What size knockout for 1/2 weldless bulkhead
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ancientmariner52
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Do have the bulkhead in hand? As a metal worker for half a century, I've learned the hard way, don't poke holes until you have the parts on hand!
Obviously, if you are making parts to print this doesn't apply, but it sure does in this case. Drill or punch the smallest hole that will clear the bulkhead, and carefully debur the hole inside and out.
Good luck!
Obviously, if you are making parts to print this doesn't apply, but it sure does in this case. Drill or punch the smallest hole that will clear the bulkhead, and carefully debur the hole inside and out.
Good luck!
ancientmariner52
Well-Known Member
7/8" is probably right, but still... measure twice, cut once.
I would definitely measure. All of the 1/2" weldless bulkheads I've installed over the years called for a 13/16" hole.
fwiw, I used a Greenlee 730BB-13/16 punch...
Cheers!
fwiw, I used a Greenlee 730BB-13/16 punch...
Cheers!
Bobby, I just received three 10 gallon spike kettles for my bday. I will need to drill some holes for the herms coil and bulkheads. Will this do the job? Pretty nervous about drilling holes in these kettles.
d3track
Are you sure about that?
Agreed, I've now used a step bit, punch, and hole saw. The hole saw was by far the best tool for the job (especially on kegs).
I've done bulkheads a half dozen different ways over the years (even TIG). The cleanest and easiest way I've found to do it;
a 13/16 greenlee punch, brewhardware pull through fittings and silver solder.
https://www.brewhardware.com/product_p/ptbulkheadmf.htm
There is very little chance of messing one up this way. Once you have the punch and pull through tool, you can install bulkheads quickly and easily on anything you want.
a 13/16 greenlee punch, brewhardware pull through fittings and silver solder.
https://www.brewhardware.com/product_p/ptbulkheadmf.htm
There is very little chance of messing one up this way. Once you have the punch and pull through tool, you can install bulkheads quickly and easily on anything you want.
Just a word of warning, using the pull through process on PUNCHED holes is a risky move. We have had some reports of the hole splitting. I'm generally convinced that the shearing force of a punch creates a micro perforated and work hardened edge.
Are you implying that I'm mistaken or lying? Keep in mind that I offer this as a service at my shop and end up pulling 1/2" NPT fittings and 1.5" TC ferrules at least 15 holes a week for the last 3 years. I think my sample size is bigger than most. When I drill the holes with a Unibit or Tungsen hole saw, zero rips. When I do it with a vessel that has been radio punched, about 20% have torn.
You can imagine how terrible I feel when someone messes up their pot so this warning is important.
fwiw, I for one would certainly defer to that experience if I was considering the pull-through bulkheads. I'd be crazy not to respect the numbers.
As to why the sawed holes are resistant to pull-through induced fracture, it's likely the heat from the hole saw is annealing the hole perimeter, increasing its ductility; whereas the punch is a virtually cold process, leaving the original metal character unchanged...
Cheers!
As to why the sawed holes are resistant to pull-through induced fracture, it's likely the heat from the hole saw is annealing the hole perimeter, increasing its ductility; whereas the punch is a virtually cold process, leaving the original metal character unchanged...
Cheers!
God. The level of sensitivity on this forum is astounding.....
I shouldn't respond, but I will. Stainless steel is not going to be cold work hardened by one pass of a punch. Stainless steel does not get "annealed" by the heat from a drill bit (it gets work hardenend).
Sorry if this hurts your feelings.
I don't quite agree with this. The punch is a shearing force that compresses the edge of the hole hardening it. The drill bit does heat up the metal but nowhere near annealing temps. It does however cut material away without compressing. Whatever the exact reason for the difference, it's there.
My feelings aren't hurt. Your reply of "uh ok" was just unhelpful and weird.
LittlejohnBrew
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I've used a step bit and greenlee hole punch and have had the best luck with step bits.
With the hole punch I tested it on an aluminum cookie sheet and it made a perfect hole. However, on my bayou classic SS kettle the hole punch made a terrible cut and ripped some of the metal outside of the circumference of the cut. Miraculously the hole still seals. The hole punch set I had stated for mild steel only which the bayou classics are claimed to be 304 SS which is a much harder material (~200 vs 130 HB). Seems like others have had success with the hole punches on SS. I did buy mine used so maybe it was too worn to use on SS.
I'm considering using a tungsten carbide hole saw to install an 1.5 TC element, but I'm concerned with stability of using the hole saw. May stick with step bits; while they wear out quick they have seem to give me the best cuts with lowest risk of damaging the pot. I just use a cordless power drill though.
With the hole punch I tested it on an aluminum cookie sheet and it made a perfect hole. However, on my bayou classic SS kettle the hole punch made a terrible cut and ripped some of the metal outside of the circumference of the cut. Miraculously the hole still seals. The hole punch set I had stated for mild steel only which the bayou classics are claimed to be 304 SS which is a much harder material (~200 vs 130 HB). Seems like others have had success with the hole punches on SS. I did buy mine used so maybe it was too worn to use on SS.
I'm considering using a tungsten carbide hole saw to install an 1.5 TC element, but I'm concerned with stability of using the hole saw. May stick with step bits; while they wear out quick they have seem to give me the best cuts with lowest risk of damaging the pot. I just use a cordless power drill though.
You just have to hold on to your drill with a death grip when the tungsten teeth start biting. The resulting hole is not perfect like punch but not bad. Sometimes I use the next size tungsten (smaller) and then drill up using a step bit as it kind of deburrs as it cuts.
So, I just spent a "free shipping" amount of money on, among other things, pull-through fittings from brewhardware.com. I plan to install them in my Megapot 1.2s. Based on this, I ordered a couple drill bits from you as well and will save my punches for another project.
Here's my concern, how will I know if the original holes in the kettles were punched (prone to tearing) or not? I'm already a little anxious about pulling because of the thick walls on these pots. Can I sleep or should I stay up worrying?
They may have been punched. Sandpaper the inside edges to smooth the micro tears and it should be fine.
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