hole punching for heating elements

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warthog

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ok, so finally after too much time, i'm back to building my electric brewery. i'm using some scavenged controllers from work, and a big ass pump, also salvaged from work. i have 2 44 qt ss cajun kettles. i've got some 4500w ultra low watt density heating elements, and a greenlee punch borrowed from my uber-brewer neighbor. here's the deal though. the only punch he had is a 1.375" dia punch, and kal's instructions call for a 1.25" dia. has anyone tried to use a slightly larger punch? i don't want to go poking big holes in my pots, and have them leak. but at the same time the right size punch is going for $87! that's more than one of my pots, and i'm only planning on punching 4 holes. can i get away with this? anyone? or, is there another way? my neighbor is using keggles, that he drilled into with a step bit, but he's on propane, and only using 7/8" holes for his valves.
 
No, 1-3/8 is too big for sure. Your best bet is Ebay for a 1.25 punch or get a bimetal hole saw instead. If I'm going out to 1.25, it's sometimes easier to rough cut it to 1" with a hole saw, then finish out with a step bit but your drill has to be a torque happy SOB for that.
 
I did what Bobby was saying with the hole saw. My drill handled it fine enough, but yeah, it's a nice drill. Personally, I'd rather spend a hundred bucks on a nice drill than on a punch you'll use twice and be done with.

Just make sure you keep that hole saw bit as steady as possible, they like to dance!
 
i've actually got a big delta floor standing 3/4hp drill press, plus a boat-load of clamps. i actually just had the idea of cutting a form to fit the inside of the pot, as a back-up, and then just cutting really slow with lots of oil into the pot with a holesaw. the form behind should keep it from tearing too badly right? i work in wood, and soft metals, i don't really have experience with stainless.
 
Use your drill press with a hole saw...easy as pie. No need for extensive blocking and clamps. Just get a second set of hands to hold her in place.
 
I did exactly as you suggest. 1.25 hole saw in a drill press with a 2x4 as back up held in drill press vise and kettle clamped to the 2x4. It worked perfectly.
 
I just used a big step bit and my really powerful hand drill with plenty of oil. Took about five minutes per hole.
 
i'm going with the hole-saw. i've got a circle cutting jig for my band saw, so i'll carve out a backing block (it'll take 30min to glue up an cut), it'll give me better clamping on the drill press too, i like having a nicely secured part, when i'm standing right there.

i'll be starting a build thread soon. i'm horrible at taking pics of things in process. i promise to do better
 
If there is a harbor freight near you, you can try their $20 metal knockout set. I used the 1 1/4 inch on my keggle and it worked just fine. Just need to make a hole for the bolt with a step bit.
 
there is a hf near me, i just looked up the set, $24.99 now. for up to 10 gauge mild steel. it might not last long, but keggles are stainless. i have some bayou classic 44 qt pots, not sure of the gauge, i'll have to look it up
 
step bits take way too long, you basically drill 8 holes. i've been using hole saws with great success for both weldless and silver soldered applications. done in about 30 seconds with a little cutting oil. occasionally i do hook the step bit up afterwards to do a little deburring on the hole :)
 
Ive used step bits, hole saws and knockouts, and in my limited experience, i would put hole saws at the bottom of the list. But in all fairness i dont have a drill press.

A step bit to make a hole big enough for a knockout is my preferred method, mainly because the end result is so clean. You just have to rub it with sandpaper for like 30 seconds, and voila! A perfect hole.

The step bits really leave a lot of burrs, and the hole saw walks too easily. Once i get a drill press i might change my mind though.
 
Everyone thinks they will drill a hole or two and then be one and done. My experience is that I've changed my brewery so much over the years that I've used the hole punch an insane number of times, from moving to bottom drain keggles to loaning it out to buddies at the brew club, to making knockouts in a control panel.

Get the KO punch. Easiest and cleanest method by far, and you might be surprised how many times you use it.

Cheers!
 
well, i bought the set from harbor freight. here's my problem. the set says 'mechanical knockout set, 1/2" to 1-1/4". those are the pipe sizes they make clearance holes for. the 1" is the exact same size as the one i borrowed (measures on my caliper as 1.375" dia). so i'm back where i began. is a 1.375" ok to use or is it too big? which size did you use comeonnow?
 
well, i bought the set from harbor freight. here's my problem. the set says 'mechanical knockout set, 1/2" to 1-1/4". those are the pipe sizes they make clearance holes for. the 1" is the exact same size as the one i borrowed (measures on my caliper as 1.375" dia). so i'm back where i began. is a 1.375" ok to use or is it too big? which size did you use comeonnow?

I used a 1in trade size electrical punch for my elements. Do you not have a piece of something you can punch a hole in and test fit this thing? You're just making a hole dude. Make it too small and file if you have to. I don't understand the need for such precision?
 
i had read kal's instructions. and i posted the original question. then someone said that the 1.375 was too big, so i started stressing over it. but never-the-less, i've got some rather expensive kettles that i can't patch, so i've really got to get it right. i'm pretty sure i do have some scrap around. and i certainly will test punch first. i think that's a great idea.
 
i had read kal's instructions. and i posted the original question. then someone said that the 1.375 was too big, so i started stressing over it. but never-the-less, i've got some rather expensive kettles that i can't patch, so i've really got to get it right. i'm pretty sure i do have some scrap around. and i certainly will test punch first. i think that's a great idea.

Even if someone said it would work, I would test it on some scrap before punching out a pricey kettle. I think you will have much success;)
 
Even if someone said it would work, I would test it on some scrap before punching out a pricey kettle. I think you will have much success;)

I use the largest size of food can that I can find, usually from crushed tomatoes, for my sample hole. That way I can remind myself how to drill into a curved surface at the same time. Proves the necessity of a center punch.
 
I just punched two holes. I started with a step bit from harbor freight, I could have easily finished with this tool. It was going smoothly and quickly, and the hole was fairly clean. Anyhow, i used the step bit for the pilot hole then the greenlee tool (borrowed from work) to finish. Man, that is a slick tool, so easy and a perfect clean cut. My point is, I think the step bits work pretty well, even a cheap HF tool. I would go step bit if I didn't have access to the free tool.
 
lschiavo said:
I used a 1in trade size electrical punch for my elements. Do you not have a piece of something you can punch a hole in and test fit this thing? You're just making a hole dude. Make it too small and file if you have to. I don't understand the need for such precision?

Well said. Ever try and see if it works? I don't believe everything on the Internet...
 
I know I'm a little late to this thread and Warthog has probably already done the hole punching, but I just figured I would throw in my two cents just in case anyone else happens upon this thread with the same question.

I use knockouts and holesaws all the time for work, and what people need to watch out for when buying knockout sets is they are typically developed for the trades. Often when a knockout says 1" the actual outside diameter is 1 3/8". This is because the 1" knockout is based on the NPT or national pipe thread size, relating specifically to a 1" pipe which has a larger outside diameter than one inch.

You can find knockouts that are sized as what is written, you just have to pay attention to the packaging.

When drilling a round surface I would highly recommend using a hole saw. A punch will want to flatten out a spot in the pot, though I think it would be mostly superficial and not damaging in any way. Just run the drill in a an extremely low speed and stainless is a b**ch to drill due to the nature of the metal.

Either way everyone, have fun with the building.
 
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