Square holes on aluminum.... how do you do it?

[BrianHG]

Buy a cheap CNC router machine from China. Something like this

https://www.aliexpress.com/item/32919397764.html?spm=a2g0o.productlist.0.0.54db57f5O012h9&algo_pvid=c1d5f8e0-b557-4959-bcf6-b11b82acb20c&algo_expid=c1d5f8e0-b557-4959-bcf6-b11b82acb20c-7&btsid=e9376042-133e-4e2f-8bca-df0b401da4fa&ws_ab_test=searchweb0_0,searchweb201602_,searchweb201603_53

It can cut any shape on metal sheets and it is really precise for hobbyist. I have the same one and have cut square holes on 1.6mm thick Aluminium sheets.

If you go this route, I have .dxf and gerber files for complete DB9 and DB25 connectors with adjacent mounting holes, DVI connectors, BNC connectors, RCA connectors, S-Video connectors, 2 Line LCD character displays, Square push buttons, LED holes, IR receiver holes, volume & rotary encoder controls and including complete front panel keypad & LCD displays with mounting PCBs & 3mm square fan grill openings.

[EEEnthusiast]

Bench top CNCs are the way to go these days. One time high cost, but they do a perfect job. You could use it to route wood, engrave on metal, cut any shape holes and much more. The drill bits are cheap too on Aliexpress. There are plenty of free software to control the CNC routers. You have to be careful though. The basic ones do not have limit switches but have some very powerful motors on them. You could damage your CNC machine and the work piece with improper programming.

[beanflying]

The question with CNC Square holes is are they Square or sort of square with rounded or dogbone corners? Even Lasers still have a beam diameter so a small curve in the corners.



The time taken to set up for a one off job doing it by hand will win out for $/hole in most cases But if you have one they are a great tool. Must get onto rewiring my router and getting it into use

[Yansi]

I am yet to see how that garbage CNC mill copes with a 3mm steel rack case panel.

I rather stick to my set of good ol files.  Good enough for aluminium, good enough for steel racks.

[EEEnthusiast]

I am yet to see how that garbage CNC mill copes with a 3mm steel rack case panel.

I rather stick to my set of good ol files.  Good enough for aluminium, good enough for steel racks.

Those are some really great pieces of work. A bench top CNC cannot cut panels that large for sure. But it can surely cut thicker metal by going 0.1mm deep in one stroke and repeating over and over again. It takes a lot of time, but the machine does the job.

[duak]

It's neither here nor there but back in the 70's & 80's I could get sheet metal punched and formed locally on a CNC turret punch.  Here's a more modern example: http://www.vandf.co.uk/tooling/what-is-cnc-punching/  Outside of my personal snack bracket though.

Actually, back then it was an NC turret punch that read from paper tape and the vendor asked us if we could repair it.  Turned out a 4 bit counter driven by a crystal oscillator had died.  I really lucked out because the board had a bunch MSI chips on it  and I didn't have a schematic.

[james_s]

I use a nibbler tool generally. Other times I drill a round hole that takes out as much of the material as possible and then square it up with a file.

[bson]

If it's for prototyping, the best IMO is to design them in a suitable CAD tool and either 3D print or mill out of acrylic.  The same design files can then be used for manufacturing when you're happy.  I find 3D printing is much easier than milling, for modest sizes.  For a large panel milling is easier since it can be done in a single piece.  Even for a 1-off DIY project I'd still do this and have someone mill me prototype panels once the 3D ones fit and seem right.  You'll get a professional looking result you can show off and learn a useful and marketable skill.

[coppercone2]

if its a big hole use a plasma cutter

[james_s]

I still struggle to find an example of something that is 3D printed (on a hobby level machine) that doesn't look like crap. Milling out of acrylic can be ok but laser cut ABS is even nicer for panels IMO. I tend to build a fair number of one-offs though so hand machining aluminum panels is something I do fairly often. In the time it would take to draw it up in CAD I could just make the panel and when I only need one there's no advantage to having the CAD file.

[beanflying]

I still struggle to find an example of something that is 3D printed (on a hobby level machine) that doesn't look like crap. Milling out of acrylic can be ok but laser cut ABS is even nicer for panels IMO. I tend to build a fair number of one-offs though so hand machining aluminum panels is something I do fairly often. In the time it would take to draw it up in CAD I could just make the panel and when I only need one there's no advantage to having the CAD file.

Surface finish on 3D Printing can be very good! This box picked at random came off my CR-10S over a year ago if I had needed holes added in the lid then a tweak to the Cad file and print another.  Maybe not quite up to injection molded plastics but given the customization available for a low cost it is the most affordable prototyping or small production run option available.

Time you had another look at 3D printing and where it now is not where it was 3+ years ago!

[james_s]

That's quite impressive, significantly better than what my friends with 3D printers generally achieve. One of my friends has printed up a lot of toys for his kid and a few marginally useful odds & ends, but I haven't been impressed by the amount of time spent screwing with the thing vs useful objects printed. I have high hopes for the future of 3D printing but so far the hobby machines have largely failed to live up to the hype.

[beanflying]

Without checking that zippy box is after 3 or 4 months of use with the printer still dead stock. It is printed on bare uber clean glass with no bed adhesive of any sort.

I actually heaped some poo on printers only six months prior to buying my first one after having a long chat to another EE. Came home watched some videos and decided they were a simple way to get a result for not to many $ and that I was wrong about them.

That said there is some jobs that are better done if you have access to them done by alternate means. Big flat slabs of fascia are a bad use for 3D Printing time so break out the Laser The Ply is just a roughy and I will get a final one done in Aluminium given the proximity to heat, the other couple are actually going on the Laser with one being a 3d printed Laser hybrid.

Use what gear you have or can afford and use it to it's best abilities is the point I guess.

[Bassman59]

I still struggle to find an example of something that is 3D printed (on a hobby level machine) that doesn't look like crap. Milling out of acrylic can be ok but laser cut ABS is even nicer for panels IMO. I tend to build a fair number of one-offs though so hand machining aluminum panels is something I do fairly often. In the time it would take to draw it up in CAD I could just make the panel and when I only need one there's no advantage to having the CAD file.

Surface finish on 3D Printing can be very good! This box picked at random came off my CR-10S over a year ago if I had needed holes added in the lid then a tweak to the Cad file and print another.  Maybe not quite up to injection molded plastics but given the customization available for a low cost it is the most affordable prototyping or small production run option available.

Time you had another look at 3D printing and where it now is not where it was 3+ years ago!

For a recent project built into one of the Hammond extrusions, I 3D printed the front and back panels using the Makerbot 2 we have in the office. The print quality is "meh."

Then there's the issue of labeling the jacks and buttons and such. For my first go-round I thought: decals!  I took DXFs of the panels and added text to them and printed them out on a variety of sticker material, like all-weather shipping labels and such. It turns out that cutting out the holes with an X-Acto knife is no fun. So I bought a Cricut machine, which (despite the shitty software) does a pretty great job of printing the text and cutting out the holes on vinyl or sticky paper.

Then I discovered that nothing sticks to the 3D printer plastic. I tried prepping the surface with spray-paint primer and that helped but it's not as permanent as I'd like. I tried the 3M "90" spray adhesive and wow, that stuff is aggressive and not really easily controlled. Next up was another spray adhesive, E6000, which when combined with weighted clamping seems to be almost reasonable.

If anyone has any ideas about adhesives that stick to 3D printed plastic and that are relatively easy to handle (such as a roll-on instead of a spray), I'm all ears!

[SiliconWizard]

Sanding first?

[Bassman59]

Sanding first?

Tried that, wasn't much good. And the surface wasn't all that smooth prior to sanding, either, but I thought that scuffing it might help.

[SiliconWizard]

Well, I suppose the right adhesive to use also depends on the type of plastics you used. Is that PLA or ABS?

[max_torque]

As soon as you have to include any of your own time as a "cost" then just farming the whole thing out to your local Laser/Waterjet cutter suddenly looks like very good value indeed, especially if you value accuracy and repeatability...

They tend to have minimum order quantities, but once over that value the cost is trivial.

[EEEnthusiast]

I have a suggestion for the front and the back panels if you are doing prototypes. Instead of cutting on the metal plates or 3D printing, you could use black acrylic sheets (2mm thick) and cut the shaped into them using a laser cutter. I have a low power laser CNC and use that to cut the acrylic panels. They come out very well and it is much faster to cut.

[coppercone2]

I still struggle to find an example of something that is 3D printed (on a hobby level machine) that doesn't look like crap. Milling out of acrylic can be ok but laser cut ABS is even nicer for panels IMO. I tend to build a fair number of one-offs though so hand machining aluminum panels is something I do fairly often. In the time it would take to draw it up in CAD I could just make the panel and when I only need one there's no advantage to having the CAD file.

Surface finish on 3D Printing can be very good! This box picked at random came off my CR-10S over a year ago if I had needed holes added in the lid then a tweak to the Cad file and print another.  Maybe not quite up to injection molded plastics but given the customization available for a low cost it is the most affordable prototyping or small production run option available.

Time you had another look at 3D printing and where it now is not where it was 3+ years ago!

For a recent project built into one of the Hammond extrusions, I 3D printed the front and back panels using the Makerbot 2 we have in the office. The print quality is "meh."

Then there's the issue of labeling the jacks and buttons and such. For my first go-round I thought: decals!  I took DXFs of the panels and added text to them and printed them out on a variety of sticker material, like all-weather shipping labels and such. It turns out that cutting out the holes with an X-Acto knife is no fun. So I bought a Cricut machine, which (despite the shitty software) does a pretty great job of printing the text and cutting out the holes on vinyl or sticky paper.

Then I discovered that nothing sticks to the 3D printer plastic. I tried prepping the surface with spray-paint primer and that helped but it's not as permanent as I'd like. I tried the 3M "90" spray adhesive and wow, that stuff is aggressive and not really easily controlled. Next up was another spray adhesive, E6000, which when combined with weighted clamping seems to be almost reasonable.

If anyone has any ideas about adhesives that stick to 3D printed plastic and that are relatively easy to handle (such as a roll-on instead of a spray), I'm all ears!

sexycyborg on youtube has a video about gluing 3d printed parts + strength testing. none are very strong

[soldar]

I like to use a manual scroll saw.

https://youtu.be/ED3ge9n-WPI?t=100

https://manualidadesybellasartes.es/seguetas-marqueteria-4654

[Gyro]

I like to use a manual scroll saw.

https://youtu.be/ED3ge9n-WPI?t=100

https://manualidadesybellasartes.es/seguetas-marqueteria-4654

(Attachment Link)

Good reminder. Actually electric scroll saws aren't ridiculously expensive these days and don't require as much dexterity. They have a much larger throat too.

Of course the panel needs to be flat(ish) in order to manoeuvrer it across the table.

A typical example:



EDIT: The better ones have cast tables rather than sheet.

[soldar]

Good point. Actually electric scroll saws aren't ridiculously expensive these days and don't require as much dexterity. They have a much larger throat too.

Of course the panel needs to be flat(ish) in order to manoeuvrer it across the table.

I could not find a picture of a manual scroll saw in English. Only electric ones. 

A good designer/engineer would cut all the holes first and then do the bending. I, on the other hand, first do the bending and folding and then the cutting holes. So manual saw it is.

In any case, aluminum cuts like butter and I have carved out holes just with a knife. If it is a one time thing and you have time you can do anything with aluminum. It is only slightly harder than wood

Some years ago I was given a Mini-ITX board but I had no case so I built one. I remember it took me forever and wondering if it was worth it. That case and computer have given me many years of service.  OTOH, I have made things that I soon discarded and thought it had not been worth the trouble.

[Gyro]

I could not find a picture of a manual scroll saw in English. Only electric ones. 

The English term is fret saw or coping saw. Great tools in skilled hands! The jewellers' tool of choice (used with a little V shaped bench plate). 

[soldar]

The English term is fret saw or coping saw. Great tools in skilled hands! The jewellers' tool of choice (used with a little V shaped bench plate). 

And I thought I could speak English! No wonder I could not find it.

Every day I learn something new. When I was younger I would remember and retain what I learned. Now I tend to forget it. Maybe I will put a label on my fret saw.