I need to cut a large hole in sheet metal.

Need a 9" dia hole in a 20# sheet metal surround of a boiler.

The hole must be neat and cut in situ.

Is there a gadget constructed like a compass that when rotated often enough will cut such a hole?

Rather like the typical rotating glass cutter used for cutting large holes in plate glass.

Please help, Frank

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Peter Jason wrote:

Sure. It's a circle cutting attachment for a plasma cutter.

GWE

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A nibbler will do the job very nicely. Followup cleaning with a file can make a hole that just belongs in the piece of sheet metal.

-- Why do penguins walk so far to get to their nesting grounds?

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Careful work taking small bites with a pair of left or right cutting snips will make a good hole of this size. Don Young

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In situ is so complex - and in this case it might be best to just say while it is mounted on top of the boiler or in a water deep basement or in the .....

For the case naturally - you could use trammel points or a Plasma / gas torch circle cutter but put a carbide scribe and cut a hole like glass but all the way through.

I surmise you have a boiler with a cover that has an 8" hole and you want to put on a 9" header pipe or some such.

Otherwise it would be easy for most sheet metal shops in town.

Martin

Martin Eastburn @ home at Lions' Lair with our computer lionslair at consolidated dot net NRA LOH & Endowment Member NRA Second Amendment Task Force Charter Founder IHMSA and NRA Metallic Silhouette maker & member

Peter Jason wrote:

-

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On Fri, 07 Apr 2006 09:27:48 +1000, Peter Jason wrote:

A makeshift trammel bar of wood (1 x 2" for ex.) with a tool steel cutter should do fine with that thin guage--pivoting on a small bolt.

Or a saber saw, with a circle-cutting guide and a toothless blade, the kind with carbide grit available at most hardware stores.

Ken Grunke

-

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Thanks for all replies, I found the following after much looking:

http://www.mk-diamond-saws.com/images/tile_hole_cutter_small.jpg

and

http://ignitiontools.com/auctionpic/CIRCLE-HOLE-CUTTER/CIRCLE-HOLE-CUTTER-1.jpg

and

http://www.trilug.org/~chilcote/images/hole-cutter-s.jpg

and

http://zenstoves.net/Supplies/CircleHoleCutter.jpg

Regards, Frank

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Peter Jason wrote:

All of these tools are meant to be used in a drill press, for the stability. I have used a circle cutter in a hand drill, but it was a much smaller hole (4" diam) and it was tricky. If you do it, be very, *very* careful. Use the very slowest speed that you can and keep a very tight grip on the drill. The problem is that the bit will grab and bind. Depending upon how flexible the boiler surround is, it may very well be impossible with a hand drill.

Bob

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All of those will be a disaster when used on thin material and large diameter. They are normally used in a drill press and the work securely clamped down. When used with a portable dirll the cutting edges will dig in and tear the metal or flip the portable drill (and user).

There is a circle cutter used by sheet metal installers that has a tramel point on one end, and a pilot bushing on the other. To use, mark the center, install guide, use a spiral cutter bit in an electric drill. Don't have a link to it.

Peter Jason wrote:

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My boiler sides and top come off fairly easily- weil-mclane gold oil boiler.

Dave

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My problem is to fix the mess left by a long-departed builder who installed a boiler half above a roof and half below it. Thus the service panel is sealed into the roof and now I have to cut another access to service the gas regulator.

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wrote:

Holy Stupid Designs, Batman!...

Forget cutting an access hole through the sheetmetal to fix the boiler long term, because then you'll have to deal with rain leaks... Sounds more like it is time to rework the boiler and/or the roof so you have proper service access.

Stick some pictures of what you've got there now (and how you get access to it now) in the drop-box, and people can make educated suggestions on a proper course of action that will look good, be fairly easy to build, and won't break the bank. Include distance and roofline silhouette shots so people can get the 'theme' of the architecture.

I have several ideas on building a little roof or housing over the unit, but random guessing wastes time without seeing the start and end points.

--<< Bruce >>--

--
Bruce L. Bergman, Woodland Hills (Los Angeles) CA - Desktop
Electrician for Westend Electric - CA726700
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Why not. I'll post some photos within the next few days.

"Bruce L. Bergman"

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wrote:

Start a new thread when you do, and announce where the pictures are.

I deal with several condo buildings where they just have a Raypak natural gas fired domestic hot water boiler and a storage tank just sitting out there exposed on the building roof. All you need to protect from rain are the pump motors.

If nothing else, I've got to see why they would think they need to seal the unit half inside the roof - they are designed for outdoor installation.

Unless some doofus couldn't figure out how to properly fix the section of the roof the boiler is sitting on, and found that sealing the whole area stopped the leak...

(For something like that, you erect an A-frame, lift the boiler an inch or two, have the roofers redo the roofing around the pedestal it's sitting on, and then you slide a new sheetmetal drip pan under the boiler before you drop it back down. Oh, and drop it on rubber waffle pads so it doesn't wiggle a hole in the sheetmetal cap.)

--<< Bruce >>--

--
Bruce L. Bergman, Woodland Hills (Los Angeles) CA - Desktop
Electrician for Westend Electric - CA726700
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    Note that he said "announce where the pictures are", which implied that they should *not* be posted to the newsgroup. Just because it is *technically* possible does not mean that it is acceptable behavior.

    rec.crafts.metalworking is a text-only newsgroup, not a binary one, so binaries (including images and sound files) are not acceptable use. Binary newsgroups may be recognized by the word "binaries" present in the newsgroup name.

    You were supposed to upload the images to some web site like the dropbox (http://www.metalworking.com -- visit there to read how to do this), and then post the resulting URL here pointing to where the images are.

    You have my comments on the presence of the images themselves here. I'll leave it to others to comment on the questions associated with the metal cutting asked here.

    Good Luck,         DoN.

--
Email: < snipped-for-privacy@d-and-d.com> | Voice (all times): (703) 938-4564
(too) near Washington D.C. | http://www.d-and-d.com/dnichols/DoN.html
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snipped-for-privacy@d-and-d.com (DoN. Nichols) writes:

It's not just a matter of etiquette-- many news servers automatically delete binary postings in non-binary newsgroups, so a lot of us don't even see them.

The binary newsgroups are kept separate because they take up a *huge* amount of bandwidth and disk space, compared to the text newsgroups, and they put a big strain on the servers (a picture is a lot more data than a thousand words).

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This tool is made to do exactly what you are doing:

http://malco.malcoproducts.com/products/shear/hc1.asp

______________________________ Keep the whole world singing . . . . DanG (remove the sevens) snipped-for-privacy@7cox.net

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Thank you; I will try to get hold of one.

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I found one, and have ordered it. Thanks again.

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