using a hole saw to drill a pot

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tkone

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is there any reason not to use a bi-metal hole saw to drill a pot? i see most of the posts here mention using a step bit (which i used for the first two holes on my pot), but i gotta drill a 1" hole and i figure why not use a hole saw to save some time?
 
I'd make sure to do a pilot hole and go pretty slowly with a high rpm. With a thin wall like a pot usually is, a holesaw will tend to heat the metal from friction and then if you are pushing hard it will warp it out of the way instead of cutting it. You might want to use a file after the cut is made to get rid of any burrs as well.
 
cool. that being said, if i'm drilling a hole for a 1" water heater element, should i drill a 1" hole? or a 15/16 hole and dremel it out until the element just fits to make it more water-tight?
 
I've never used a water heater element, so I can't really tell. I know there are several electric system build threads around. I think most of the water tightness comes from sandwiching silicone O-rings between stainless washers, though.
 
For me a step drill worked best and easiest. I burned up a hole saw.Cut several with a step drill and its still good.
 
cool. that being said, if i'm drilling a hole for a 1" water heater element, should i drill a 1" hole? or a 15/16 hole and dremel it out until the element just fits to make it more water-tight?

Unless you have a jig you can't get it round enough with a dremel. And you can't drill a pilot hole for the larger one. The OD of the threads on the element (at least the one in front of me) is 1.285" so even 1 1/4 won't quite do but it might be a reasonable start.

The machine shop that does our work advises to go slow on Stainless when drilling and use lots of pressure, take lots of breaks to let it cool and use cutting oil. You might try the 1 5/16 of these:

http://www.hougen.com/cutters/sheetmetal/Holcutters.html

Edit: That's one and 5/16 not 15/16
 
Drilling the hole for a electrical element with a step bit is a hard job. Be prepared. I used cutting oil and a harbor freight bit. I've done two and it took at least 15 minutes (maybe more) for the first and longer for the second (the bit was a bit worn by then.

I have cut largish (1.5") holes in metal with a hole saw. It goes much faster. I think this is a much less precise hole and there is the potential for warpage and other aberrations, especially at the moment the hole saw breaks through. I might try it on a keggle, but not on a nice Blichmann pot. No way.
 
You can call around to the tool rental places (home depot and others) and rent a conduit punch. You still have to drill a small center hole but you end up with a very clean punch out for your element.
 
Drilling the hole for a electrical element with a step bit is a hard job. Be prepared. I used cutting oil and a harbor freight bit. I've done two and it took at least 15 minutes (maybe more) for the first and longer for the second (the bit was a bit worn by then.

I have cut largish (1.5") holes in metal with a hole saw. It goes much faster. I think this is a much less precise hole and there is the potential for warpage and other aberrations, especially at the moment the hole saw breaks through. I might try it on a keggle, but not on a nice Blichmann pot. No way.

for a UniBit (step bit) the best bet is to get a good bit (i would suggest Irwin). I use them on a daily basis at work, and it takes less than 3 minutes to drill a 1 7/8 hold through 1/4 inch thick steel. It's all in having a high quality bit. We've gotten cheap ones before to save a few bucks, they are poor quality, don't cut well and don't last. The down side is the Irwin bits can be quite expensive if its for only a few uses, so i can understand a decision to get a cheap bit and dealing with the time exchange.

I would, use the uni-bit over a hole saw though. Having used both extensively, the uni-bit gets a much more precise diameter. Hole saws are welded together down one side if you look closely. That weld can (and often does) throw a very small off-round effect to the bit, and when you're trying to get a precision hole, that small amount can make a big difference.
 
You can call around to the tool rental places (home depot and others) and rent a conduit punch. You still have to drill a small center hole but you end up with a very clean punch out for your element.


Knockout punches are for flat surfaces. The side of a pot is curved. Better off just drilling with a holesaw.
 
is there any reason not to use a bi-metal hole saw to drill a pot? i see most of the posts here mention using a step bit (which i used for the first two holes on my pot), but i gotta drill a 1" hole and i figure why not use a hole saw to save some time?

I always use a bimetal hole saw to drill pots, and use a 18 volt hand held to power the job. The process takes less than a minute. Use cutting oil, push hard, and have no fear...:D
 
Low RPMs, high pressure and cutting oil. A hole saw should be fine if sharp. Make sure you're cutting and not rubbing.
 
+1 on low rpm, high pressure.

I just drilled a keggle today, not a pot. Took about 30 seconds of high pressure low rpm with hole saw.

I'm not too concerned about a perfect hole. I drill the hole then dremel it to make the it just large enough to fit the nipple through with minimal to no resistance. I've done 5 now and not a leaker yet using weldless.
 
Better take a tape measure to it. I'm betting that it will require a 1 3/8 hole.

did they teach this in the school of inaccuracies?

For me a step drill worked best and easiest. I burned up a hole saw.Cut several with a step drill and its still good.

did you use a quality cutting lubricant?
 
Knockout punches are for flat surfaces. The side of a pot is curved. Better off just drilling with a holesaw.

Did not think about that. I've seen some posts saying it works if you position the cutting edge up and down so it cuts in at the same time.

I personally have not punched or drill the bigger element holes in stainless but it would seem the step bits and hole saws would work the same no matter how large you a hole you are drilling.
 
My boil kettle is made from 3/16" stainless. I drilled 4) 1" holes in it in about 10 minutes. The hole saw worked great. I drilled 12 holes in my kettles with the same hole saw and was still sharp. I used Marvel Mistery Oil for the cutting.
 
I've used both hole saws and step bits and I think steps are great for perfect holes. Even if I were going to go with a 1.25" hole, I'd go to 1" first with a hole saw, then use the step to make it larger. If you have to live with the hole saw cut only, undersize the hole by 1/8" because the bit does walk a bit and create a slightly larger oblong hole. Use a file or dremel to clean it up.
 
I've used both hole saws and step bits and I think steps are great for perfect holes. Even if I were going to go with a 1.25" hole, I'd go to 1" first with a hole saw, then use the step to make it larger. If you have to live with the hole saw cut only, undersize the hole by 1/8" because the bit does walk a bit and create a slightly larger oblong hole. Use a file or dremel to clean it up.

Great advice.
 
this is great stuff guys, thanks. i think i'm gonna do the 1" hole saw and then use a step bit to bring it out to 1.25" and then a dremel for more precise fitting.

looks like it's time for a home depot trip...
 
Are you using a weldless type system?

If you are going with a welded fitting then your hole will need to be bigger than 1". I did a hole saw 1.5" which was a bit smaller then my fitting.

I brazed my fittings so I felt it was easier in the long run to make the hole a bit smaller then dremel it to fit. The tighter tolerance helped me flow the brazing rod easier.

I like what bobby_m wrote. My step bit was not big enough for my element hole. It worked great for 1/2" fittings but too small for the big guy. I did not have any problems using a standard bi-metal bit. It went real quick.
 
yeah this is weldless (thanks bargain fittings!). the threaded part of the element is about 1.25" across (which is also the size hole pol says in his e-herms build). so i've got a 1 3/8 step bit so i'm gonna get a 1" hole saw and have at it.

getting to 7/8" for my spigot and thermometer/sight glass was such a pain with just the step bit -- i'd like to make this a little easier going.
 
getting to 7/8" for my spigot and thermometer/sight glass was such a pain with just the step bit -- i'd like to make this a little easier going.


I hear ya! I found that out too. All in all I drilled 9 holes two weekends ago. The first one I did with the step bit only and it was PIA. So all the next ones I used a standard drill bit to make a pilot hole then used the step bit. It went so much easier.
 
I bought a step bit on ebay and it did last long (link to seller step bit list). 3 clean holes (1-1/8") and it was dull. SS is really hard on cutting tool...

I revert to my hole-saw and it cut like a charm. Slow RPM, good pressure and cutting oil. Note; I couldn't re-cut my "bad" holes (from the worn out step bit). The hole saw would walk all around rather than cut no matter what without the pilot drill bit in the pilot hole. Maybe with a 16" vise...:rolleyes:
 
I very highly recommend reading what Kal has done to install his heating elements. It involves cutting a slightly larger hole, and filling the gap tightly with a smushed o-ring between the element and a sealed gang box. His cuts were made with a chassis punch and die, and they work just fine on the curved surface.
http://theelectricbrewery.com/node/9?page=show

edit: misinterpreted, the kettle hole is not oversized, its the washer size that is.
 
I very highly recommend reading what Kal has done to install his heating elements. It involves cutting a slightly larger hole, and filling the gap tightly with a smushed o-ring between the element and a sealed gang box. His cuts were made with a chassis punch and die, and they work just fine on the curved surface.
http://theelectricbrewery.com/node/9?page=show

edit: misinterpreted, the kettle hole is not oversized, its the washer size that is.

This is the same method that most of the Blichmann weldless fittings use. Using the washer to hold the o-ring means the o-ring will not get deformed. You can get Greenlee punches for pretty cheap on EBay. Just remember that a standard punch is in conduit size (i.e. a 1/2" punch makes a 7/8" hole). Sometimes you can find someone selling a radio punch which is a 1:1 size (i.e. a 13/16" punch makes a 13/16" hole).
 
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