Drilling problems through pot

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gnatp2

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I've drilled through some other pots before and haven't had anywhere near the problems that I'm having now. I purchased this pot from morebeer.com and just can't seem to drill through it. http://morebeer.com/view_product/20770/102211/Modified_Brewing_Kettle_-_Economy_15_Gallon

I've tried using various cobalt bits (from 3/32" to 3/16"), cutting oil and the low speed setting on my drill (400 RPM). All it seems to do is creating a dent as I'm applying significant pressure (I even broke one of my bits from pushing too hard). If i keep going, I think I'll eventually get through, but it will take several hours. I keep getting very fine particles of metal come off, but no nice shavings like i'm used to.

Is this because it is a different type of stainless? Is there another technique or tool I should try?

Nate
 
Cobalt is a great drill for SS. A good amount of cutting oil would be advised. One thing you might try.. although I don't think you will have to go this far, is to make a small "dam" of clay.. fill it with something like Marvel Mystery Oil.. or tranny fluid. Slow speed with a sharp drill and moderate pressure should do it. I would certainly start with a small drill. Once you penetrate the metal, go to the next larger size. You might try using a small paint brush to keep a fluid puddle at the cutting point. Then you can jump up to a step drill.. they work well once you have a decent hole going.. Moderate pressure. If you hear the drill squealing, you are running dry.. not good. If you don't use enough pressure.. heat builds up and the metal work hardens.
 
How new are your bits? It seems like you're doing it right using the cutting oil and slow speed setting on your drill. Sharpening bits on a bench grinder can be tough, but I'm sure like a lot of other stuff there is a YouTube how to video. We use the drill doctor at work and it helps a ton. From working in a shop with 25 guys drill bits can get used incorrectly and put back, and when your really need them they are dull.
 
Maybe you have dull or cheap bits. If you can, get a new one or sharpen the bits you have. I have a 1/2" cobalt bit and don't use a pilot hole. I drilled at least 20 holes in stainless kettles and kegs. Still using the same bit. No oil, it doesn't need it. At 100rpm the drill is through in 15 seconds. It doesn't even get warm. After the 1/2" hole is drilled I use a set of punches to get whatever size hole I am looking for.
 
Bits are brand new. Made by Ridgid. Its almost like the stainless is sooooo smooth that the bits can't find anything to grab on. I'll try to take a video tonight and you can see what I'm doing.
 
jeepinjeepin said:
If the bit is walking around, you need to use a center punch to give the bit a divot to start at.
Click to expand...

Yeah, used it. No issue on that. Actually from drilling so long and applying pressure, I have created a small divot. No issue with the drill moving around on me. Also the divot has helped to keep it well oiled so I don't get much heat buildup.
 
Sounds like trying to drill titanium. Cost me almost a hole set of bits. I was using cheap bits I was told at that time. Maybe get a better bit?
 
Hmm, weird.. If you have a Dremel tool, you could grind your starting hole pretty quickly. That'll at least give you the starting point.. from there it's smooth sailing. Another thing you could do is to back up the hole with a piece of 2x2 with a small radius on it.. wedge it into the pot.. and punch a hole thru the pot with a nail. Starting point. The purpose of the 2x2 is only to prevent deforming when assaulting the pot with the hammer and nail..or better yet a sharp center punch or awl. While at it, you might as well make the hole large enough to accept the smallest drill size on your step drill. Pressure and lubrication.. it's a key. BTW, while I would love to have done mine with a Greenlee punch, the cheap step drill set I got at Harbor Freight has served me well.. they all come with a titanium nitride coating... but still a thick grease of some sort.. works well as will the above mentioned lube's.

OBTW If you decide to do the thing with the pinpunch.. I would be careful to not make that hole too large. You could potentially create a stress fracture.. don't want to do that. Just a hole about 1/8" in diameter.. then hit it with your 3/16 bit.. then go with the step drill and lube.
 
+1 to HbqBill's idea about stiffening it with a backup. Sounds as if you have work hardened the stainless and will have a tough time getting through it. At this point the primary idea should be to get the hole through and then large enough to get past the work hardened area without adding enough heat to harden a larger area. Low speed with plenty of lubricant, mainly used as a coolant, should do it.
 
How big is the hole gonna be when you're done? Like are you gonna use a hole saw or is 3/16" gonna be as big as you go? Sounds like you could have hardened the stainless. You could try with a fresh quality bit to start a new hole right next to it or on top or bottom. When you started drilling was the drill going fast or did u start out slow. A good rule of thumb I use when drilling (especially stainless) low speed high feed.
 
HbgBill said:
Hmm, weird.. If you have a Dremel tool, you could grind your starting hole pretty quickly. That'll at least give you the starting point.. from there it's smooth sailing. Another thing you could do is to back up the hole with a piece of 2x2 with a small radius on it.. wedge it into the pot.. and punch a hole thru the pot with a nail. Starting point. The purpose of the 2x2 is only to prevent deforming when assaulting the pot with the hammer and nail..or better yet a sharp center punch or awl. While at it, you might as well make the hole large enough to accept the smallest drill size on your step drill. Pressure and lubrication.. it's a key. BTW, while I would love to have done mine with a Greenlee punch, the cheap step drill set I got at Harbor Freight has served me well.. they all come with a titanium nitride coating... but still a thick grease of some sort.. works well as will the above mentioned lube's.

OBTW If you decide to do the thing with the pinpunch.. I would be careful to not make that hole too large. You could potentially create a stress fracture.. don't want to do that. Just a hole about 1/8" in diameter.. then hit it with your 3/16 bit.. then go with the step drill and lube.
Click to expand...


Grinding with a dremel sounds like a good idea. I've got a 13/16" greenlee punch so as long as I don't make it too messy, I'll be fine using the punch afterword. That nail idea sounds like a good idea, but I think dremmel would be safer.

I've got something like this in my dremmel box. Is that what I should be using for the starter hole? http://www.amazon.com/SE-Diamond-Wheel-DW13-Shank/dp/B000P49NCC/ref=sr_1_6?s=hi&ie=UTF8&qid=1348504261&sr=1-6&keywords=dremel+metal+cutting
 
Last edited by a moderator:
Could try a carbide drill with cutting fluid. It'll work better than HSS or cobalt on hardened metals. If ur burning up cobalt I don't think a HSS hole saw is gonna fair much better and a knockout might really do some funky stuff to that pot or the tool. Especially if the material work hardens. If your drilling really close to the bottom that's also gonna be where all the stress in the metal is at and it will be harder to cut. Maybe try moving up on the pot if you can.
 
I work with SS a lot and I would say you have definetly work hardened it. Life will not be easy puttin that hole in it now. I totally agree with 1/8,3/16,and so on til you get out of the work hardened part.
 
I agree starting with a small drill and working up but use paraffin as your lubricant NOT OIL unless it is a water soluble oil and do not let the surface burn and discolour or you can have problems with oxidisation down the track.
 
Thanks everyone for the ideas. I finally got it to work!!!

Here's how I got it to work. Probably shouldn't be 6 separate videos but I got no idea how to splice them all together. Sorry for the shoddy camera work, but hopefully this will help someone else if they end up hardening their stainless steel pot while drilling like I did.

Nate











 
Last edited by a moderator:
Glad to see you finally made it. Looking at the first video... the result really looked like a dull drill bit. That can happen very rapidly when the metal work hardens.
 

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