For aligning a variety of holes to match PCB placements and the like try using a simple cad program or even Paint on your computer to make a template. Make it to scale then print it out on a sheet of paper. Cut the image out and tape it to the surface you want to drill with all the little holes, switch cutouts etc where you want them and tape the paper template in place with clear tape. Use a pin punch or even a needle if you really want accuracy and put a small mark through the centers of the images that you need holes for. If the template is drawn and placed accurately you get perfect fits.
By printing my PCB silk screens and cutting the paper to shape I get an exact image of a PCB that I can line up and attach to the outside of an enclosure or fit inside where the real PCB will go. This is how I lay out for PCB mounted LED's, switches, wire holes, connectors etc. that have to line up with holes in the enclosure. It's also a great way to proof your design. I often populate the paper PCB with real components and place it in the enclosure to confirm fits and test for interference problems.
By printing my PCB silk screens and cutting the paper to shape I get an exact image of a PCB that I can line up and attach to the outside of an enclosure or fit inside where the real PCB will go. This is how I lay out for PCB mounted LED's, switches, wire holes, connectors etc. that have to line up with holes in the enclosure. It's also a great way to proof your design. I often populate the paper PCB with real components and place it in the enclosure to confirm fits and test for interference problems.
Hi Copper Dog.
What you post is fine and the standard way to do this, and what the OP already tried, even using the PCB itself as a drilling guide, but for some reason it has not worked for him.
I suspect at least one factor has been his use of a very high speed drill, which in my opinion will rather melt plastic than simply cut its way in.
What you post is fine and the standard way to do this, and what the OP already tried, even using the PCB itself as a drilling guide, but for some reason it has not worked for him.
I suspect at least one factor has been his use of a very high speed drill, which in my opinion will rather melt plastic than simply cut its way in.
You're right. I missed that part of his post. Ha ha, disregard the superfluous information there Peter. When I reread the thread my first thought was excessive feed rate and/or incorrect drill speeds. A feed rate that's to fast for the speed will run the bit out like that. As a rule, the smaller the bit the faster the drill speed.
JM Fahey... no it didn't work for me, but I wasn't doing exactly what Copper dog suggested. I was using an actual PC board mounted to the inside, on 1/4" standoffs, with a very thin drill.
Copper Dog... I think thats a great idea, because I'm thinking that way too now
Look at my original post where I uploaded a picture of the box, and notice the square recessed area the box has for a label. Now look at the label / face plate I'm working on, attached here. Its not a final, but it illustrates the point, You can see where each hole for each button or control has both an outline (so I know where to punch an opening), and a center guide. So in addition to trying again using the PCB as a guide, this time clamped right up against the outside of the box, I'm also planning to try your approach, using my faceplate template to mark and pre punch my drill locations. And yes, by the way, I did make this faceplate by starting with a "to-scale" image of the silk screen layer of the PCB itself, so it must be exactly correct!
Copper Dog... I think thats a great idea, because I'm thinking that way too now
Look at my original post where I uploaded a picture of the box, and notice the square recessed area the box has for a label. Now look at the label / face plate I'm working on, attached here. Its not a final, but it illustrates the point, You can see where each hole for each button or control has both an outline (so I know where to punch an opening), and a center guide. So in addition to trying again using the PCB as a guide, this time clamped right up against the outside of the box, I'm also planning to try your approach, using my faceplate template to mark and pre punch my drill locations. And yes, by the way, I did make this faceplate by starting with a "to-scale" image of the silk screen layer of the PCB itself, so it must be exactly correct! Attachments
I've always found drilling through a guide to be problematic. It's nearly impossible to tell if the drill is starting correctly.
Fit the label inside the box facing the same way the PCB would face to make sure there aren't any interference issues when the real PCB goes in. This will also let you see how much clearance you have around the board. Some clearance will allow for minor placement errors with the template. Then if everything is ok secure the label to the box face in the proper position and gently pin punch the drill centres for each hole. Remove the label and check the hole line with a straight edge before drilling. Do not drill through your label you may need it nor I would recommend drilling through the PCB as a guide. It rarely works and if you have plated through holes it may destroy them.
Feed rate is everything in drilling. Test drill some scrap plastic to get it right. Support the the back side to prevent chipping and reduce the feed rate when the drill gets close to exiting. Another pointer is the pilot hole. If you are using a pilot drill make sure it isn't to big because this causes the next drill to grab unevenly and run out. Again there's nothing like test drilling to get this stuff right. I test drill a lot.
When you're ready to drill stop and have a cup of tea first. It always looks different when you come back. That's when I catch most of my own errors. One last thing; drills are ground to suit the material they're meant to be used in. Twist drills ground for plastic cutting are available and the best choice if you do a lot of it.
If this works out for you I'd love to see the result.
Fit the label inside the box facing the same way the PCB would face to make sure there aren't any interference issues when the real PCB goes in. This will also let you see how much clearance you have around the board. Some clearance will allow for minor placement errors with the template. Then if everything is ok secure the label to the box face in the proper position and gently pin punch the drill centres for each hole. Remove the label and check the hole line with a straight edge before drilling. Do not drill through your label you may need it nor I would recommend drilling through the PCB as a guide. It rarely works and if you have plated through holes it may destroy them.
Feed rate is everything in drilling. Test drill some scrap plastic to get it right. Support the the back side to prevent chipping and reduce the feed rate when the drill gets close to exiting. Another pointer is the pilot hole. If you are using a pilot drill make sure it isn't to big because this causes the next drill to grab unevenly and run out. Again there's nothing like test drilling to get this stuff right. I test drill a lot.
When you're ready to drill stop and have a cup of tea first. It always looks different when you come back. That's when I catch most of my own errors. One last thing; drills are ground to suit the material they're meant to be used in. Twist drills ground for plastic cutting are available and the best choice if you do a lot of it.
If this works out for you I'd love to see the result.
Copper Dog: Well I just wanted to report that using a combination of methods and improved techniques I've gotten from you and several others here, I've been able to do a much better job on one case I had left. So now I'm going to go ahead and order some more cases and re-do them all. Thanks to everyone!!! What seemed like such a simple task was not as easy as it seemed, but now its something I can do repeatedly.
The only thing I don't feel good about in your advise is that I drill from the inside. I don't want to do that anymore, and believe its part of what got me in trouble the first time. Like you said, a pilot hole is best drilled small. But when the final hole is already small, that means I'm using a VERY small pilot. And if there is any bending of the small bit as it goes through the plastic, I'd rather do correcting on the inside rather than the outside where it's so obvious.
Good tip about putting something under the work too! A block of wood that the box fits over really made a difference, not so much because of the chipping when I exit, but to prevent errors due to the plastic itself bending ans you push through! I'd have never thought that could have been a problem, until I looked at all my failed attempts, and noticed an odd "bowing", where the holes were following a slight curve. When I realized that there was less flexing of the plastic near the edges (where the sides offered support), it was an "ah-ha" moment!
Something else too. Yes, I do drill plastic quite often, but never realized there was a such thing as drills specifically made for plastic! If you have a product recommendation there I'd like to see a link!!!
Thanks again. As soon as I get my new cases, I will post a nice close up of something I can show with maximum pride!
The only thing I don't feel good about in your advise is that I drill from the inside. I don't want to do that anymore, and believe its part of what got me in trouble the first time. Like you said, a pilot hole is best drilled small. But when the final hole is already small, that means I'm using a VERY small pilot. And if there is any bending of the small bit as it goes through the plastic, I'd rather do correcting on the inside rather than the outside where it's so obvious.
Good tip about putting something under the work too! A block of wood that the box fits over really made a difference, not so much because of the chipping when I exit, but to prevent errors due to the plastic itself bending ans you push through! I'd have never thought that could have been a problem, until I looked at all my failed attempts, and noticed an odd "bowing", where the holes were following a slight curve. When I realized that there was less flexing of the plastic near the edges (where the sides offered support), it was an "ah-ha" moment!
Something else too. Yes, I do drill plastic quite often, but never realized there was a such thing as drills specifically made for plastic! If you have a product recommendation there I'd like to see a link!!!
Thanks again. As soon as I get my new cases, I will post a nice close up of something I can show with maximum pride!
The only thing I don't feel good about in your advise is that I drill from the inside.
Sorry about that Peter. I re-read it and see how it can be interpeted that way. I didn't mean for you to drill from the inside. I was suggesting you use the template inside to check for PCB interference problems and then attach the template on the outside to make the hole marks. I agree with you 100 % that drilling from the inside is difficult.
I'm very glad you got some use from the comments posted here. Again, try to post the results when you can.
Hi,
A pilot hole is not best drilled small at all. It is what is is and the bigger
the better up to a certain point, the best accuracy. Depending on the
control of the initial and final hole and direction it may be bigger.
FWIW drills basically come in wood and high speed steel varieties.
(We are clearly not discussing masonry hammer drills here, )
You don't need HSS for plastic, but basically not the speed, HSS
does wood and plastic at lower speeds just as well as the others.
A wood drill into steel is a exercise in futility.
Can't see the problem with good pilots from the inside and then
drilling the final from the outside, and then manually using a big
drill clean up both sides of the hole, i.e. adding slight bevels.
rgds, sreten.
A pilot hole is not best drilled small at all. It is what is is and the bigger
the better up to a certain point, the best accuracy. Depending on the
control of the initial and final hole and direction it may be bigger.
FWIW drills basically come in wood and high speed steel varieties.
(We are clearly not discussing masonry hammer drills here,
)You don't need HSS for plastic, but basically not the speed, HSS
does wood and plastic at lower speeds just as well as the others.
A wood drill into steel is a exercise in futility.
Can't see the problem with good pilots from the inside and then
drilling the final from the outside, and then manually using a big
drill clean up both sides of the hole, i.e. adding slight bevels.
rgds, sreten.
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The drill "starting right" shouldn't be an issue unless the work isn't center punched and spotted first. Good light is essential and some of us have to use magnifier. Some old time tricks from manual machining days get lost over time. One is to grind your center punch with what they called a "bright point". Instead of holding the punch parallel to the grinder axis and rotating it to get circular rings, point it straight up in the air so the grinding lines start at the point and go down the body. That lights up the point much better in use. Any tilt or bowing of the surface will cause the drill to walk sideways, so support is essential. That's often a problem with electronic chassis work and it's worth it to rig up some wood supports to get right under the work, rather than relying on other lips and edges. If you Google "center drill" you'll see what those look like. To spot for drilling you only go in a little ways- don't bury the thing. So, mark (or use a printed template), center punch, check punch mark for location and fix if necessary (hit at angle), center drill, drill. I rarely do pilot holes if I'm working under 3/16". Very soft plastics are a problem because the drill wants to drag itself in. Dub or use a special drill.
sreten: I was having the proverbial "perfect storm" of errors (or maybe comedy of errors). Drilling my pilot holes with a tiny bit, because the final hole is only about 130 mills (sorry... doin't PC boards makes me measure everything in mills ). So a tiny bit can tend to bend as it pushes through the plastic. Thats especially true if you drill too fasty, which i did because you can't feel much resistance with a tiny bit. then, the PBCcontaining the guide holes was being mounted on standoffs, and was not flush against the inside (the result of the sides being tapered, so that the PCB only fit up to a certain depth) So, that made for even more opportunity for the drilling to drift. I could go on but I'd be repeating stuff I already explained ( post has gone on a while).
So taking everything I've heard here into account, I'd done much better already. A lot of my problem was all wrapped up in my continued asserting this as a "simple" task. In other words, I wasn't respecting the task and the preparation necessary, and so was getting a very UN-respectable result. ;-)
Now I did pretty good this time using that same very thin (about 40 mil) pilot hole bit, and did use the PCB (with its 42 mil guide holes) to start. But, I mounted it it up against the OUTSIDE, with NO spacers, a solid block of wood behind it, and I fed much slower. The guide holes looked perfect, and I followed up with the larger bit. My only goof was on the very last hole (of course) where I stopped holding the work firmly down when i withdrew the bit, so that it grabbed a little. But still, 1000% better.
I am curious now though as there seems to be a disagreement about pilot holes being better off small. Not trying to start an argument between the experts here, but there must be some reasoning behind each philosophy. I mean, I assume if a programmable automated machine was doing this, there would not be any guide holes done at all in a soft material like plastic right? So guide holes have to be an aid to use mortal humans. So other than the issue of a thinner bit having a tendency to bend, what is the downside of drilling a smaller initial guide hole?
). So a tiny bit can tend to bend as it pushes through the plastic. Thats especially true if you drill too fasty, which i did because you can't feel much resistance with a tiny bit. then, the PBCcontaining the guide holes was being mounted on standoffs, and was not flush against the inside (the result of the sides being tapered, so that the PCB only fit up to a certain depth) So, that made for even more opportunity for the drilling to drift. I could go on but I'd be repeating stuff I already explained ( post has gone on a while). So taking everything I've heard here into account, I'd done much better already. A lot of my problem was all wrapped up in my continued asserting this as a "simple" task. In other words, I wasn't respecting the task and the preparation necessary, and so was getting a very UN-respectable result. ;-)
Now I did pretty good this time using that same very thin (about 40 mil) pilot hole bit, and did use the PCB (with its 42 mil guide holes) to start. But, I mounted it it up against the OUTSIDE, with NO spacers, a solid block of wood behind it, and I fed much slower. The guide holes looked perfect, and I followed up with the larger bit. My only goof was on the very last hole (of course) where I stopped holding the work firmly down when i withdrew the bit, so that it grabbed a little. But still, 1000% better.
I am curious now though as there seems to be a disagreement about pilot holes being better off small. Not trying to start an argument between the experts here, but there must be some reasoning behind each philosophy. I mean, I assume if a programmable automated machine was doing this, there would not be any guide holes done at all in a soft material like plastic right? So guide holes have to be an aid to use mortal humans. So other than the issue of a thinner bit having a tendency to bend, what is the downside of drilling a smaller initial guide hole?
Conrad: Yep! I definitely learned my lesson about making sure I have support behind the work! But listening to your discussion, I don't feel so bad, because you've described the common mistakes, and I happen to have pretty much made them all. That was forgivable perhaps. But real anger in my original post was really because of my own stupid pressing on, with the same bad technique that obviously wasn't working, expecting a different result. Live and learn!
Center drills definitely sound interesting.
But listening to your discussion, I don't feel so bad, because you've described the common mistakes, and I happen to have pretty much made them all. That was forgivable perhaps. But real anger in my original post was really because of my own stupid pressing on, with the same bad technique that obviously wasn't working, expecting a different result. Live and learn!Center drills definitely sound interesting.
Hi,
Consider using a very accurate reamer to finish off a hole.
The piece must be held flat and the reamer held vertical.
But F/B & L/R ? You want the reamer to correct errors
by clamping and aligning it F/B and L/R? It only can by
bending somewhat, so for the straightest vertical hole
the reamer has to to be free self centering on the pilot
hole, which is barely less than the size of the reamer.
Still the straightness of of the hole will depend on the pilot.
Inaccuracy propogates, and assuming your using a press
drill that is vertical with a flat bed free F/B and L/R draw
your own conclusions about the the size and way the
pilot holes are drilled and the size they have.
I wouldn't have a problem with a MDF template that
just fits over the box and you just drill the holes,
outside to in and clean them up.
The problem transfers to making the template.
rgds, sreten.
Consider using a very accurate reamer to finish off a hole.
The piece must be held flat and the reamer held vertical.
But F/B & L/R ? You want the reamer to correct errors
by clamping and aligning it F/B and L/R? It only can by
bending somewhat, so for the straightest vertical hole
the reamer has to to be free self centering on the pilot
hole, which is barely less than the size of the reamer.
Still the straightness of of the hole will depend on the pilot.
Inaccuracy propogates, and assuming your using a press
drill that is vertical with a flat bed free F/B and L/R draw
your own conclusions about the the size and way the
pilot holes are drilled and the size they have.
I wouldn't have a problem with a MDF template that
just fits over the box and you just drill the holes,
outside to in and clean them up.
The problem transfers to making the template.
rgds, sreten.
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yeah, as others have said, a brad point bit in the drill press is great for soft materials. I've had troubles getting holes in a straight line also, but it takes a lot of patience to get it right, and I started using pilot holes and really good jobber bits with good results so far. Of course, I center punch first, then pilot drill, then final drill. It's time consuming but it works better. Of course, I de-burr the holes afterwards.
Conrad: Yep! I definitely learned my lesson about making sure I have support behind the work!
Center drills definitely sound interesting.
Yes, a fresh piece of wood works well to support the work while drilling.
The pilot hole has to be large enough for you to be able to center the final bit size in the hole. Too small relative to the final drill size, and you can tell if the point is exactly in the middle of the pilot hole. Too big and you might as well just use the final drill size. So, I guess about half or a little less the final drill size is fine.
Your problem seems to be more around really thin bits bending. As someone said before, you have to go really slow with the feed to prevent that.
I think the only way I'm going to really know how well these brad point bits will work is to get a few and try it. Everything I've read online about these refer to their use for wood. To look at them, that little point in the center seems like a no-brainer, and a very good idea. I'm not having much luck finding them in sizes below 1/8", but 1/8 (125 mills ) might just work. At least one poster mentioned that using wood bits for plastic is an exercise in futility. But as I've often contemplated writing a book by that title (exercises in futility by ME!) , I guess i should at least try it! ;-)
Also, an unrelated but interesting update. It looks like all the pieces I originally cut so badly might be salvageable after all, now that I've gotten to the labeling! I was experimenting with the idea of making a label that fit into the entire top recessed area of the box, and I found some really good products at onlinelabels.com. I had posted the proposed label I was working on several posts back, but never would have thought they looked so amazingly good when actually printed onto the adhesive backed Inkjet label products I'd gotten some samples of (onlionelabels is REALLY good about samples!). So, using a leather punch, I punched out all the holes in the label (which I did surprisingly well compared to my drilling escapades!). Well these holes are small enough so that the punched label, once placed, pretty much acts like a faceplate, correcting and hiding all my sins! Of course I'm VERY glad I've finally learned to drill aligned holes. But its nice when you have one of those times when things actually work out in the end!
Also, an unrelated but interesting update. It looks like all the pieces I originally cut so badly might be salvageable after all, now that I've gotten to the labeling! I was experimenting with the idea of making a label that fit into the entire top recessed area of the box, and I found some really good products at onlinelabels.com. I had posted the proposed label I was working on several posts back, but never would have thought they looked so amazingly good when actually printed onto the adhesive backed Inkjet label products I'd gotten some samples of (onlionelabels is REALLY good about samples!). So, using a leather punch, I punched out all the holes in the label (which I did surprisingly well compared to my drilling escapades!). Well these holes are small enough so that the punched label, once placed, pretty much acts like a faceplate, correcting and hiding all my sins! Of course I'm VERY glad I've finally learned to drill aligned holes. But its nice when you have one of those times when things actually work out in the end!
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