Kettle Drilling Problem

Well Guys,

I just ruined what I was going to use as a MLT in a Countertop Brutus 20 build this week. I read all the stainless soldering threads and being a car guy and an engineer, had little worries about this project. I've done soldering and welding before so I had a decent idea about what was going on.

I started by drilling a hole in the lid so that I could solder in a coupling to use for recirculation. I didn't use any lubricant due to the fears I heard about the hydrocarbon contamination and even though the steel got a bit hot, I had no problems and it turned out perfect once I soldered it.

Now I had some confidence and was going to take the plunge and drill the stainless kettle. I used a punch and marked the hole and started drilling. I again did not use any lubricant but I did use a higher quality step bit and everything went really well until I ran out of steps on the good step bit. This left me at an 11/16" diameter hole so I decided to use the lower quality step bit to finish out to the 7/8" diameter hole I needed. Unfortunately, just as I was about to break through to the 7/8" diameter step, the bit caught a little bit and tore a nice big gouge in my kettle. I was stunned. I've drilled more holes than I can count in sheet metal and I have never seen anything like this. From what I can tell, it was a combination of drill speed, drill bit quality, stainless quality and stress concentrations due to the manufacturing process. You can see in the pictures below, the tear is perfectly linear and it follows the tooling marks around the circumference on the pot.

Once this happened, I decided to do some more research and I found that you can use olive oil as a lubricant and not risk the contamination. So I decided I had already ruined the pot and I might as well try and learn from this so I decided to drill another hole. Everything except the oil was the same. The oil never even began to smoke and indicate too much heat, yet I had the EXACT same results.

At this point I had accepted that I will need to purchase two new kettles (already needed one for the system) but now i have major concerns with trying this same process on one of the economy brew kettles I was eying up with any on the online HB stores. Are this pots going to be any better than this cheapo 4 gallon that I just ruined? Am I doing something wrong that I just can't see?





I appreciate any help you guys can give me. It is very frustrating to have stuff like this happen when it feels like such an easy project to complete.

Caleb

Would your silver solder would fill the gap after squeezing it back flat?? If not, JB Water Weld or take it to someone who can weld stainless.

IMO, using a step bit on very thin metal is asking for trouble and espeically so with the cheaper bits. A hole saw would have been my choice or a conduit punch. I do not understand the concern over hydrocarbon contamination. Cutting oil and such should wash right off with a little BKF or something similar. Where did you buy that kettle? It appears to be paper thin.

Wait.... you can weld and you call that kettle trash now? Just pound it and and weld it up. Unless your going for the bling bling factor. Then ship it to me and I'll use it

Catt22 said:

IMO, using a step bit on very thin metal is asking for trouble and espeically so with the cheaper bits. A hole saw would have been my choice or a conduit punch. I do not understand the concern over hydrocarbon contamination. Cutting oil and such should wash right off with a little BKF or something similar. Where did you buy that kettle? It appears to be paper thin.

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+1. Holesaws actually work better and are cheaper. BTW, it looks like you have TWO gouges in there, one on each side of the hole.

The problem with that type of metal is the press marks. There's a stress riser at every groove there, ant the metal is thin to begin with.

I agree with everyone else though. Just even it out and solder it. It should be strong enough.

I will absolutely not use jb weld on anything that touches my beer. I could teach myself to weld it, I have a tig at my parents house but I can't even get a hole drilled and I've never welded stainless before. As far as solder goes, solder will not reliably hold that joint together. Solder needs an overlapping joint at a minimum to be effective.

I don't have access to a conduit punch but was certainly considering a hole saw. I made the assumption that all the people on here had no problems with the step bit so why should I. I guess that's a lesson learned.

I think the pot came from Walmart. Any idea if the economy brew kettles that can be had for forty bucks (5 gallon) are any heavier?

Kegs. Craigslist.

cjp4627 said:

I will absolutely not use jb weld on anything that touches my beer. I could teach myself to weld it, I have a tig at my parents house but I can't even get a hole drilled and I've never welded stainless before. As far as solder goes, solder will not reliably hold that joint together. Solder needs an overlapping joint at a minimum to be effective.

I don't have access to a conduit punch but was certainly considering a hole saw. I made the assumption that all the people on here had no problems with the step bit so why should I. I guess that's a lesson learned.

I think the pot came from Walmart. Any idea if the economy brew kettles that can be had for forty bucks (5 gallon) are any heavier?

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I use a aluminum one from Target called Imusu or something along those lines. It cost me $20 and it's soft metal so you can probably put a hole through that with ease. The pot itself is very sturdy, even with 8 gallons of water in it. I was quite surprised when lifting it to do some mashes.

The pot itself is designed for steaming, so it comes with a inner plate with large holes. But get some mesh and solder it onto the inner plate and make the hole just below that and you got a decent semi-effective filter.

I've got a 20qt from MoreBeer & it has the same tooling marks in it. I guess this justifies the $$ for the knockout punches. I'm guessing a hole saw may end up doing the same thing.

Ouch!!!

Take to a welder. Have him weld in the bung and fill in the cut at the samed time. It's about a 5 minute job.

cjp4627 said:

Am I doing something wrong that I just can't see?

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You overheated the pot (you didn't use any cutting oil) and because of that stress it cracked. Next time use cutting oil, when it starts to smoke, stop and re-apply some oil. You can use anything from actual cutting oil to PAM. I'd also be willing to bet that your bits are fairly dull now from the overheating. Next time use a bit of oil and you should be just fine.

cjp4627 said:

As far as solder goes, solder will not reliably hold that joint together. Solder needs an overlapping joint at a minimum to be effective.

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Two big stainless washers. Curve them to the pot. Solder them together inside to seal them.

cjp4627 said:

I will absolutely not use jb weld on anything that touches my beer. I could teach myself to weld it, I have a tig at my parents house but I can't even get a hole drilled and I've never welded stainless before. As far as solder goes, solder will not reliably hold that joint together. Solder needs an overlapping joint at a minimum to be effective.

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I wouldn't use solder on a pot you will be direct firing anyway, the chance to overheat it and melt the solder is just to great IMHO. Get it welded or grab a new pot, that's about all you can do.

I agree..Just weld it. It will make no difference to the person that welds it up.

But I will add this. It looks like you heated up the metal while drilling it without coolant/lubrication of any form..In essence, you work hardened the material.
That is where the tearing came from. A bit that was dulled and work hardened material.

Cheap step bit didn't help.

Holy moley... can't believe you didn't use a cutting oil or heed all the warnings about heating up the work, taking your time etc. Sorry for your loss, but this is a good lesson for others.

+1 on washing the pot well when you are done and not worrying about trace amounts of chemicals that can't possibly be of that much significance.

This will not be a direct fired pot, it is going to be heated by a water heater element in the kettle. I have no worries about the solder not holding up to the heat.

The hydrocarbon thing didn't concern me from a sanitation stand point. Others had said that the oil affected the soldering characteristics of the stainless. That's all I was worried about and missed the part about vegetable based oils being acceptable.

I don't think it was heat alone that caused this. Heat was my first guess but when I drilled a second hole, with oil, I saw the EXACT same results. I checked them temp all around the hole as I was drilling and it wasn't even warm to the touch. I can also tear the metal along the split as far as I would like to with bare hands. There is more to this than just work hardening.

I am going to try putting patches over the holes for the short term and go from there. I am also going to try the holesaw and see where that takes me. I've never had such bad luck with step bits but always used them on slightly thicker materials. Also used a much higher quality bit.

wyzazz said:

I wouldn't use solder on a pot you will be direct firing anyway, the chance to overheat it and melt the solder is just to great IMHO. Get it welded or grab a new pot, that's about all you can do.

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The solder is on the inside of the pot and theoretically will never go above 230 degrees.

OneHoppyGuy said:

The solder is on the inside of the pot and theoretically will never go above 230 degrees.

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Theoretically yes, but I still wouldn't do it.

cjp4627 said:

I don't have access to a conduit punch

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Unless they on a deserted island, EVERYONE has access to a conduit punch. Just go to the local tool rental shop. I can think of three places near me right off the top of my head.

If you need a 7/8" hole, I would HIGHLY suggest this:

http://www.toolbarn.com/greenlee-31962.html

I used a 1 1/8" one to do the holes in my kegs, and it worked AWESOME. Makes a superb hole and I didn't even have to debur it or worry about cutting oil. I just had to drill a small 3/8" hole using a standard drill bit (rated for metal obviously) and then use the punch and a ratchet/wrench to do the rest. I tried doing mine with a step bit at first but this was a LOT faster, and I didn't ruin any more step bits.

I can see the heat discoloration in the metal around the hole. You overheated it and the steel got brittle, and BANG.
I can't for the life of me, fathom why you wouldn't use some kind of lubricant!

Update:

I found out we had a set of conduit punches at work today and I made a beautiful hole with very little effort. Brought the kettle home, tried using the keg tool to flare/enlarge the hole to fit the half coupling and here are the results. I used lubricant while using the tool as well.



I think this is proof that the issue not related to heat but more to the material thickness, induced stresses in the part due to manufacturing and possibly the alloy as well. I think I am going give up on this pot for now and try to find something better. Not sure what that will be yet.

the striations appear to be the sign of very poor quality machining and or material quality

Bummer

That definitely looks like it would be an issue..Step bits: 0-0, Conduit punch: 0-0..

Mind identifying this pot and or where you got it? It might save others time, money and aggravation.

The pot looks like it was formed by "spinning". Just an observation.

Sometimes expense is the best economy.

The pot was for sure made using a spinning process.

The pot was something I picked up when I first started extract brewing. It came in a set of three from Walmart for something like $20. It was a 16qt pot.

Now, moving forward, any recommendations for a pot that will stand up to this type of fab? Whether I end up welding or soldering, I really dont want to end up with another pot like this. I can't afford a Blichman or anything but I think it would be dumb to go as small as I was planning if I have to buy decent pots anyways. I might try calling about kegs tomorrow but I was think something more like 10 gallon capacity. Looking to spend between 75 and a hundred dollars. How about the bayou classic pots? Any other suggestions?

Get a keg. Even a used keg will be better quality then that pot.

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Great SS pots on Overstock.com. Good prices and quality too. I love mine. Drilling was a cinch with a hole saw. SS ball valve and bulk head in, high temp o-ring and zero leaks! Delicious beer is the result!

cl330b said:

Great SS pots on Overstock.com. Good prices and quality too. I love mine. Drilling was a cinch with a hole saw. SS ball valve and bulk head in, high temp o-ring and zero leaks! Delicious beer is the result!

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P.S. now oils or chemicals on drill day either. Just slow and steady.

Here is a suggestion:
50 qt Tamale Pot

Or this one which is a bit more money than your plan:
ballington_60_qt_stainless_steel_stock_pot_with_steamer_insert

Kegs kegs kegs !! If you want 15 gallons just cut the top, if you want smaller cut them down !

you're scaring the begeezus out of the guy who's too nervous to make a hole in his pot!

outside92129 said:

you're scaring the begeezus out of the guy who's too nervous to make a hole in his pot!

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at least with keggles the cutting tools wear out before the kegs do

joeybeer said:

Kegs kegs kegs !! If you want 15 gallons just cut the top, if you want smaller cut them down !

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I second this. I picked up 3 empty kegs from a local bar for $30 each. Cut the tops out with my angle grinder, and I now have 3 excellent brewpots to do 10 gallon all-grain batches.

Yep. It's a veeery thin pot. I have one just like the OP's that's why I mentioned the stress risers on page 1. All the bit has to do is bind and the metal will split. I measured 20 thousandths on the top, so imagine what the grooves are!

Is there any difference between the pot the op used and a Polarware economy pot? I have a Polarware economy pot that looks very similar and don't want to have the same problem, but I need to drill a hole for a valve also.

cjp4627 said:

Looking to spend between 75 and a hundred dollars. How about the bayou classic pots? Any other suggestions?

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for that you should be able to get 3 kegs! Another vote for kegs they are very heavy duty!

3 kegs...... legally?! How do you figure?

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