holey cow

I prefer hole saws for large round holes because after drilling a center pilot hole, the drill in a hole saw can generally be replaced with a 1/4" rod, which almost certainly insures that the hole saw won't go skidding across the workpiece. Extended lengths of plain 1/4" rod can make an angled approach fairly stable, where only one side of the saw starts cutting first.. this works better for thicker materials where an angled hole or large counterbore is needed.

I bought some new high quality ones on eBag recently, and the seller had some in that size range at very reasonable prices (better than local retail). They sometimes make oversized holes, so using a smaller size and finishing to an acccurate hole size may be required.

With flycutters, the full load is only on one side of the cutter's swing, and things can get exciting very quickly when the cutter grabs and also when it starts to break thru the back side of the material.

The 'Large Print' says that one tops out at 5" diameter (as you imply).

Consider one of these:

I see that HF no longer lists their clone, the 'Adjustable sheet metal hole cutter' model 97645. I'm considering ordering replacement parts for mine:

Item Description Qty

2 CAP w/BEARING (NSK 965 V2) 1 4 BIT (M730-2) 4-3/8"L x 3/16" 3 6 SPACER w/SET SCREW 1 8 HEX WRENCH 3mm 1 9 BOTTOM BEARING 1 10 SHOE PLATE 1 11 SCREWS FOR SHOE PLATE (Set) 12 PIVOT PIN 1 13 PIVOT PIN NUT 1 14 GRAY DIE-CAST HANDLE/BODY 1

Call 1-800-444-3353, Monday thru Friday,

6:00 am to 4:30 pm PST Freight Customer Service, 3491 Mission Oaks Blvd., Camarillo, CA 93011-5034.

Oh Yaasss. :)

--Winston

I didn't know Malco made this item. This company is located 15 miles from my house. Milady worked there as a temp purchase agent for about six months ten years ago.

Karl

It looks like the perfect thing for some duct work I'm contemplating.

--Winston

When I last cut holes in computer-case sides for additional fans, I used a one-blade flycutter, with no excitement, but it cut slowly -- probably because of belts slipping on the drill press. I now have a two-blade flycutter, which balances the load better. Even so, I agree that a hole saw is a better choice if available.

The other night my drill press was making a horrendous noise. BanginAndBanginAndBanginAndBanginAndBanginAndBanginAndBanginAndBanginAnd

Turns out the 25 year old belt was finally giving it up.

Dam. I hate when that happens!

Do you get an image with that page? My browser has it saying "Image Coming Soon!". :-)

And -- some wood to back where the hole breaks through, and some

*serious* clamps, so you don't have the sheet metal spinning like mad on breakthrough, cutting whatever part of you is in line with the corners.

How far from the long edge of the metal is the center of the holes? Could determine what size of drill press you will need. And it should be a *rigid* drill press, not a cheap Chinese one, because those cutters like to play with any give in the drill press.

And how slow will it go? 150 RPM will give 216 SFM at a 5.5" diameter -- and I don't think that my Taiwanese drill press will go quite that slow.

How good a finish do you need in the hole? Would a 5.5" circular saw do for you? (Again, the speed will probably be a problem.)

The metal looks a bit thin for using a Greenlee chassis punch, assuming that you can find one close enough in size.

Good Luck, DoN.

That's an interesting circle cutter.. and should be almost idiot-proof as far as personal safety is concerned (not trying to imply here, just sayin).

Something like that tool would be fairly easy to fabricate in a home shop, having a small lathe (or 2) would be a plus (always is).

I have a RotoZip TC1 tile cutter* (1/8" diameter kept in my Dremel case) that would suffice as the cutting tool, suitable for numerous materials, as it's carbide and prickly sharp cutting teeth.. making it practical for sideways cutting in any direction. Dremel probably has a circle cutting guide available, if one couldn't fabricate or improvise one (sheetmetal screw in the hole center and a loop of wire adjusted to the proper diameter).

*TC1 package states: cuts ceramic wall tile, cement board and plaster. Will not cut floor tile!

I like hole punches. Knockout punches. 5.5 sounds like a standard.

Check out Conduit hole punches at Home Depot or your electrical supply.

Mart> A friend asked:

Other option is a cnc plasma or laser system.

Mart> A friend asked:

(...)

That's funny. I get "Image Coming Soon" as well. I guess it hasn't arrived yet. :)

--Winston

'S OK. I'm used to it.

Or you could *repair yours* with parts ordered from HF:

Item Description Qty

2 CAP w/BEARING (NSK 965 V2) 1 4 BIT (M730-2) 4-3/8"L x 3/16" 3 6 SPACER w/SET SCREW 1 8 HEX WRENCH 3mm 1 9 BOTTOM BEARING 1 10 SHOE PLATE 1 11 SCREWS FOR SHOE PLATE (Set) 12 PIVOT PIN 1 13 PIVOT PIN NUT 1 14 GRAY DIE-CAST HANDLE/BODY 1

Call 1-800-444-3353, Monday thru Friday,

6:00 am to 4:30 pm PST Freight Customer Service, 3491 Mission Oaks Blvd., Camarillo, CA 93011-5034.

I've never used one of those but don't they run at a really high RPM with almost no torque?

Steel needs much slower RPM and plenty of torque. (IMHO)

--Winston

I don't have a RotoZip rotary tool, just mentioning the TC1 carbide cutter as a cutting tool. It's 1/8" dia and can be used with almost any drill or other rotary tool, flex shaft etc.

You're absotively correct, steel does dictate slower tool speeds.. and in most cases cutting lubricant is of great benefit for tool life.

Greenlee seems to go up to 4-1/2". Irwin, DeWalt, and Morse have bimetal 5.5" hole saws, though.

-- The unexamined life is not worth living. --Socrates

I see a 5.625" punch in the Greenlee catalog (19980 743BB) but I didn't see a 5.5"

I think a 19-1/2 gauge piece of steel might 'taco' pretty badly under that amount of stress. Perhaps not. I dunno.

A thousand dollarettes is a chunk of change too.

--Winston

I didn't see either during a quick romp to the Greenlee site.

It probably depends on the method of cut.

Is _that_ all they want for the little thing? I'm glad this isn't my project.

-- The unexamined life is not worth living. --Socrates

Yeah, Greenlee gets Real Proud of their stuff when it gets that big.

I could use the 4" NPT Conduit Punch (4-1/2" OD) for installing a few standard truck tail lights - or for (gasp!) 4" conduit, but at those prices I'll wait to run across a good used one. Same for a 5"

I'd start thinking Plasma Cutter and a circle template sized 1/4" bigger (or as needed for the tip) to pop the hole. Works in Stainless, too.

Hole saws tend to rip up thinner stuff, and a big hole saw freehand tends to grab and buck and throw you - and someone already mentioned snapped pilot drills when they grab. And work-hardening Stainless...

-->--

Their site is a nightmare.

5.5" chassis punch cutting 0.039" sheet? Oh yeah.

That is one vendor's price for the 5.625" punch. Are they proud of that or what?

--Winston

(...)

I've never used one of these, (or a plasma for that matter). Would this work for your taillights and electrical boxes?

--Winston