Making accurate long thin rectangular cut-outs at home - Page 1
Forum section: electronics / projects

author: david77
author_rank: Frequent Contributor
timestamp: November 13, 2012, 12:08:13 am
content: A question to the mechanics people here.How do you make accurate long thin rectangular cut-outs into aluminium or FR4 at home?In my particular case I need to make several uniform cut-outs 110x3mm for slider pots into a 250x400mm 3mm FR4 panel.I have a relatively good assortment of tools at hand but have failed to accomplish the task in the past.Maybe somebody's got an idea, something I've missed/don't know?

author: george graves
author_rank: Super Contributor
timestamp: November 13, 2012, 12:22:32 am
content: plunge router

author: david77
author_rank: Frequent Contributor
timestamp: November 13, 2012, 12:24:34 am
content: Mh, yeah. The one thing I haven't got. Maybe time to get one...

author: Psi
author_rank: Super Contributor
timestamp: November 13, 2012, 01:04:59 am
content: As George said, a router.Though you'd probably need a cutting bit intended for metal to cut aluminum.FR4 would probably be fine with a typical bit at slow speed though.The issue with plunge routers is they're hard to control. They wander all over the place and it's hard to cut a straight line.To fix this issue i made a wooden platform and mounted the router underneath to create a table router.That way i can clamp wood to the sides and get perfectly straight cuts. (Since the blade is round the clamp angle doesn't matter unlike a table saw)

author: PaulAm
author_rank: Frequent Contributor
timestamp: November 13, 2012, 01:56:30 am
content: A carbide bit will work for aluminum. Don't try cutting steel with it though.Drill a hole first so the bit doesn't wander.What you really need for this job is a mill (now there's an excuse to blow the tool budget)

author: Mechatrommer
author_rank: Super Contributor
timestamp: November 13, 2012, 02:00:36 am
content: this plunge router...1) i never thought this thing exist!googling now2) can it make thin staight line? say 0.5 or 1mm thick cutout line?

author: Psi
author_rank: Super Contributor
timestamp: November 13, 2012, 02:27:25 am
content: It depends on the router bit you use. They come in all sizes and shapes.From decorative ones which cut curved moldings to straight cuts.Obviously if you want to cut a 1mm channel the entire bit needs to be 1mm wide.For 0.5/1mm channel cuts you might be better with a dremel plunge router attachment (or similar).Typical plunge routers are usually for bigger cuts.

author: free_electron
author_rank: Super Contributor
timestamp: November 13, 2012, 03:01:58 am
content: flowjet ?if you are a member of techshop you have access to those.

author: Mechatrommer
author_rank: Super Contributor
timestamp: November 13, 2012, 04:15:25 am
content: Quote from: david77 on November 13, 2012, 12:08:13 ambrainstorming this ever expanding thread, i think i will buy one original dremel kit and figure out how to build a stand for it so it'll plunge router look alike. the stand already sold in ebay i know. but its for specific dremel model which i cant find it sold...http://www.ebay.com.my/itm/Dremel-335-Plunge-Router-Attachment-335-26150335JA-/310374677321?pt=UK_Home_Garden_PowerTools_SM&hash=item4843c5bb49and i think i'll need horizontal stand not vertical and use this type of round saw bladehttp://www.ebay.com.my/itm/7pc-HIGH-SPEED-STEEL-WOOD-CUTTING-SAW-BLADES-DREMEL-SS45HS-5-BLADES-2-MANDRELS-/380454785463?pt=Power_Tools&hash=item5894df51b7and build a table rig just as Psi's, except smaller, to cut my panelized pcb. so what do you think guys?

author: notsob
author_rank: Frequent Contributor
timestamp: November 13, 2012, 04:38:25 am
content: Search the web, I remember seeing a complete article on a home made base for a dremel, to make a mini version of what psi has.

author: Kremmen
author_rank: Super Contributor
timestamp: November 13, 2012, 09:37:11 am
content: Even for a 2 mm bit (that i use), do bear in mind that the bit will generate a significant side load when biting into the material. If your fixture has any flex then you will get a wavy line depending on the variations of feed pressure. Been there, suffered that. So make sure that your table fence is solid, as well as the support for the router.Another hint - for FR4 forget anything but carbide. With HSS bits you will get through maybe a couple of boards and thats it.Been there as well...

author: robrenz
author_rank: Super Contributor
timestamp: November 13, 2012, 12:40:46 pm
content: Quote from: Mechatrommer on November 13, 2012, 04:15:25 amLook for a small table saw style tile cutting saw with a plated (not sintered) diamond blade. These are available in the US from Harbor freight for $40 to$150. The wet versions will keep you from having fiberglass dust all over the work area. It will work dry but I suggest doing it outdoors. The plated style of blade with a single layer of diamond is very important, It gives a very free cutting action on epoxy glass. If you were cutting tile the plated blade is junk and you would want a sintered blade that has a deep layer of diamond in a metal matrix. Sintered blades need an abrasive slurry from the tile to slowly erode the metal matrix exposing fresh diamond. That mechanism does not work on fiberglass and it will not cut well if at all. The plated blades have a layer of nickel plating holding a single layer of visible diamond particles. coarser grit works better and still will leave a very nice finish on the edge of the board. If you already own a table saw you can buy a diamond blade for it but the fiberglass dust is very abrasive and may slowly ruin any equipment not designed for it if you plan on using it a lot.

author: Kremmen
author_rank: Super Contributor
timestamp: November 13, 2012, 12:57:30 pm
content: That works for de-panelizing but trying anything else than separation cuts will probably be problematic. With a router or mill you can create slots and free form openings that are not possible using a disk saw. Best would be to have both i guess, but it depends on the actual requirements.

author: kripton2035
author_rank: Super Contributor
timestamp: November 13, 2012, 01:05:24 pm
content: I would use my small mill to do such a work... will be better than the router.

author: Kremmen
author_rank: Super Contributor
timestamp: November 13, 2012, 01:29:31 pm
content: I could also use my mill, but maybe not...

author: Mechatrommer
author_rank: Super Contributor
timestamp: November 13, 2012, 01:37:24 pm
content: duh is it just me or is it too difficult to meet the requirement from "extreme machinist". i'll order the dremel first and see how it works (imitation actually not originalbut i think should be alot better than what i currently have). the problem i'm anticipating is the blade will vibrate too much due to imbalance. i'll see if horizontal cutting is better than vertical cutting (plunge router type), if not i'll just switch method. i'll keep the advices in mind thanks. experience will also teachps: i also have bigger mill than kripton but punny compared to kremmen. the only problem is it doesnt have that x (or xy or xyz) stiff table and maybe it cannot grip 1mm drill bit too well.

author: kripton2035
author_rank: Super Contributor
timestamp: November 13, 2012, 01:42:11 pm
content: with a dremel and a 3mm drill (or end mill better) the whole system WILL vibrate(and you will also...)it will be very difficult to be parallel between all the slots you have to makeonly a mill with cross table can do a nice jobof a router with a table to fix the whole thingdont do it "hands free" with a dremel in a hand. it could be quite ok on wood, but certainly not in aluminium.

author: TorqueRanger
author_rank: Frequent Contributor
timestamp: November 13, 2012, 01:45:14 pm
content: What about using a table saw with a guideI don't about you guys but this is becoming more complicated that it has too....

author: Mechatrommer
author_rank: Super Contributor
timestamp: November 13, 2012, 01:53:04 pm
content: Quote from: kripton2035 on November 13, 2012, 01:42:11 pmi posted earlier that i will build a rig table for it, i know how it feel try to make a straight line handfree, even with pencil. if i cannot build the rig i'll buy one if i can afford it.

author: Mechatrommer
author_rank: Super Contributor
timestamp: November 13, 2012, 02:50:56 pm
content: yeah yeah the "files". i did that along with my onehunglow "not-dremel" "super vibrating" drilling toolkit using sanding disc, no straight edge table rig, handsfree (or free hand?) no route no guide, with exception that i used ruler and scratched a straight line before hand saw'ed it (with the "apple patented" round corner too!). another pop quiz... which edges that i cut?, which edges come from factory? i provide the full size zipped image if you are interested with the quiz (no cheating looking at the expired quiz earlier. only if you have your answer fixed then only you can, but no prize here). i've de-panelized all 9 of them, but just for 1 board, there's 9 boards to come.ps: to mods, please delete the 1MB attachment in 48 hours. the size is not worth it compared to its usefullness to this thread.

author: PaulAm
author_rank: Frequent Contributor
timestamp: November 13, 2012, 03:42:56 pm
content: A real low tech way is to just get a jeweler's saw and a bunch of blades. If you haven't used one of these, you're liable to break a couple of blades in the beginning. Scribe the slot, drill a small hole, thread the blade through and cut to the mark. Finish with a file if needed. It's amazing how accurate you can be with a hand saw if you take your time.

author: grenert
author_rank: Frequent Contributor
timestamp: November 13, 2012, 04:30:19 pm
content: A Dremel cut-off wheel will easily get through FR-4 to split up PCBs.

author: robrenz
author_rank: Super Contributor
timestamp: November 13, 2012, 04:49:37 pm
content: Quote from: grenert on November 13, 2012, 04:30:19 pmAgreed and the diamond plated cutoff wheels are even better in the FR-4

author: robrenz
author_rank: Super Contributor
timestamp: November 13, 2012, 05:48:51 pm
content: Quote from: Mechatrommer on November 13, 2012, 01:37:24 pmSince when is suggesting a $50.00 Harbor Freight tile saw and reccomending a proper blade type from past experience extreme?

author: robrenz
author_rank: Super Contributor
timestamp: November 13, 2012, 06:12:10 pm
content: This is the type blade that will work well on the FR-4 for cutoffhttp://www.ebay.com/itm/4-inch-4-100mm-Diamond-coated-CUT-off-CUTTING-saw-blade-wheel-disc-/121015230313?pt=LH_DefaultDomain_0&hash=item1c2d11df69This type you can use to cutoff and also use the sides of the wheel to round the corners of the boards or grind edges.http://www.ebay.com/itm/100mm-Diamond-Cutting-Disc-Cut-Off-Wheel-Grinding-Tool-Gold-Tone-/290683067457?pt=LH_DefaultDomain_0&hash=item43ae0f9c41

author: G7PSK
author_rank: Super Contributor
timestamp: November 13, 2012, 06:51:36 pm
content: If it is just a few slots I would mark them out then score the lines with a Stanley knife then drill a succession of holes and clean it up with a needle file. It is possible to make a slot this way faster than a mill can be set up.

author: Mechatrommer
author_rank: Super Contributor
timestamp: November 14, 2012, 04:20:17 am
content: Quote from: robrenz on November 13, 2012, 04:49:37 pmi believe your suggestion is about durability and faster cutting. other cheapo material also can do imho, but slower and will need frequent replacement.Quote from: robrenz on November 13, 2012, 05:48:51 pmfirst its $50 for the small thing, and then it needs to travel (alone?) half the globe for additional cost and i'm not sure if i can figure out what you say... diamond blade? i believe i've came across this term previously but i doubt they were the real things.you know how hard it is to be here working in the "ghetto"?Quote from: robrenz on November 13, 2012, 06:12:10 pmnow! you are making things ALOT easier! thanks!edit: HOLD ON! wait a second pal, thats for normal hand grinder! grrrri was talking for dremel tool.Quote from: G7PSK on November 13, 2012, 06:51:36 pmremind me of this pcb cutter (get the quality one, this is chinese!) but i suspect we need to exert significant force and few passes before the pcb is cut (from normal paper cutter experience).http://www.ebay.com.my/itm/TH-897-Utility-Cutting-Hook-Knife-Box-Cutter-PCB-Copper-clad-Plate-3-Blade-/170883622910?pt=LH_DefaultDomain_0&hash=item27c97527fe

author: robrenz
author_rank: Super Contributor
timestamp: November 14, 2012, 04:38:08 am
content: Quote from: Mechatrommer on November 14, 2012, 04:20:17 amBuy a hand grinder instead of the dremel and make a wooden plate to mount the hand grinder underneath like a mini table saw. clamp a guide parallel to the blade at the distance you want to cut at.

author: Mechatrommer
author_rank: Super Contributor
timestamp: November 14, 2012, 04:48:49 am
content: Quote from: robrenz on November 14, 2012, 04:38:08 amgot one already. with a mill, hand drill/bore and press down steel cutter somemore (bought when i was renovating my house), but i believe they all will be overkill for a 1mm thick slot cut or 3mm panel. but anyway, maybe i got to try your idea sometime, thanks

author: david77
author_rank: Frequent Contributor
timestamp: November 14, 2012, 03:01:18 pm
content: FYI: Bought a cheap router today and a 4mm bit. Works quite well, I have my cut-outs now.

author: T4P
author_rank: Super Contributor
timestamp: November 14, 2012, 04:46:23 pm
content: Quote from: PaulAm on November 13, 2012, 03:42:56 pmThey are essentially coping saws aren't they, if i recall it was hard to make any straight cuts?Anyway. China makes these sort of thingsEssentially a modified bench grinder

author: Psi
author_rank: Super Contributor
timestamp: November 14, 2012, 10:30:19 pm
content: The problem with cheap china stuff is that it's always out of alignment when you get it and they never have any adjustments so you cannot easily fix the problem

author: Kibi
author_rank: Unknown
timestamp: November 14, 2012, 10:53:52 pm
content: That thing is amazing! It's labelled a lathe. It bears no resemblance to a lathe at all!OK, so maybe one could mistake it for a grinder, but where is the work rest? Not even a wood butcher could sharpen his chisels on that!! Even if it's a buffing wheel, you could do with a work rest.Moving over to the right, the fence, how can one guarantee it's parallelism to the blade without having to measure every time one moves said fence? The riving knife is miles away from the blade too!Lol.

author: mrflibble
author_rank: Super Contributor
timestamp: November 14, 2012, 11:23:04 pm
content: The hand grinder and dremel approach both work fine. I generally use the grinder if I want to make long strips of copper clad, and the dremel for short cuts or grooves and such.The upsidedownrouterinnatable approach looks like a good plan too, haven't tried that one yet. Can anyone recommend a cheap source of reasonable quality bits that don't die horribly after they smell their first whiff of FR4?

author: IanB
author_rank: Super Contributor
timestamp: November 15, 2012, 02:49:47 am
content: Quote from: mrflibble on November 14, 2012, 11:23:04 pmIn the USA, Rotozip bits are cheaply available in multi-packs. If they go blunt, just use a fresh one. Also the Rotozip tool is going to be far better than a Dremel in plunge routing and cutting applications.

author: Mechatrommer
author_rank: Super Contributor
timestamp: November 26, 2012, 08:27:58 pm
content: knock-off dremel arrived. built a rig for it, and another detachable table rig. depanelized cut, sand and smooth all my pcb very well in an hour or so (81 pieces all), its a few days ago. but i believe i used the steel saw blade is a bad idea to cut FR4, i think better with that dark brownish grinding bit, it seems to cut FR4 very well, but i realized after cutting all my pcb, so its too late for that. basically the tool has done what its meant to be bought for...

author: robrenz
author_rank: Super Contributor
timestamp: November 26, 2012, 09:10:26 pm
content: Nice, I especially like the elastic latch on the back end.

author: DavidDLC
author_rank: Frequent Contributor
timestamp: November 26, 2012, 10:54:02 pm
content: Quote from: david77 on November 14, 2012, 03:01:18 pmPlease post some pictures, a lot of people maybe interested to see the results !

author: Mechatrommer
author_rank: Super Contributor
timestamp: November 27, 2012, 06:55:05 am
content: Quote from: robrenz on November 26, 2012, 09:10:26 pmi cant think of anything better. i'm thinking of long extruded bolt shaft going up through the "fastener" and a nut or "quick snap in mechanism " to lock it, but the tooling is out of my reach. so thats the best i can do with whats available to me

author: robrenz
author_rank: Super Contributor
timestamp: November 27, 2012, 12:37:58 pm
content: Quote from: Mechatrommer on November 27, 2012, 06:55:05 amI was serious, that was a complement on your mechanical ingenuity. I can appreciate things based on what people have to work with. Not comparing it to something made in a fully equipped manufacturing facility. Sorry you missunderstood