I need help, because I have no idea what I'm doing wrong here. I can't seem to drill a line of holes that exactly line up to save my life. Its a bummer because on a project I'm looking to market (which means it has to look decent) involving a small plastic box (about 2.5" square), there are 8 small buttons, requiring holes no bigger than 0.13, and space only about 0.285" apart. Needless to say, even slight misalignment or un-even spacing is very easy to see and looks very unprofessional. I'm almost ready to throw out 6 cases I've tried to drill so far because of this. Here's what I did so far attempting to make these holes...
1. I have had PC boards professionally cut, and made sure the boards had tiny (about 40 mil) holes where each actual hole is going to be needed. I figured the PC board would be made to a precision of 1-mil, so it would make a great drill guide.
2. The PCB fits very tightly into the transmitter case, so I'd place it firmly in the box. Then using those tiny holes as a guide, I'd use an equally tiny drill bit, the same size as the holes, in my drill press, to drill tiny pilot holes through the guide holes and through the plastic.
3. From the outside I could now see all my pilot holes, and I would use them as guides to drill my 0.13 holes. Maybe drilling from the inside though to the outside was a bad idea, because already I could see they weren't absolutely perfect. The plastic it thick, but the idea of the drills bending on their way though soft plastic is mind boggling. Still, they appeared to be what I called "good enough", so I proceeded...
4. I then went up to my 0.13 diameter drill bit, and now from the outside of the box, I'd use each tiny hole as a guide and drill the bigger hole. With each hole, I was careful to go slow at first, allowing the drill bit to "find" and center itself in the guide hole, and then I'd hold the work more tightly while I completed the hole.
When I was done, time after time the slight misalignment from hole to hole were obvious. I'd end up trying to salvage the work using the drill to make slight corrections, by putting it in the holes that were more obviously "off" than others, and "side"-drilling to make the hole line up. BUT THAT SUCKS!!!!
Attached is an example of my headache. I've tried slow and high drill RPM speeds. I'm considering buying new plastic cases and starting over. But they say its a form of insanity to do the same thing the same way and expect a different result. At my small quantities, I definitely can't afford the set up charge to have the holes drilled for me.
Any ideas? Also... any thoughts on salvaging the existing work are appreciated too. I have 6 more boxes whose holes did not turn out much better than this one.
1. I have had PC boards professionally cut, and made sure the boards had tiny (about 40 mil) holes where each actual hole is going to be needed. I figured the PC board would be made to a precision of 1-mil, so it would make a great drill guide.
2. The PCB fits very tightly into the transmitter case, so I'd place it firmly in the box. Then using those tiny holes as a guide, I'd use an equally tiny drill bit, the same size as the holes, in my drill press, to drill tiny pilot holes through the guide holes and through the plastic.
3. From the outside I could now see all my pilot holes, and I would use them as guides to drill my 0.13 holes. Maybe drilling from the inside though to the outside was a bad idea, because already I could see they weren't absolutely perfect. The plastic it thick, but the idea of the drills bending on their way though soft plastic is mind boggling. Still, they appeared to be what I called "good enough", so I proceeded...
4. I then went up to my 0.13 diameter drill bit, and now from the outside of the box, I'd use each tiny hole as a guide and drill the bigger hole. With each hole, I was careful to go slow at first, allowing the drill bit to "find" and center itself in the guide hole, and then I'd hold the work more tightly while I completed the hole.
When I was done, time after time the slight misalignment from hole to hole were obvious. I'd end up trying to salvage the work using the drill to make slight corrections, by putting it in the holes that were more obviously "off" than others, and "side"-drilling to make the hole line up. BUT THAT SUCKS!!!!
Attached is an example of my headache. I've tried slow and high drill RPM speeds. I'm considering buying new plastic cases and starting over. But they say its a form of insanity to do the same thing the same way and expect a different result. At my small quantities, I definitely can't afford the set up charge to have the holes drilled for me.
Any ideas? Also... any thoughts on salvaging the existing work are appreciated too. I have 6 more boxes whose holes did not turn out much better than this one.
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These appear to be hand drilled, given the gouging on the sides by having the drill at an angle to the hole.. are you, in fact, hand drilling these?
Hand drilling would be a no-go. Borrow someone's drill press, buy a used on off craigslist for 20-30$ or pick up a new one at home depot for $80-100. well worth it.
Hand drilling would be a no-go. Borrow someone's drill press, buy a used on off craigslist for 20-30$ or pick up a new one at home depot for $80-100. well worth it.
Clamp a scrap board to the drill press table and use that as a fence.
Then cut slices of scrap and stack them, each one is as thick as your hole spacing.
Drill the first hole with all scraps in place, next hole pull 1 scrap and drill next hole, rinse lather & repeat. That will be as close as machine shop youll get with standard tools.
Then cut slices of scrap and stack them, each one is as thick as your hole spacing.
Drill the first hole with all scraps in place, next hole pull 1 scrap and drill next hole, rinse lather & repeat. That will be as close as machine shop youll get with standard tools.
Using a drill template should work, but a 40 mil (1 mm) drill will bend as it goes through the plastic. Especially if you apply too much pressure. I would have used a 2 mm drill.
That said, you could make a drill template from aluminum. If it's thick enough, you can drill directly with the 3.3 mm drill. As long as the workpiece is clamped properly, that should be fine. I used a piece of 0.063" thick (1.6 mm) aluminum perforated plate as a drill template for drilling the 0.125" (3.3 mm) vent holes in my 300B amp. I used a couple of brass pins to hold the perf plate in place and just drilled through with the 0.125" drill. No pilot hole...
Plastic sucks a**. Drills tend to bite into it. Either get an enclosure made from a type of plastic that's easier to machine or switch to metal.
~Tom
That said, you could make a drill template from aluminum. If it's thick enough, you can drill directly with the 3.3 mm drill. As long as the workpiece is clamped properly, that should be fine. I used a piece of 0.063" thick (1.6 mm) aluminum perforated plate as a drill template for drilling the 0.125" (3.3 mm) vent holes in my 300B amp. I used a couple of brass pins to hold the perf plate in place and just drilled through with the 0.125" drill. No pilot hole...
Plastic sucks a**. Drills tend to bite into it. Either get an enclosure made from a type of plastic that's easier to machine or switch to metal.
~Tom
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The eye is very intolerant of small errors when looking at straight lines of holes or marks or whatever.
You need accurate marking out.
You need accurate centre punching.
You need accurate pilot hole drilling.
With a drill that has been accurately sharpened such that the angles of the two cutting edges are equal and the lengths of the two cutting edges are equal.
You need to drill at the correct speed and near the correct feed.
If you can do all of that by hand and get a good line of holes, then you have become quite skilled. I suspect apprentices are set this task quite a few times until they pass.
You need accurate marking out.
You need accurate centre punching.
You need accurate pilot hole drilling.
With a drill that has been accurately sharpened such that the angles of the two cutting edges are equal and the lengths of the two cutting edges are equal.
You need to drill at the correct speed and near the correct feed.
If you can do all of that by hand and get a good line of holes, then you have become quite skilled. I suspect apprentices are set this task quite a few times until they pass.
Yes.. it was the bending of the bit as it passed through the plastic that I hadn't counted on, nor could likely control. Making a drill template is something i doubt I could do, certainly not with any better accuracy. The PC board with the added holes were supposed to be my template, but maybe I can take one of those boards and widen the holes... maybe ever stack a few PC boards.
I really don't have the choice of a metal enclosure in this case. The product/project is a wireless remote control, which works without an external antenna because of the antenna is a trace on the PC board (its UHF). So besides the higher price metal will cause, it will invalidate the whole design. Surely I'll somehow learn to drill holes more accurately.
The drills biting into the plastic though... is there anything I could do to improve on that? maybe there are better drill bits, or better RPM choices when plastic is involved?
The thing is, when you're planning to test marketing a complicated product, where even the parts and components are costly, there are so many choices where your costs can skyrocket or stay manageable, based on the choices of what you do yourself and what you have done. Do you have your PC boards populated for you? Have your control labels screened or laser printed for you instead of making your own labels? Have your holes cut for you instead of drilling your own? So many things. At a certain quantity, of course it way better to have everything done for you. But when you're trying to make a handful of something, its harder to justify the setup costs. That's especially true when you know a test market might prove that some modifications are a necessity. But among all those choices, I'd never have believed that drilling holes would be one of the things I'd have to consider having done. :-(
Well I might. Another possibility... I'm printing labels for the controls, and the label will completely cover the recessed square are you see. They make really good moisture resistant self stick plastic labels, and I was very pleasantly surprised how good my set prints looked, even with a totally black background. So... maybe if I can do a better job with the holes in the labels, it will save the day! I'm thinking of using one of those craft leather punches, the kind you hold in your hand, adjust the hole size, squeeze, and twist your work.If I print the proper size hole outlines on the labels, I'm hoping that unlike a drill that can "grab" and change position in the blink of an eye, it should be possible to EXACTLY align the punch before i apply pressure.
BUT... even if that works, i STILL want to learn to drill holes properly. This is almost embarrassing!
I guess I should have made clearer that I was using a drill press, both for the pilot holes and the final cuts. That makes it even more embarrassing! It must be the way the plastic, or this particular plastic (ABS I think) is interacting with the drill bit. I'm sure I've never had such a mess drill a series of holes in wood or metal, ever.
OK... that was one of my problems. I did use the highest speed on my drill press, 3000 RPM. But going slow into this ABS plastic was causing another problem. If I didn't get the hole done in a second, it would start to melt, and cake up on the drill bit.
Maybe my usual high speed drills are no good for plastic. Maybe there's a better type of bit. Or an entirely different process, like punching or burning my holes.
WOW!!! Thanks! i think this is the winning solution! I'd have never thought I'd have had to do this, but you're right... setting up a fence definitely sound like a good idea!!! That should make at least ONE plane totally accurate. And a series of properly sized scraps to use as progressive spacers for the other plan is another great idea! If I the spacers are all cut from one pass on my table saw, the will HAVE to be exactly the same size, and ought to set up the drill position for me. I'll have to make an initial wooden setup jig, but once I do it should get the dril positioning down to a repeatable process! And I should be able to hold the work really firm against the fence and spacers. And since I'll now be able to do my cutting from the outside in, and bending of the bit as I drill through the plastic will affect the invisible inside more than the outside!
This is great! I'm excited now, because I might finally have a workable solution. I've wasted a few boxes, but I really want my product to look good. Home made should NOT mean it looks home made! I'll let you know know how this works out!
So if I were doing things this way, should I still start with smaller pilot holes? Maybe I shouldn't? One poster pointed out that the tiny bits are going to have more of a tendency to bend. And if the position is right to start with, and the full size holes aren't that big anyway, maybe one pass with one drill is fine?
I develop new products for my own company a 2 or 3 times a year. I am OK at plastic and metal fabrication after many years of doing this, but a hand-made plastic case still looks hand-made to me. When I am beta testing or test marketing a short run of a new product, looking even slightly hand-made just doesn't cut it - at least for me. For my own personal stuff, I am OK with it, but not for my business.
One company I have used over the years, Polycase, in Avon, Ohio (polycase.com) does short-run case customization on their cases for a very reasonable rate. You can get quotes on their website - they are very up-front on their cost structure. For example, a small case (about 1" x 2" x 3/4") with three holes and a beveled LCD display cutout, cost me about $300 for 50 cases. This includes the cost of the case, the machining, and the setup fees. The results look like a custom injection mold. I have found that having this done saves me a lot of time and headache, and the results look like production work.
I understand this is not a real solution for a hobbyist, but it sounds like these will be prototypes for generating sales. A good impression on a prototype will directly translate into more sales and that makes this cost minimal. Also, knocking out 50 prototype cases using ANY method I might do by hand, takes valuable hours away from running the business, making sales, or inventing new products.
One company I have used over the years, Polycase, in Avon, Ohio (polycase.com) does short-run case customization on their cases for a very reasonable rate. You can get quotes on their website - they are very up-front on their cost structure. For example, a small case (about 1" x 2" x 3/4") with three holes and a beveled LCD display cutout, cost me about $300 for 50 cases. This includes the cost of the case, the machining, and the setup fees. The results look like a custom injection mold. I have found that having this done saves me a lot of time and headache, and the results look like production work.
I understand this is not a real solution for a hobbyist, but it sounds like these will be prototypes for generating sales. A good impression on a prototype will directly translate into more sales and that makes this cost minimal. Also, knocking out 50 prototype cases using ANY method I might do by hand, takes valuable hours away from running the business, making sales, or inventing new products.
Thanks, and I completely agree. This is a whole other topic, but I appreciate your comments. I am using polycase for the other "half" of this project by the way, but they have nothing of the size I need for the part I've uploaded, which is made by by BUD. That company may have a similar deal, but if not I'm sure there is a company somewhere that could do the drilling for me.
But back to your point. In the end the problems you are describing may do me in. The fact is, I'm out of work, and already having to be very cost conscious to get a small quantity out. I can't afford to make 50 pcs right now, so my best hand work will have to do. I'm banking on the fact that in the world of musicians, a unique product that there is a need for can still be sold, and that musicians appreciate that a small business won't have the resources of a big company. If not, I guess it will be a dead end for me. I won't settle for a hand made look either, so I hope I can at least learn to drill my holes straight.
As I mentioned in a previous post, its not just fabrication, but also labeling of controls, packaging, the list of things that each require another $300 to have professionally done. It's just out of my reach now. Maybe I need a couple of people to work with to share the load. But for now, all I have is me, and best work can do. Who knows... maybe it will be good enough, or at least good enough to attract an angel investor.
I confess I'm a much better engineer than a business guy. Perhaps I should be risking "it all" to get this done top shelf. I guess I don't have the stomach for that.
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