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mill 1.75 sq. hole for meter
- Thread starter VicR55
- Start date
- Replies 22
- Views 2,060
14g? whats the enclosure look like? I've done it with a small enclosure, but it is literally shaky given the work is going to be largely unsupported. 3/8 or 1/4 end mill then clean up the corners is where I;d start....but it its in the middle of big flat area, better to drill a hole and put a metal cutting blade in a decent quality jigsaw then file to size.
memphisjed
Titanium
- Joined
- Jan 21, 2019
- Location
- Memphis
I think rotozip uses the term bit? actually a rotozip x bit might be the best option.....
Limy Sami
Diamond
- Joined
- Jan 7, 2007
- Location
- Norfolk, UK
I'm with Mcgyver, jig saw and file, .........masking tape to protect any surface finish applied, ..............for a truly square hole you're going to have to file the corners anyway
BT Fabrication
Titanium
- Joined
- Nov 3, 2019
- Location
- Ontario Canada
drill a couple holes in opposite corners, then use a saw blade, jig saw or reciprocating. why mill it?
EmGo
Diamond
- Joined
- Apr 14, 2018
If you do decide to mill it, I've been happy sandwiching sheet metal between a couple pieces of wood, or aluminum, or sometimes even plastic ....
Thunderjet
Stainless
- Joined
- Jun 24, 2019
We use these all the time:
McMaster-Carr
I'm sure you can rent one from your local rental place.
Fast, easy and safe.
McMaster-Carr
I'm sure you can rent one from your local rental place.
Fast, easy and safe.
ChipSplitter
Titanium
- Joined
- May 23, 2019
- Location
- Maybe
SIP6A
Titanium
- Joined
- May 29, 2003
- Location
- Temperance, Michigan
You'll need one of them square endmills.
Warning: hard to find.......
and EXPENSIVE
Strostkovy
Titanium
- Joined
- Oct 29, 2017
You'll need one of them square endmills.
Warning: hard to find.......
Well given how a two flute drill will make a triangular hole in sheet metal, maybe he just needs a three flute drill.
thermite
Diamond
- Joined
- Sep 21, 2011
"Mill" is the wrong term. What you want is the classical Greenlee square or rectangular "panel" punch. Buy, borrow, rent, or hire the hole made by he who has one.
Any size smaller than your hole. Align it with each corner, punch.
Fourth go, you have your hole, complete.
Standard size? ONE go. Complete.
Next box, please?
Knockout punch - Wikipedia
No more need to use a round milling cutter to make square holes in sheet metal than there is to spread peanut butter on a pair of eyeglass lenses.
"That does not compute".
Another option wants a DIY "guide".. With which one utilizes an oscillating saw.
Even a cheap (corded) H-F one can work. Just put a better than H-F grade of blade on it!
Do-able freehand. But it can get ugly. MUCH better with a guide or brace.
And then there is the way they taught it in school.
With a hammer and chisel. On the scribed line. STRAIGHT DOWN against a hard backplate. Sounds daft. Works a treat.
EPAIII
Diamond
- Joined
- Nov 23, 2003
- Location
- Beaumont, TX, USA
I have several square Greenlee punches, but the largest is 1" so it would take four wacks to make this hole. I have done it that way, but an alternate method is to use a 1/8" end mill and run past the corners by 1/16". The bezel on most electrical meters will cover that much.
As far as renting a square punch at a local rental place, GOOD LUCK. Even in the middle of Silicone Valley finding one for rent will be a tall task.
I obtained a collection of over three dozen Greenlee chassis punches by purchasing them in lots on E-Bay. The used ones are a lot more reasonable and the collections seem to sell for even better prices. They are easily sharpened and then work as good as new. If the draw bolt is missing a grade 8 one will work. Grade 5 will not cut it and lower grades will break on the first use. I sharpened all of the punches I got that way and sold the duplicates in individual auctions, again on E-Bay. I came close to breaking even and was left with a great collection of punches which would have cost $1000 or more new. Many people incorrectly call them knock-out punches, which really only applies to the few sizes of round punches that make holes for electric conduit, so that is a good search term to use.
As far as renting a square punch at a local rental place, GOOD LUCK. Even in the middle of Silicone Valley finding one for rent will be a tall task.
I obtained a collection of over three dozen Greenlee chassis punches by purchasing them in lots on E-Bay. The used ones are a lot more reasonable and the collections seem to sell for even better prices. They are easily sharpened and then work as good as new. If the draw bolt is missing a grade 8 one will work. Grade 5 will not cut it and lower grades will break on the first use. I sharpened all of the punches I got that way and sold the duplicates in individual auctions, again on E-Bay. I came close to breaking even and was left with a great collection of punches which would have cost $1000 or more new. Many people incorrectly call them knock-out punches, which really only applies to the few sizes of round punches that make holes for electric conduit, so that is a good search term to use.
EPAIII
Diamond
- Joined
- Nov 23, 2003
- Location
- Beaumont, TX, USA
PS: I have a steel cover in my shop right now that I need to mount a digital meter in. I plan to use an 1/8" milling cutter, just as I described above. Some other components will be mounted in round holes so I can do that as well as drilling those round holes all in one set-up on the mill. And everything will fit with NO FILING.
Let the chips fall where they may!
Let the chips fall where they may!
thermite
Diamond
- Joined
- Sep 21, 2011
"No filing" with the oscillating saw, either. One recent target the electrical outlet cut-throughs in the stainless steel I used for lower wall backsplash in the "hot" section of my kitchen, either side of the cooktop.
Stainless is hard on Greenlees. Very!
Needless to say, the wide outlet covers hide the sins even better than a meter's narrow bezel!
If I HAD to use the mill? Horizontal. Small saw.
So long as straight lines? It's just easier and cheaper.
thermite
Diamond
- Joined
- Sep 21, 2011
The F**k it will! Makes a royal MESS as teeth have their way with metal that thin!
Grit-edged blades work. Just kinda slow and gnarly.
A laminate trimmer - poor boy's template-guided "vertical mill" - actually works far better.
Tried getting a(ny) large size sheetmetal into the throat of a mill to pierce it well away from the edges? Sabre saw can reach. Router-style cutter makes nicer edges and is easy to fab a templet for. Corners still need squared with a file.
FWIW, not much, I also have a powered "nibbler" that goes on a hand-held power drill motor.
Does nice clean edges, anyway. Still a PITA to guide well.
EmGo
Diamond
- Joined
- Apr 14, 2018
If you are really allergic to files and still want to mill the opening, you could push a 1/4" square broach through the corners then connect them up on the Bridgeport.
I don't mind a little filing, myself
Thunderjet
Stainless
- Joined
- Jun 24, 2019
If you are really allergic to files and still want to mill the opening, you could push a 1/4" square broach through the corners then connect them up on the Bridgeport.
I don't mind a little filing, myself
You can screw up every drill in my index, And dull every tap.......Just DON'T TOUCH MY FILES!
Strostkovy
Titanium
- Joined
- Oct 29, 2017
I remember seeing a tool for this in high school. It was a punch ground flat on one side and brought to a round nosed wedge. You drill a hole in the sheet metal, and put the nose of the punch through and line the flat edge to an equally flat anvil. It worked great for making arbitrary straight cuts anywhere on a piece of sheet metal.
My description is lacking, I might have to draw something.
My description is lacking, I might have to draw something.
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