Gunsmithing What gauge metal for gun oven

[buds444]

I currently work in a sheet metal fabrication shop and am going to build my own gun oven. I am wondering what gauge metal I can get away with. This will not be for commercial use. At the same time I want to make it right the first time. Your thoughts are appreciated.

- Brandon

 

[300sniper]

Re: What gauge metal for gun oven

i don't think i'd go any heavier than 16ga. i'd probably use 18ga or 16ga hr (p&o if you can get it local) for the skins over a box tube structure.

i also see a lot of people using gypsum board for insulation. the design of gypsum board may be a good fire barrier but i feel there are better insulators. the foil backed foam board insulation is probably a much better choice and possibly even easier to work with. i've had my eye on superwool 607 to insulate the fire box on the smoker/cooker i'm planning. it may be a good choice for an curing oven too.

 

[Mark Housel]

Re: What gauge metal for gun oven

<div class="ubbcode-block"><div class="ubbcode-header">Quote:</div><div class="ubbcode-body">the foil backed foam board insulation is probably a much better choice </div></div>

In all of the threads on this topic I have never yet seen a link to any real source of this material?

I've looked all over for it but never found a retail source that didn't cost about twice as much for shipping as the product and the didn't require purchase of enough material to build a house.

Similar material I can buy all day long a Home Despot doesn't handle high temperatures.

What am I missing here?

 

[hero's machine]

Re: What gauge metal for gun oven

You could do a simple tube frame and get away with 29ga. What do you have to work with? There is not much structure needed beyond holding itself up and staying square.

 

[buds444]

Re: What gauge metal for gun oven

Have access to any gauge. I've thought about double walled with 22 gauge sandwhiching a form of insulation. We used to build safes so I am going to mimic the front door of a gun safe. Not confident in what insulation would be best either.

 

[300sniper]

Re: What gauge metal for gun oven

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Mark Housel</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Quote:</div><div class="ubbcode-body">the foil backed foam board insulation is probably a much better choice </div></div>

In all of the threads on this topic I have never yet seen a link to any real source of this material?

I've looked all over for it but never found a retail source that didn't cost about twice as much for shipping as the product and the didn't require purchase of enough material to build a house.

Similar material I can buy all day long a Home Despot doesn't handle high temperatures.

What am I missing here?

</div></div>

you are right. i was going off of memory and thought it had a suitable service temperature. after looking at it again, it has a max service temp of 250*. i'd still use a real insulation instead of gypsum board. i'd be looking at insulation made for ovens such as the material i mentioned earlier, especially if you were going to sandwich it between a couple layers of sheet metal.

 

[Mark Housel]

Re: What gauge metal for gun oven

Actually my final "plan of record" (if I ever get the time) is to sandwich regular fiberglass insulation between layers of something like Hardibacker board or other cement board used as tile underlayment.

They are easy to cut and are fire resistant AFAIK.

If the outer layer is attached to the box with standoffs and the inner layer is only attached to the outer layer and not to the box then the screws hopefully won't transfer heat to the outside as badly.

More work, but seems like it would be OK.

Yeah, 250F seemed marginal.

 

[buds444]

Re: What gauge metal for gun oven

Mark. Any guesses on what that insulation setup would cost for a 2x2x4 oven? And where you can get it. I'd rather do it right the ffirst time tthan be pissed at myself.

Thanks for the help.

 

[ugsly]

Re: What gauge metal for gun oven

I stopped by a HVAC Place and picked up some mineral fiber insulation. It has a flash point of 1200-1300 degrees I believe. I would sandwich that between an Outside wall and inside wall. That's how I didn't mine and it came out really well.

Kc

 

[Straight Shooter]

Re: What gauge metal for gun oven

The double foil rigid foam insulation you get at the local lumber yard hold up fine to 400 degrees. I know it's rated lower but it works great. Hardi board and drywall just suck up heat. With the rigid foam the oven get up to heat in about 2-3 minutes. Then when you done it drops it almost as fast once you open the door. You can touch the insulation after 5 min and it will be back to room temp. Don't touch the interior metal parts (racks) as they stay hot a lot longer. On a warm day the outside of my over never gets much over 90 degrees even with the inside at 400 degrees.

 

[buds444]

Re: What gauge metal for gun oven

What form and shape does mineral wool come in? And any ideas on general cost

 

[hero's machine]

Re: What gauge metal for gun oven

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: *Straight Shooter*</div><div class="ubbcode-body">The double foil rigid foam insulation you get at the local lumber yard hold up fine to 400 degrees. I know it's rated lower but it works great. Hardi board and drywall just suck up heat. With the rigid foam the oven get up to heat in about 2-3 minutes. Then when you done it drops it almost as fast once you open the door. You can touch the insulation after 5 min and it will be back to room temp. Don't touch the interior metal parts (racks) as they stay hot a lot longer. On a warm day the outside of my over never gets much over 90 degrees even with the inside at 400 degrees. </div></div>

That is what I use, r-max. I knew it had a working rating of 250* going in, but I made the assumption that was likely a safety factored number. I have not taken my oven to 400* but I run 300* without issue. My findings are similar on in and outside temps.

 

[Mark Housel]

Re: What gauge metal for gun oven

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: hero's machine</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: *Straight Shooter*</div><div class="ubbcode-body">The double foil rigid foam insulation you get at the local lumber yard hold up fine to 400 degrees. I know it's rated lower but it works great. Hardi board and drywall just suck up heat. With the rigid foam the oven get up to heat in about 2-3 minutes. Then when you done it drops it almost as fast once you open the door. You can touch the insulation after 5 min and it will be back to room temp. Don't touch the interior metal parts (racks) as they stay hot a lot longer. On a warm day the outside of my over never gets much over 90 degrees even with the inside at 400 degrees. </div></div>

That is what I use, r-max. I knew it had a working rating of 250* going in, but I made the assumption that was likely a safety factored number. I have not taken my oven to 400* but I run 300* without issue. My findings are similar on in and outside temps. </div></div>

Excellent! That's what I get by believing the (.gov inspired I'm sure) labels.

Maybe now I will get back on this project.

 

[Sean the Nailer]

Re: What gauge metal for gun oven

As we had shown in our build-thread on making our oven, we used school lockers and Firewall. For the box structure, I personally would simply suggest that you use anything that you are comfortable in working with.

But for insulation, we would definitely recommend that you use an actual insulation as opposed to the Firewall that we were 'aimed towards'. While it may have "some" heat retention ability, it is primarily a "traveling heat slower-downer" and not very efficient.

While it does help to retain heat in the beginning, after about a half-hour to 45 minutes, one cannot touch the outside of the oven anymore. That is simply heat-loss. We do intend to dismantle ours in time, and re-line it with something much better. As has been suggested many times in this thread, and others.

Another one of those O-DIG jobs. One-Day I'm Gonna.....

The thing is though, the oven itself performs so well as it is. This is primarily because of the PID Controller that we're running, and the temperatures we're wanting are held near perfect and exact. 'Down to the degree' is not exactly needed here, but it sure works great. That controller makes the whole unit work so good, that there's little reason to do the tear-down & re-build. Except for the energy usage.