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Metalworking (rec.crafts.metalworking) Discuss various aspects of working with metal, such as machining, welding, metal joining, screwing, casting, hardening/tempering, blacksmithing/forging, spinning and hammer work, sheet metal work. |
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#1
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Taper pin vs split pin
A taper pin is so much more work to use - is it that much better than a
split pin (aka spring pin)? Or, putting it another way, in what circumstances would a split/spring pin be inadequate and a taper pin be required? Thanks, Bob |
#2
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Taper pin vs split pin
On Jan 20, 8:06*am, Bob Engelhardt wrote:
A taper pin is so much more work to use - is it that much better than a split pin (aka spring pin)? *Or, putting it another way, in what circumstances would a split/spring pin be inadequate and a taper pin be required? Thanks, Bob One thing would be where you want your joint assembled in one position and one position only. Kind of hard assembling a taper pinned joint with the inner part 180 degrees out. Appearance would be another. For most things they used to use taper pins, though, a roll pin will work. Stan |
#3
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Taper pin vs split pin
When the operator was a hog for punishment?
Bob Swinney "Bob Engelhardt" wrote in message ... A taper pin is so much more work to use - is it that much better than a split pin (aka spring pin)? Or, putting it another way, in what circumstances would a split/spring pin be inadequate and a taper pin be required? Thanks, Bob |
#4
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Taper pin vs split pin
On Jan 20, 3:06*pm, Bob Engelhardt wrote:
A taper pin is so much more work to use - is it that much better than a split pin (aka spring pin)? *Or, putting it another way, in what circumstances would a split/spring pin be inadequate and a taper pin be required? Thanks, Bob A spring pin has obviously some spring in it. So where a control arm is secured to a shaft with a spring pin and the arm is moved in both directions, the spring pin will wallow out. A taper pin especially one with a threaded small end will not wallow out. See Cub Cadet steering arm as an example of a control arm secured with a spring pin. See Ebay for people selling taper pin replacements for the Cub Cadet. Dan |
#5
Posted to rec.crafts.metalworking
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Taper pin vs split pin
"Bob Engelhardt" wrote in message ... A taper pin is so much more work to use - is it that much better than a split pin (aka spring pin)? Or, putting it another way, in what circumstances would a split/spring pin be inadequate and a taper pin be required? Thanks, Bob Roll pins (spring pins) are made to keep things from falling apart. Taper pins are made for precisely locating parts relative to each other. For example, a roll pin might be used to hold a flexible joint onto a shaft. A taper pin (or pairs of them, actually) might be used to locate the sections of a multi-part stamping die on a common die plate. There has been some inappropriate use of taper pins in the past. Today, there is some inappropriate use of roll pins. Roll pins flex and have limited ability to locate. But their shear strength is adequate for many jobs that formerly depended upon straight pins. To get the big picture, you have to consider four kinds of pins. Straight pins are used like roll pins, only they're capable of handling much greater shear loads. They might be used to hold a drill chuck onto a spindle, in a light-duty application. To keep the pin from falling out and to prevent backlash, the pin might be a press fit into its hole. A roll pin is a cheaper way to accomplish the same thing, with much less shear strength but with an easier press fit. They've replaced straight pins in many production applications. A taper pin should not be used to hold things together, without some kind of clamping or other locating to hold them in place. A screw tapped alongside of the head of the taper pin, with the screw head overlapping the edge of the pin, is one way to accomplish this. In much tool work, the pins are not subject to strong shear loads so they may hold without a clamp. But they can slip out of their holes without a clamp. The fourth kind of pin is just a further illustration of what the taper pin is about. It's a tapered diamond pin. It only contacts the work along two lines, rather than a long the sides of a cone. It's used only for super-precision locating in gage work, and in making master tooling that's used only to qualify the production tooling. The idea is that you can't get perfect contact on each of any pair of tapered pins, but you can locate one tapered pin perfectly and then restrain motion relative to that pin by locking the part along two lines that lie on the radius of an arc from the tapered pin. I know, following that in words -- or my words -- can give you a headache. g If it's important, I'll try again. But the point is that there are two ends of the scale in terms of locating precision, and roll pins are at the low end. But roll pins stay in place and do the job well when all that's required is to keep parts from slipping apart. -- Ed Huntress |
#6
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Taper pin vs split pin
Ed Huntress wrote:
"Bob Engelhardt" wrote in message ... A taper pin is so much more work to use - is it that much better than a split pin (aka spring pin)? Or, putting it another way, in what circumstances would a split/spring pin be inadequate and a taper pin be required? Thanks, Bob Roll pins (spring pins) are made to keep things from falling apart. Taper pins are made for precisely locating parts relative to each other. For example, a roll pin might be used to hold a flexible joint onto a shaft. A taper pin (or pairs of them, actually) might be used to locate the sections of a multi-part stamping die on a common die plate. There has been some inappropriate use of taper pins in the past. Today, there is some inappropriate use of roll pins. Roll pins flex and have limited ability to locate. But their shear strength is adequate for many jobs that formerly depended upon straight pins. A taper pin in AL, subject to shock loads, will flex and batter the walls until failure. Not a pretty sight. |
#7
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Taper pin vs split pin
"Jim Stewart" wrote in message ... Ed Huntress wrote: "Bob Engelhardt" wrote in message ... A taper pin is so much more work to use - is it that much better than a split pin (aka spring pin)? Or, putting it another way, in what circumstances would a split/spring pin be inadequate and a taper pin be required? Thanks, Bob Roll pins (spring pins) are made to keep things from falling apart. Taper pins are made for precisely locating parts relative to each other. For example, a roll pin might be used to hold a flexible joint onto a shaft. A taper pin (or pairs of them, actually) might be used to locate the sections of a multi-part stamping die on a common die plate. There has been some inappropriate use of taper pins in the past. Today, there is some inappropriate use of roll pins. Roll pins flex and have limited ability to locate. But their shear strength is adequate for many jobs that formerly depended upon straight pins. A taper pin in AL, subject to shock loads, will flex and batter the walls until failure. Not a pretty sight. Sure. But that's not the pin's fault. That's an inappropriate use of a pin -- any kind of pin of that size. The problem there is that the material (aluminum) doesn't have sufficient compressive yield strength for the chosen fastener/locator: the pin. Since a steel pin has roughly 3X the stiffness (Young's Modulus) of the aluminum, and many times its strength, it's probably a case of the aluminum yielding locally. -- Ed Huntress |
#8
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Taper pin vs split pin
On Wed, 20 Jan 2010 10:06:41 -0500, Bob Engelhardt
wrote: A taper pin is so much more work to use - is it that much better than a split pin (aka spring pin)? Or, putting it another way, in what circumstances would a split/spring pin be inadequate and a taper pin be required? Thanks, Bob The hole was reamed with a taper? Gunner The current Democratic party has lost its ideological basis for existence. - It is NOT fiscally responsible. - It is NOT ethically honorable. - It has started wars based on lies. - It does not support the well-being of americans - only billionaires. - It has suppresed constitutional guaranteed liberties. - It has foisted a liar as president upon America. - It has violated US national sovereignty in trade treaties. - It has refused to enforce the national borders. ....It no longer has valid reasons to exist. Lorad474 |
#9
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Taper pin vs split pin
Old Cub Cadet garden tractors used to use split or "roll" pins in the
steering mechanism. The Torque applied to the place they were used caused the metal in the holes to wear, leaving the pin loose and causing an annoying amount of "slop" in the steering mechanism. A taper pin totally solves the problem. See: http://www.spaco.org/loose.htm Actually, I see it as less work to use. The exact size of the tapered hole isn't even important, as long as the taper pin isn't too short. Pete Stanaitis ------------------ Bob Engelhardt wrote: A taper pin is so much more work to use - is it that much better than a split pin (aka spring pin)? Or, putting it another way, in what circumstances would a split/spring pin be inadequate and a taper pin be required? Thanks, Bob |
#10
Posted to rec.crafts.metalworking
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Taper pin vs split pin
Ed,
That's a good explanation of the use of tapered pins, but as a user of tapered pins over many years I have to disagree with them ever falling out. In point of fact, once they are set, they can be very difficult to remove. Also, another really big advantage they have over other types of pins is that they do not remove as much shaft strength, as other types often cause shaft failure at the drilled hole. Steve "Ed Huntress" wrote in message ... "Bob Engelhardt" wrote in message ... A taper pin is so much more work to use - is it that much better than a split pin (aka spring pin)? Or, putting it another way, in what circumstances would a split/spring pin be inadequate and a taper pin be required? Thanks, Bob Roll pins (spring pins) are made to keep things from falling apart. Taper pins are made for precisely locating parts relative to each other. For example, a roll pin might be used to hold a flexible joint onto a shaft. A taper pin (or pairs of them, actually) might be used to locate the sections of a multi-part stamping die on a common die plate. There has been some inappropriate use of taper pins in the past. Today, there is some inappropriate use of roll pins. Roll pins flex and have limited ability to locate. But their shear strength is adequate for many jobs that formerly depended upon straight pins. To get the big picture, you have to consider four kinds of pins. Straight pins are used like roll pins, only they're capable of handling much greater shear loads. They might be used to hold a drill chuck onto a spindle, in a light-duty application. To keep the pin from falling out and to prevent backlash, the pin might be a press fit into its hole. A roll pin is a cheaper way to accomplish the same thing, with much less shear strength but with an easier press fit. They've replaced straight pins in many production applications. A taper pin should not be used to hold things together, without some kind of clamping or other locating to hold them in place. A screw tapped alongside of the head of the taper pin, with the screw head overlapping the edge of the pin, is one way to accomplish this. In much tool work, the pins are not subject to strong shear loads so they may hold without a clamp. But they can slip out of their holes without a clamp. The fourth kind of pin is just a further illustration of what the taper pin is about. It's a tapered diamond pin. It only contacts the work along two lines, rather than a long the sides of a cone. It's used only for super-precision locating in gage work, and in making master tooling that's used only to qualify the production tooling. The idea is that you can't get perfect contact on each of any pair of tapered pins, but you can locate one tapered pin perfectly and then restrain motion relative to that pin by locking the part along two lines that lie on the radius of an arc from the tapered pin. I know, following that in words -- or my words -- can give you a headache. g If it's important, I'll try again. But the point is that there are two ends of the scale in terms of locating precision, and roll pins are at the low end. But roll pins stay in place and do the job well when all that's required is to keep parts from slipping apart. -- Ed Huntress |
#11
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Taper pin vs split pin
Absolutely...... I have a very cherished set of taper pin reamers from No 5 'till 07. When carefully done, the pin virtually
welds in place. As Ed stated, they work extremely well if the loading isn't high. Higher loads require keys and key ways and then if very high, splines are more appropriate. Pins were was once very common in punch card equipment, card punches, sorters and collators. Steve "Gunner Asch" wrote in message ... On Wed, 20 Jan 2010 10:06:41 -0500, Bob Engelhardt wrote: A taper pin is so much more work to use - is it that much better than a split pin (aka spring pin)? Or, putting it another way, in what circumstances would a split/spring pin be inadequate and a taper pin be required? Thanks, Bob The hole was reamed with a taper? Gunner The current Democratic party has lost its ideological basis for existence. - It is NOT fiscally responsible. - It is NOT ethically honorable. - It has started wars based on lies. - It does not support the well-being of americans - only billionaires. - It has suppresed constitutional guaranteed liberties. - It has foisted a liar as president upon America. - It has violated US national sovereignty in trade treaties. - It has refused to enforce the national borders. ...It no longer has valid reasons to exist. Lorad474 |
#12
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Taper pin vs split pin
"Steve Lusardi" wrote in message ... Ed, That's a good explanation of the use of tapered pins, but as a user of tapered pins over many years I have to disagree with them ever falling out. In point of fact, once they are set, they can be very difficult to remove. Also, another really big advantage they have over other types of pins is that they do not remove as much shaft strength, as other types often cause shaft failure at the drilled hole. Steve Yeah, the "falling out" is more theoretical than real. If you press a steel pin into a steel hole with any force, even if it's tapered, it can stick there like it's welded. But, technically, even a locking taper can't take certain kinds of cyclic forces without coming loose. Anyone with a B&S-taper milling machine, or even a Morse or other "self-locking" taper, probably has had a tool drop out at some time in their lives. Hopefully, it's been a rare experience for those who have had it happen (I have). I never did any real-world toolmaking but I studied the hell out of it decades ago, when I covered tooling for magazines and then when I sold EDMs. Once upon a time I knew more about tapered pins, much of which I've forgotten. But the basic principles are there. In any case, their purpose really is locating rather than retaining. Straight pins and roll pins are for retaining. -- Ed Huntress "Ed Huntress" wrote in message ... "Bob Engelhardt" wrote in message ... A taper pin is so much more work to use - is it that much better than a split pin (aka spring pin)? Or, putting it another way, in what circumstances would a split/spring pin be inadequate and a taper pin be required? Thanks, Bob Roll pins (spring pins) are made to keep things from falling apart. Taper pins are made for precisely locating parts relative to each other. For example, a roll pin might be used to hold a flexible joint onto a shaft. A taper pin (or pairs of them, actually) might be used to locate the sections of a multi-part stamping die on a common die plate. There has been some inappropriate use of taper pins in the past. Today, there is some inappropriate use of roll pins. Roll pins flex and have limited ability to locate. But their shear strength is adequate for many jobs that formerly depended upon straight pins. To get the big picture, you have to consider four kinds of pins. Straight pins are used like roll pins, only they're capable of handling much greater shear loads. They might be used to hold a drill chuck onto a spindle, in a light-duty application. To keep the pin from falling out and to prevent backlash, the pin might be a press fit into its hole. A roll pin is a cheaper way to accomplish the same thing, with much less shear strength but with an easier press fit. They've replaced straight pins in many production applications. A taper pin should not be used to hold things together, without some kind of clamping or other locating to hold them in place. A screw tapped alongside of the head of the taper pin, with the screw head overlapping the edge of the pin, is one way to accomplish this. In much tool work, the pins are not subject to strong shear loads so they may hold without a clamp. But they can slip out of their holes without a clamp. The fourth kind of pin is just a further illustration of what the taper pin is about. It's a tapered diamond pin. It only contacts the work along two lines, rather than a long the sides of a cone. It's used only for super-precision locating in gage work, and in making master tooling that's used only to qualify the production tooling. The idea is that you can't get perfect contact on each of any pair of tapered pins, but you can locate one tapered pin perfectly and then restrain motion relative to that pin by locking the part along two lines that lie on the radius of an arc from the tapered pin. I know, following that in words -- or my words -- can give you a headache. g If it's important, I'll try again. But the point is that there are two ends of the scale in terms of locating precision, and roll pins are at the low end. But roll pins stay in place and do the job well when all that's required is to keep parts from slipping apart. -- Ed Huntress |
#13
Posted to rec.crafts.metalworking
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Taper pin vs split pin
Bob Engelhardt wrote:
A taper pin is so much more work to use - is it that much better than a split pin (aka spring pin)? Or, putting it another way, in what circumstances would a split/spring pin be inadequate and a taper pin be required? Thanks, Bob I think this has been covered before but again brings up the different nomenclature in different parts of the world. In the UK I think I know what a taper pin is but what are you referring to as a split pin (spring pin), see http://www.ondrives.com/mechanical-d...ring-pins.html , they mention slotted and coiled spring pins (often referred to as spiral pins here IIRC). I suspect it makes a difference. I've seen the slotted spring pins fail but not the coiled, yet!. Taper cotters used on many bikes with steel cranks in the US IIRC and the likes of MG midget kingpin to lower trunnion, but they are cylindrical with a tapered flat. British born, but lived in the US for 12 years, I'm glad I had UK parents so made adapting back to the UK easy. Confusing for some in the US though as some language differences are notable. Confused one of my English teachers no end for a short while as I pronounced "schedule" the English way. |
#14
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Taper pin vs split pin
Ed, I admire your ability to describe this with clarity and precision. A
very thorough and concise job. I would like to add one application of taper pins which is not so common - in fixing the wing-spars of some aircraft, a taper pin is used, with some kind of keeper. Usually, the small end is threaeded, and a nut with washer keeps it in place, thus allowing no slop or flex. There is an element of shear involved here. Flash "Ed Huntress" wrote in message ... "Bob Engelhardt" wrote in message ... A taper pin is so much more work to use - is it that much better than a split pin (aka spring pin)? Or, putting it another way, in what circumstances would a split/spring pin be inadequate and a taper pin be required? Thanks, Bob Roll pins (spring pins) are made to keep things from falling apart. Taper pins are made for precisely locating parts relative to each other. For example, a roll pin might be used to hold a flexible joint onto a shaft. A taper pin (or pairs of them, actually) might be used to locate the sections of a multi-part stamping die on a common die plate. There has been some inappropriate use of taper pins in the past. Today, there is some inappropriate use of roll pins. Roll pins flex and have limited ability to locate. But their shear strength is adequate for many jobs that formerly depended upon straight pins. To get the big picture, you have to consider four kinds of pins. Straight pins are used like roll pins, only they're capable of handling much greater shear loads. They might be used to hold a drill chuck onto a spindle, in a light-duty application. To keep the pin from falling out and to prevent backlash, the pin might be a press fit into its hole. A roll pin is a cheaper way to accomplish the same thing, with much less shear strength but with an easier press fit. They've replaced straight pins in many production applications. A taper pin should not be used to hold things together, without some kind of clamping or other locating to hold them in place. A screw tapped alongside of the head of the taper pin, with the screw head overlapping the edge of the pin, is one way to accomplish this. In much tool work, the pins are not subject to strong shear loads so they may hold without a clamp. But they can slip out of their holes without a clamp. The fourth kind of pin is just a further illustration of what the taper pin is about. It's a tapered diamond pin. It only contacts the work along two lines, rather than a long the sides of a cone. It's used only for super-precision locating in gage work, and in making master tooling that's used only to qualify the production tooling. The idea is that you can't get perfect contact on each of any pair of tapered pins, but you can locate one tapered pin perfectly and then restrain motion relative to that pin by locking the part along two lines that lie on the radius of an arc from the tapered pin. I know, following that in words -- or my words -- can give you a headache. g If it's important, I'll try again. But the point is that there are two ends of the scale in terms of locating precision, and roll pins are at the low end. But roll pins stay in place and do the job well when all that's required is to keep parts from slipping apart. -- Ed Huntress |
#15
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Taper pin vs split pin
On Jan 20, 5:52*pm, "Steve Lusardi" wrote:
Ed, That's a good explanation of the use of tapered pins, but as a user of tapered pins over many years I have to disagree with them ever falling out. In point of fact, once they are set, they can be very difficult to remove. Also, another really big advantage they have over other types of pins is that they do not remove as much shaft strength, as other types often cause shaft failure at the drilled hole. Steve "Ed Huntress" wrote in ... "Bob Engelhardt" wrote in ... A taper pin is so much more work to use - is it that much better than a split pin (aka spring pin)? *Or, putting it another way, in what circumstances would a split/spring pin be inadequate and a taper pin be required? Thanks, Bob Roll pins (spring pins) are made to keep things from falling apart. Taper pins are made for precisely locating parts relative to each other. For example, a roll pin might be used to hold a flexible joint onto a shaft. A taper pin (or pairs of them, actually) might be used to locate the sections of a multi-part stamping die on a common die plate. There has been some inappropriate use of taper pins in the past. Today, there is some inappropriate use of roll pins. Roll pins flex and have limited ability to locate. But their shear strength is adequate for many jobs that formerly depended upon straight pins. To get the big picture, you have to consider four kinds of pins. Straight pins are used like roll pins, only they're capable of handling much greater shear loads. They might be used to hold a drill chuck onto a spindle, in a light-duty application. To keep the pin from falling out and to prevent backlash, the pin might be a press fit into its hole. A roll pin is a cheaper way to accomplish the same thing, with much less shear strength but with an easier press fit. They've replaced straight pins in many production applications. A taper pin should not be used to hold things together, without some kind of clamping or other locating to hold them in place. A screw tapped alongside of the head of the taper pin, with the screw head overlapping the edge of the pin, is one way to accomplish this. In much tool work, the pins are not subject to strong shear loads so they may hold without a clamp. But they can slip out of their holes without a clamp. The fourth kind of pin is just a further illustration of what the taper pin is about. It's a tapered diamond pin. It only contacts the work along two lines, rather than a long the sides of a cone. It's used only for super-precision locating in gage work, and in making master tooling that's used only to qualify the production tooling. The idea is that you can't get perfect contact on each of any pair of tapered pins, but you can locate one tapered pin perfectly and then restrain motion relative to that pin by locking the part along two lines that lie on the radius of an arc from the tapered pin. I know, following that in words -- or my words -- can give you a headache. g If it's important, I'll try again. But the point is that there are two ends of the scale in terms of locating precision, and roll pins are at the low end. But roll pins stay in place and do the job well when all that's required is to keep parts from slipping apart. -- Ed Huntress I had a Saab 96 that used a taper pin to connect the ~15mm diam. shifter shaft to the gearbox. In this application it had torsion and longitudinal loads applied but it was sized properly for the loads and worked great. What was neat was that both ends of the tapered pin had an external thread - after sliding it into place, a nut on one side of the shaft pulled it home and retained it. To remove the pin you just took the nut off and put it on the opposite end and used it to pull the pin out. Nice, and no trauma to the shaft or gearbox from hammer blows to drive out a stuck pin! |
#16
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Taper pin vs split pin
On Jan 20, 5:48*pm, "Ed Huntress" wrote:
A taper pin should not be used to hold things together, without some kind of clamping or other locating to hold them in place. A screw tapped alongside of the head of the taper pin, with the screw head overlapping the edge of the pin, is one way to accomplish this. In much tool work, the pins are not subject to strong shear loads so they may hold without a clamp. But they can slip out of their holes without a clamp. Ed Huntress Morse tapers are designed to release. Jacobs tapers have less taper and are designed to hold but can be released. I believe that taper pins are designed to be harder to release than Jacobs tapers. Standard taper pins have a taper of 1/4 inch per foot. In my previous post, I mentioned taper pins with a threaded section on the small end. My mistake. They do not exist. There are taper pins with a threaded section on the big end so a nut can be used to pull the pin. Sorry about that. Dan |
#17
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Taper pin vs split pin
"Flash" wrote in message ... Ed, I admire your ability to describe this with clarity and precision. A very thorough and concise job. I would like to add one application of taper pins which is not so common - in fixing the wing-spars of some aircraft, a taper pin is used, with some kind of keeper. Usually, the small end is threaeded, and a nut with washer keeps it in place, thus allowing no slop or flex. There is an element of shear involved here. Flash Thanks, Flash. Those tapered fasteners with the threaded small end are an interesting case. Someone mentioned tie-rod ends, or some other suspension part, that's tapered and held tight that same way. Once you put a screw on the end you have something that's functionally a little different, but which does have that property of generating a tight fit along the whole cone -- in this case, with a preload that can be adjusted with the screw. The refinement of tapered locating pins came along a little over a century ago, when the art and science of precision toolmaking and gage making went through a rapid period of development. It happens that I had to study that work and that period to help write the 100th Anniversary Issue of _American Machinist_, back in 1977, and since then it's been one of the most interesting parts of the machine trades to me. There were a lot of brilliant people who perfected the art, and then turned the whole thing into a combination of art and science. There are few people I can talk to about things like diamond pins, toolmaker's buttons, and toolmaker's faceplate work. They don't believe that people could work to tenths, or even better, in 1900. Or, they think I'm nuts to care about it. d8-) -- Ed Huntress "Ed Huntress" wrote in message ... "Bob Engelhardt" wrote in message ... A taper pin is so much more work to use - is it that much better than a split pin (aka spring pin)? Or, putting it another way, in what circumstances would a split/spring pin be inadequate and a taper pin be required? Thanks, Bob Roll pins (spring pins) are made to keep things from falling apart. Taper pins are made for precisely locating parts relative to each other. For example, a roll pin might be used to hold a flexible joint onto a shaft. A taper pin (or pairs of them, actually) might be used to locate the sections of a multi-part stamping die on a common die plate. There has been some inappropriate use of taper pins in the past. Today, there is some inappropriate use of roll pins. Roll pins flex and have limited ability to locate. But their shear strength is adequate for many jobs that formerly depended upon straight pins. To get the big picture, you have to consider four kinds of pins. Straight pins are used like roll pins, only they're capable of handling much greater shear loads. They might be used to hold a drill chuck onto a spindle, in a light-duty application. To keep the pin from falling out and to prevent backlash, the pin might be a press fit into its hole. A roll pin is a cheaper way to accomplish the same thing, with much less shear strength but with an easier press fit. They've replaced straight pins in many production applications. A taper pin should not be used to hold things together, without some kind of clamping or other locating to hold them in place. A screw tapped alongside of the head of the taper pin, with the screw head overlapping the edge of the pin, is one way to accomplish this. In much tool work, the pins are not subject to strong shear loads so they may hold without a clamp. But they can slip out of their holes without a clamp. The fourth kind of pin is just a further illustration of what the taper pin is about. It's a tapered diamond pin. It only contacts the work along two lines, rather than a long the sides of a cone. It's used only for super-precision locating in gage work, and in making master tooling that's used only to qualify the production tooling. The idea is that you can't get perfect contact on each of any pair of tapered pins, but you can locate one tapered pin perfectly and then restrain motion relative to that pin by locking the part along two lines that lie on the radius of an arc from the tapered pin. I know, following that in words -- or my words -- can give you a headache. g If it's important, I'll try again. But the point is that there are two ends of the scale in terms of locating precision, and roll pins are at the low end. But roll pins stay in place and do the job well when all that's required is to keep parts from slipping apart. -- Ed Huntress |
#18
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Taper pin vs split pin
"oldjag" wrote in message ... On Jan 20, 5:52 pm, "Steve Lusardi" wrote: Ed, That's a good explanation of the use of tapered pins, but as a user of tapered pins over many years I have to disagree with them ever falling out. In point of fact, once they are set, they can be very difficult to remove. Also, another really big advantage they have over other types of pins is that they do not remove as much shaft strength, as other types often cause shaft failure at the drilled hole. Steve "Ed Huntress" wrote in ... "Bob Engelhardt" wrote in ... A taper pin is so much more work to use - is it that much better than a split pin (aka spring pin)? Or, putting it another way, in what circumstances would a split/spring pin be inadequate and a taper pin be required? Thanks, Bob Roll pins (spring pins) are made to keep things from falling apart. Taper pins are made for precisely locating parts relative to each other. For example, a roll pin might be used to hold a flexible joint onto a shaft. A taper pin (or pairs of them, actually) might be used to locate the sections of a multi-part stamping die on a common die plate. There has been some inappropriate use of taper pins in the past. Today, there is some inappropriate use of roll pins. Roll pins flex and have limited ability to locate. But their shear strength is adequate for many jobs that formerly depended upon straight pins. To get the big picture, you have to consider four kinds of pins. Straight pins are used like roll pins, only they're capable of handling much greater shear loads. They might be used to hold a drill chuck onto a spindle, in a light-duty application. To keep the pin from falling out and to prevent backlash, the pin might be a press fit into its hole. A roll pin is a cheaper way to accomplish the same thing, with much less shear strength but with an easier press fit. They've replaced straight pins in many production applications. A taper pin should not be used to hold things together, without some kind of clamping or other locating to hold them in place. A screw tapped alongside of the head of the taper pin, with the screw head overlapping the edge of the pin, is one way to accomplish this. In much tool work, the pins are not subject to strong shear loads so they may hold without a clamp. But they can slip out of their holes without a clamp. The fourth kind of pin is just a further illustration of what the taper pin is about. It's a tapered diamond pin. It only contacts the work along two lines, rather than a long the sides of a cone. It's used only for super-precision locating in gage work, and in making master tooling that's used only to qualify the production tooling. The idea is that you can't get perfect contact on each of any pair of tapered pins, but you can locate one tapered pin perfectly and then restrain motion relative to that pin by locking the part along two lines that lie on the radius of an arc from the tapered pin. I know, following that in words -- or my words -- can give you a headache. g If it's important, I'll try again. But the point is that there are two ends of the scale in terms of locating precision, and roll pins are at the low end. But roll pins stay in place and do the job well when all that's required is to keep parts from slipping apart. -- Ed Huntress I had a Saab 96 that used a taper pin to connect the ~15mm diam. shifter shaft to the gearbox. In this application it had torsion and longitudinal loads applied but it was sized properly for the loads and worked great. What was neat was that both ends of the tapered pin had an external thread - after sliding it into place, a nut on one side of the shaft pulled it home and retained it. To remove the pin you just took the nut off and put it on the opposite end and used it to pull the pin out. Nice, and no trauma to the shaft or gearbox from hammer blows to drive out a stuck pin! I love to see that kind of finesse in the mechanical details. I've never worked on a Rolls-Royce, but I've been told by people who have that they used to be -- maybe still are -- things of mechanical beauty like that. Finesse is a great thing. Unfortunately, it's not cost-effective. g -- Ed Huntress |
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Taper pin vs split pin
wrote in message ... On Jan 20, 5:48 pm, "Ed Huntress" wrote: A taper pin should not be used to hold things together, without some kind of clamping or other locating to hold them in place. A screw tapped alongside of the head of the taper pin, with the screw head overlapping the edge of the pin, is one way to accomplish this. In much tool work, the pins are not subject to strong shear loads so they may hold without a clamp. But they can slip out of their holes without a clamp. Ed Huntress Morse tapers are designed to release. Jacobs tapers have less taper and are designed to hold but can be released. I believe that taper pins are designed to be harder to release than Jacobs tapers. Standard taper pins have a taper of 1/4 inch per foot. In my previous post, I mentioned taper pins with a threaded section on the small end. My mistake. They do not exist. There are taper pins with a threaded section on the big end so a nut can be used to pull the pin. Sorry about that. Dan You were sort of right the first time! g I wouldn't call them "pins," but there are tapered fasteners that are threaded on the small end. I have one in my fastener junk box. I don't know what it was used for; I inherited the junk box. I don't think they were used the way we think of tapered pins, but that concept has been used in various mechanical fasteners, where you need both the tight fit of a taper and a preload to hold the thing in place, or to hold parts together. -- Ed Huntress |
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Taper pin vs split pin
"Steve Lusardi" wrote in message ... Absolutely...... I have a very cherished set of taper pin reamers from No 5 'till 07. When carefully done, the pin virtually welds in place. As Ed stated, they work extremely well if the loading isn't high. Higher loads require keys and key ways and then if very high, splines are more appropriate. Pins were was once very common in punch card equipment, card punches, sorters and collators. Steve "Gunner Asch" wrote in message ... On Wed, 20 Jan 2010 10:06:41 -0500, Bob Engelhardt wrote: A taper pin is so much more work to use - is it that much better than a split pin (aka spring pin)? Or, putting it another way, in what circumstances would a split/spring pin be inadequate and a taper pin be required? Thanks, Bob The hole was reamed with a taper? Gunner The current Democratic party has lost its ideological basis for existence. - It is NOT fiscally responsible. - It is NOT ethically honorable. - It has started wars based on lies. - It does not support the well-being of americans - only billionaires. - It has suppresed constitutional guaranteed liberties. - It has foisted a liar as president upon America. - It has violated US national sovereignty in trade treaties. - It has refused to enforce the national borders. ...It no longer has valid reasons to exist. Lorad474 All those counters in the mechanical cash registers and bank proof machines were put together with taper pins. As well as a lot of the shift plates. In years of working for NCR I only saw a couple pins come loose. Most likely because someone did not set them forcefully enough. They keep parts precisely aligned. |
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Taper pin vs split pin
Here is the major early use of tapers:
http://www.archive.org/stream/locomo...nrich_djvu.txt Also engine flywheels and propellors. I've seen the propellor shaft for a nuclear sub on the lathe at the Portsmouth naval shipyard. The prop end is a keyed taper and threads just like the crank on my old B&S lawnmower engine, naturally MUCH larger. However the thread pitch is about the same. jsw |
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Taper pin vs split pin
Ed Huntress wrote:
... To get the big picture, you have to consider four kinds of pins. ... Thanks - nice explanation. (Your writing background coming to the benefit of RCM'ers once again G.) The background for my question as this: I had made slip rolls and fastened the handle to the roll with a taper pin. My reasoning was that I could get a better fit than _I_ could with a straight pin & avoid wallowing out from a loose fit. But a split/spring/roll pin would have been so much easier. Not nearly as good, I see now. Thanks to all, Bob |
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