275 oil tank on a trailer build

[Rufus T. Doofus]

I've been wanting to build a smoker for a few years. I signed up here about 2 years ago and have been reading and learning off and on. It's time to try to put this knowledge to use.

I started fabricating the trailer last weekend. The axle is out of a mid-60s van with the kingpins welded. The springs and shackles are from the front of a solid axle 84 Toyota diesel pickup. I pulled the tank out of our house when we switched from an oil boiler to natural gas. I've had all of these parts hanging around for a few years.

The centerline of the frame rails is 32" which matched the spring pin location on the axle perfectly. Frame is 2" x 4" 1/8" .120" wall tube.

The "U" shape of the back of the frame will be part of the firebox. Firebox will be 2" thick insulated walls. Exterior dimensions of the FB are 34"L x 34"W x 24" H. Plan to use 1/4" plate inside and 1/8" outside. Likely something thicker on the outside of the door area.

I found an online engineering tools calculator for trailer design to come up with the length and axle placement. I'll mount the axle after the CC and FB are mounted.

What do people usually use for shocks on their smoker trailers? I'll need to find something and fabricate some shock mounts.

A few photos:

[Rodcrafter]

Looking forward to seeing your build, these tanks make very nice big smokers. Pace yourself it is a journey not an event.


Making memories.

[forty_creek]

Welcome Rufus!


Drankin, Smokin and Dreamin

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[Rufus T. Doofus]

I plan to build it over the course of a month or two. Would be nice to use it this fall to smoke some venison.

[bluecatfish]

I like the design of the trailer. I am not sure but I don't think most guys put shocks on smoker trailers. They might be good to have on big heavy smoker trailers. Press on! Like you I like to use the junk I have laying around on my smoker builds!

[Big T]

[Rufus T. Doofus]

Did a little work on the trailer tongue area today. Added some plate gussets to help deal with the stress the front will endure on our terrible roads in Maine.

I'm still waiting on some tubing to arrive at my friend's machine shop so I can get started fabricating the FB.

Thinking I'll cut the openings in the tank for the CC next. Not sure if I should have the factory NPT ports on the bottom or the top. I'm thinking having those NPT ports the bottom might make it easier to clean if the bottom plate is removable. Anyone have thoughts/experience in this area?

First image is the bottom side of the trailer frame


Top side. The vertical 2" post is being used to mock up placement of a possible spare tire mounting location


I plan to completely box-in the area around the 2" hitch mount tube.

[bluecatfish]

On the smoker I am building I am leaving the ports on the bottom and planing on welding my BP drain to one of the 1 1/2" ports on the inside and putting a valve on it on the outside. The other 1 1/2" port I plan on capping with a removable plug to remove when cleaning the area below the BP. The 1" ports I am just going to plug. Saves a lot of unnecessary fabricating, cutting and welding in my opinion.

[Rufus T. Doofus]

I did a little more welding today. The lower portion of the firebox is mostly done. It will extend up 17" above the frame rails. It's sitting on the axle now but I still need to get the spring u-bolts modified to work with this axle.



The 2x4 tubing is configured as a duct system. (It's not done yet.) I'll cut rectangular fresh air ports into the frame rails. The intake air will be preheated flowing through the tubes and eject directly under the basket in the FB. I have a couple wood stoves that use this same concept of preheating combustion air and routing it to the fuel. It works really well in an airtight wood stove. It might turn out to be a really stupid idea for a smoker. It's easy enough to change the intake air configuration later but I want to test it to see if it works.

[Rodcrafter]

Cool I like new ideas.


Making memories.

[Rufus T. Doofus]

Had some time over the past few days to do some work on the smoker. The firebox frame is mostly done. The cook chamber is in a roughed-in state. CC is still loose on the trailer until I can finish the FB. The photos kinda give an idea of how it will mount.

I hope to get some sheet metal sheared next week for the FB. I placed an order for hinges, latches, seals and thermometers yesterday. When they arrive I'll get to work on the doors for the CC and FB.

I'm really happy with the the balance of the trailer thus far. I can move it around my driveway by hand without much effort. There's not much tongue weight at the moment. There will be when I mount the fenders, spare tire and front charcoal/wood storage basket.

[Rodcrafter]

Making progress


Making memories.

[Tom_Heath]

Looking good. From past builds I do believe you will be moving the axle to the rear. A lot. I could be wrong, just my personal thoughts. Then again, I'm that guys that always runs heavy on tongue weight.


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[Rufus T. Doofus]

Looking good. From past builds I do believe you will be moving the axle to the rear. A lot. I could be wrong, just my personal thoughts. Then again, I'm that guys that always runs heavy on tongue weight.

Thanks.

I did use a trailer weight calculator to come up with axle placement. There's a site out there somewhere with engineering calculators. One of them is for trailers. You specify the centers of various loads along the length of the trailer and it determines axle placement. I can't move the too much to the rear in the current setup because the FB drops below the trailer frame rails.

The FB will have 1/4" steel inside and 1/8" outside to save weight. I don't intend to do a warming cabinet. The spare tire and mount will add about 75 - 80 lbs to the tongue.

I'll primarily be moving this around in my yard with my ATV. I don't intend to go to competitions. It might move to a friend's house once in a while within a 20 mile radius from my house. I plan to buy magnetic mount lights for those rare occasions. I'm not planning to wire this up for lights a the moment.

[Rodcrafter]

Those are some long leaf springs.


Making memories.

[Rufus T. Doofus]

They are a spare set from my 84 Toyota diesel pickup.

[Rufus T. Doofus]

Those are some long leaf springs.

I may end up changing the springs to something shorter and moving the axle back a foot or so.

I got most of the sheet metal for the firebox sheared today. I set it all down on top of the firebox frame and the trailer tongue promptly lifted like a magic levitating spell. Of course I don't have most of the stuff on the front of the trailer yet that will load the tongue down a bit.

Hope to be building some doors later this week and skinning the FB inside and out.

[Tom_Heath]

Conventional trailer calcs don't generally work with pits. It's a touch and go kinda thing. My first trailer needed additional weight to hold the tongue down. Oh wait the second trailer was light up front prior to adding weight to that one also.


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[Rodcrafter]

I agree, the best way to get it right is build everything on the trailer then set the axle unit 1 or 2 under and check the balance then weld it. Or use a block of wood to find the balance point then set the axle unit about a foot behind it.


Making memories.

[Rufus T. Doofus]

Thankfully I don't have any plans to move this thing around much or very far. I do plan to put a storage box on the tongue. I can always fill it with rocks

[dportz87]

I understand your concept of the air intake, where is the air intake opening in your frame? How are you going to control the intake to keep a constant temp? I like your ideas.

[Rufus T. Doofus]

I hadn't cut the air intakes into the frame yet on my previous batch of photos. Here's where they are located. I'm going to fill the opposite end of the frame rail (near the tongue end) with spray foam to block the air. There's a slot cut into each side and I bought some pre-fabbed slider ports from a link here on this site that match the intake ports.





If this intake setup doesn't work I can always cut some new ports into the sides in the area below the frame rails and weld these ones shut.

[dportz87]

Thank you for the clearing that up

[Rufus T. Doofus]

I just hope it works. I know that in this type of setup it's going to be very important for my doors to seal completely and reliably in order to draw the air through the ducts. I'm treating it like a an airtight wood stove.

I may need to tinker with exhaust pipe lengths to establish enough draw through the intake plumbing. The pit calculator shows I need just under 32" of 6" round pipe for a traditional firebox. I've downsized the FB by about 10% which I think should be OK considering it's insulated and the ducting will preheat the combustion air.

[Rufus T. Doofus]

I've made a little progress recently. Got the door frames welded up. I ordered the sheet metal to finish the doors and the firebox. Progress is slow but feels nice. There's something soothing about the sound of a MIG welder laying down a nice bead.

Hoping to maybe test fire it in about 2 weeks. Deer season started around here today. Gotta be ready to smoke Bambi and maybe some of her siblings.

Anyone have suggestions on ideas for fenders that will be useful as a work surface too?