How to cut a rectangular hole, smaller than 1", in sheet aluminum?

[Gadgeteer]

I wonder if there might be a tendency to over engineer this project. If the aluminum is no thicker than 0.012", then this is about equal to an aluminum pie plate.

I punched the four sides of a hole in 0.012 aluminum sheet with two wood chisels, although I did not have chisels of the dimensions needed, so mine are not to scale, but close. I, then, used the produced hole as a template to mark on another piece for replication. The chisels easily cut through the sheet with plywood as a backing by leaning on the tool, and rocking it just a bit from side to side... the cut running with the grain in the wood.

[Ironman]

Originally Posted by johnyradio

wow, amazing tute!!!!
this might just be our option.
what equipment do you recommend for drilling?
if that's all there is to it, why do they cost so much money to buy?
can you think of a way to achieve a rectangular punch?

THANKS!

Johny, yer welcome.
I would recommend making this in a drill press, but with care and patience you could do it with a hand drill.
A rectangular punch would be possible with two drilled holes, figure the spacing right. Much more complex, but the idea is to achieve a hollowed centre with a sharp edge. And you would definitely need a drill press to control the depth of the larger drill bit so all edges were even.

[johnyradio]

Originally Posted by Scrapper Greg

One other question that comes to mind. can you remove the nuts and pull the metal shield off? If so, you could clamp that end cap in between the main body and the metal shield. Would take a bit of the tedium out of this.

Thx, sir, tho i don't quite understand your suggestion.

The purpose of the DB15 is to feed about 14 wires from the user-panel to the main body (user-controls for power, microcontroller, and radio features). My intention is to eliminate a rat's nest of fragile wires, by containing them all within one multi-conductor cable. The cable is a kind of umbilical cord for the end cap. The aluminum end-cap is removable, for servicing the inside of the system. I'm using 2 caps, a 6" and a 4"-- the 6" fits into the 6" sonotube. Then, the 4" cap is bolted on the underside of the 6", to conceal all the wiring and user-control terminals. The DB15 is mounted on the underside of the 4", to consolidate all the wires that go to the circuitry inside the sonotube. Pix:

I too would talk to a few of the companies mentioned. You are a non profit, tax year is coming to an end. Companies are always looking for that last bit of corporate savings.

Yes, we are getting some stuff donated, and i must get more!

[johnyradio]

Originally Posted by Gadgeteer

I wonder if there might be a tendency to over engineer this project. If the aluminum is no thicker than 0.012", then this is about equal to an aluminum pie plate.

i agree-- that thickness was given me by the ebay vendor, and i'm not convinced it's correct. Time to get some calipers.

[johnyradio]

i'm narrowing it down to a scroll saw. if it can do THIS, then surely it can do a simple trapezoid (as well as other shapes we might need).


a manual scroll saw can be had for under $25, an electric under $100. so far, i found the following options:

Electrics:

• $70: http://www.micromark.com/microlux-ji...-saw,6673.html
• $84: http://www.ebay.com/itm/16-Variable-...item20dc2c978a
• $90: http://www.amazon.com/Dremel-MS20-01...ini+scroll+saw
• DIY: http://www.rcgroups.com/forums/showthread.php?t=1595780

Of the electrics, the micromark seems the least bang for the buck, and it still needs an external power supply for another $75! So that's out.

The $84 ebay electric seems best: 16 in. throat, cast iron base, dust pump, 25 lbs, free shipping, US source. Wow, somebody tell me why i shouldn't buy this thing right now!

Manual:

• $15: http://www.ebay.com/itm/Japanese-EB-...item3f275131e1
• $50+, pro quality: http://knewconcepts.com/3-inch.php
• many more on ebay, new

I'm also going to try attaching a high-quality jeweler's or scroll saw blade to a small hacksaw from the dollar store. If it works, that can be our base option for each maker, for when they do not have access to the electric. That would rock!

but, i still need to evaluate these two suggestions:

Dremel's plunge router attachment, then make a jig/template of the D-sub cutout, and just trace around the template. A proper router bit should cut through the aluminum like butter.
http://www.workshopaddict.com/forum/...html#post20593

and

for what your doing you cannot beat a dremel tool, there is the depth cutter guide attachment that could easily be adapted to follow a pattern. Id get a die grinder and set it up like a vertical spindle sander
http://www.workshopaddict.com/forum/...html#post20578

[GWIZ]

The $84 ebay electric seems best: 16 in. throat, cast iron base, dust pump, 25 lbs, free shipping, US source. Wow, somebody tell me why i shouldn't buy this thing right now!

Maybe this is the same saw.
http://www.harborfreight.com/16-inch...saw-93012.html

[johnyradio]

Originally Posted by GWIZ

Maybe this is the same saw.
http://www.harborfreight.com/16-inch...saw-93012.html

even cheaper, incl shipping! sweet. thx! the customer reviews for it are generally very positive. "great value", etc. One review said had no trouble with 90 degree angles.

the Dremel scroll on the other hand got a lot of mediocre reviews on amazon. and it uses proprietary blades

it's looking good for the green machine.

that, or a Dremel (original Dremel rotary tool, not the Dremel scroll) with plunge router and/or depth cutter guide. Looks like about $20 to $40 for the rotary tool and $40 for the plunge router. Basically same price range as the green machine.

this Dremel rotary runs 8000 to 35,000 rpms, vs 400 to 1600 rpms for the green machine! Does it matter?
http://www.harborfreight.com/variabl...kit-68696.html

So that's the current decision.... Opinions/other options welcomed

[Scrapper Greg]

Originally Posted by johnyradio

Thx, sir, tho i don't quite understand your suggestion.

The purpose of the DB15 is to feed about 14 wires from the user-panel to the main body (user-controls for power, microcontroller, and radio features). My intention is to eliminate a rat's nest of fragile wires, by containing them all within one multi-conductor cable. The cable is a kind of umbilical cord for the end cap. The aluminum end-cap is removable, for servicing the inside of the system. I'm using 2 caps, a 6" and a 4"-- the 6" fits into the 6" sonotube. Then, the 4" cap is bolted on the underside of the 6", to conceal all the wiring and user-control terminals. The DB15 is mounted on the underside of the 4", to consolidate all the wires that go to the circuitry inside the sonotube. Pix:





Yes, we are getting some stuff donated, and i must get more!

Ok, what I was talking about was to take the nuts (circled in red) off and slide off the metal shield (green arrow), then put the main part on the inside of the lid with the terminal area out through the hole you cut and replace the shield on the outside of the lid. Sandwiching the lid between the plastic and the metal shield. That would also secure it without any extra hardware.

[johnyradio]

Originally Posted by Scrapper Greg

Ok, what I was talking about was to take the nuts (circled in red) off and slide off the metal shield (green arrow), then put the main part on the inside of the lid with the terminal area out through the hole you cut and replace the shield on the outside of the lid. Sandwiching the lid between the plastic and the metal shield. That would also secure it without any extra hardware.

ah yes, thx for suggestion. i considered that. But i believe that would cause the sockets to be recessed (due to the thickness of the sheet metal), and so the male pins would not insert fully into the sockets.

[johnyradio]

new info which might change everything.

This piece is not all aluminum. The outer material is 28 GA galvanized steel. Inner liner is aluminum.

Would that affect my choice of rotary dremel, electric scroll, die grinder (new option), or manual coping or jeweler's saw?

not sure if 28 GA is the thickness of just the steel outer layer, or if it is the steel + aluminum layers. waiting to hear back from selkirk.