Making Holes in Stainless Stockpots

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Socrates
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Making Holes in Stainless Stockpots

Post by Socrates » Tue Sep 09, 2008 8:56 am

Hi all...

As a few of you know, I'm new here and about to embark on my first Bok Mini based on a mid priced SS stockpot. Like many of you I've spent many hours reading the main site and the forums, which led to my decision. There's nice summarized info on things like soldering, assembly, coiling, cleaning and distilling. Just about everything.

Missing seemed to be a good summary on cutting or making holes in spun SS stockpots, lids and bowls. After much research and a goodly number of PM's to many of the well known and respected distillers here, I was able to accumulate a bunch of very good info which I thought would be worth sharing in this one post. Here goes:

1. Stainless steel is difficult to work with and requires better drills and tools. Working with it requires special techniques - SS can easily work harden and mess up your project.

2. SS stockpots/lids/bowls tend to be made of lower grades of stainless that are spun or stamped - which means the SS is already work hardened to some degree. They are also thin - another factor requiring special techniques.

3. The two type of holes usually needed include a large hole (say 3 or 4 inches) for the column flange or SS drain, made in the lid or bowl serving as the cover. The other hole(s) include small (say 1 to 1-1/2 inches) to be made in the lower side of the stockpot for inserting heating elements.

Now let's consider some of the techniques I found:

1. Plasma Cutting and/or SS Welding: expensive equipment and process that most of us are not equipped to do.

2. Hole Saws: ordinary hole saws will not work on SS. At the least this requires what are called bi-metal hole saws. This is practical and affordable. More expensive are the carbide or tungsten carbide tipped hole saws. All require the same technique - very slow speed and use of ordinary or cutting oil, lots of pressure. Allowing ANY tool to spin fast on SS will work harden it and your hole drilling is over.

The key - you must keep cutting, slow and with pressure to avoid any work hardening slippage or spinning. But not so much pressure that the saw stalls or catches. SS pots/lids are often less than 1/16" thick and need to be supported from the back, so you can use adequate pressure without bending them.

Before you actually cut the large hole, it is acceptable to lightly centerpunch the center, then drill a small starter hole, then drilling to enlarge it to the same size as the center guide on the hole saw (to avoid the center guide breaking through without warning). Now you can drill the large hole. Use oil or a bit of oil soaked sponge which you can stuff into the hole saw - avoids need for a third hand.

3. Hole Punch: these are VERY expensive ($50 for a small hole, hundreds for a large hole), but do a great job. You could pay a plumber to punch your holes, and a few rental centers will rent them. Unbelievably, IKEA sells one of their "Fixa" tool sets for $9.95 (available in the kitchen/sink department). This amazing kit includes a nice tubing cutter - great for copper - and a 1.4 inch hole punch - designed for cutting holes in their SS sinks.

4. Drills: "High Speed Steel" bits can be used (though NOT at high speed). Carbide or Tungsten Carbide tipped are better, but more expensive. "Coated" drills don't improve the drilling, cost more.

The technique is the same. Very slow speed, lots of pressure, cutting oil - keep cutting! Begin by prick punching so the drill won't wander and you can apply plenty of cutting pressure from the get go. Start with 1/8" - then 1/4" - then 3/8". As drill size increases, the already slow speed gets slower and the pressure gets higher. Keep cutting or else.

Be careful - take your time. Thin SS overheats easily - if the metal turns blue it is overheating and you are work hardening it. Don't.

5. Step Drills: same considerations as drilling (above). These are expensive, and it would be a shame to ruin one for a few holes in your still.

Other distillers

Bourbonbob: Hi Soc. I used a 4" angle grinder with a worn down disk, you have to be careful but it is possible. Alterately you could use a drill and half round file, drill a pilot hole and then use a large bit, you should be able to use the drill like a router to gouge the hole out, then use the file to get a neat finsh. I have used both methods and with a bit of patience you will be successful.

Tracker: Lid is pretty thin so I used a hand operated nibbler to cut large hole.

As-Ol-Joe: I drew the outline of the holes I wanted to make. Then used a small drill bit, 1/8", and drilled holes just to the inside of my outlilne. After all the holes were drilled, I took a dremel tool with a grinding wheel on it and cut between the holes and clean it up the best you can with the grinder. Then use a file and sand paper to dress it up. It took me about 3 hours to cut the hole in the lid.

GingerBreadMan: I found Stainless steel to be hard to cut. The only holes I made was small holes using a drill bit. I started with a small bit and drilled, went to a slightly bigger one, drilled and repeated until I had the hole the size I wanted. To cut the Stainless steel bowl I used a dremel tool. That worked pretty well - went through about 20 cut off disks to cut a SS mixing bowl in half.

Some recommendations

1. Cutting large hole in lid or bowl: the easiest, simplest, cheapest way would be to buy 1/8" high speed steel drills, pack of 10 maybe 25 cents each. They will be ruined after your still is done, but so what. Mark the diameter of the hole needed, prick punch for a series of holes around the circumference, and drill the holes (as above). Support the lid as needed. Connect them by using a Dremel using cutoff discs. File or not as desired or needed, or use a Dremel grinding head.

2, Making small holes (for heating elements): The IKEA punch is close to perfect as it makes a 1.4 (1-2/5) inch hole. This will accomodate the standard water heater element whose thread is 1-1/4" (I plan to use a copper or SS female threaded coupler on the inside), SS washer and sealant outside). Alternative: appropriate bi-metal hole saw used as above. In either case you need to prick punch and drill the series of holes (starting with 1/8") for the center guide (hole saw) or for the tightening bolt (IKEA punch).

3. Cutting Oil: Some recommend WD-40 (reputed to run) or ordinary oil. One experienced source recommended "Rapid Tap" cutting fluid, as it "tends to resist running, is affordable in the very small quantities needed, has excellent cooling capability - your drills will last much longer".

4. Drills: Best bought from an industrial supply rather than from WalMart or even Home Depot. Their high speed steel are better quality and cost not much more.

In summary, let me quote one expert "Drilling SS is a pretty brutal process; when you get going, have immediate, continuous, strong, even, correct angle, speed and steady pressure on the drill and pour on the cutting fluid, which is as much of a coolant as anything".

Thanks to all for your kind responses... let's all offer our methods and experiences here.


Soc
Last edited by Socrates on Tue Sep 09, 2008 11:07 am, edited 3 times in total.

HookLine
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Re: Making Holes in Stainless Stockpots

Post by HookLine » Tue Sep 09, 2008 9:16 am

Very nice post. I vote this one gets made a sticky.
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eternalfrost
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Re: Making Holes in Stainless Stockpots

Post by eternalfrost » Tue Sep 09, 2008 9:42 am

nice write up

my vote is for a dremel(or any high speed rotary) and the beefy cut off discs (not the flimsy ones that come with like 50 in a package)

easily tore a 1.5 inch hole in a stainless keg (which is much thicker then most any pot lid) only took about 10 minutes, no other tools required and it didnt destroy the dremel or the cutting wheel at all

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Re: Making Holes in Stainless Stockpots

Post by theholymackerel » Wed Sep 10, 2008 6:38 am

I'm with eternal frost on this one.

I took the entire top off of a SS keg with 4 or 5 of the heavy-duty cutoff discs and it only took a short while.

Let the roto-tool do the work... the tinyest bit of pressure and the cutoff disc will dissentigrate.

Hack
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Re: Making Holes in Stainless Stockpots

Post by Hack » Wed Sep 10, 2008 8:23 pm

You can also get a mandrel for the cutting discs that will fit in an ordinary drill. These are very inexpensive.


Also, thought I'd add that a cutting torch will work nicely in some situations. This is what I used to cut the 8" hole in the top of my keg. I then used an angle grinder to dress up the edges.

Socrates
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Re: Making Holes in Stainless Stockpots

Post by Socrates » Thu Sep 11, 2008 6:36 pm

Guys, thanks for your posts, but keep in mind this thread is aimed at working with the thin and relatively flexible, spun stainless of stockpots, not with the thick and more rigid SS of kegs. Now I'm sure there are lots of you who've done battle with stockpots, and we'll all appreciate your methods and results...

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Re: Making Holes in Stainless Stockpots

Post by theholymackerel » Fri Sep 12, 2008 7:10 am

Ye of little faith...

... I took the top rim and few inches off of a thin spun SS Bowl with a cutoff disc and my rotoshaft. The second time I tried a diamond saw, but destroyed a 40someodddollar diamond blade. I finished up the project with a handheld dremel and a cutoff disc and it worked great.

If a cutoff disc will cut through the several millimetres of a SS keg, why would the fraction of a millimetre of the spun bowl or pot be a problem?

Socrates
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Re: Making Holes in Stainless Stockpots

Post by Socrates » Sat Sep 13, 2008 7:50 am

Good info, again thanks. It's nice to know that cut-off discs work well with thin SS. I was thinking more of hole saws and larger drills, and other techniques that require slow rpm's and relatively heavy pressure. No problem on a keg, but one resource I noted above states the thin SS must be supported to avoid bending, deformation and work hardening.

In one case he advised clamping the thin SS between two sanded (to conform) blocks of wood, which were then supported to resist heavy pressure. The wood also disipated some of the heat to reduce work hardening.

Thanks in advance to any SS pot experiences...

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Re: Making Holes in Stainless Stockpots

Post by CoopsOz » Mon Sep 15, 2008 4:09 am

I've stuffed more than my fair share of hole saws on stainless, I'm gonna have to get out the dremel it would seem. Thanks for the tip. :D
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Re: Making Holes in Stainless Stockpots

Post by Trid » Mon Sep 15, 2008 12:45 pm

Well written, thank you!

Incidentally, I don't know if I've had exceptional luck or stumbled upon just the right piece of hardware, but I've had fantastic success with stainless mixing bowls using my 2 3/8" hole saw. I've punched half a dozen holes for a 2" column and it's still going strong. I also failed (bad me) to use any cutting fluid in doing so...I was impatient and didn't have any immediately on hand.

The info on the Ikea punch is quite the bonus, thanks! I'm going to have to go get one and try it out. If it's designed for stainless, it ought to do amazingly on copper.

Socrates
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Re: Making Holes in Stainless Stockpots

Post by Socrates » Mon Sep 15, 2008 3:19 pm

Thanks Trid, very interesting. What brand/quality of hole saw did you use? Ordinary? Bi-metal? Or better yet?

Trid
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Re: Making Holes in Stainless Stockpots

Post by Trid » Tue Sep 16, 2008 9:34 am

If I recall correctly, it's a Lenox bi-metal. The trick, as you mentioned, is slow speed and constant pressure. I used to work with a fellow who thought the secret to everything was high speed and always chose a drill motor that had the highest possible RPMs when using a hole saw. Took him forever to get through mild steel. I would grab the slow speed gearbox-of-doom Makita drill motor (I swear that thing can take an arm off if the bit grabs) and would be through 4 holes by the time he'd make it through his first.

One thing I haven't tried, though, is annealing the spot to be drilled...perhaps with a mapp torch? Thoughts?

Trid
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Re: Making Holes in Stainless Stockpots

Post by Dnderhead » Tue Sep 16, 2008 12:16 pm

300 series(,304/316 etc )stainless work hardens ( bending , hammering, rolling etc) not by heat, to anneal needs to be heated to 1010-1020c held there
about 1 hour ( preferable o2 free) then cooled quickly. if you try in just one spot you will git stress cracks, 300 series stainless is more "tuff" and "gummy" builds up in front of cutting blades. and tends to bind. other stainless as 400 series can be harden with heat treating, but most likely you will not be useing them ( used as in razor blades , knives etc) (these will be magnetic)

farmerdfw
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Re: Making Holes in Stainless Stockpots

Post by farmerdfw » Sun Feb 01, 2009 7:03 am

I have found that 18000 rpm 3"die grinder cut the top hole of the keg the best. resting the head on the inside rim and handle on your top hole makes true round hole also if your cutting a fermenter the cut out can be saved for the boiler

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Re: Making Holes in Stainless Stockpots

Post by Sunnmoring » Tue May 26, 2009 12:51 am

A easy and afordable way of cutting holes. Go to http://www.ebay.com" onclick="window.open(this.href);return false;" rel="nofollow search for diamond hole saw. Remember to include free shiping and worldwide search. there are some great suppliers in Hongkong.

This way you get a hole saw that cuts glass, steel, copper, stone and more. The price is around 5-15 $.

If you get one of those without pilot bit, just drill a similar hole in a wooden plank. Attach it to the stainless steel with clamps and you have a very good guide.

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Re: Making Holes in Stainless Stockpots

Post by Mud » Tue May 26, 2009 10:48 am

I use a jigsaw with bi-metal blades. I've cut a stock pot, several kegs, and an 1/8" thick aluminum project box for electronics. Works great, but the keg was hell on the ears.

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Re: Making Holes in Stainless Stockpots

Post by theholymackerel » Wed May 27, 2009 5:36 am

Mud wrote: but the keg was hell on the ears.

Fill yer keg with water and it'll deaden noise and vibration.

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Re: Making Holes in Stainless Stockpots

Post by Mud » Wed May 27, 2009 5:39 am

A brilliant idea. Thanks, THM.

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Re: Making Holes in Stainless Stockpots

Post by cob » Sun Aug 02, 2009 11:36 am

i don't have a plasma torch yet and havn't used diamond hole saws on ss. glass yes ss no. i do use abrasives on ss all the time. for drilling i settled on cobalt bits and bacon grease, yes i tried every lube mentioned and many others and bacon grease was best for me. low and slow is important. this application was the skin of mci greyhound busses for coach conversion and other components. the skin is a little thicker than stock pot lids and much thinner than a keg. i posted this because i saw no metion of cobalt bits for ss drilling. here is a thought on bigger holes use any old dull hole saw of correct size with no pilot bit. make a wood guide with a backer board under it and well clamped. put a couple tablespoons of silica blast media, sand from the driveway or any other grit with enough water in your guide/well to flow the grit. slow enough to not sling the water. if the holesaw is already toast what you got to lose? cob
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Re: Making Holes in Stainless Stockpots

Post by plonker » Mon Aug 03, 2009 7:41 am

I used a jigsaw and a half round file.. it was a bastard.. never want to do it again..... very thin SS

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Re: Making Holes in Stainless Stockpots

Post by myerfire » Mon Aug 03, 2009 12:06 pm

I used my Milwaukee sawsall to cut a slot in the lid of my boil pot and also to cut the top out of a keg. Drilled a 1/2" hole for the sawsall and cut out the lid of the keg. Then used a half round file to remove any sharp points and burrs. Oh yeah, on the pot lid, I made two cuts about an inch apart and 1.5" long and then made a score with a drywall knife, bent the small piece of metal back and forth a few times and it broke off nice and clean. It sounds crazy, but scoring metal with a knife works great on anything up to about 1/16". In drywall, we do it all the time.
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malcontent
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Re: Making Holes in Stainless Stockpots

Post by malcontent » Wed Aug 26, 2009 3:47 pm

I cut stainless a lot at work with hole saws and we never use cutting oils they really dont work that well . Believe it or not use water. only water. Keep the speed kind of slow and keep it wet with a splash of water when it starts to dry out. The water keeps the saw cool enough to cut and if you keep the speed down and it wet it wont heat up and ruin the temper of the blade. I dont think I have ever tried larger than a 2" hole .
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Re: Making Holes in Stainless Stockpots

Post by irish_moonshiner » Tue Dec 08, 2009 5:48 am

I used the the same method that Tracker suggested, I used a hand operated nibbler tool to cut the large hole for the colum in my lid, it was quick and easy, you need to drill a small hole first so you have a place to start, the nibbler i used can cut up to 1mm thick SS.
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Re: Making Holes in Stainless Stockpots

Post by markx » Wed Dec 09, 2009 4:33 am

I've used a variable speed jigsaw on medium rpms and regular metal blades for cutting holes in 1,5mm stainless. If the radius is not too small (less than 2cm) then it works like a charm....but you gonna need ear protection for sure. Stainless is a pain to work with no matter what you do, it can catch tools and wear them beyond repairing, not to mention the distortion after welding. But polished to a mirror finish it really looks good and lasts basically forever :)

The most spectacular mishap that I witnessed was when one of my former colleagues accidentally confused titanium and stainless. He TIG welded a piece of stainless pipe to a titanium flange but upon cooling the stress of different heat expansion fractured the weld with a horrible bang and the pipe was shot off the flange with a force that caused it to embed a deep imprint into the concrete ceiling of the workshop. The mark is still there after years have passed. Good thing my friend was not leaning over the piece as it happened.
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Re: Making Holes in Stainless Stockpots

Post by rumlover » Tue Dec 15, 2009 3:54 pm

I work in foodservice repair and I have found that cobalt drills work best for me. As far as the brand name I prefer Irwin. They really just eat up stainless. I am sure there are better, but Irwin are readily available. I use Lenox hole saws and have found them adequate for thin stainless (Volrath brand mixing bowls). I can only comment about items available in th US. I have a couple of fly-cutters I use in my drill press for aluminum , but I don't think they would cut the mustard on ssteel.
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Re: Making Holes in Stainless Stockpots

Post by upinthehills » Tue Mar 23, 2010 8:50 pm

I'll second the idea of using grit. It's especially good if you have destroyed your hole saw trying to do the job. I was trying to get thru the lid of a 5 gallon soda syrup keg. In frustration I just hung a weight on the drill press arm and left it for a couple of hours. No real progress. Bought another hole saw, not bi-metal just a cheap $5 1 3/4" one. I could see the teeth were all flattened out after a while. Then I remembered my children's rock polishing kit, and a half teaspoon of course grit and a few more minutes of work I was done.

It didn't seem worth it to buy an expensive saw blade for one cut. Abrasive attack for stainless seems good for these jobs. The lid was thicker then most stock pots probably, I think 1/16". Stainless is pretty tough stuff...

malcontent
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Re: Making Holes in Stainless Stockpots

Post by malcontent » Mon Dec 27, 2010 6:40 am

We work with stainless a fair amount at work and the best Hole sawing and cutting fluild is water.Constant pressure and a medium to low speed. As soon as you see smoke the bit is shot. Keep it wet with small splashes of water and we have been able to use bits many times over.The idea is as soon as it heats up it changes the temper. Oil doesnt work.

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Re: Making Holes in Stainless Stockpots

Post by SuburbanStiller » Mon Dec 27, 2010 11:14 pm

You guys are doing much nicer work than me. I drilled a sloppy torn hole in my SS bowl with a well used hand-me-down bit. Just big enough to get this guy thru:
http://www.harborfreight.com/nibbling-c ... ag=froogle" onclick="window.open(this.href);return false;" rel="nofollow

I just nibbled around until I got it good enough. Didn't even try to clean it up with a file. Used the same process to punch a matching hole in a 2" copper end cap that mated to the bowl. Easy, cheap at $6.99 for the Harbor Freight junk, pretty quick work. Left a terrible jagged hole that would cut the hell out of your finger if you went poking at it. But it's on the inside and the joint hasn't given me an ounce of trouble since I bolted it together.
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Re: Making Holes in Stainless Stockpots

Post by BillTheChemist » Tue Dec 28, 2010 9:48 am

Stainless work hardens quickly so you really only have one go. Depending on the stainless type, cutting with a torch can cause cracking or corrosion - was metallurgist some years ago.

SuburbanStiller has it right. I used the nibbler from Harbor Freight and it is definitely the way to go - cheap and effective.

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Re: Making Holes in Stainless Stockpots

Post by robs » Wed Dec 29, 2010 4:38 am

I tried drilling through some ss plate about 4mm thick with a 1/4" cheap drill bit not knowing it was ss. Spent a lot of time at the grinder trying to sharpen the drill bit before i realised it was ss. Then with a nice sharp drill on slow speed and some lube got through it in no time.
When i cut a 2" hole in the top of the ss fire extinguisher for my boiler i filled it right up with water to keep it cool and used a bi-metal holesaw at the slowest speed i could maintain and kept the water running. Got through in about 10 minutes applying constant pressure. Each time the water steamed i would run more water on the cut and holesaw.
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