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Pulley question
I decided to improve my Delta 9" disk/6" belt sander. It suffers from
a lot of vibration which I've put up with for many years. I thought I'd upgrade to a larger/heavier machine but that hasn't happened. So I got the idea to change the belt to a link belt. (Let's not get into a debate on the merits of Link belts here. I like them and they have made big reductions to vibrations on machinery where I've used them.) I pulled the covers off to discover Delta uses a ribbed belt with like pulleys on this unit. I pulled the pulleys off and went to a transmission shop. They matched the sizes and off I went with 2 nicely machined 1/2" V groove pulleys. I go to put them on and behold, they don't want to go on the shafts. I have checked them with a micrometer and they seem to be the exact size of the old pulleys. I oiled the holes and shafts and have filed edges of the shafts to ensure I don't have any burrs. They seem to be fine. I haven't resorted to blasting them with a rubber mallet yet. Is this a common problem? Is there a "trick" to getting snug fitting new pulleys on shafts? Any thoughts to resolve this issue will be appreciated. Neil |
Two things you can do...
1. Thoroughly run a file around the shaft to make sure that all areas of the shaft are really clean and bump/burr/muck free. Repeat on the inside of the pulley with a round file. Be careful not to totally ruin the parts... If the shaft has a keyway (which it should!) make sure the keyway is fully clean and that the key is inserted all the way. If the keyway has a "ramp" towards the back portion, the key may walk up and jam the pulley. Try keeping the key out until the pulley is already on if you can (keyway has to extend to end of shaft). 2. Return the pulleys and/or ream them out slightly larger. Regards, Joe Agro, Jr. http://www.autodrill.com http://www.multi-drill.com V8013 In or near NJ and ride a Motorcycle: http://tinyurl.com/4zkw8 Young Life? eMail me! "toolguy" wrote in message oups.com... I decided to improve my Delta 9" disk/6" belt sander. It suffers from a lot of vibration which I've put up with for many years. I thought I'd upgrade to a larger/heavier machine but that hasn't happened. So I got the idea to change the belt to a link belt. (Let's not get into a debate on the merits of Link belts here. I like them and they have made big reductions to vibrations on machinery where I've used them.) I pulled the covers off to discover Delta uses a ribbed belt with like pulleys on this unit. I pulled the pulleys off and went to a transmission shop. They matched the sizes and off I went with 2 nicely machined 1/2" V groove pulleys. I go to put them on and behold, they don't want to go on the shafts. I have checked them with a micrometer and they seem to be the exact size of the old pulleys. I oiled the holes and shafts and have filed edges of the shafts to ensure I don't have any burrs. They seem to be fine. I haven't resorted to blasting them with a rubber mallet yet. Is this a common problem? Is there a "trick" to getting snug fitting new pulleys on shafts? Any thoughts to resolve this issue will be appreciated. Neil |
Run emery paper on the shaft.
WL "Joe" wrote in message news:dOV0e.23881$qN3.2461@trndny01... Two things you can do... 1. Thoroughly run a file around the shaft to make sure that all areas of the shaft are really clean and bump/burr/muck free. Repeat on the inside of the pulley with a round file. Be careful not to totally ruin the parts... If the shaft has a keyway (which it should!) make sure the keyway is fully clean and that the key is inserted all the way. If the keyway has a "ramp" towards the back portion, the key may walk up and jam the pulley. Try keeping the key out until the pulley is already on if you can (keyway has to extend to end of shaft). 2. Return the pulleys and/or ream them out slightly larger. Regards, Joe Agro, Jr. http://www.autodrill.com http://www.multi-drill.com V8013 In or near NJ and ride a Motorcycle: http://tinyurl.com/4zkw8 Young Life? eMail me! "toolguy" wrote in message oups.com... I decided to improve my Delta 9" disk/6" belt sander. It suffers from a lot of vibration which I've put up with for many years. I thought I'd upgrade to a larger/heavier machine but that hasn't happened. So I got the idea to change the belt to a link belt. (Let's not get into a debate on the merits of Link belts here. I like them and they have made big reductions to vibrations on machinery where I've used them.) I pulled the covers off to discover Delta uses a ribbed belt with like pulleys on this unit. I pulled the pulleys off and went to a transmission shop. They matched the sizes and off I went with 2 nicely machined 1/2" V groove pulleys. I go to put them on and behold, they don't want to go on the shafts. I have checked them with a micrometer and they seem to be the exact size of the old pulleys. I oiled the holes and shafts and have filed edges of the shafts to ensure I don't have any burrs. They seem to be fine. I haven't resorted to blasting them with a rubber mallet yet. Is this a common problem? Is there a "trick" to getting snug fitting new pulleys on shafts? Any thoughts to resolve this issue will be appreciated. Neil |
"toolguy" wrote in message oups.com... I decided to improve my Delta 9" disk/6" belt sander. It suffers from a lot of vibration which I've put up with for many years. I thought I'd upgrade to a larger/heavier machine but that hasn't happened. So I got the idea to change the belt to a link belt. (Let's not get into a debate on the merits of Link belts here. I like them and they have made big reductions to vibrations on machinery where I've used them.) I pulled the covers off to discover Delta uses a ribbed belt with like pulleys on this unit. I pulled the pulleys off and went to a transmission shop. They matched the sizes and off I went with 2 nicely machined 1/2" V groove pulleys. I go to put them on and behold, they don't want to go on the shafts. I have checked them with a micrometer and they seem to be the exact size of the old pulleys. I oiled the holes and shafts and have filed edges of the shafts to ensure I don't have any burrs. They seem to be fine. I haven't resorted to blasting them with a rubber mallet yet. Is this a common problem? Is there a "trick" to getting snug fitting new pulleys on shafts? Any thoughts to resolve this issue will be appreciated. Neil Evidently they are not the same size. If cleaning all the burrs, keyway size and height are correct, then the hole is too small. Dave (Who won't bother with the link belt issue) Posted Via Usenet.com Premium Usenet Newsgroup Services ---------------------------------------------------------- ** SPEED ** RETENTION ** COMPLETION ** ANONYMITY ** ---------------------------------------------------------- http://www.usenet.com |
"toolguy" wrote in message oups.com... Any thoughts to resolve this issue will be appreciated. Neil Are you certain that the shaft and new pulleys are the right size? I question whether this sander is made "over seas" and may be metric. Greg |
"toolguy" wrote in message oups.com... I decided to improve my Delta 9" disk/6" belt sander. Is there a "trick" to getting snug fitting new pulleys on shafts? Any thoughts to resolve this issue will be appreciated. Neil Is this the sander? Model 31-695? http://www.deltawoodworking.com/index.asp?e=136&p=830 If it is then the shafts are definitely metric. Greg |
That's it! Thanks for pointing out my oversight. They measured the
old pulleys and assumed they were 5/8". When in fact they are 16 mm shafts. The 5/8" pulleys they sold me are about 15.8 mm. Back to the store! |
"toolguy" wrote:
Is there a "trick" to getting snug fitting new pulleys on shafts? Any thoughts to resolve this issue will be appreciated. No need to use hammers or open out the holes. Just stick the pulleys in a pan of boiling water for ten minutes - they will fly on easily. -- |
On Fri, 25 Mar 2005 18:15:07 +0000, No Spam
wrote: "toolguy" wrote: Is there a "trick" to getting snug fitting new pulleys on shafts? Any thoughts to resolve this issue will be appreciated. No need to use hammers or open out the holes. Just stick the pulleys in a pan of boiling water for ten minutes - they will fly on easily. ....Never to be removed. -- LRod Master Woodbutcher and seasoned termite Shamelessly whoring my website since 1999 http://www.woodbutcher.net Proud participant of rec.woodworking since February, 1997 |
Emery paper on the shaft and heat the pulley. It will expand a couple of
thousandths max Run emery paper on the shaft. WL "Joe" wrote in message news:dOV0e.23881$qN3.2461@trndny01... Two things you can do... 1. Thoroughly run a file around the shaft to make sure that all areas of the shaft are really clean and bump/burr/muck free. Repeat on the inside of the pulley with a round file. Be careful not to totally ruin the parts... If the shaft has a keyway (which it should!) make sure the keyway is fully clean and that the key is inserted all the way. If the keyway has a "ramp" towards the back portion, the key may walk up and jam the pulley. Try keeping the key out until the pulley is already on if you can (keyway has to extend to end of shaft). 2. Return the pulleys and/or ream them out slightly larger. Regards, Joe Agro, Jr. http://www.autodrill.com http://www.multi-drill.com V8013 In or near NJ and ride a Motorcycle: http://tinyurl.com/4zkw8 Young Life? eMail me! "toolguy" wrote in message oups.com... I decided to improve my Delta 9" disk/6" belt sander. It suffers from a lot of vibration which I've put up with for many years. I thought I'd upgrade to a larger/heavier machine but that hasn't happened. So I got the idea to change the belt to a link belt. (Let's not get into a debate on the merits of Link belts here. I like them and they have made big reductions to vibrations on machinery where I've used them.) I pulled the covers off to discover Delta uses a ribbed belt with like pulleys on this unit. I pulled the pulleys off and went to a transmission shop. They matched the sizes and off I went with 2 nicely machined 1/2" V groove pulleys. I go to put them on and behold, they don't want to go on the shafts. I have checked them with a micrometer and they seem to be the exact size of the old pulleys. I oiled the holes and shafts and have filed edges of the shafts to ensure I don't have any burrs. They seem to be fine. I haven't resorted to blasting them with a rubber mallet yet. Is this a common problem? Is there a "trick" to getting snug fitting new pulleys on shafts? Any thoughts to resolve this issue will be appreciated. Neil |
Emery paper on the shaft and heat the pulley. It will expand a couple of
thousandths Should he ever need to remove the pulley, the heating process might have to be repeated... I'd suggest getting it the right size to slid on at room pemperature the first time. Regards, Joe Agro, Jr. http://www.autodrill.com http://www.multi-drill.com V8013 In or near NJ and ride a Motorcycle: http://tinyurl.com/4zkw8 Young Life? eMail me! |
Oh, the pulley can be removed, all right. I have worked with machinery drive
coupling halves of 1,400 lbs weight, with a 12" bore, 24" through the hub, with a 2" square key. They are heated and installed with a .002 inch of shrink fit for each inch of shaft diameter, being .024 undersize in this case. Whenever removal is necessary, heat and a puller is used, same as most cases, just a hell of a lot bigger hydraulic one. Hopefully the pulleys one has aren't potmetal G In any case anti-sieze compound should be used for this type of mechanical assembly. It makes installation and removal much easier, and reduces broaching of the bore. In general, keys should be pre-fitted by marking the "top" of the key to retain orientation. Fit the key to the shaft by dressing key and shaft carefully with a file to match, then fit key to hub using same method. Fit hub to shaft by polishing with abrasive cloth, considering whether it will be a shrink or a slide fit. Mark top of key of a slide fit with magic marker and attempt to install pulley over it. Alternately, key height can be measured with the proper tools. If it doesn't go, file the top of the key to remove scratch marks left by the hub until it does. The height of the key should normally be the only factor left at this point, barring unseen complications. This is a tried and true millwright technique that works. I hope this can help someone along the way. RJ, Millwright foreman of days gone by. "LRod" wrote in message ... On Fri, 25 Mar 2005 18:15:07 +0000, No Spam wrote: "toolguy" wrote: Is there a "trick" to getting snug fitting new pulleys on shafts? Any thoughts to resolve this issue will be appreciated. No need to use hammers or open out the holes. Just stick the pulleys in a pan of boiling water for ten minutes - they will fly on easily. ...Never to be removed. -- LRod Master Woodbutcher and seasoned termite Shamelessly whoring my website since 1999 http://www.woodbutcher.net Proud participant of rec.woodworking since February, 1997 |
Won't expanding the pulley make the hole smaller?
"max" wrote in message ... Emery paper on the shaft and heat the pulley. It will expand a couple of thousandths max Run emery paper on the shaft. WL "Joe" wrote in message news:dOV0e.23881$qN3.2461@trndny01... Two things you can do... 1. Thoroughly run a file around the shaft to make sure that all areas of the shaft are really clean and bump/burr/muck free. Repeat on the inside of the pulley with a round file. Be careful not to totally ruin the parts... If the shaft has a keyway (which it should!) make sure the keyway is fully clean and that the key is inserted all the way. If the keyway has a "ramp" towards the back portion, the key may walk up and jam the pulley. Try keeping the key out until the pulley is already on if you can (keyway has to extend to end of shaft). 2. Return the pulleys and/or ream them out slightly larger. Regards, Joe Agro, Jr. http://www.autodrill.com http://www.multi-drill.com V8013 In or near NJ and ride a Motorcycle: http://tinyurl.com/4zkw8 Young Life? eMail me! "toolguy" wrote in message oups.com... I decided to improve my Delta 9" disk/6" belt sander. It suffers from a lot of vibration which I've put up with for many years. I thought I'd upgrade to a larger/heavier machine but that hasn't happened. So I got the idea to change the belt to a link belt. (Let's not get into a debate on the merits of Link belts here. I like them and they have made big reductions to vibrations on machinery where I've used them.) I pulled the covers off to discover Delta uses a ribbed belt with like pulleys on this unit. I pulled the pulleys off and went to a transmission shop. They matched the sizes and off I went with 2 nicely machined 1/2" V groove pulleys. I go to put them on and behold, they don't want to go on the shafts. I have checked them with a micrometer and they seem to be the exact size of the old pulleys. I oiled the holes and shafts and have filed edges of the shafts to ensure I don't have any burrs. They seem to be fine. I haven't resorted to blasting them with a rubber mallet yet. Is this a common problem? Is there a "trick" to getting snug fitting new pulleys on shafts? Any thoughts to resolve this issue will be appreciated. Neil |
"Don" wrote in message k.net... Won't expanding the pulley make the hole smaller? Nope, when you heat a ring shape, such as a pulley, the hole will get larger. Greg |
In article ,
"Greg O" wrote: "Don" wrote in message k.net... Won't expanding the pulley make the hole smaller? Nope, when you heat a ring shape, such as a pulley, the hole will get larger. Greg Is that because the air in the hole expands more than the metal and forces it to be bigger? |
"Richard Cline" wrote in message ... In article , "Greg O" wrote: "Don" wrote in message k.net... Won't expanding the pulley make the hole smaller? Nope, when you heat a ring shape, such as a pulley, the hole will get larger. Greg Is that because the air in the hole expands more than the metal and forces it to be bigger? I wonder what scientific property allows one portion of the metal to expand (the outside surface of the pulley) while the other part contracts (the hole). |
Don wrote:
"Richard Cline" wrote in message ... In article , "Greg O" wrote: "Don" wrote in message link.net... Won't expanding the pulley make the hole smaller? Nope, when you heat a ring shape, such as a pulley, the hole will get larger. Greg Is that because the air in the hole expands more than the metal and forces it to be bigger? I wonder what scientific property allows one portion of the metal to expand (the outside surface of the pulley) while the other part contracts (the hole). None. Once upon a time, I though the hole contracted as the piece was warmed, but only because I am not a materials person and didn't really visualize what would happen. But, someone explained the shape/size of the control acts just like the piece of metal taken from the hole. As an example, the diameter of a dime sized piece expands .004 inches from temperature A to B, if you measure a dime size hole in a plate of the same material, the hole diameter will expand .004 inches from temperature A to B. It also makes sense from a visualization of molecules. In a solid, the molecules will be fixed at a specific distance from each other at a specific temperature. As the temperature increase, the vibrate faster and the distance between molecules increases. Visualize the molecules as a single layer of marbles touching each other, then take a bunch of marbles out so that a hole is formed, i.e, there is a ring of touching marbles around the hole. As the item gets warmer the marbles push away from each other and thus the hole gets bigger. The marbles around the hole can't get closer to each other unless the molecules become colder and they can't squeeze past each other into the hole because the repelling forces won't let them. |
None. Once upon a time, I though the hole contracted as the piece was
warmed, but only because I am not a materials person and didn't really visualize what would happen. But, someone explained the shape/size of the control acts just like the piece of metal taken from the hole. As an example, the diameter of a dime sized piece expands .004 inches from temperature A to B, if you measure a dime size hole in a plate of the same material, the hole diameter will expand .004 inches from temperature A to B. It also makes sense from a visualization of molecules. In a solid, the molecules will be fixed at a specific distance from each other at a specific temperature. As the temperature increase, the vibrate faster and the distance between molecules increases. Visualize the molecules as a single layer of marbles touching each other, then take a bunch of marbles out so that a hole is formed, i.e, there is a ring of touching marbles around the hole. As the item gets warmer the marbles push away from each other and thus the hole gets bigger. The marbles around the hole can't get closer to each other unless the molecules become colder and they can't squeeze past each other into the hole because the repelling forces won't let them. In short, the material doesn't expand in the path of least resistance, it expands as a whole from the center. Sorta... Try bending a small tube. It is harder to bend initially than a solid rod because you have to "crimp" four walls of material versus just the two outside walls of a bar. In a pulley, the inside ring cannot shrink into itself so the unit expands outwards and "stretches" the outer portion of the ring rather than compressing the molecules of the inner ring. Sorta... -- Regards, Joe Agro, Jr. http://www.autodrill.com http://www.multi-drill.com V8013 In or near NJ and ride a Motorcycle: http://tinyurl.com/4zkw8 Young Life? eMail me! |
"George E. Cawthon" wrote in message ... Don wrote: "Richard Cline" wrote in message ... In article , "Greg O" wrote: "Don" wrote in message hlink.net... Won't expanding the pulley make the hole smaller? Nope, when you heat a ring shape, such as a pulley, the hole will get larger. Greg Is that because the air in the hole expands more than the metal and forces it to be bigger? I wonder what scientific property allows one portion of the metal to expand (the outside surface of the pulley) while the other part contracts (the hole). None. Once upon a time, I though the hole contracted as the piece was warmed, but only because I am not a materials person and didn't really visualize what would happen. But, someone explained the shape/size of the control acts just like the piece of metal taken from the hole. As an example, the diameter of a dime sized piece expands .004 inches from temperature A to B, if you measure a dime size hole in a plate of the same material, the hole diameter will expand .004 inches from temperature A to B. It also makes sense from a visualization of molecules. In a solid, the molecules will be fixed at a specific distance from each other at a specific temperature. As the temperature increase, the vibrate faster and the distance between molecules increases. Visualize the molecules as a single layer of marbles touching each other, then take a bunch of marbles out so that a hole is formed, i.e, there is a ring of touching marbles around the hole. As the item gets warmer the marbles push away from each other and thus the hole gets bigger. The marbles around the hole can't get closer to each other unless the molecules become colder and they can't squeeze past each other into the hole because the repelling forces won't let them. So, are you saying the metal, upon expansion, acts like the hole is not there, that the whole thing is solid? Incidently, I know that heating metal up, like pulleys, works because I've done it. |
"Joe" wrote in message news:Hzz1e.23138$Ue6.22152@trndny04... None. Once upon a time, I though the hole contracted as the piece was warmed, but only because I am not a materials person and didn't really visualize what would happen. But, someone explained the shape/size of the control acts just like the piece of metal taken from the hole. As an example, the diameter of a dime sized piece expands .004 inches from temperature A to B, if you measure a dime size hole in a plate of the same material, the hole diameter will expand .004 inches from temperature A to B. It also makes sense from a visualization of molecules. In a solid, the molecules will be fixed at a specific distance from each other at a specific temperature. As the temperature increase, the vibrate faster and the distance between molecules increases. Visualize the molecules as a single layer of marbles touching each other, then take a bunch of marbles out so that a hole is formed, i.e, there is a ring of touching marbles around the hole. As the item gets warmer the marbles push away from each other and thus the hole gets bigger. The marbles around the hole can't get closer to each other unless the molecules become colder and they can't squeeze past each other into the hole because the repelling forces won't let them. In short, the material doesn't expand in the path of least resistance, it expands as a whole from the center. Sorta... Try bending a small tube. It is harder to bend initially than a solid rod because you have to "crimp" four walls of material versus just the two outside walls of a bar. In a pulley, the inside ring cannot shrink into itself so the unit expands outwards and "stretches" the outer portion of the ring rather than compressing the molecules of the inner ring. Good explanation. Sorta... I think. LOL |
"Don" wrote in message k.net... So, are you saying the metal, upon expansion, acts like the hole is not there, that the whole thing is solid? Incidently, I know that heating metal up, like pulleys, works because I've done it. It may clear it up if you think of a metal ring instead of a pulley. Cut the metal ring and lay it out flat and heat it up. The length will change considerably, although at the same proportion as the diameter. If the metal rod was rolled back into a ring and heated you have the "length" expanding and pushing against its self causing the hole to get larger. Although the pulley will expand in all directions, the ring shape causes the hole to open up when heated. Confused yet? Greg |
"Greg O" wrote in message ... "Don" wrote in message k.net... So, are you saying the metal, upon expansion, acts like the hole is not there, that the whole thing is solid? Incidently, I know that heating metal up, like pulleys, works because I've done it. It may clear it up if you think of a metal ring instead of a pulley. Cut the metal ring and lay it out flat and heat it up. The length will change considerably, although at the same proportion as the diameter. If the metal rod was rolled back into a ring and heated you have the "length" expanding and pushing against its self causing the hole to get larger. Although the pulley will expand in all directions, the ring shape causes the hole to open up when heated. Confused yet? LOL Actually, that was a good explanation, Greg. |
Don wrote:
"George E. Cawthon" wrote in message ... Don wrote: "Richard Cline" wrote in message ... In article , "Greg O" wrote: "Don" wrote in message thlink.net... Won't expanding the pulley make the hole smaller? Nope, when you heat a ring shape, such as a pulley, the hole will get larger. Greg Is that because the air in the hole expands more than the metal and forces it to be bigger? I wonder what scientific property allows one portion of the metal to expand (the outside surface of the pulley) while the other part contracts (the hole). None. Once upon a time, I though the hole contracted as the piece was warmed, but only because I am not a materials person and didn't really visualize what would happen. But, someone explained the shape/size of the control acts just like the piece of metal taken from the hole. As an example, the diameter of a dime sized piece expands .004 inches from temperature A to B, if you measure a dime size hole in a plate of the same material, the hole diameter will expand .004 inches from temperature A to B. It also makes sense from a visualization of molecules. In a solid, the molecules will be fixed at a specific distance from each other at a specific temperature. As the temperature increase, the vibrate faster and the distance between molecules increases. Visualize the molecules as a single layer of marbles touching each other, then take a bunch of marbles out so that a hole is formed, i.e, there is a ring of touching marbles around the hole. As the item gets warmer the marbles push away from each other and thus the hole gets bigger. The marbles around the hole can't get closer to each other unless the molecules become colder and they can't squeeze past each other into the hole because the repelling forces won't let them. So, are you saying the metal, upon expansion, acts like the hole is not there, that the whole thing is solid? Incidently, I know that heating metal up, like pulleys, works because I've done it. Yep. Doesn't matter whether is a hole or not, at least theoretically for all practical purposes. |
"Don" wrote in message k.net... "Greg O" wrote in message ... "Don" wrote in message k.net... So, are you saying the metal, upon expansion, acts like the hole is not there, that the whole thing is solid? Incidently, I know that heating metal up, like pulleys, works because I've done it. It may clear it up if you think of a metal ring instead of a pulley. Cut the metal ring and lay it out flat and heat it up. The length will change considerably, although at the same proportion as the diameter. If the metal rod was rolled back into a ring and heated you have the "length" expanding and pushing against its self causing the hole to get larger. Although the pulley will expand in all directions, the ring shape causes the hole to open up when heated. Confused yet? LOL Actually, that was a good explanation, Greg. Some years back, in another lifetime, I worked part time for a good friend who owned a service station. Learned a trick from him about the pressed on alternator pulleys used by Chrysler. When doing alternator work that required removing the pulley, when it was time to reinstall it, he would put the alternator in the ice dispenser for a while, then put the pulley itself on an electric hotplate for about five minutes. Get alternator from freezer, pick up pulley with channelocks, voila! Pulley falls right on, no need to press it on. Once the temperatures return to normal, shaft has expanded & pulley has contracted, now it will require a puller to remove it again. -- Nahmie Those on the cutting edge bleed a lot. |
Some years back, in another lifetime, I worked part time for a good friend
who owned a service station. Learned a trick from him about the pressed on alternator pulleys used by Chrysler. When doing alternator work that required removing the pulley, when it was time to reinstall it, he would put the alternator in the ice dispenser for a while, then put the pulley itself on an electric hotplate for about five minutes. Get alternator from freezer, pick up pulley with channelocks, voila! Pulley falls right on, no need to press it on. Once the temperatures return to normal, shaft has expanded & pulley has contracted, now it will require a puller to remove it again. Except for the fact that the water on the alternator might do it's own negative magic to future performance, that is a better way to do it anyhow. It removes the danger of overstressing any bearings via the press procedure. -- Regards, Joe Agro, Jr. http://www.autodrill.com http://www.multi-drill.com V8013 In or near NJ and ride a Motorcycle: http://tinyurl.com/4zkw8 Young Life? eMail me! |
"Joe" wrote in message news:6rS1e.20262$jt6.2484@trndny07... Some years back, in another lifetime, I worked part time for a good friend who owned a service station. Learned a trick from him about the pressed on alternator pulleys used by Chrysler. When doing alternator work that required removing the pulley, when it was time to reinstall it, he would put the alternator in the ice dispenser for a while, then put the pulley itself on an electric hotplate for about five minutes. Get alternator from freezer, pick up pulley with channelocks, voila! Pulley falls right on, no need to press it on. Once the temperatures return to normal, shaft has expanded & pulley has contracted, now it will require a puller to remove it again. Except for the fact that the water on the alternator might do it's own negative magic to future performance, that is a better way to do it anyhow. It removes the danger of overstressing any bearings via the press procedure. -- Only "water" involved was whatever small amount of condensation could occur on the alternator after it was removed from the freezer. To clarify, the ice "dispenser" was one of those big chests with bagged ice in it. Pay the cashier, open the door and take the bag out. Occasionally got a strange look if someone went for their bag while an alternator was in there. -- Nahmie Those on the cutting edge bleed a lot. |
Occasionally got a strange look
if someone went for their bag while an alternator was in there. Just be glad nobody brought it to the register for purchase. :) -- Regards, Joe Agro, Jr. http://www.autodrill.com http://www.multi-drill.com V8013 In or near NJ and ride a Motorcycle: http://tinyurl.com/4zkw8 Young Life? eMail me! |
On Sun, 27 Mar 2005 05:30:52 GMT, "Don"
wrote: "Richard Cline" wrote in message ... In article , "Greg O" wrote: "Don" wrote in message k.net... Won't expanding the pulley make the hole smaller? Nope, when you heat a ring shape, such as a pulley, the hole will get larger. Greg Is that because the air in the hole expands more than the metal and forces it to be bigger? I wonder what scientific property allows one portion of the metal to expand (the outside surface of the pulley) while the other part contracts (the hole). the hole isn't part of the metal. it's where the metal isn't. look at it like this: say you have a piece of wire. you heat it, it expands and gets longer. now say you bend it into a circle. you heat it, it gets longer. the corcle gets bigger, both inside and outside diameters |
Cooling the shaft does work. The mechanics, at the utility where I
worked, sometimes wrapped the shaft with dry ice to cool it. A simpler approach is to follow the coupling and bearing manufacturer's recomendations. Instead of the 1 to 2 thousanths of shrink per inch of shaft that mechanics seem to hold sacred, machine it for 1/2 thousanths shrink per inch of shaft with a minimum of 1/2 thousanth as per mfg. recomendations. They also recommend that the coupling, bearing or whatever be heated in an oil bath to 300 to 350 deg F. It's a lot better for the metal than a torch or the shock of a superhot coupling suddenly being slamed onto a shaft that has been frozen with dry ice. With the smaller shrink fit this heating is more than enough to let it slide on easily. It comes off more easily too. I switched to that approach and never had any problems. Warning: Following mfg. recomendation could lead to more serious illnesses like reading instruction manuals. Ken |
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Richard Cline wrote:
In article , s wrote: Yea but when you heat the wire, it gets thicker. That means one side would move toward the center of the circle. Let me offer another way to think about the problem: Let's look just at the atoms that make up just the inner surface of a ring. As the ring is heated, these atoms move farther from each other. As they move farther from each other, the circumference of this inner surface increases - and so, then, must the diameter. -- Morris Dovey DeSoto Solar DeSoto, Iowa USA http://www.iedu.com/DeSoto/solar.html |
In article ,
Richard Cline wrote: In article , s wrote: the hole isn't part of the metal. it's where the metal isn't. look at it like this: say you have a piece of wire. you heat it, it expands and gets longer. now say you bend it into a circle. you heat it, it gets longer. the corcle gets bigger, both inside and outside diameters Yea but when you heat the wire, it gets thicker. That means one side would move toward the center of the circle. Wrong! counter-intuitive as it may be, that is *NOT* what happens. Simple disproof: Consider a _square_ of metal. With a square hole in the middle of it When the sides of the square expand, the top/bottom move further apart. The part of the sides that are against the top/bottom, expand exactly as much as the top/bottom do. The part of the sides against the hole _also_ expand. When the top/bottom of the square expand, the sides move further apart. The part of the top/bottom that are against the sides, expand exactly as much as the sides do. The part of the top/bottom against the hole _also_ expand. There's another simple proof: take a _solid_ chunk of material and draw a circle on it, to "represent" the 'hole'. Now heat it up. what happens to the size of the drawn circle? Now, for the_hard_ question: Does it make any difference if you cut along that drawn line, before or after you heat the material? Just cut along the line, leave both pieces where they are, and heat. Hmmm. the center circle gets bigger. yet it still fits in the outer piece. The hole _must_ get larger, too. grin |
On Tue, 29 Mar 2005 21:42:07 -0800, Richard Cline
wrote something .......and in reply I say!: In article , s wrote: Yea but when you heat the wire, it gets thicker. That means one side would move toward the center of the circle. But it expands the same proportion both lengthwise and widthwise. So the length increases by far more than the width. Hence the hole gets bigger, because it's effectively a wrapped round side of the rod.. ************************************************** **************************************** Whenever you have to prove to yourself that you are not something, you probably are. Nick White --- HEAD:Hertz Music remove ns from my header address to reply via email !! ") _/ ) ( ) _//- \__/ |
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