Cutting Rectangular Holes

[KE6DF]

Looking at W7XXX's rig picture brings up a question.

How does one cut a large rectangular hole in a panel (like the ones showing the tubes in his rig) without it looking like it was cut with a hack saw by a metal shop dropout?

Greenlee has big rectangular punches, but a punch big enough to cut a hole to view a large tube would cost more than all the parts in the rig.

Is there another solution?

Nice looking rig, by the way. I like that blue art-deco color.

[WA1GFZ]

Meet Mr. Flat file and careful arm motion

[W7XXX]

Elbow action! Draw it out then drill the corners making a hole large enough to get the jigsaw with a metal blade in the hole and saw just inside the lines. Take your time. Then use a corner file to clean up the corners and a flat file to get the edges on the lines nice and straight and clean. I countersunk the holes for the screws holding the high carbon acrylic, giving it a smoother look. Good files, patience, and a steady hand, none of which I have anymore except the files. Here is a close up ... it isn't a perfect job as you can see.

[KE6DF]

Thanks. It looks pretty dang good to me. 

[WA1GFZ]

Coat the panel with duct dape or heavy paper if you use a jigsaw so the saw doesn't mark the panel.

[w3jn]

Drill small (1/4" or so) holes in each of the 4 corners.  Mark the lines for the edges of the square hole with masking tape at the outer perimeter of the holes you drilled.  Use a Dremel with a miniature saw blade, cut along the edge of the tape.  Finish with a file as necessary.  This makes a nice square hole with rounded off corners.

[xe1yzy]

Small jewlery hand saw works great!, I use some metal tiny german saw blades, and give a profesional finish.

RGDS

[Opcom]

can also be done on a drill press - drill the four corners, then an electric jigsaw to cut the square out. Some people put a bezel over the edges of the hole and have a screen in the bezel for shielding.

[KL7OF]

If the panel is aluminum....Drill the corners and the use a skill saw (with a thin carbide blade) to cut the straight lines....Quick and easy and no jumping around as with a jig saw.  Pin the blade guard up so you can see the blade and cut almost to the corner hole....easy as pie.......  a small 5 inch or 6 inch saw is a little easier to use than a 7 1/4 but either will work....Take it from an old aluminum fabricator...  really cuts down on the filing.....A large corner hole makes a nice large radius professional look..
.Sam ...your rig is great looking....Nice craftsmanship..

[wb1aij]

If the holes aren't huge a sheet metal nibbler works great. As the name indicates they take small bites thet are straight lines. They are inexpensive & readily available. I think Radio Shack even has one. They did at one time.

[KF1Z]

A Roto-Zip works well, run it along a straight-edge.

[w8khk]

Rather than square corners, I prefer rounded corners.  I use a Greenlee socket punch for each corner, then scribe cutting lines for the four sides.  I apply masking tape and cut from the back side of the panel with a Sears Sabre Saw.  Then I use a file to smooth out the cut.

[WBear2GCR]

...milling machine...

get one, find a friend with one, or find a friendly local machinist/school-college/machine shop.

or. buy a panel pre-made and engraved to order from one of the many online services that do this sort of job...

                 _-_-bear

[W1RKW]

Or simply cut the rectangular hole as best as possible then dress the edges with some sort of edging. Or some sort of pre-made or factory made frame to go around the rectangular hole to dress it up.

[KL7OF]

I like rounded corners as well....  The RF deck panel on my 100TH rig..

[W1ATR]

Oh, another thread on making holes in things.

In my dreams, I would break out the CNC WaterJet, but I have a backyard hack that works just as nice.

For nice big holes with those sweet 1" radius corners, all you need is a 1" Greenlee knockout, a jig saw, some nice straight 1" square stock, a couple of strong C-clamps, and a sharp pencil. Measure and mark out the panel for the hole, or holes that you want making nice square corners. Use the cutting side of the punch (the threaded side that actually makes the hole.) and put it into one of the corners so it's on the lines in the 90. Mark the panel thru the center hole in the cutter (centering punch works well for this.) and dimple it hard so the 3/8" drill bit doesn't walk.

Drill the small hole, then assemble the knockout punch so it pulls thru the front of the panel to the rear. (in other words, you' be turning the pulling screw from the rear.) I like to do it like that so I can double check the cutters position against the lines before actually making the hole but it makes these two little dimples that we'll get to in a minute. If you pull from the front, you'll have two bumps which are a little harder to deal with than two dimples. Put a wrench on the knockout and make the hole.

For the straight sides. Most, if not all, jig saws have a shoe that measures 1" from the edge of the shoe to the blade. Just clamp the square stock in place with the two c-clamps to position the blade on your line and make that cut from hole to hole. Use a high quality, bi-metal, fine tooth blade to do the cutting and stop every coupe inches to let the blade cool. (Safety glasses are a must.)

Use a nice sharp, fine, flat file to break all the sharp edges using smooth, long strokes. This is the most time consuming part as you have to take it slow so you don't foul up your nice straight lines.

About the dimples. pulling the holes thru the front like I do leaves these two small dimples where the cutter initially contacts the material. Pulling from the rear will leave two bumps that will need to be ground down which can lead to wrecking an otherwise nice surface. I like to use a dab of 'Spot putty" (made by Bondo) to fix this issue. Get yourself a tube in any parts store for a couple bucks and using your finger, put a little over the whole area around the corner covering area around the dimples as well. Use a plastic bondo squeegee, take a swipe across the hole and take away the extra. Don't get crazy and try to make it fat while the putty is still wet, that's not gonna happen.

Jeez, this is getting long, what the hell were we talking about? Oh yeah...Let the putty dry and come back to it later with some 220 grit on a block of wood, a rubber block, or a palm sander, whatever, just don't hold the sandpaper in your hand. I use a pneumatic air board for this. Just sand over the area to rid the excess putty and you'll see how nicely it filled in the dimples and makes them disappear.

Primer it up, paint it up, wet sand everything, put on some tire shine, and your ready for the cruise on Friday night. (Wait, we're not talking about cars, I mean radios.)

Enjoy,
Jared 

[WBear2GCR]

Otoh, there is the hand held milling machine: AKA Router.

For aluminum panels, a router, carbide tipped tool will cut it fine. Many fine chipz, and much noise... what is needed is a follower bit, either with the bearing on the top or bottom. Then you need a form/pattern to follow. Clamp the pattern, follow the  pattern. The pattern can be wood, plastic, metal... it works. Test on scrap first to figure out the lube & cutting speed.

             _-_-bear

PS. wear hearing protection when using power tools that make big noise like this.

[KE6DF]

This is a great thread. I thought of one or two ways that might work.

But never did I think there were this many ways to cut holes in a panel.

You might even say there are a hole lot of ways.

Thanks a lot.

Keep 'um coming.

Dave