#61
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Bottle holder
On 5/23/2019 3:45 AM, John B. Slocomb wrote:
snip But before you start telling tall tales you should realize that when the hole is drilled it removes not only the center punch indentation itself but considerable (in reference to the size of the center punch dimple) material around the indentation. It is not the issue of the punch indentation remaining, it's the issue of using a spring-loaded punch on thin metal. But you probably wouldn't want to do this on very thin steel either. Bottom line is that as Jobst said, "I don't know many riders who believe that drilling a hole in a frame tube is a reasonable concept. I assume the rivnut was securely tightened and painted to prevent motion, corrosion and water intrusion." There's no reason to start drilling holes in a perfectly good frame. It sucks that the manufacturer didn't provide the bottle cage mounts at the time the frame was fabricated but there are many better ways of achieving the desired result of adding a bottle holder. |
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#62
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Bottle holder
On 5/23/2019 5:55 AM, AMuzi wrote:
On 5/23/2019 5:45 AM, John B. Slocomb wrote: snip Like door panels in cars, water always gets in. The key point of design is to vent the piece with drainhole(s). What percentage of frames still have drain holes in the bottom bracket? I see all sorts of posts on mountain bike forums about drilling drain holes in bottom brackets. Should we all be drilling drain holes in our bottom brackets if we ride in the rain? |
#63
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Bottle holder
On 5/23/2019 9:56 AM, sms wrote:
There is just no way that any course in machining would not teach about how to reduce stress concentration of holes drilled into metal. You might want to ask for a partial refund if that school is still in existence. SMS, will you please tell us about your personal training in machining? I ask because you seem to have quite few odd ideas about it. -- - Frank Krygowski |
#64
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Bottle holder
On 5/23/2019 12:53 AM, Jeff Liebermann wrote:
On Thu, 23 May 2019 10:43:29 +0700, John B. Slocomb wrote: I would have to say, "But Why?" 1. With a drill guide, there's no need to center punch the frame tube or drill a pilot hole. Just clamp the jig to the tube, and drill. 2. Even with a pilot hole, keeping the drill bit from wandering is not easy. I'm rather bad at eyeballing an electric hand drill so that the bit is exactly perpendicular to the tube. 3. Because it's possible to do the drilling in my sleep, which is likely to be the case. 4. With an fully assembled bicycle (or frame), an off center hole, bad spacing between the Rivnuts, slip of the drill, or other alignment error, and much of the bicycle might be considered scrap metal. Best to build a proper jig and do it perfectly the first time. 5. Chances are good that one might be drilling holes in other frames for Rivnuts. It would therefore pay to build a jig to make it easier. After all it is only two holes about 7 cm apart. It is not, as they say, "Rocket Science". Not everyone has a machine shop or a machinists skills. Backyard mechanics are not known for their precision drilling. Best to give them a mechanical assist (i.e. a jig). Why not just mark the spot(s) for the holes on the frame and than just drill the holes? Even, if necessary, ding a bit of a mark on the tube with a center punch - I say that with a certain amount of caution, as I don't mean Whap It!, just a tiny little dimple, just enough to get the drill started. Then drill a pilot hole with, maybe a 1/16" drill, to make sure that the full size drill doesn't wander off the mark. Than just drill it. Sounds good, which brings me back to the previous problem. How is one going to rigidly clamp the frame to be able to drill the holes? However, that's now where the aforementioned procedure is going to screw up. What will happen is that both the center punch mark and pilot hole will probably be perfectly placed. What will fail is that the actual Rivnut hole drill will wander sideways if the drill is not perfectly perpendicular to the tubing. The drill needs some kind of clamping jig to keep it perpendicular. If it can't be done on a drill press or mill, then clamping a v-block and drill guide to the tube is a good substitute. You don't even have to be terribly accurate as all the bottle cages I've seen have at least one of the mounting holes elongated to fit even if the mounting holes in the frame aren't perfectly spaced. Remind me not to let you work on any of my bicycles. I think that, like many things, it's a question of benefits vs. detriments. A person with an average mechanic's skill who is going to Rivnut one water bottle cage - or even one per year - probably needn't bother buying such a jig. A person who routinely builds frames, or modifies them for customers, will probably recoup the cost of the jig in time savings after just a few frames. And the jig might be appropriate for the kind of person who thinks drilling two holes requires a fully equipped machine shop. It's a "safety inflation" way to do a simple job even safer! IOW, it's a nice "safety" addition to one's collection: bike helmet, day-glo vest, super-bright high-beam daytime running light headlight, nautical strobe beacon taillight, horizontal flippy flag, electric horn, etc. etc. etc. -- - Frank Krygowski |
#65
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Bottle holder
On 5/22/2019 11:56 PM, sms wrote:
Good idea to use this kind of tool to keep the bit straight and to prevent it from wandering, since you probably don't want to use a center punch on an aluminum frame. Why on earth would you not want to use a center punch before drilling an aluminum frame? (What was your machine shop training??) Also to achieve proper spacing. What do you suppose the tolerance is on that hole-to-hole spacing? Do you really think it's measured in thousandths of an inch? -- - Frank Krygowski |
#66
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Bottle holder
On 5/23/2019 1:16 AM, Jeff Liebermann wrote:
On Tue, 21 May 2019 21:21:12 -0400, Joy Beeson wrote: I'm puzzled by the comment that one could cut oneself on the metal strap. I've been scratched by various bike parts, but the hose clamps have never even thought about it. That would be me. What I did was cut off the loose end of the metal strap flush with the hole clamp body. The down tube paint was protected by a strip of hard rubber. Over a few months, the clamp and rubber strip decided to move. So I tightened the screw on the clamp, which then exposed the end of the metal strap from the clamp body. I had previously rounded the sharp corners, but did not deburr the cut end. The result was a rather messy, but fortunately not very deep, slice in my leg when I performed an unscheduled and graceless dismount. I cut the metal strap shorter to avoid a repeat performance, but did nothing with the exposed hex screw head, which produced a minor gouge in the same place on my leg about a year later. Sorry to jump context, but both of those boo-boos would have been registered in the Portland study of bike commuters, Hoffman et. al., "Bicycle Commuter Injury Prevention," Journal of Trauma, V. 69 No. 5 They took great pains to record _every_ injury, no matter how tiny, and used the results to say we need bike lanes everywhere. IOW: Scratched by your hose clamp? Oh, if only there were a bike lane!!! Back to the topic: I'm a big fan of deburring sharp edges. It takes only a few seconds with a fine grinding wheel or a hand file. -- - Frank Krygowski |
#67
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Bottle holder
On 5/23/2019 9:25 AM, sms wrote:
On 5/23/2019 5:55 AM, AMuzi wrote: On 5/23/2019 5:45 AM, John B. Slocomb wrote: snip Like door panels in cars, water always gets in. The key point of design is to vent the piece with drainhole(s). What percentage of frames still have drain holes in the bottom bracket? I see all sorts of posts on mountain bike forums about drilling drain holes in bottom brackets. Should we all be drilling drain holes in our bottom brackets if we ride in the rain? Rain? Condensation from outdoors to room temperature and back is enough. Drainholes would have avoided these: http://www.yellowjersey.org/coln14b.jpg If only the holes were drilled to actually vent instead of being small and blocked by the headset cups. I take a lot of frames apart and internal rust of any significance is rare, almost always in unvented frames. -- Andrew Muzi www.yellowjersey.org/ Open every day since 1 April, 1971 |
#68
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Bottle holder
On 23/05/2019 8:49 a.m., AMuzi wrote:
On 5/22/2019 10:56 PM, sms wrote: On 5/22/2019 7:59 PM, Jeff Liebermann wrote: snip Ok, I yield.* A V-block won't work on a finished bicycle frame.* I tend to think in terms of what can be done on a drill press or milling machine.* As you might suspect, I've never used Rivnuts on an a frame. Water Bottle Mount Drill Jig https://www.steintool.com/portfolio-items/water-bottle-mount-drill-jig/ snip Good idea to use this kind of tool to keep the bit straight and to prevent it from wandering, since you probably don't want to use a center punch on an aluminum frame. Also to achieve proper spacing. You could use this on a finished frame with a right-angle drill. One person wrote: "I found that a standard power drill was difficult to align on the cylindrical steel tube; the bit tended to drift around the tube. Even after I created a small pilot hole for each boss, the bigger drill bit shifted to the side a little. In the end, once the cage was bolted in place, I realized that one of the bosses was misaligned along its cylindrical axis. Fortunately, it wasn’t off by much, but it tweaked the alignment ever so slightly and caused the cage to twist." Of course if you do go the Rivnut route you also want to ensure that you seal everything so moisture can't get in since you won't be painting the frame afterward. "don't want to use a center punch on an aluminum frame." Why ever not? "drill bit shifted to the side a little." With a centerpunch dimple and a drill sharpened to be symmetric they don't walk. Much simpler to just make sure the bike has a couple of water bottle mounts when you buy it... |
#69
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Bottle holder
On Thursday, May 23, 2019 at 10:18:56 AM UTC-4, sms wrote:
On 5/23/2019 3:45 AM, John B. Slocomb wrote: snip But before you start telling tall tales you should realize that when the hole is drilled it removes not only the center punch indentation itself but considerable (in reference to the size of the center punch dimple) material around the indentation. It is not the issue of the punch indentation remaining, it's the issue of using a spring-loaded punch on thin metal. But you probably wouldn't want to do this on very thin steel either. Bottom line is that as Jobst said, "I don't know many riders who believe that drilling a hole in a frame tube is a reasonable concept. I assume the rivnut was securely tightened and painted to prevent motion, corrosion and water intrusion." There's no reason to start drilling holes in a perfectly good frame. It sucks that the manufacturer didn't provide the bottle cage mounts at the time the frame was fabricated but there are many better ways of achieving the desired result of adding a bottle holder. BULL****! Rivnuts are one of the simplest most elegant ways of adding mounts for bottle cages there is. Once installed a Rivnut looks just like a factory installation or even a brazed on bottle fitting. I can only assume from your posts that you do NOT know how to drill a simple hole in a bicycle tube nor do you know how easy it is to install a Rivnut in a hole in a bicycle tube. Cheers |
#70
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Bottle holder
On Thu, 23 May 2019 07:49:10 -0500, AMuzi wrote:
On 5/22/2019 10:56 PM, sms wrote: On 5/22/2019 7:59 PM, Jeff Liebermann wrote: snip Ok, I yield. A V-block won't work on a finished bicycle frame. I tend to think in terms of what can be done on a drill press or milling machine. As you might suspect, I've never used Rivnuts on an a frame. Water Bottle Mount Drill Jig https://www.steintool.com/portfolio-items/water-bottle-mount-drill-jig/ snip Good idea to use this kind of tool to keep the bit straight and to prevent it from wandering, since you probably don't want to use a center punch on an aluminum frame. Also to achieve proper spacing. You could use this on a finished frame with a right-angle drill. One person wrote: "I found that a standard power drill was difficult to align on the cylindrical steel tube; the bit tended to drift around the tube. Even after I created a small pilot hole for each boss, the bigger drill bit shifted to the side a little. In the end, once the cage was bolted in place, I realized that one of the bosses was misaligned along its cylindrical axis. Fortunately, it wasn’t off by much, but it tweaked the alignment ever so slightly and caused the cage to twist." Of course if you do go the Rivnut route you also want to ensure that you seal everything so moisture can't get in since you won't be painting the frame afterward. "don't want to use a center punch on an aluminum frame." Why ever not? "drill bit shifted to the side a little." With a centerpunch dimple and a drill sharpened to be symmetric they don't walk. Ah but... it sounds as though your shop can sharpen a drill bit, but from what I read here it is a very difficult task that only certain shops can accomplish :-) Perhaps the subject got an advert? We can sharpen a drill bit! -- Cheers, John B. |
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