UDS design question

[phyx]

OK. So I've got her built, but I'm waiting on my weber 22.5 inch grates that I ordered to get here (I'm in no man's land for new or used charcoal cookers).

I did a quick "seasoning" burn yesterday to get some cooking oil baked in. I didn't even put a thermometer in to check temps, just wanted to get some heat in there.

Anyway, I put a couple of pounds of unlit lump in the basket and about 1/2 a Weber chimney of lit on it. The heat lasted about 3 hours before crapping out--of those 3 hours, about 30 minutes of it was hot enough to burn the hand when touching the drum.

I've got 2.5" long 1/2" black iron pipe nipples welded 2" off the bottom of the drum. My basket is a 15" diam. cooking grate from an old Weber wannabe grill with expanded metal welded around it. The basket is 15" diameter by 12" tall and it has 2" steel bolts welded to the bottom to use as legs for the basket.

I was running 3 holes open. I've got 8 half-inch holes drilled into the lid spaced evenly in a circle around the top for exhaust.

I'm wondering if my exhaust holes aren't enough. I can't help but wonder if the fire is getting choked. BTW, 50% of the lump is still useable.

I know that I didn't really give it a fair chance as I only had about 3-4 lbs total of lump in there. I should put 10lbs or so to give it a fair run.

Thoughts?

[Kenny 13]

Sounds very similar to the trouble I had Friday night with my trial run, only I did use a full 9# bag of briquettes. I got about 5 hours of burn time in the 215* - 234* range before my temps dropped and couldn't get them back up, and more than half the charcoal was unburned.

I'm also using 1/2" inlets and have a Weber kettle lid, so I only have the 4 exhaust holes. Based on the response I've gotten here, I'm probably going to try more exhaust but it sounds like you already have more exhaust than I do.

[Smokin Gator]

From my experiences four exhaust holes are plenty. With eight you may find you need to plug a few of them with foil. I only use briqs in my UDS so I can't really say much about a burn with lump.

[Cliff H.]

Could you take some pics of your unit. Inside and out. Something isn't adding up.

Lump burns just fine in my drum with less than 1/2 of the exhuast you have.

on edit : How old was your bag of lump ?

[Kenny 13]

From my experiences four exhaust holes are plenty. With eight you may find you need to plug a few of them with foil. I only use briqs in my UDS so I can't really say much about a burn with lump.

Smokin Gator, you're using 1/2" inlets too, aren't you? What size are your exhaust holes? I haven't measured, but I believe the ones in the kettle lids are a little larger than 1/2" so I figured I had enough exhaust.

How many inlets do you have open to keep your temps up? I had mine going fine with 2 open all the way and a ball valve about 1/2 open before my temps started to plummet and wouldn't go back up, even with all 4 wide open. Based on how my charcoal burned, I attributed it to having the exhaust vents on the same side of the drum as the inlets that were open the entire time. It's kinda hard to explain so tonight I'm gonna try to take pics of what the charcoal looks like. It's basically like a perfect circle of burned charcoal offset to one side of the circular basket - like taking a dime and putting it on top of a quarter all the way to one edge. Didn't pay attention at the time, but realized later that the open exhaust probably should have been turned to where it was over the closed inlet.

Comments?

[Dr_KY]

Dittto we need to see what you are working with. ie drum, vents, ashpan , basket ect.

PHIX- sounds like you running penty of air through it this sounds silly but are the pipes on the bottom clear and yes how old is your lump?

When I place unlit fuel in the basket I leave a hole in the middle to place the burning embers. ( Big Mista mod)

[phyx]

Thanks guys.

I'll see about getting some pics up (have to borrow the digicam). In the meantime, I'll give more details. Hope they make sense:

In a nutshell, it's a standard 55gal drum (34.5" high, by 23.5" diameter--if I'm remembering correctly).

The 4 half-inch pipe nipples are at the bottom, evenly spaced apart, welded in place--2 with caps, 2 with ball valves. I had both ball valves open full and 1 cap off. The lid is the standard 55gal drum lid, just with 8 holes (half-inch bit used) drilled in even distances around the top.

The basket is a 16 inch diameter cooking grate from an old grill with expanded metal welded to it. The expanded metal is 12" tall, and 15" in diameter. The basket has four 2" long "legs" so it keeps it off the bottom of the cooker (no ash pan).

The bottom of the basket sits about 1-2mm above the intake pipes so that oxygen can be sucked into and under the fire itself. I wanted a basket that would have NO air restriction.

My grates are done like BigMistas' (6" from the top, then another 6" below that). I don't have the standard 24" from the bottom of the basket build. I figured if it doesn't work out using BigMistas' as a template, I'll go the standard route, but his seems to work just fine.

EDIT: Lump was 1 day old (from the store, and stored inside, in a cool, dry place).

[phyx]

Hey Kenny! Glad to see you're here too. :D

[Kenny 13]

Hey Kenny! Glad to see you're here too. :D

Ditto!!!!

[phyx]

Dr KY--I'm pretty certain the pipes on the bottom are clear...didn't really check that as the UDS had never been used, didn't figure that there'd be any blockage. I'll take a look though(maybe the weld didn't go so well).

[Dr_KY]

Other than that this one's got me stumped. Get a thermometer in there.

[phyx]

Yeah I will. Because I wasn't cooking, I thought "Fark it...just get some heat and get her seasoned". I just thought it odd that the UDS was stone cold after about 5 hours with 3 vents open. And I mean completely cold with 50% of the lump left.

I'll definitely check the pipes again, but I don't think they're blocked.

[radmanct]

By no means an expert since I will be building my own UDS in the next few months when I acquire all the pieces.

But, I have seen here that a lot of people will suggest a good kick or two to knock ash off and thru the grate.

[Midnight Smoke]

Maybe I can help. My UDS did not produce the results others had posted. If I put just a few lbs of charcoal KF I could not get long burns. I started putting in about 14lbs piled in a concave minion method, using my CC starter filled about 3/4 full I can now get 10+ hour burns at 225º-240º

I have 2 3/4 ball valves and I need to adjust a few times during the cook. For exhaust I use the 2 bung holes in the lid, I adjust these during the cook as well. I also have to shake the FB after 6+ hours a couple times.

After a 10-12 hour fire I start losing temp, unless I remove the lid and let it fire up hot and adjust back down. I always have a few lbs remaining after a long cook.

My point is when there is little CC I cannot seem to maintain a good burn, if I load it heavy I am golden.

[phyx]

Thanks guys. I think you're on to something with the small amounts of charcoal. I have a feeling that if I loaded it up, it'd hold temps much better.

Then again, this was my first burn, so I'm not sure...

[Dr_KY]

One recuring pont I see here and in other threads is the fact that

a) Ash build up is a downer
b) there must be more exhaust that intake.

I mostly use lump an it's some off brand with a few coals and I burn just fine and always have the manditory unburnt lump after the cook is done.

I also foung that when cooking without enough fuel the meat drips and puts out most of the fire. So again I quote Big Mista...''Slow and wide for the fire."

[sksmoker]

Remember about ash buildup and bridging with the lump. I have this problem in my BDS clone in that the lump chunks won't be "tight" like you need for them to burn properly. If the valves haven't changed positions, and your temp is dropping, you may need to shake the basket _very_ gently to settle the lump so it may burn.

Just like wood in a fireplace, it needs to be together to burn properly. I use lump and get about 14 hours with some left over. Your basket is very large as well. We have the same diameter, but mine is only 9" high and will hold almost 30 lbs of briq's, or 14 lbs of lump. You have a 2" air gap which is good.

[Dr_KY]

Don't forget to read this thread...

http://www.bbq-brethren.com/forum/showthread.php?t=23436

[phyx]

Thanks guys. I never thought about the lump needing to be tight. There was very little ash in there when it was all done.

Dr KY--that thread is what pushed me over the edge of whether I should build one. LOL I've read it end to end twice. One of the greatest threads of all time in BBQ...

[phyx]

Sksmoker,

When loading up your basket, how much unlit and how much lit do you put in?

I don't have a weed burner/tiger torch, so I'll be using my Weber chimney. Would you put a whole lit chimney or less?

[txschutte]

Shaking or kicking your can while cooking is a must. The simple buildup of ash will kill your fire. Try it again, this time kiccking or shaking the drum every 2 hrs. or so. This will expose fresh fuel from under the ash.

[Kenny 13]

Sksmoker,

When loading up your basket, how much unlit and how much lit do you put in?

I don't have a weed burner/tiger torch, so I'll be using my Weber chimney. Would you put a whole lit chimney or less?

Phyx, I can tell you when I did my burn the other night I put a whole 9# bag of unlit briquettes in mine and formed a small cavity in the center. I poured 12 lit coals from my chimney into the cavity, and with 2 inlets open my temp at the lower cooking grate climbed to 205* in 4 minutes. After that I had to open a little more to get it up into the 215* - 235* range. Problem wasn't getting the temp up - it was keeping it there.

[Dr_KY]

That's what she said.lol

[Kenny 13]

That's what she said.lol


:lol:

[phyx]

LOL

Thanks Kenny. I'm normally a lump user, but it looks like with this method, bricks are the way to go.

[Kenny 13]

No problem. I had planned on using lump in my drum. I just used briqs because I didn't want to spend the extra money on lump if I wasn't cooking anything. After what I've been reading here I think I'm going to reconsider and stick to the briqs.

[Dr_KY]

Use a combo of both that way the coals tend to stay lit and help the lump along. I use lump and about 10% coal.

[BBQ Grail]

I get much longer burns with steadier temps with briqs than I do with lump. I would rather use lump but for some reason in my UDS it just isn't fun.

That being said, I find it rather interesting that even identically built UDS' all work differently. That's got to be part of the mystery that intriques us about this wonderful Qing device.

[h20loo]

LOL

Thanks Kenny. I'm normally a lump user, but it looks like with this method, bricks are the way to go.


Don't forget the temp difference between his La. and your Ca. Try throwing a blanket over your UDS and watch the internal temp. jump.

[Dr_KY]

I get much longer burns with steadier temps with briqs than I do with lump. I would rather use lump but for some reason in my UDS it just isn't fun.

That being said, I find it rather interesting that even identically built UDS' all work differently. That's got to be part of the mystery that intriques us about this wonderful Qing device.
Same here, so far I have been lucky by sorta sticking to the rules of KISS and hitting good marks but i'm starting to explore the darker 'what if' side. lol

[thirdeye]

Shaking or kicking your can while cooking is a must. The simple buildup of ash will kill your fire. Try it again, this time kiccking or shaking the drum every 2 hrs. or so. This will expose fresh fuel from under the ash.

With all due respect.....kicking or shaking the drum will releases a lot of ash. The natural draw of the cooker will move that ash right onto your meat.

The easy fix here is to take a section of 1/4" rod, bend an "L" in the end. The L must be long enough to reach up into your charcoal basket when inserted through one of your vent holes. A gentle side-to-side rocking or slight jiggle will knock plenty of ash loose. Repeat this in two or three locations in the basket and you will be good to go. Here is a picture of mine. My drum is 43" tall, so I guess that wigggle rod is about 25" or 28" long. I put a T handle on the other end to make the rocking easier. I just leave it in during the cook.

http://img.photobucket.com/albums/v377/thirdeye2/BDS/25bbadff.jpg

[hcarter]

With all due respect.....kicking or shaking the drum will releases a lot of ash. The natural draw of the cooker will move that ash right onto your meat.

The easy fix here is to take a section of 1/4" rod, bend an "L" in the end. The L must be long enough to reach up into your charcoal basket when inserted through one of your vent holes. A gentle side-to-side rocking or slight jiggle will knock plenty of ash loose. Repeat this in two or three locations in the basket and you will be good to go. Here is a picture of mine. My drum is 43" tall, so I guess that wigggle rod is about 25" or 28" long. I put a T handle on the other end to make the rocking easier. I just leave it in during the cook.

http://img.photobucket.com/albums/v377/thirdeye2/BDS/25bbadff.jpg


So, ThirdEye, I was looking at your BDS. I've been trying to figure out how I want to build mine. I notice that you just have holes about, what, 1.5 in from the bottom? What kind of charcoal basket did you get? I'm really not mechanically inclined, so any help would be greatly appreciated.

[Kenny 13]

So, ThirdEye, I was looking at your BDS. I've been trying to figure out how I want to build mine. I notice that you just have holes about, what, 1.5 in from the bottom? What kind of charcoal basket did you get? I'm really not mechanically inclined, so any help would be greatly appreciated.


I can give you a pretty simple idea for a charcoal basket the way I did mine. I got a piece of 12" x 24" expanded metal from Home Depot and cut it in half with an angle grinder so that I had 2 pieces that were 6" x 24". I put them end to end with just enough overlap so I could slip a couple of stainless bolts through using fender washers, lock washers & nuts so it wouldn't come apart. For the most difficult part, I had to bend it around into a ring with the same overlap and bolt that end together the same way. That just sits on a regular cooking grate to give me a basket that's roughly 16" OD x 6" deep.

[txschutte]

With all due respect.....kicking or shaking the drum will releases a lot of ash. The natural draw of the cooker will move that ash right onto your meat.

We have never had the problem of sending ash into the food. We don't violently shake the can, just a simple rocking motion.

[thirdeye]

So, ThirdEye, I was looking at your BDS. I've been trying to figure out how I want to build mine. I notice that you just have holes about, what, 1.5 in from the bottom? What kind of charcoal basket did you get? I'm really not mechanically inclined, so any help would be greatly appreciated.


Actually I didn't build mine, the BDS line is designed and built by Rocky Richmond. I guess 1.5 inches sounds about right. My charcoal basket is a cylinder of heavy duty expanded stainless. Although I don't measure it, I believe it holds about 10 pounds of charcoal. HERE (http://www.bigdrumsmokers.com/index.htm)is a link to the BDS website.

[thirdeye]

We have never had the problem of sending ash into the food. We don't violently shake the can, just a simple rocking motion.

I guess I was picturing you getting pretty western with the drum...

[Norcoredneck]

Here is a demo of me doing mine.
http://youtube.com/watch?v=jCwcZfcyRqU&feature=related

[thirdeye]

Here is a demo of me doing mine.
http://youtube.com/watch?v=jCwcZfcyRqU&feature=related

Now that's funny :biggrin:

[Meat Burner]

Now that's funny :biggrin:
What thirdeye said.:lol::lol::lol:

[phyx]

OK. You asked for pics, so here you go!

She ain't pretty, she just looks that way:

http://img255.imageshack.us/img255/4694/udsvl5.th.jpg (http://img255.imageshack.us/my.php?image=udsvl5.jpg)

My basket. The bolts on the bottom act as legs that let the basket sit about 1/8 inch higher than the pipe nipples:
http://img255.imageshack.us/img255/957/basketse9.th.jpg (http://img255.imageshack.us/my.php?image=basketse9.jpg)

Here's the bottom of the barrel--literally. :biggrin:
http://img255.imageshack.us/img255/4581/insideudswo5.th.jpg (http://img255.imageshack.us/my.php?image=insideudswo5.jpg)

Basket in the UDS, top of pipes are 2 inches from the bottom:
http://img255.imageshack.us/img255/3808/basketinudsvs2.th.jpg (http://img255.imageshack.us/my.php?image=basketinudsvs2.jpg)

Here's the lid, with the 8 holes drilled at 1/2 inch diameter each. This thing is still in production so I haven't got the permanent therm for it. The Mavericks' probes are just hanging down at grate level:
http://img255.imageshack.us/img255/8559/lidvq5.th.jpg (http://img255.imageshack.us/my.php?image=lidvq5.jpg)

I dumped about 10-12#s of lump in the basket (on top of what wasn't burned last weekend, and it's been sitting out in the elements this whole time), put half a Weber chimney of lit into it, and it held over 400 degrees (424F!) for an hour with all 4 intakes wide open (and I checked--no blockage). I then capped 1 intake and it went to 366F for another hour. I then capped another intake--240ish for another hour. I closed a ball valve half way leaving 1 open and one 1/2 open--215F for an hour. Lifted the lid at the 3 hour mark, gave the basket a shake (hardly any lump had burned which is great!), and opened the ball valve full so there's 2 wide open intakes--240F again in about 30 seconds. It's now been 4.5 hours total, and about 1 hour since I shook the basket, and it's sitting at 237F with 2 intakes wide open.

My wife is scared to leave it burning all night. I tried explaining that it's perfectly safe, but don't think I'm going to win the battle. I'd really like to see how long this thing can go. I'm willing to bet that maybe 1/3 of the fuel has been consumed at this point--if that much. I'll shut down all the intakes in a few hours and check the temps an hour after that.

I can see that I've already had better results than the original burn. I think the key is to have more fuel in there so it settles better (like someone here said) and burns properly.

I'm going to give briquettes a try sometime too...just to see what difference it makes. I can't wait for my grates to come in. I'm going to smoke a picnic for its maiden voyage. I've never smoked a butt or picnic, so figured I might as well give it a go with a smoker I've never used. If it works out as well as I think it will--butts and briskets are going in there!.

[phyx]

OK, time to update...

I choked the fire completely about 9 hours into the burn. The next day, I went to check the amount of fuel burned. I had originally made a little cavity in the center of the pile of unlit lump and poured the lit lump into it. I burned *maybe* 1/4 of the fuel (pic to come!). There's a bit burned in the center of the basket, where the lit was dumped. Everything surrounding it was left untouched. It held steady in the 230's from the last time I had checked it at 4.5 hours in.

My wife, though not as enthusiastic about me building this thing to begin with, was surprised at how little fuel was used, and even remarked that we're going to save a lot of money in charcoal costs. That's a step in the right direction. I just can't wait to actually cook on it now. I should be getting a picnic on there this weekend.

[Dr_KY]

Now that's a winner right there! I love the way the are sop efficient with fuel and being that it tough to get year around over here I can stockpile it.