Picture of KEG LATHE
I have found instructions on how to convert kegs, using reciprocating saws, grinder, and plasma cutters. But in my experience, kegs which are ground or sawed generally produce uneven or oval openings. Plasma cutters on the other hand produce outstanding openings; unfortunately I don't have many friends who have them at their disposal. So I came up with a different way of cutting the opening. In essence, I have created a hand turned lathe for a keg. It cost me around 30 dollars, but depending on your own personal inventory of tools, the cost may be higher or lower. The project took about 3 hours which included the construction, cutting out the opening and smooth out the edges.

Note that working with tools and metals always have the potential to cause harm, therefore I explicitly state that none of this information is guaranteed NOT to make you suffer an injury, lawsuit, material economic loss, time in jail or impotence. I refuse to take any responsibility for anything that happens to you as a result of using the advice stated in this instruction set. In short if you feel responsible enough to take on the project, then you are responsible enough to deal with the consequences of your own actions.
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Step 1: Tools Used On The Project

Picture of Tools Used On The Project
The image below has been color code to help you identify what each item is and when each item is used. Yellow designates the set-up process (Phase 1), Green the cutting process (Phase 2), and Blue the clean up process (Phase 3). The Brown color denote items which are used in more than one phases.

A: Small Vise
B: Marker
C: Saw
D: Drill bits
E: Tape Measure
F: Screw driver bit.(use the one which match your fasteners)
G: Lathe Tool Holder.
H: Wrench sized for Tool Holder
I: Tool Steel Lathe Bit
J: Pliers
K: Half round steel file
L: Aluminum Oxide Sand Paper
M: Aluminum Oxide Spindle Sander
N: Drill/Screw Driver
O: A paper towel.

Other tools "Not Shown":
If you are using an unaltered keg you may need a pair of needle nose pliers, and a firm rubber mallet.
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AR10NZ2 years ago
Hi all : I have modified a few stainless steel kegs, making stills ( leagal in NZ, for home use ), and brewing vessels. From my research, they are heat treated, after robotic welding, and will handle up to 90 PSI. If they are modified, and any welding done on them, they should NEVER again be used as a pressure vessel. When cutting & tig welding, to "stack ), to increase volume, I use a modified el-cheapo vice grip, with a piece of steel banding, with holes drilled, about 40mm apart, using a uni-bit. Clamped around the circumferential weld site, this allows for quick & easy tacking, prior to welding.
mrmath7 years ago
crapflinger asked my question, so I'll just leave this comment:


There ==> A place, as in "over there"
They're ==> They are, as in "they're to young"
Their ==> Belonging to them, as in "enact legislation in some states to protect their assets."

Sorry, but I can't help myself.

Otherwise, a very detailed and well done instructable. Good pictures. Great step by step. You included what problems we would run into. Good example of how to post here.
two ==> one more than one, as in "now there are two comments on grammar"
to ==> towards, in so far as, as in "working to rule"
too ==> in excess, as in "they're too young"

Sorry, it looks like you can't help yourself
SMACK! ==> The sound my hand makes against my forehead when I realize I made a grammar mistake while correcting grammar!
Pader mrmath2 years ago
SMACK! ==> The sound my hand makes against my forehead when I realize I made a grammatical mistake while correcting grammar! :-p
GitarGr8 mrmath7 years ago
"They're ==> They are, as in "they're to young"


To ==> Preposition. "I'm going to the market."
Two ==> The number 2. "I have two apples"
Too ==> In excess of something. "I have too much time, so I correct people's grammar"
mrmath GitarGr87 years ago
Yea, Mister_Caipirinha already pointed out how much of an idiot I am! :)
GitarGr8 mrmath7 years ago
Lol, guess I should scroll down and read all the comments next time...
mrmath GitarGr87 years ago
No. When you do something as stupid as I did here, you deserve to have it pointed out however many times it gets pointed out. I mean, how much more of an idiot can you be thatn to say "You're an idiot because you did something that I'm doing right now!" I know that my treatment of fredan was not as harsh as calling him and idiot, but it still works out the same in the end!
fredan (author)  mrmath7 years ago
Thanks for the input, grammar and spelling have always been my kryptonite.
mrmath fredan7 years ago
Mine as well. That's where the pet peeve comes in. It took me so long, and I had to work so hard, at getting over the There/They're/Their and Your/You're things (and now the To/Too/Two!) that it became a pet peeve for me to see them used wrong. But, if you have a kryptonite, that makes you Superman!
fredan (author)  mrmath7 years ago
Thanks Lex :-)
What are you guys doing with these? I seem to be lost as to why you want kegs opened up
daywalker425 years ago
trust me, you don't want to use a threading tool to cut a piece of metal. it seems like a good idea at the time, but it isn't, and this is the enwisened tone of experience talking. the finishing is also a bad idea. I'm an engineer and I have worked in a machine shop, and of these your best bet would be the grooving one. just turn your tool holder so that the front of the tool is parallel to the face of metal to be cut, and the blade is facing against your rotation, i.e. if you are spinning keg clockwise, and tool is at bottom of keg, the sharpest part of the blade should be to the left. it will definitely turn out better no pun intended, it should take less time, and be easier on you and your tools.
oops. I put left. I meant right. sorry mate, I miss small details from time to time.
Scubaholic6 years ago
As a Keg is designed to be emptied standing up, you can tip it on its side to depresurize. This will take the lifter snorkle out of any liquid left in the bottom of the keg. This is assuming your not using a keg thats more than half full.
BrewBeemer6 years ago
I had a good curb side find 3 years ago, a complete but old Shop Smith that will swing a 16 1/2" object. The Vari-drive pulley system was stuck with a bolt missing allowing the pulley to jam against the frame tubes and trip the motor overload. I added a bolt and washer, all is well. Added a live center with a machined step sleeve that fits into the filler neck. A 1/4" metal disc 14" diameter is threaded, bolts thru the Shop Smith's 6" aluminum face plate to become one with the Shop Smith's spindle. This steel disc fits past the rolled bottom of the keg's edge. On the disc I welded three 1/2-13 nuts. Thru the nuts are long allen bolts with a point to bite into the bottom kegs skirt above the rolled base lip to center and turn true plus drive the keg. With the vari-drive at the lowest setting plus the use of a 20 amp autotransformer the rpm's become rather slow. I did use a lathe parting bit in a tool holder to cut 10" open tops into my kegs. A plate with a tool post arm that is "U" bolted to the Shop Smith's frame tubes. A smaller open top allows for a lot less open surface area for less wasted boil off hence more net bier. For cutting a keg body a 10" vertical and horizontal rotary table with a crame mount and the same live center for the filler end with the keg horizontally mounted on the Bridgeport Mill. With the hand crank rotary table for cutter feed speed control. A 1/4" stubby carbide 4 flute cutter leaving five 3/16" long uncut sections to keep the cut apart keg sections together until all mill cutting is completed. Later cut the five 3/16" bridges and dress flat. This way kegs can be extended to higher volume plus a light tight gap to be Tig welded later. The Shop Smith can also be used to polish kegs which is useless as they will be insulated anyway. Function before beauty when dealing with your taste buds. Your lathe idea parallels what I came up with instead of a grinder as I wanted a narrow machined gap to reuse the cut top as lids again, just add SS tabs. A great idea your lathe built, congrats. The only complaints are from those that did not machine their keg lids off, just using grinders. Cheers and hats off to your project. member.
yeagerxp6 years ago
Very good idea using the rollers. This idea can be used for cutting other Cylindrical items
t0mbutler6 years ago
Could a commercial keg like this, with a hole cut in the bottom and a valve added, be used to brew a batch of beer and then turned right side up and put in to a kegerator system for force carbonation and serving? What would you use to seal the new hole in the keg and have it stand up to pressure? Thanks
fredan (author)  t0mbutler6 years ago
I don't feel it would be feasible due to the heating issues you would have with the seals for the stem
ok thanks, i figured out its much easier just to open up the sankey kegs and put the batch in there for forced carbonation anyway
naught1017 years ago
This wouldn't work with your set-up, but a mate of mine had a keg that has an ovoid hole, and a similarly shaped, but larger ovoid lid, with a rubber seal. you put the lid INSIDE the barrel (you can't do this with a circular lid, obviously), and then turn it 90 degrees, and pull it up. his had a screw-up fastener, but it only needed to be tightened a little bit, because after a couple of hours, the pressure from the beer would push the lid up, tightening the rubber seal. Worked pretty nicely.
Excellent idea. You could adapt this to anything large diameter & cylindrical. Well done!
unibox7 years ago
The keg looks to be made out of aluminum. If it is stainless it looked really easy..... Nice work on everything. I really like this idea.
Transquesta7 years ago
This one's genius. Sheer genius! Legal issues aside, I now know a great way to build a keg washing machine for my campsite. :-)
Bobby_M7 years ago
Great job. I used an angle grinder on a "compass" type jig to do the same thing on three kegs. I think my method is a little faster, but you need a grinder too.
fredan (author)  Bobby_M7 years ago
I have converted kegs using both methods, if you remove the build out of the equation, it only takes about 15-25 minutes to cut and dress the opening. Using a grinder took me about 30 to 40 minutes to accomplish the same task. Depending on one's abilities these times could easily be inverted. I want to be clear, I am not saying your process is wrong or bad, only that this process works very well for me. I suppose if speed is what you're after, create a hybrid version use the roller cradle in combination with the grinder mounted in the vise.
Bobby_M fredan7 years ago
I'm not knocking your project by any means but if you watch my video, you can see that each keg cut took 2-3 minutes. The concept of both of our methods is making a repeatable, perfect circle... Either way, beer is made.
Bobby_M, have you posted anything on building your angle grinder jig? Are there any got-ya's that people should be aware of when using your method? I saw that you had to watch for the electrical cord and at one point you removed the jig, walked out of the frame and returned. What was up with that? I like the idea of the jig, as well as the Keg Lathe. Thanks,
There are a couple tips. First, you've noticed it's a pain that the cord gets in the way, but you can see that you just deal with it. I removed the jig once just to unwind the cable. Second, you want to make sure you don't wear the disc down to far as you do multiple kegs, eventually you won't be able to move the grinder down on the jig far enough to hit the keg. Finally, you'll want to leave 3-4 spots uncut around the diameter to support the pivot point. Once you cut 99% of the slot around, just hit those spots with a hammer like you see in the video.
fredan (author)  Bobby_M7 years ago
Sorry, I did not notice the link to the video. I like your project it is a great way of cutting the hole. Thanks
jdlink7 years ago
How did you do the cool illustration?
fredan (author)  jdlink7 years ago
The first illustration was made using a cad application called Solidworks. The majority of the images were snap shot taken with my digital camera then edited using Microsoft's The last few images were public domain.
Woodwave fredan7 years ago
Actually, Paint.NET is not from Microsoft. Paint.NET is a free graphics program started as a senior project at Washington State University. It is a great free program (#19 of the top 100 products of 2007 by PC World), has great tools, supports layers, and plugins. Visit to download a free copy for yourself. It's nice to see people using Paint.NET and acknowledging it.
swihart7 years ago
Fantastic! This is wild and wonderful, glad a friend sent it to me. But I gotta continue in the vein of step one. Vice: (n) a moral weakness or failing Vise: (n) a clamping device :-D
doggo7 years ago
Sorry, just one more correction: vise. It should be vise, not vice. Well, I guess if you're brewing ten gallons of beer, it could be a vice. But to hold things firmly, you would use a vise. But other than that, great bit of ingenuity.
fredan (author)  doggo7 years ago
Thanks, I made the corrections.
karrock7 years ago
Nice tool labeling! The clear color-coded tags on the photo are a very effective and thoughtful touch. Something that should be done more often for these DIY walk-throughs.
frechetn7 years ago
Well documented instructable. A low RPM friction wheel motor assembly would probably to the trick. Similar to what a pitching machine uses, but much slower. Did you have to increase pressure or adjust the cutting bit while cutting? Well good job, fredan...
fredan (author)  frechetn7 years ago
I did have to adjust the bit as it got a bit dull from the cutting process. If you were to add a motor to this process you would have to have a method of driving the bit into the metal. Currently, I am doing this manually, when I spin the keg I pull the keg to the cutting bit. If you were to add a motor drive, most likely you would also add a tensioning roller to the rear of the keg. This would allow you to apply the forward trust and push the metal into the bit. Another solution could be to have a vice that mounts to an adjustable slide, and then you could push the bit into the metal. In the latter solution you would still need a roller to control the kegs motion. In the end I still think that adding a motor is cool but way to much work. Thanks for posting.
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