Cutting rectangular openings in project boxes? - Page 1
Forum section: electronics / beginners

author: elroy
author_rank: Regular Contributor
timestamp: January 14, 2018, 07:27:42 am
content: When browsing writeups of projects, I'm always impressed by crisp rectangular openings cut in plastic or metal cases for LCD displays or other components.I used to have a punch tool that would nibble away in a (more or less) straight line. This followed by cleanup with a straight file would result in adequate rectangular openings. (I.e. first I would drill a round hole, then use the nibbler tool to enlarge it to a rectangle, then use the file to clean it up.) But some of the examples I'm seeing online look really, really clean. Is there a slicker way to do this?

author: IanB
author_rank: Super Contributor
timestamp: January 14, 2018, 07:33:42 am
content: A panel punch, maybe?

author: Messtechniker
author_rank: Frequent Contributor
timestamp: January 14, 2018, 07:46:56 am
content: I use a water jet cutter.Specifically this thing here:http://www.perndorfer.at/en/products/wss-2d/wss-portal.htmlOK. A friend of mine close by runs a machining shop so that I can simply hand in dwg files.His water jet cutter is 6x4 m and accurate to just under1/10th of a mm.Capable of cutting through steel 20 cm thick , if needed. A pity they dont't come a bit smaller(and cheaper).

author: paulca
author_rank: Super Contributor
timestamp: January 14, 2018, 09:50:40 am
content: I wonder how much it costs and if the "PCB House" style companies are missing a spot, to have enclosures ordered to spec.I mean, I have a small fetish for transparent laser cut acrylic cases, I might have to google and find out how much they cost for short runs and what software is needed to design them.

author: janekm
author_rank: Unknown
timestamp: January 14, 2018, 09:59:50 am
content: Quote from: Messtechniker on January 14, 2018, 07:46:56 amThey do come smaller & cheaper:But apparently not cost-effective to operate due to the low momentum of the cutting medium needing a lot of material for making small amounts of cuts.

author: ovnr
author_rank: Frequent Contributor
timestamp: January 14, 2018, 10:31:51 am
content: Well, the proper way to do it is with milling machines or routers, to be honest. Waterjets not so much.I put a small X-Y table (Proxxon; do not buy the absolute cheapest shit) on a cheap shitty drill press, and added CNC control to the X and Y axes. Works a treat if you can put up with the slight peculiarities. I believe there are some fairly inexpensive ($200 and up) CNC routers on eBay, but they're probably also terrible in many exciting ways, and have fairly significant limits in the Z axis.

author: RoGeorge
author_rank: Super Contributor
timestamp: January 14, 2018, 10:40:11 am
content: For plastic, also laser cutting.CNC laser cutters are cheap enough now. Many fab-labs/maker-clubs/enthusiast have one. Also, laser cutting is available as an online service, similar with online 3D printing or PCB houses.

author: elroy
author_rank: Regular Contributor
timestamp: January 14, 2018, 04:34:18 pm
content: Quote from: ovnr on January 14, 2018, 10:31:51 amI have a vertical mini-mill and a router, but am still a little stuck -- how do you get crisp corners with either of them?

author: IanB
author_rank: Super Contributor
timestamp: January 14, 2018, 04:45:08 pm
content: Quote from: elroy on January 14, 2018, 04:34:18 pmPerhaps many connectors or other things that go in the opening might also have rounded corners?

author: phil from seattle
author_rank: Super Contributor
timestamp: January 14, 2018, 05:28:04 pm
content: use the smallest bit you can find and then gently file the corners.If you can find or make (3d print) a bezel, that's how you get a good looking package.

author: Cyberdragon
author_rank: Super Contributor
timestamp: January 14, 2018, 06:08:24 pm
content: Cut a rough hole then use corner files.

author: cstratton
author_rank: Regular Contributor
timestamp: January 14, 2018, 07:12:40 pm
content: Quote from: paulca on January 14, 2018, 09:50:40 amSome people simply use the PCB process to make a front panel. It's not a bad way to commission a small CNC machining job, if FR4 is an acceptable material and you're already familiar with generating files for that process as a result of designing the circuit boards.QuoteThere are of course companies providing this service too, ranging from upload files and money, get express package to more hackerspace like places that will let you take a class and then book time on their machine.And then there are FDM type 3d printers and increasingly accessible photopolymer machines.Or in a pinch you use what is on hand at a startup's office by drilling a bunch of holes and wire cuttering the webs between, then pick up a mini hacksaw for $4 at home depot on the way home figuring the smaller blade will work better for that the next time around.

author: cdev
author_rank: Super Contributor
timestamp: January 14, 2018, 07:20:31 pm
content: It seems that I am able to get a fairly good cut with my nibbling toolif I am not thinking too hard about itand the piece of metal I am cutting through is something I have already dismissed in my mind as junk.However, I hate to waste money so much that the thought of spending a bit of money on a nice case and then screwing it up is getting in the way of my finishing projects at this point.

author: edpalmer42
author_rank: Super Contributor
timestamp: January 14, 2018, 07:38:36 pm
content: They're not cheap, but there are companies that will produce custom front panels. They give you the software, you design your front panel, pick the material, colors, etc. and they produce it for you. One company that I've heard of ishttps://www.frontpanelexpress.com. No experience or association with them.Ed

author: cdev
author_rank: Super Contributor
timestamp: January 15, 2018, 01:01:50 am
content: what about "dremel" style tools? - with aluminum, not steel..

author: cdev
author_rank: Super Contributor
timestamp: January 15, 2018, 01:21:14 am
content: I recently got a small XY-table also, quite similar to the Proxxon but built a bit more sturdily, but still very similar.. Its one that is also used in milling, I know thetableis capable of it. the manufacturer says so.but Ive only done drilling using it, no lateral cutting yet.I'd like to try that.. if I can be confident- of its safety by some means of being sure the tool wasn't going to fall out unexpectedly. () And only going very slowly as to not cause the bit to become deformed.What kinds of bits do you use to do that?and how do you keep them in? Do you heat up the drill's part that accepts the chuck's arbor so as to make it expand so it then can contract around the arbor? (I may have the terms backwards here)First I would like to try that for doing one off on PCBs, especially very simple ones.. cutting lines etc, first.. with a small router bit or something like that.Cutting holes sideways, I am kind of worried about detachment. The problem is drills are not meant for lateral motion and mills are. On a drill the only thing holding the chuck in is the taper. A mill actually locks the cutting tool in.Until I'm satisfied enough with my knowledge that Ive figured out a way to eliminate what I see now as significant risk the of drill bit and chuck detaching and falling out, becoming a projectile, I am not so eager to do it.This is mostly because I still have very little experience with using it in the normal fashion.Quote from: ovnr on January 14, 2018, 10:31:51 am

author: Dubbie
author_rank: Unknown
timestamp: January 15, 2018, 01:45:50 am
content: cdev,For endmills (the name of the tools that you use) you need a collet holder to hold the endmill in. These grip the tool very tightly and with high precision. A common type for small machines is an ER16 collet. You use a different size collet of each different size tool that you use. It must match very closely within 1/2 mm to get it nice and concentric.A jacobs chuck is very wrong for milling. It is not designed to withstand lateral forces nor, to prevent the tool pulling out. Because an endmill is helical, it constantly wants to pull itself out of the holder.

author: ovnr
author_rank: Frequent Contributor
timestamp: January 15, 2018, 01:51:50 am
content: Quote from: cdev on January 15, 2018, 01:21:14 amYou use endmills; there are a breathtaking variety, but if you're cutting straight through the material it's not very critical. Buy cheap ones, because they don't deform - they break. You will break a number of them.On having the chuck fall off of the taper: I had it happen once, and just jammed it on with a large helping of force. Hasn't come off since. YMMV.If itdoesfall off, it'll just drop straight down. You might wreck the workpiece, but it's not going to go chase you across the room.In my experience, milling soft plastics like ABS works without any fuss whatsoever. Harder plastics like PMMA/plexiglass works fine, but it's noticeably less happy. Aluminium works OK, but it's obviously not thrilled about it. Steel is a no-go.If you want OK surface finishes, you need to take a roughing cut and leave 0.5-1mm of material, which you then take off in a finishing cut. If you can, avoid angles of engagement (how much of the endmill is actually in contact with the workpiece) higher than 90 degrees; that means slotting right through the material is something to be avoided if you can, but I'll usually just deal with the chattering and complaining.One last word of warning: You want to clamp your workpiece in properly. You'd be surprised how easily it can come loose, and in the best case you'll ruin the workpiece - worst case it smacks you in the face. Wear safety glasses!

author: ovnr
author_rank: Frequent Contributor
timestamp: January 15, 2018, 01:53:27 am
content: Quote from: Dubbie on January 15, 2018, 01:45:50 amWell, you can't put an endmill holder onto a drill press taper. Yes, chucking endmills is a terribly bad practice, but I do believe the purpose of this thread is "ghetto-machining"; if you actually have a proper milling machine, you probably also know better.

author: cdev
author_rank: Super Contributor
timestamp: January 15, 2018, 01:54:07 am
content: I do have a very nice Jacobs chuck which is not currently on my cheap drill. I just got the drill also and the chuck it came with is the default one. So suppose I wanted to put a collet holder on there for milling from time to time, what would I buy to do this? Its the cheapest harbor Freight drill, its not a fancy one at all. that said I'm willing to go very slowly. Its just the occasional square hole that i would like to make.. infrequently. Safely.the milling table is actually ideal for that if I can cross all the ts and dot all the i's so to speak.Its quite heavy duty for what I paid for it. Its made by the same company that makes the green cheap ones and its also fluorescent greenBut its their bigger brother.. and its quite substantial.Quote from: Dubbie on January 15, 2018, 01:45:50 am

author: bson
author_rank: Unknown
timestamp: January 15, 2018, 02:05:42 am
content: I've been eyeing a Carbide 3D Shapeoko (https://shop.carbide3d.com/collections/machines/products/shapeoko3?variant=42721918086) exactly for this purpose - to cut panels out of (opaque, dyed) acrylic. They use regular trim routers, so won't get super high speeds, but I figure for acrylic or even aluminum prototyping it's fine. I'd also make or find a hood for it to make cleanup easier, just something I can put over it while it's running to contain the mess and any accidents.

author: cdev
author_rank: Super Contributor
timestamp: January 15, 2018, 02:19:20 am
content: Here is the X-Y table I have now. This was when I was re-lubricating it with better grease, so it hadn't been used at all yet.The base fits my drill perfectly.

author: CatalinaWOW
author_rank: Super Contributor
timestamp: January 15, 2018, 02:36:30 am
content: While panel punches, CNC and other methods are good and widespread, many of those beautiful holes in panels are done by hand. It is a skill, enhanced by the possession of proper tools. Much like hand lettering of signs. Rectangular holes are much easier than lettering signs, and the skill can be developed by most.I am sure there are other approaches, but mine involves a rough cut undersize hole and then improvement of the hole with successively finer files. Files with dead edges help a lot. Different sizes allow access to narrow holes and also do quick work on larger hole sizes. I am sure you are aware of running the file as close to parallel to the panel as possible. The quality of the hole depends on how much time and effort I am willing to put into it. The time to completion drops as your skill improves. It isn't quick, but not that much slower than doing the programming for a CNC and then getting everything set up on the machine (which is a whole set of skills in itself) and running it.

author: Dubbie
author_rank: Unknown
timestamp: January 15, 2018, 02:53:22 am
content: if you aren't confident in your filing skills, you can cheat a little by clamping a couple of pieces of scrap steel either side of your line you are filing to and using them as a guide/stop. You can get very precise results this way.

author: elroy
author_rank: Regular Contributor
timestamp: January 15, 2018, 07:19:27 am
content: Thanks for all the suggestions. In my situation, it sounds as though the best solution would be to use a small end mill to cut openings, and optionally finish off the corners with a hand file. I've got a 3D printer on order, so using it to fabricate either bezels or entire front panels may be an option too.

author: BurningTantalum
author_rank: Frequent Contributor
timestamp: January 15, 2018, 01:51:23 pm
content: A really low-tech technique, especially useful as these jobs tend to be one-offs, is the tension file that fits in a standard hacksaw frame. I have used these for years, and they give very good results on complex shaped holes. The best brand is 'Abrafile' although I'm not sure if they are still available. RS used to stock them. I have had mine for 40 years and have never worn one out or snapped one. I have even used them on stainless sheet. Their USP is that the 'pitch' of the abrasive gradates from fine to coarse down the length so starting each stroke is easier.Only a small hole need be drilled in the panel to insert the file (3.5mm?)BT

author: Fludo
author_rank: Regular Contributor
timestamp: January 15, 2018, 02:15:53 pm
content: For metal control panels I'd start with 3/8" or 1/2" clearance hole for a jigsaw blade in one corner of the square. After that cut the straight lines to the other corners with the jigsaw and clean the edges up with a file. If you're using plastic or wood, a coping saw would be able to do it using the same technique. The trick is to not bend the cut to much or the blade will bind/snap. The jigsaw will work as a router by moving the blade side to side as well. A jigsaw can be bought for under $50 and will produce a clean hole with some practice. They also come in handy for cutting fan holes as well.Depending on the component mounting, there's normally a lip around the outside to cover any imperfections.

author: cdev
author_rank: Super Contributor
timestamp: January 15, 2018, 02:25:04 pm
content: Do you mean a small table style jigsaw ?Ive seen those and wondered how well they worked with metal, specifically aluminum.I need to read up on and understand more about the various power tools.Quote from: Fludo on January 15, 2018, 02:15:53 pm

author: Fludo
author_rank: Regular Contributor
timestamp: January 15, 2018, 03:31:43 pm
content: The handheld ones with a vise or clamp work great on steel and aluminum. It's important make sure the blade TPI is matched for the material.

author: MarkL
author_rank: Unknown
timestamp: January 15, 2018, 03:57:55 pm
content: These corner punches can be used to finish the corner on plastics and would probably work ok on thin aluminum:http://www.micromark.com/search?keywords=corner%20punch

author: cdev
author_rank: Super Contributor
timestamp: January 15, 2018, 05:07:21 pm
content: The handheld jigsaws? How smooth are the cuts they cut? (with a linear metal ruler used as a guide)I think the very largest hole that I might want to make would be at the most 75-100 cm on its largest side.That would actually be an unusually large example, I think The typical application I need a rectangular hole ability for is likely a display or hole for some kind of interconnect.The circular holes for switches I can do with my drill.Quote from: Fludo on January 15, 2018, 03:31:43 pm

author: Fludo
author_rank: Regular Contributor
timestamp: January 15, 2018, 06:34:50 pm
content: With a good layout and careful work, the cut will be acceptable. It will take a bit of file work to get panel meters and displays to fit correctly. Not CNC machine quality but will need some deburring.For a display hole you could edge the bare metal with the split rubber gasket material and epoxy or silicone it into place. The edge will cover any mistakes made while cutting too.https://www.grainger.com/category/rubber-edge-trim-seals/rubber/raw-materials/ecatalog/N-iqu

author: CatalinaWOW
author_rank: Super Contributor
timestamp: January 15, 2018, 06:39:41 pm
content: Unless you are very good a hand sawn hole will not match a CNC hole. But after hand filling it can be better than all but the very best.

author: IanB
author_rank: Super Contributor
timestamp: January 15, 2018, 06:47:44 pm
content: I think it needs shop skills. You saw inside the line and then file to the line. Chris from Clickspring shows how it's done.Also, why does everyone assume CNC is needed for precision? You can manually control a milling machine and get perfectly good cuts, even better if you have a DRO.CNC is good for production where you need to make many identical parts. But for a single job you can have it finished before you have even got half way through setting up a CNC program.

author: Gregg
author_rank: Super Contributor
timestamp: January 15, 2018, 06:52:19 pm
content: Quote from: cdev on January 15, 2018, 05:07:21 pmI have a Bosch hand held jigsaw that I hold upside down in a vise to cut small things. Holding the saw by hand causes the blade to catch on thin work and not make a nice cut. Most of the blades cut toward the saw and make a burr along the cut that somewhat obscures the line; upside down, it leaves the line visible. My Bosch is variable speed and has settings for the orbital action (aggressiveness of the cut) both features that make it a good candidate for thin plastic and sheetmetal. Holding the work with two hands is much better than holding the saw and trying to clamp thin parts solidly.For aluminum or steel, lube the blade with stick wax (available at machine shop suppliers) to keep the aluminum from sticking and to lube the blade for much faster and better results. Cutting a little short of the line and finishing with a file is always a good idea for the really neat stuff.

author: Habropoda
author_rank: Regular Contributor
timestamp: January 15, 2018, 07:45:36 pm
content: It seems like a jewelers hand saw would work well for this. I haven't tried one but they are made to cut intricate holes and you can get many different blades for them. I've seen one used for cutting the fancy sound holes for a lute.

author: phil from seattle
author_rank: Super Contributor
timestamp: January 15, 2018, 08:58:13 pm
content: Quote from: elroy on January 15, 2018, 07:19:27 amYou'll love the 3D printer. Gone are the days of scrounging for the right box and hacking it up to get your project to fit. I've printed a number of boxes at this point. I do like the look of metal or molded plastic better though. Learn to use ABS as that can be smoothed to get rid of the most of the extruder ridges.

author: ez24
author_rank: Super Contributor
timestamp: January 15, 2018, 11:07:59 pm
content: Quote from: Gregg on January 15, 2018, 06:52:19 pmThanks I now need to look for my Bosch and get a vise

author: joeqsmith
author_rank: Super Contributor
timestamp: January 15, 2018, 11:25:18 pm
content: For thin aluminum or plastic I use a nibbler.

author: joeqsmith
author_rank: Super Contributor
timestamp: January 16, 2018, 12:45:57 am
content: Just in case some of you have not heard of or seen a nibbling tool.https://www.amazon.com/Premium-Life-360-022-Nickel-Nibbling/dp/B0002KRACO/ref=sr_1_4/146-4349405-5311219?ie=UTF8&qid=1516063461&sr=8-4&keywords=nibbler

author: ez24
author_rank: Super Contributor
timestamp: January 16, 2018, 01:06:35 am
content: Quote from: joeqsmith on January 16, 2018, 12:45:57 amThank you very much for including a link - I put one in my Cart. I thought they were very expensive.

author: Bratster
author_rank: Frequent Contributor
timestamp: January 16, 2018, 01:55:33 am
content: Quote from: ez24 on January 16, 2018, 01:06:35 amI've got that same one and it works great,... as long as you don't use it on 1/16" steel... But it's nice and cheap.Another good nibbler tool is this:https://www.amazon.com/dp/B00MPHC4TQ/ref=cm_sw_r_cp_apa_Y1vxAbYYTZ5D4Not as good for precision, but faster due to being drill powered.Sent from my Nexus 6 using Tapatalk

author: neo
author_rank: Super Contributor
timestamp: January 16, 2018, 02:20:59 am
content: My personal favorite way can be done with just a hacksaw blade, some tape and a metal file.Wrap some tape around one end of the saw blade, enough to hold, as well as some on whatever you are cutting, lay the tape in the outline and then using a ruler for a straight edge mark the exact lines. Remember you can always take a little more away so aim a little bit shy.Once you get the lines slowly cut the two sides and then angle across the middle. You can then saw out the remainders and file any imperfections out.REMEMBER, very important, go slow and do not rush. Take your time and be sure. Yes you will cut yourself, but a bit less with practice, yes you will err, but again a bit less with practice.Masking tape works best.Also if the hole needs to in the middle and not edge, a couple well placed hole drilled into it and a smaller metal file will help

author: nes999
author_rank: Contributor
timestamp: January 16, 2018, 07:05:24 pm
content: I good bezel can hide a hideous hole.Sent from my VS988 using Tapatalk