Drilling straight through aluminum square tube
I've worked with wood most of my life, but I'm not as experienced with
metals... I recently found that I have to do a project for work that involves drilling multiple holes through both sides of 3/4"x 3/4" and 1/16 thick square aluminum tube to make antennas. Imagine a TV antenna basically... There needs to be multiple matched holes along each tube, and into those holes, 1/4" solid round will be inserted through both sides. In other words, the holes on both sides of the tubing have to be aligned pretty darn well, otherwise a slight misalignment will translate to the 1/4" round being way off center by the time it gets to the end... Which is about 1-2 feet long. There will be a tad bit of wiggle room since the round will be attached by threads on the end, and a nuts on both sides of the square tube, but not a whole lot. I had no idea this would be so difficult. I went and got a Sears 9" bench drill press and proceeded by clamping the tube into a press vise. I figured once I had it lined up and centered, I could just slide the tube down for each hole... Wrong. There seems to be no rhyme or reason to how it turns out in the end. If both holes end up being centered on both sides, it seems to be luck more then anything. There seemed to be a lot of slop in the spindle on the drill, so I took that back and tried a Ryobi... Worse. The run-out on it was so bad, I could see it with the naked eye on just a 1/8" bit. When I rotated the bit 180 degrees and made an indentation, there was almost 1/32 of an inch space between the two. Ridiculous. I can't believe there isn't even a decent small bench press available nowadays, but that's a different story. I've tried using short bits, center punching first, not center punching, 1/16" pilot holes, a countersink for a starting point... Nothing works. I've actually had better luck just drilling with a hand drill, but that only works for the top hole... There's no chance at getting the alignment right with bottom hole by had. I tried one of those portable drill press stands, but it just wasn't precise enough. Is there some kind of a portable drill guide I could use with a bushing or something? I'm kind of lost at this point... Am I really trying to do something that can't be done without a mill? That's hard to believe. The actual physical aspects of the holes is good... Nice and clean. It's just the alignment I seem to have a problem with. I had no idea something that seemed so simple would give me such grief. I have a lot more respect for you metal heads now. Any ideas are welcome. Thanks, Dave |
Dave:
Since you are working with such a thin wall on your tubing, I would suggest trying a 1/4 inch end mill. You can chuck it up in your drill press since it is hardened, it may slip if it hangs, but if you get a center cutting one, it may resolve your problem. I would suggest a 4 flute end mill. If you can resolve the slop in the drill spindle, that would help. I drill a lot of 2 inch square tubing for trailer hitches. We use an annular cutter in a drill/mill. also, be sure you are not drilling thru the side where the seam is. It is hardened and thicker and will caouse drifting of your drill. |
Can you purchase a bushing block to stabilize the drill bit prior to it
hitting the tube? How many holes are we talking about for the whole project? 100, a million, etc. Joe - V#8013 - '86 VN750 - joe @ yunx .com Northern, NJ Ride a Motorcycle? Ask me about "The Ride" http://www.youthelate.com/the_ride.htm Born once - Die twice. Born twice - Die only once. Your choice... Have unwanted music CDs or DVDs of any type? I can use them for our charity. eMail me privately for details. Donation receipts available. My eBay Stuff: http://tinyurl.com/4hpnc wrote in message oups.com... I've worked with wood most of my life, but I'm not as experienced with metals... I recently found that I have to do a project for work that involves drilling multiple holes through both sides of 3/4"x 3/4" and 1/16 thick square aluminum tube to make antennas. Imagine a TV antenna basically... There needs to be multiple matched holes along each tube, and into those holes, 1/4" solid round will be inserted through both sides. In other words, the holes on both sides of the tubing have to be aligned pretty darn well, otherwise a slight misalignment will translate to the 1/4" round being way off center by the time it gets to the end... Which is about 1-2 feet long. There will be a tad bit of wiggle room since the round will be attached by threads on the end, and a nuts on both sides of the square tube, but not a whole lot. I had no idea this would be so difficult. I went and got a Sears 9" bench drill press and proceeded by clamping the tube into a press vise. I figured once I had it lined up and centered, I could just slide the tube down for each hole... Wrong. There seems to be no rhyme or reason to how it turns out in the end. If both holes end up being centered on both sides, it seems to be luck more then anything. There seemed to be a lot of slop in the spindle on the drill, so I took that back and tried a Ryobi... Worse. The run-out on it was so bad, I could see it with the naked eye on just a 1/8" bit. When I rotated the bit 180 degrees and made an indentation, there was almost 1/32 of an inch space between the two. Ridiculous. I can't believe there isn't even a decent small bench press available nowadays, but that's a different story. I've tried using short bits, center punching first, not center punching, 1/16" pilot holes, a countersink for a starting point... Nothing works. I've actually had better luck just drilling with a hand drill, but that only works for the top hole... There's no chance at getting the alignment right with bottom hole by had. I tried one of those portable drill press stands, but it just wasn't precise enough. Is there some kind of a portable drill guide I could use with a bushing or something? I'm kind of lost at this point... Am I really trying to do something that can't be done without a mill? That's hard to believe. The actual physical aspects of the holes is good... Nice and clean. It's just the alignment I seem to have a problem with. I had no idea something that seemed so simple would give me such grief. I have a lot more respect for you metal heads now. Any ideas are welcome. Thanks, Dave |
Why not get ahold of the traffic department where you live, and ask
them about buying a length of the pole they use to mount road signs? Look around your neighborhood and you'll notice most of the traffic signs are mounted on a piece of square tube that has holes every inch on all four sides. It may be worth it to you to make some adjustments in your project, materials, etc., to not have to drill all those holes. Ronnie |
I'll bet that in addition to the drill chuck being junk, the table is
not square with the spindle. If you did this in a bridgeport, it would work fine, so it should in a good drill press. THink about finding a good quality used drill press. An old delta, rockwell or some other, with a real chuck and a sqare table. I really like ht esears drill presses, but I alway replace the chuck , usually with a taiwanese albrecht clone wrote: I've worked with wood most of my life, but I'm not as experienced with metals... I recently found that I have to do a project for work that involves drilling multiple holes through both sides of 3/4"x 3/4" and 1/16 thick square aluminum tube to make antennas. Imagine a TV antenna basically... There needs to be multiple matched holes along each tube, and into those holes, 1/4" solid round will be inserted through both sides. In other words, the holes on both sides of the tubing have to be aligned pretty darn well, otherwise a slight misalignment will translate to the 1/4" round being way off center by the time it gets to the end... Which is about 1-2 feet long. There will be a tad bit of wiggle room since the round will be attached by threads on the end, and a nuts on both sides of the square tube, but not a whole lot. I had no idea this would be so difficult. I went and got a Sears 9" bench drill press and proceeded by clamping the tube into a press vise. I figured once I had it lined up and centered, I could just slide the tube down for each hole... Wrong. There seems to be no rhyme or reason to how it turns out in the end. If both holes end up being centered on both sides, it seems to be luck more then anything. There seemed to be a lot of slop in the spindle on the drill, so I took that back and tried a Ryobi... Worse. The run-out on it was so bad, I could see it with the naked eye on just a 1/8" bit. When I rotated the bit 180 degrees and made an indentation, there was almost 1/32 of an inch space between the two. Ridiculous. I can't believe there isn't even a decent small bench press available nowadays, but that's a different story. I've tried using short bits, center punching first, not center punching, 1/16" pilot holes, a countersink for a starting point... Nothing works. I've actually had better luck just drilling with a hand drill, but that only works for the top hole... There's no chance at getting the alignment right with bottom hole by had. I tried one of those portable drill press stands, but it just wasn't precise enough. Is there some kind of a portable drill guide I could use with a bushing or something? I'm kind of lost at this point... Am I really trying to do something that can't be done without a mill? That's hard to believe. The actual physical aspects of the holes is good... Nice and clean. It's just the alignment I seem to have a problem with. I had no idea something that seemed so simple would give me such grief. I have a lot more respect for you metal heads now. Any ideas are welcome. Thanks, Dave |
It's tough to get better than about +/- 0.015" accuracy when locating
holes with a center punch and drill press. The slop in the quill bearings, chuck, table, and the starting point of the drill all add up pretty quick, as you found out. If you need better accuracy than that, you'll have to build a jig and spot-drill each hole before going in with the bigger bit. Of find a cheap milling machine -- almost anything will have better rigidity and accuracy than what you're using now. wrote: I had no idea this would be so difficult. I went and got a Sears 9" bench drill press and proceeded by clamping the tube into a press vise. I figured once I had it lined up and centered, I could just slide the tube down for each hole... Wrong. There seems to be no rhyme or reason to how it turns out in the end. If both holes end up being centered on both sides, it seems to be luck more then anything. There seemed to be a lot of slop in the spindle on the drill, so I took that back and tried a Ryobi... Worse. The run-out on it was so bad, I could see it with the naked eye on just a 1/8" bit. When I rotated the bit 180 degrees and made an indentation, there was almost 1/32 of an inch space between the two. Ridiculous. I can't believe there isn't even a decent small bench press available nowadays, but that's a different story. |
.... the holes on both sides of the tubing have to be
aligned pretty darn well, ... .... works for the top hole... There's no chance at getting the alignment right with bottom hole ... I must be missing something here. As I understand it, you need to have holes on opposite sides of the tube aligned. It seems obvious that you would just start at the top and continue through the other side. That it seems so obvious is why I think that I must be missing something. What is it? The other part is how the series of holes down the length of the tube are aligned. There are 2 parts: how far apart they are and how closely they are to a straight line. You need to quantify both of these. E.g., they have to be 1" apart +- 1/32 and they need to be within a 1/32 of a line. A 1/32 was just an example, but your being a woodworker and not having much metalworking experience, 1/32 would be a realistic goal. If it needs to be much better than that, you'll probably need some help. If 1/32 is good enough, a simple jig should get you there. Let us know and I'll go into it more. Bob BTW - you're in luck using aluminum - it works more like wood than it does steel. |
On 29 Jan 2005 10:02:00 -0800, the inscrutable "Ronnie"
spake: Why not get ahold of the traffic department where you live, and ask them about buying a length of the pole they use to mount road signs? Look around your neighborhood and you'll notice most of the traffic signs are mounted on a piece of square tube that has holes every inch on all four sides. It may be worth it to you to make some adjustments in your project, materials, etc., to not have to drill all those holes. Ronnie Has anyone here EVER successfully purchased anything from "the city" or "the county"? All I've ever heard was "We're not set up to do that." Of course, I haven't tried the "bribing the lone workman with cold beverages ploy" yet, either. ================================================== ====== TANSTAAFL: There ain't no such thing as a free lunch. http://diversify.com Gourmet Web Applications ========================== |
|
On Sat, 29 Jan 2005 19:54:54 -0800, Larry Jaques
wrote: On 29 Jan 2005 10:02:00 -0800, the inscrutable "Ronnie" spake: Why not get ahold of the traffic department where you live, and ask them about buying a length of the pole they use to mount road signs? Look around your neighborhood and you'll notice most of the traffic signs are mounted on a piece of square tube that has holes every inch on all four sides. It may be worth it to you to make some adjustments in your project, materials, etc., to not have to drill all those holes. Ronnie Has anyone here EVER successfully purchased anything from "the city" or "the county"? All I've ever heard was "We're not set up to do that." Of course, I haven't tried the "bribing the lone workman with cold beverages ploy" yet, either. ================================================= ======= TANSTAAFL: There ain't no such thing as a free lunch. http://diversify.com Gourmet Web Applications ========================== Purchase? No. But a lot of the time the workmen will give you small stuff for free. Ask in the yard, not the front office. --RC "Sometimes history doesn't repeat itself. It just yells 'can't you remember anything I've told you?' and lets fly with a club. -- John W. Cambell Jr. |
It is a no brainier if the tube was centered under the drill.
If it is not - then a slight off center hole through the wall wouldn't show up as defective as much. Seems if that is the issue - maybe drill through isn't possible - then a JIG is the way again - drill one side as needed. Now have a jig with a pin. the jig holds the tube firmly and the pin slides into the hole with a sliding fit. Just have the pin centered under the drill and you are set. Martin Bob Engelhardt wrote: ... the holes on both sides of the tubing have to be aligned pretty darn well, ... ... works for the top hole... There's no chance at getting the alignment right with bottom hole ... I must be missing something here. As I understand it, you need to have holes on opposite sides of the tube aligned. It seems obvious that you would just start at the top and continue through the other side. That it seems so obvious is why I think that I must be missing something. What is it? The other part is how the series of holes down the length of the tube are aligned. There are 2 parts: how far apart they are and how closely they are to a straight line. You need to quantify both of these. E.g., they have to be 1" apart +- 1/32 and they need to be within a 1/32 of a line. A 1/32 was just an example, but your being a woodworker and not having much metalworking experience, 1/32 would be a realistic goal. If it needs to be much better than that, you'll probably need some help. If 1/32 is good enough, a simple jig should get you there. Let us know and I'll go into it more. Bob BTW - you're in luck using aluminum - it works more like wood than it does steel. -- Martin Eastburn, Barbara Eastburn @ home at Lion's Lair with our computer NRA LOH, NRA Life NRA Second Amendment Task Force Charter Founder |
Has anyone here EVER successfully purchased anything from "the city"
or "the county"? All I've ever heard was "We're not set up to do that." Of course, I haven't tried the "bribing the lone workman with cold beverages ploy" yet, either. Purchased, no... But I've got friends there and I've acquired some decomissioned stuff for the price of a question... Regards, Joe Agro, Jr. http://www.autodrill.com http://www.multi-spindle-heads.com V8013 My eBay: http://tinyurl.com/3n8gj |
Those are all good suggestions guys, thanks. As to the idea of the
table being off square, that was the first thing I checked. So it wasn't that. But I did end up building a jig as suggested, and it helps a lot. But as a side note... I noticed Harbor Freight had it's little press on sale for a ridiculous 39.95 this week. I had absolutely no expectations, since I tried two presses that were more, with poor results. But I figured for $39.95, what did I have to lose. If it didn't work, I was going to give it to a friend... Well, guess what... Not only is it better quality then the two over $100 presses I tried, but it seems to drill straight. Go figure. Maybe I just had bad luck with the others. Thanks for the help, Dave |
wrote: I've worked with wood most of my life, but I'm not as experienced with metals... I recently found that I have to do a project for work that involves drilling multiple holes through both sides of 3/4"x 3/4" and 1/16 thick square aluminum tube to make antennas. Imagine a TV antenna basically... There needs to be multiple matched holes along each tube, and into those holes, 1/4" solid round will be inserted through both sides. In other words, the holes on both sides of the tubing have to be aligned pretty darn well, otherwise a slight misalignment will translate to the 1/4" round being way off center by the time it gets to the end... Which is about 1-2 feet long. There will be a tad bit of wiggle room since the round will be attached by threads on the end, and a nuts on both sides of the square tube, but not a whole lot. much snippage Dave Since you work with wood, do you happen to have one of those self-centering dowling jigs? Like this: http://www.woodcraft.com/family.aspx?familyid=782 Mine's a lot older and uses cast clamping jaws instead of extrusions, but I use it periodically for putting in centered cross-holes where a drill press would be hard to use. If you've got one, give it a whirl. Try those piloted sheetmetal bits, too("Bullet bits"). Spacing your holes might be a problem, but not unsolvable. Stan |
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