Cutting Holes
Greenlee punches are a good bet. However, they need to be sharp to work well, especially in sticky metals such as some aluminum alloys. It also helps to put some heavy machine oil on the threads and under the drive bolt's head. I prefer to use 6061 or 2024 alloys, as they machine well.
I have a access to Bridgeport vertical mill with a Criterion boring head which can be adjusted over a continuous range of diameters. This approach gives the best results, although setting things up takes a bit of time. It is easy to get perfectly round holes with tolerances to to a few mils.
Greenlee punches are a good bet. However, they need to be sharp to work well, especially in sticky metals such as some aluminum alloys. It also helps to put some heavy machine oil on the threads and under the drive bolt's head. I prefer to use 6061 or 2024 alloys, as they machine well.
I have a access to Bridgeport vertical mill with a Criterion boring head which can be adjusted over a continuous range of diameters. This approach gives the best results, although setting things up takes a bit of time. It is easy to get perfectly round holes with tolerances to to a few mils.
In the end the simplest, cheapest, and simply intelligent idea of printing it on paper, taping it over the plate, and using this as a template seems to me the way to go on the cheap. Thanks for that simple but brilliant idea!
Only one mention of stepped bits? That's all I use in a drill press (mandatory)with clamps (double-mandatory). I have 2, one English from 1/8" to 7/8" and a big metric to 35mm. These work equally well in aluminum or steel w/o lube but bigger holes require some up and down just as though they were Forstner bits in wood.
For the really big capacitor holes I use hole saws by Rigid but only in aluminum.
My trick for perfect placement off a paper template is to use the aforementioned spring-loaded punch by Proxxon, wonderful gadget, then a 1/8" hole with a hand-held drill, finally the drill press.
Radial vent holes laid out by hand aren't all that difficult. After the 1/8" hole is drilled just bisect the circle with a line drawn through it, then another at 90 degrees. Anyone can use the mark One Eyeball to halve those sections until you get to eighths and you're done.
For the really big capacitor holes I use hole saws by Rigid but only in aluminum.
My trick for perfect placement off a paper template is to use the aforementioned spring-loaded punch by Proxxon, wonderful gadget, then a 1/8" hole with a hand-held drill, finally the drill press.
Radial vent holes laid out by hand aren't all that difficult. After the 1/8" hole is drilled just bisect the circle with a line drawn through it, then another at 90 degrees. Anyone can use the mark One Eyeball to halve those sections until you get to eighths and you're done.
An externally hosted image should be here but it was not working when we last tested it.
I wish I had a nice set of punches: especially some of the odd shapes on the Mouser page. Life would be better had I not put my binding posts with D shaped mounts into round holes. I was just too lazy to cut it with the jeweler's saw.
I greatly enjoy my step drills. The make a good deal less mess (burr) to clean up than my standard drills. I recently needed accurate 1 3/16" holes for some octal sockets. I had good luck with a 1 1/8" wood bit, followed by a 1 1/8" dowel wrapped in good sandpaper. Clean, round, perfectly sized holes.
I cover the panel in wide masking tape, then draw the cutouts and holes. The tape won't tear or move like paper. It also protects the panel from scratches and marks. I use a little punch to make a divot for each hole, followed in most cases by a small drill and then to size. It works well in thin panels, not as well in thick ones. I wish I had a drill press, but then I'd have to move it around with me!
Paul
Wild Burro Audio Labs - DIY Full Range Speakers
I greatly enjoy my step drills. The make a good deal less mess (burr) to clean up than my standard drills. I recently needed accurate 1 3/16" holes for some octal sockets. I had good luck with a 1 1/8" wood bit, followed by a 1 1/8" dowel wrapped in good sandpaper. Clean, round, perfectly sized holes.
I cover the panel in wide masking tape, then draw the cutouts and holes. The tape won't tear or move like paper. It also protects the panel from scratches and marks. I use a little punch to make a divot for each hole, followed in most cases by a small drill and then to size. It works well in thin panels, not as well in thick ones. I wish I had a drill press, but then I'd have to move it around with me!
Paul
Wild Burro Audio Labs - DIY Full Range Speakers
Here's my $.02
A Bridgeport is nice but if you don't need ~.001 inch accuracy it will take more time to set up and locate each hole than a center punch, drill press, and clamps. Cutting speed will not be much advantage. If you can't get within a few thou with your hand tools then it's probably best to send it out. For rectangular holes the mill rocks, but if it's only 1 or 2 small holes it will still take more time than a saw and file.
I like to attach a large piece of 3/4" MDF sheet (18"x24") to the drill press table for working top plates. It gives a nice big stable surface and something to clamp to and drill into if you accidentally go too far. I also sometimes attach a 1/4" MDF or masonite sheet to the top plate being worked as a drill backer. These can be reused when painting...
If you clamp the work when drilling the drilled holes will be round. If you don't clamp the work, the holes will be triangular ;-)
Step bits need something behind the work to push against. I use a wood block behind each hole. These can be reused for several holes before they go into the woodstove. You can pre-drill the block or just let the step bit do it.
Aluminum:
Step bits are the way for aluminum. The adjustable-radius single point tool is great also but it requires patience and a heavy duty drill press. Punches actually don't work as well on aluminum for me; they distort the metal around the hole. Other woodworking tools e.g. spade bits, forstners, etc. will do the job but are suboptimal. WD-40 is an OK cutting lubricant/coolant for aluminum; so is a detergent solution but will rust your iron tools. Special purpose cutting fluids are available in oil and water base.
Steel:
Punches work better for steel. Step bits will work well also but need lots of lubricant/coolant and they make a lot of heat and nasty swarf on steel. Heavy cutting oil, marvel mystery oil, or special purpose water base cutting fluid are best on steel; WD40 is better than nothing.
Vent holes:
All you need is some patience. I lay mine out with a compass for the circle and a 30/60 triangle for 30 degree spacing (12 holes). I make a 1:1 sketch first to determine the best size and spacing.
Layout with paper, sticky paper, tape, etc:
I never have had much success with this method, what with all the cutting oil and handling involved. The accuracy is much better using a sharp scriber right on the metal. Layout fluid ("prussian blue") is sometimes useful if the metal is hard or has a scratchy surface.
Templates:
This is a great way to go for repeated patterns. There are ready-made pre-hardened drill bushings available way way cheaper than you can make them. Check any machine supply house (Enco has them).
A Bridgeport is nice but if you don't need ~.001 inch accuracy it will take more time to set up and locate each hole than a center punch, drill press, and clamps. Cutting speed will not be much advantage. If you can't get within a few thou with your hand tools then it's probably best to send it out. For rectangular holes the mill rocks, but if it's only 1 or 2 small holes it will still take more time than a saw and file.
I like to attach a large piece of 3/4" MDF sheet (18"x24") to the drill press table for working top plates. It gives a nice big stable surface and something to clamp to and drill into if you accidentally go too far. I also sometimes attach a 1/4" MDF or masonite sheet to the top plate being worked as a drill backer. These can be reused when painting...
If you clamp the work when drilling the drilled holes will be round. If you don't clamp the work, the holes will be triangular ;-)
Step bits need something behind the work to push against. I use a wood block behind each hole. These can be reused for several holes before they go into the woodstove. You can pre-drill the block or just let the step bit do it.
Aluminum:
Step bits are the way for aluminum. The adjustable-radius single point tool is great also but it requires patience and a heavy duty drill press. Punches actually don't work as well on aluminum for me; they distort the metal around the hole. Other woodworking tools e.g. spade bits, forstners, etc. will do the job but are suboptimal. WD-40 is an OK cutting lubricant/coolant for aluminum; so is a detergent solution but will rust your iron tools. Special purpose cutting fluids are available in oil and water base.
Steel:
Punches work better for steel. Step bits will work well also but need lots of lubricant/coolant and they make a lot of heat and nasty swarf on steel. Heavy cutting oil, marvel mystery oil, or special purpose water base cutting fluid are best on steel; WD40 is better than nothing.
Vent holes:
All you need is some patience. I lay mine out with a compass for the circle and a 30/60 triangle for 30 degree spacing (12 holes). I make a 1:1 sketch first to determine the best size and spacing.
Layout with paper, sticky paper, tape, etc:
I never have had much success with this method, what with all the cutting oil and handling involved. The accuracy is much better using a sharp scriber right on the metal. Layout fluid ("prussian blue") is sometimes useful if the metal is hard or has a scratchy surface.
Templates:
This is a great way to go for repeated patterns. There are ready-made pre-hardened drill bushings available way way cheaper than you can make them. Check any machine supply house (Enco has them).
- Status
- Not open for further replies.