Another drilling question: making a drilling jig - Page 1
Forum section: electronics / general

author: Buriedcode
author_rank: Super Contributor
timestamp: November 10, 2016, 01:53:33 pm
content: I have posted before about an awkward problem drilling aluminium enclosures that had PCB guides, but that was a fairly rare occurrence. Something I regularly have to do is drill 1.5mm aluminium panels, mostly the end panels of a hammond alu enclosure.Skip down three paragraphs to get to the pointAs I only have to do 3-5 of these at a time, my usual tactic - without a pillar drill - is to glue a printed out template (done in eagle CAD believe it or not) onto the plate, use a 1mm bit in a pin vice and do a few turns just to get a dent in the exact spots, then drill 2mm pilot holes. From this holes are 3-6mm, and for a Dsub, 4 x 4.5mm holes at the corners, and then dremel out the middle, finally, file to a reasonably good Dsub shape.It is time consuming, and for the most part it works rather well providing I am rather careful, take my time, and use a step drill for widening holes larger than 3mm. I have no idea how many of these I will need to do for the future because my customer seems to randomly call me up and ask for some so I am hesitant to invest anything for future orders. Also I barely make £10/hour on this, so on principle I'm not willing to fork out 100 on a pillar drill just yet. Right now its the only 'machining' job I have, the rest are all design or PCB population.I have an order for 8 now, which is probably two days of drilling, and my purely 'manual' approach seems lengthy and depressing, so I thought I would invest at least some time in making a drilling jig, as all the panels are identical.The panel only requires 8 holes (two large holes, and 6 for the Dusb - 2x3mm + 4x4.5 for the actual Dusb shape) some of which are very close together. My (simple) idea is an MDF block with 4 steel dowels and two threaded rods. The steel dowels are where the panel mounting holes are, and use to align the bottom MDF block to the top drill jig, the threaded rods are there so I can use wing nuts to hold the top part down - sandwiching the plate between. Its all doable and fairly simple but the real question is: what material to use for the drill guide?Would high density MDF be ok for a drill guide? Perhaps 10mm+ (all the holes will be 3mm) or is there a relatively cheap way of getting a steel block made up? I know there are drill bushes, but I have yet to see any under $8, and for 8 holes thats $64. Also, I suspect this will only be used for 8 panels (I can stack them to drill 2-3 at the same time) so it doesn't have to last. All the drill jigs I've seen on google are either plain wood, used for wood working, where I suspect precision isn't vital, OR... full on 12mm steel plate with dirll bushes, very rugged and precise.Does anyone have any examples of effective drill jigs they use with hand drills?

author: DTJ
author_rank: Super Contributor
timestamp: November 10, 2016, 02:10:36 pm
content: Look out for a used old style drill press, it will pay for itself.I have used drilled out root nuts for drill jig guides, when they wear out I just punch them out and pop a new one in.MDF will wear WAY to quickly for use as a drill guide.Visit your local sheet metal workshop and see what you can find in their scrap bins......

author: H.O
author_rank: Frequent Contributor
timestamp: November 10, 2016, 02:26:22 pm
content: MDF on its own is probably not a very good but combines with drill bushings it should be fine I think. Then again I'm not sure I see the need for one in this case....Stack the 8 panels on top of each other, put your printed out layout on top, punch and then drill them thru all at once.I don't know how accurate you need to be but without a drillpress its hard to keep the drill perpendicular to the panel which obviously makes the position of the hole "creep" as you work your way thru the stack.Or perhaps the panels aren't simply flat panels but some sort of extrusion?

author: Buriedcode
author_rank: Super Contributor
timestamp: November 10, 2016, 02:57:45 pm
content: The panels are completely flat with a nice finish - typical hammond end panels.And you're right, I would have stacked them so I could do many at the same time, but then I risk ruining all, instead of just one! I would fork out for a nice steel template, but at 10mm thick I suspect it would cost as much s a cheap pillar drill, or even the same as getting panels manufacturer from 1.5mm alu stock.I have got panels made up before for another project (which had a better budget) from 'front panel express' in Germany. Excellent results, obviously accurate as they use 2mm mill bit in a huge CNC, but they worked out to be about £20 each for 78x30mm, with 12 holes and 4 cutouts.Also, drilling steel with a hand drill doesn't inspire me... with alu its soft, but hard to be accurate as it will wander and make oval holes, but with steel.. I reckon I'll be fighting it all the way.It really does seem whether I make a drill jig, or do it all manually, a pillar drill is required. Which means this job will end up costing me, rather than making money.

author: langwadt
author_rank: Super Contributor
timestamp: November 10, 2016, 03:23:21 pm
content: Quote from: Buriedcode on November 10, 2016, 02:57:45 pmhttps://youtu.be/4HOxfZKIZQk

author: MosherIV
author_rank: Super Contributor
timestamp: November 10, 2016, 04:53:32 pm
content: HiHow about this :Create your MDF block with 4 steel dowels and two threaded rods.Do not use it to guide the drill. Use it as a template to centre punch the panels.The centre punched dents will allow a 1 to 2mm drill bit to drill perfectly aligned holes.You can then enlarge the holes with progressively larger bits.

author: Buriedcode
author_rank: Super Contributor
timestamp: November 10, 2016, 05:19:52 pm
content: I see your point, and that would make it easier than gluing the templates to the plates - after drilling them have to be peeled off with acetone, nasty business. But if I'm using it for that, then surely i can use it to just start the holes off with a 3mm bit?Ultimately It would be good to have a material that can easily be drilled for the template, but strong enough to survive 8+ uses. Several of the holes have to be widened, but I'll do that with a step drill which seems to widen holes much better than just using a larger bit (as in, doesn't wander). Also for the Dsub cutout, the four holes are quite close together, about 1mm gap so any drill bushes will have to be ground. Perhaps rather than finding a material that fits the above specs, I should be asking if there are any things that are relatively cheap that can be used as drill bushes? Obviously metal, 3mm ID steel tube glued/hammered into MDF? Unfortunately brass M3 spacers of course have an internal diameter of 3.1mm, which is probably too much slack, although if they are quite long (20mm?) on paper that should be ok.In terms of precision, only +/- 0.5mm absolute - relative accuracy should be tighter because the Dsub mounting holes have to be spaced 25mm, but the other holes are all for separate things like LED bezel and DC jack. I'm looked at punches for Dsub, with the price, its just not an option.Looks like I'm going to have to phone around to get access to a workshop with a drill press, OR, just deal with it and spend the time doing it the old way.

author: langwadt
author_rank: Super Contributor
timestamp: November 10, 2016, 05:56:59 pm
content: Quote from: Buriedcode on November 10, 2016, 05:19:52 pmconsidered just getting cheap PCBs (possible aluminium) made to use as front panels?https://youtu.be/Yj0Bv4UEFSshttps://youtu.be/gSio28SH38E

author: nctnico
author_rank: Super Contributor
timestamp: November 10, 2016, 06:11:56 pm
content: If I need to do many front panels I have them laser cut from anodised aluminium.For smaller batches I use drafting paper on which I print the hole pattern and drill from there. I advice against stacking the panels because drills are quite flexible and the holes will be on the wrong place on the bottom panels.

author: Buriedcode
author_rank: Super Contributor
timestamp: November 10, 2016, 06:16:09 pm
content: I have! Fired off an email to PCBway who were happy to do it, but, these hammond enclosures (1455k1201) have 4 mounting holes on each corner, for #6 screws (~3.1mm) that are pretty much bang on 4mm diameter. This leaves 2mm from the edge of the mounting hole to the edge of the panel. Countersink this and there's even less material left.With a Dsub and DC jack in the middle of the panel, I wasn't confident there will be enough PCB material around them to prevent the panel coming off when things are unplugged. I know FR4 is pretty tough, but as a test I drilled a 4mm hole near the corner of some scrap FR4 I had. It took some effort but I could snap off that corner by soldering a large test hook to the solder side, and bolting it to a flat plate, and puling a bit. There will of course be 4 of these, and the force will be perpendicular. On that video mikes mounting holes looked further in and it doesn't look like any connectors were actually mounted on it - so a great front panel with lettering, and no need for strength.If there was a need for labeling, I might risk it as I would have the cost of printing the end panels anyway, but these panels only require holes and a Dsub cutout, and come with the enclosures. The number of these I have to make up is right on that awkward point between 'one-offs' 1-3, can all be done by hand.. and.. 'enough to warrant getting panels custom made' at about the 15-20 point.Sorry for ranting, I do seem to get these awkward projects on where of course, cost is an issue. If I could guarantee that my customer would require >10 in future, I'd get the lot made up because I know I could recoup costs, but sadly this isn't that case.

author: nctnico
author_rank: Super Contributor
timestamp: November 10, 2016, 06:55:24 pm
content: I see Sub-d mentioned: a set of punches is well worth the money.

author: ChunkyPastaSauce
author_rank: Unknown
timestamp: November 10, 2016, 07:45:16 pm
content: Quote from: Buriedcode on November 10, 2016, 01:53:33 pm1. Printout template layover2. Use $10-$40 automatic center punch over template, then drill. Buy a 10$ drill guide block if you need perpendicularity (but think not since it's only 1.5mm sheet)3. Use dremel with a $0-$20 router guide for sub-d over template (guide is free if you make own, people make them out of bottle lids)

author: Buriedcode
author_rank: Super Contributor
timestamp: November 10, 2016, 07:59:42 pm
content: I considered using the dremel as a router, rather than manually filing it out, but its not easy as the panel is only 78x43mm, the router woudl be find for larger panels with the cutout near the centre. I'll try to make a template though as I have Acrylic and nylon about.Secondly, I've giving up using a centre punch on sheet aluminium. Much easier to just use a 'hobby drill pin vice' and twist a few times.Also, all these methods are fine for one or two, but up to 10?

author: IanB
author_rank: Super Contributor
timestamp: November 10, 2016, 08:05:32 pm
content: I guess you need to consider your cost structure and your pricing. If you price your time per hour and determine how long it takes you to make one panel by whatever means, then you need to set a price where that is profitable and hopefully acceptable to the client. After that, making 10 panels is just 10x as much work (and profit) as making one panel. You just have to treat it as a job and do it.

author: rrinker
author_rank: Super Contributor
timestamp: November 10, 2016, 08:18:06 pm
content: If it's a flat panel that needs to be drilled, stack a bunch together rather than do one at a time. Doesn't help with the routing of the square opening but you could drill it out, drilling all of them together same as the plain holes, then clean each one up individually. Another way to make the opening is a nibbling tool, you can get nice square edges on the corners and a straight line without much trouble. Still time consuming to do one by one.

author: KL27x
author_rank: Super Contributor
timestamp: November 11, 2016, 03:29:39 am
content: QuoteA small rotary tool router table might work for the D-sub cutout. Certainly doable for small runs like this. It is a lot easier to see what you're doing with just 1/8" of the endmill sticking up through the work piece.

author: Ian.M
author_rank: Super Contributor
timestamp: November 11, 2016, 03:58:52 am
content: 3mm ID bushings made out of steel tube, press fitted or epoxied into MDF might be good enough for the guides for a limited run if you are careful to minimise side loading, break the edges of the drill flutes except at the tip with a stone and keep them greased. There are some suppliers for stainless tube on Ebay that might be suitable. e.g.http://www.ebay.co.uk/itm/6MM-OD-X-3MM-ID-1-5MM-WALL-316-SEAMLESS-STAINLESS-STEEL-TUBE-/321817034062However, without a drill press to drill the initial holes perpendicular to the jig, its going to be a real b****r to make.