bricks.  I've repositioned them from this photo to force the hot air from the burner up and around the bricks instead of allowing it to flow in between.  This helps more evenly heat the cabinet, but even still, it doesnt really get temperatures exactly the same in all 4 corners of the case.

 

[siegelscott]

I originally tried to use a hotplate to generate the necessary heat to get the cabinet up to 150-160 degrees, but it was an epic failure.  Not sure why - I bought a very nice professional hotplate made by Waring.

Anyway, below are a few photos from one of the smoke tests I did.  The first is the plume of smoke rising from the vents cut in the ceiling of the cabinet.  There are 2 vents so you should be able to barely see 2 plumes.  I can control the size of the vents so I can redirect smoke across the case and regulate heat using these.

The picture below is the inside of the cabinet, taken from the vent hole in the roof.  You can see straight down (before I installed shelves or the propane burner) and that the cabinet is actually pretty well distributed with smoke.

 

[siegelscott]

So thanks for checking out the photos.  I have around 100 more on my personal blog that I made to share with my coworkrs, so if anyone wants to see anything from another angle or during an in-between stage, let me know.

If you have any questions or advice for a newbie, please let me know.  I am going to hold off the first real world cook in it a few more days in case I missed anything major (I don't want to waste $100+ in beef). What I can tell you that isnt shown in the photos:

1. The unit seems to heat pretty evenly up and down, meaning the top shelf and the bottom shelf aren't far off from each other.

2. Across the shelves, left to right, there is a large change in temperature.  The right side, where the burner is located, gets 20 to 25 degrees hotter than the left.  I wish I could even that out a bit, but I guess I can also just stack the meat so thicker cuts are on the right side, as they require more heat or more time to dry out.

3. Once I wrapped the unit in the welder's blanket, it does a good job in maintaining heat when I turn the burner from high to low, but it does take a LONG time to get the box up to 165 degrees in the first place - maybe a half hour.  That could be because the mass of the bricks and steel is pretty high and it takes a while to get all that material up to temperature with a single burner.  When I used charcoal, it also took a while to get the coals hot and all, but I just feel like propane should have a quicker impact than I'm seeing.

4, I haven't tried to see the smoke or heat distribution when this thing is full of slices of beef.  I'll get there soon enough, but filling 3400 square inches of shelving with meat is an expensive mistake to make.

Thanks again!

-Scott

PS - a big thanks to the guys who posted info on their own smoker cabinet using an old server rack.  While our smoking needs are different and I used different kinds of hardware, seeing your post made me believe that building this thing was possible.  Without that, I probably would still be drawing it out on paper instead of tinkering with it in person!

 

[siegelscott]

Martin,

Before I put the blanket on, the max temperature I could get this to was 196 degrees, and as soon as I cut the propane, the temp dropped literally a degree every second or two.

Today, after I wrapped it in the blanket (which was $35 from Harbor Freight and Tool, btw) I ran it up to 220 degrees before deciding to cut the gas (this was just a goal in my mind to see if I could get to rib temperature) and once I cut the gas, the temp held okay.  It did start to come down, but only a degree or two a minute.

I think the blanket just helps to keep the air and wind from taking the heat off the case.  I think any blanket would do (like the one you sleep with) except I dont want a fire to start, so using the welding blanket gives me a little comfort since its rated for 1000 degrees and I'm aiming around 165 on the high side.

As a side note, they use similar ideas to insulate hot water tanks, so that is where I originally got the idea and saw that others tried it on a smoker with success when researching it further.

 

[oldschoolbbq]

Scott , try some 'foil backed Insulation attactched to the blanket , should hold heat better. Nothing wild , thin 1/2" or foamboard glued on blanket with corners cut to fit speed rack and a piece for the top. No insulation close to food when it's attached on the outside.

Just thinking...

 

[siegelscott]

Thanks oldschoolbbq.  That sounds interesting.  Also, I saw some people using those reflective foil blankets that they sell for emergencies.  I wonder if that would reflect a good amount of heat without the expense of the foamboard?  In the meantime, I'm gonna try to find some of that foamboard and see what the cost is to do as you mentioned.  Good tip!  Thanks again.

 

[cdldriver]

 

[daveomak]

Scott, morning..... Great build..... Nice shelving......  You will get many years of use from that smoker.....  

About the burner.....   Have you adjusted the flame for a "blue" flame ??  The yellow flame might deposit "soot" on the food....  Just thinking ??  

If you find adjusting the flame to blue makes the smoker too warm, plugging some of the holes in the burmer might cool it down some....

I'm in for the Q-Views...

....     Dave

 

[siegelscott]

Hi Dave, thanks for your thoughts.  

The burner is quite adjustable and I usually do keep the flame low.  The photo happened to capture the flame running with the propane flowing (I shot it during a max heat test). If I lower the propane to get a bluer flame (I do prefer to run it low), I find that the box actually struggles to move up in temperature.  I wonder if the burner is inadequate given the volume of the box and the mass of the bricks and steel.  So I'm not sure what to do.  You mention that the blue flame might make the smoker too warm, but unfortunately, I wind up with the reverse problem.  I thought insulating it a bit might help, and it did, but still, I dont want to spend an hour getting the box from 78 to 160 degrees.

I think this is where a combo of lowering the flame as you recommend and insulating it with the foil foamboard as oldschoolbbq recommended might solve 2 problems.

Can anyone give me an alternative burner recommendation that might put out more heat with a lower flame, and also help heat the case a little more evenly as right now the case has a 20 degree difference between the left and right sides, and the case in just 18 inches wide!

-Scott

PS - I think I'll pick up some flank tonight and see about getting a smoke on this weekend.  I'll take a ton of pics so I'll post a few if it happens!

 

[siegelscott]

Early in the build, before I had shelving I simply placed the burner in the cabinet, shut the door the best I could, and ran it on low (as you see below).  The temperature capped at 153 degrees on this low setting, but this was also pre-insulation, and with the door slightly ajar.  Also, that heat is literally the air temperature, there was no heat retained in bricks or shelving or anything, so once the case opened the temperature dropped all the way back down in just a few seconds. 

But to answer Dave with a pic, this is basically the look of the burner on a low setting, where I'd prefer to run it.  I cannot get a much longer blue flame than what you see below. 

 

[daveomak]

There should be an air adjustment on the back side of the burner...  a rotating plate or something like that....  the more gas, the more air needed for proper combustion.... 

Does your burner have something like that ?????  

Also, Pops has a burner in his smoker...  Has 3 separate adjustable burner rings for heat....  Others use this burner also...... works well....   Dave

http://www.northerntool.com/shop/tools/product_15490_15490

 

[siegelscott]

This looks really cool.  A few questions though -

what kind of hose or adapter is needed to connect this to a propane tank?  Does it use a standard size brass fitting or do I need to look for a special connector?  Also, the burner I currently use allows me to shut it down or open up the propane from outside the cabinet.  This looks like it has 3 valves on it so that would require opening the case to make adjustments.  Do you see that as a concern or no?  I suppose I can always regulate up or down using the valve on the propane tank itself.  But otherwise, its 2x as powerful as the one I currently have and I can position this directly in the center meaning I can probably reduce the differences in temperature from the left and right side of the case.

As to the question about an air adjuster, I think this is it (this isn't the exact burner I own, but a very, very similar design). I can play around with it and see if I cant get it the way you recommended.

 

[mneeley490]

Siegelscott, nice build! I do have a question for you though. Where did you get your racks from? They sound about the right size for what I need. I'm using flattened cooling racks that are okay for now, but yours look much sturdier.

Thanks!

 

[siegelscott]

mneely, they are:

Universal Gas Barbecue Grill Replacement Galvanized Steel Rock Grate 95301

I found them on Amazon for $35 apiece (free shipping) which is highway robbery.  I eventually located the following source:

ThePartsBiz.com for $18.93 plus shipping

I ordered 8 racks and they cost me $197 including shipping.  Shipping was around $6 per rack.  The 8 racks combined weigh in at roughly 50 lbs.

This is the description:

Universal Gas Barbecue Grill Replacement Galvanized Steel Rock Grate 95301

Replacement universal rock grate for gas barbeque grills. This replacement galvanized steel rock grate is made to fit a variety of different outdoor barbeque grills, including the Turbo models listed below. Rock Grate may also be known as a Flavor Grid, Flavor Grate, Anti Flare Up, and Lava Grate. Get your gas grill working like new again simply by replacing your rock grid grate. Use dimensions to determine fit if your model is not listed. Universal grill part replacement part numbers 95301, #95301.

Dimensions: 17 1/2" x 23 1/2"

Material: Galvanized Steel

 

[daveomak]

Thread on needle valve for fine tuning the heat.....

http://www.smokingmeatforums.com/t/88700/love-those-needle-valves

Hose from the tank to the burner... Needle valve gets installed after the regulator.....



http://www.northerntool.com/shop/tools/product_53127_53127

For full details, PM Pops6927.... I think this is what he uses with good success....    Dave

 

[jirodriguez]

If you want to even out your temps from left to right replace the metal plate directly above the burner with one that uses rows of graduated holes. Smallest holes on the hot side and larger holes on the coolest side. A flat sheet of metal and a step drill bit works great... you might even find a sheet pan that fits that space perfectly. Start with the first third of the rack using smallest holes, then after that start increasing the size till you get to the far side with holes that are approx. 1" or so in diameter. That will allow some heat to come up directly above the burner, but most of it will deflect sideways and then start to move up as it hits the larger holes.