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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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Request for advice regarding cantilevered mounted bearing housing, deflections and shaft stresses
Hello everyone,
I would like to ask for some advice regarding a cantilever mounted bearing housing. Due to various design constraints, I have two choices as to how I implement a cantilevered mounted bearing housing. I have uploaded two simple dimensioned jpeg images for reference, at the following site. You can Save or print the images as needed. http://www.ice9.zoomshare.com The housing has two drawn-cup needle roller bearings pressed into it, and the housing oscillates rotationally on a stationary shaft (i.e., a hardened steel dowel pin). As shown in the drawings, I can use a 7/16" OD dowel with the bearings spaced closer together, or I can use a 3/8" OD dowel with the bearings spaced further apart. 1. I mainly need to know the correct way to model how the bearing forces act on the shaft, due to the housing load, so I can determine how far the end of the shaft & housing will deflect, and whether the dowel can withstand the stresses without taking a permanent set. The maximum load on the housing will probably be about 130 pounds, but I would like for the dowel to be able to withstand a 200 pound housing load if possible, for a safety factor. I can calculate the force at each bearing, but I am not sure exactly how the force actually acts on the dowel. It seems to me that the load on the bearings will almost be a torque moment, where the the shaft is being bent between the contact points of the two bearings, with bearing #2 pushing down, and bearing #1 pushing almost upwardly. Here is the formula I used to calculate the bearing loads, the letters are shown with the corresponding dimensions, on the two drawings. Where (LA) = the housing load Load on bearing #1 = (LA) * B / A Load on bearing #2 = (LA) * C / A 2. The bearing shaft is a hardened steel pull dowel pin, made from C1541, 4037, or 4140 steel (thats all the info I can get from Mcmaster Carr). The single shear strength for the pin is 130,000 PSI. The pins have a core hardness of Rockwell C47-58, and a surface hardness of C60 (they meet ASME B18.8.2 standards). Since the dowel is hardened I am not sure what the maximum yield strength is, I know tensile goes up with hardening but I don't have any information on the yield strength of the hardened dowel pin. I am hoping someone can shed some light on this issue. I have a beam design program I can use to help determine stress and deflection of the dowel, but I am not sure If I should model a torque moment with the rotation axis between the two bearings, or perhaps a combination of a torque moment and vertical forces. Using a housing load of 130 pounds, the formula given above, and a downward force on both bearing #1 & #2, it seems the 3/8" OD dowel has slightly less stress than the 7/16" dowel, but it deflects about .001" further. The end of the dowel is 1.26" from the cantilever support. The loaded end of the housing is 1.48" from the cantilever support, and there is a ..031" space between the housing and the cantilever support. I have a 3/8" OD, lever "connection socket" that screws into the bearing housing, perpendicular to the housing, right next to the cantilever steel support. The advantage of housing #1 is that I can "step" the bearing bore in the housing so that I have a little more housing material to thread the connection socket into, since bearing # 1 is moved out from under the connection socket, and closer to the load end of the housing. The advantage of housing #2 is that the bearings are spaced further apart, and this helps reduce housing deflection due to bearing misalignment. The trade off is that I have a little less housing material to thread the connection socket into, since the socket threads in, right on top of bearing #1. The housing is oscillated by hand, and never gets hot. The radial clearance between the bearing ID and the shaft OD will be .0002" Min. to .002" maximum. If there is no way to model this to get a close estimate, I would appreciate your gut feelings as to which method is best, as far keeping the deflections at the load end of the housing to a minimum, and avoiding overloading the dowel so that it does not incur a permanent set due to the housing load. Obviously, if the dowels had the same OD in each case, then housing #2 would be best, since the bearings are spaced further apart. I think that either arrangement could take 130 pounds, but I am not sure about 200 pounds. I would like to be able to estimate the maximum housing load the dowel pin could withstand without taking a permanent set, and make a close estimate on the deflection of the dowel and housing. I want to keep the deviations of the housing end from it's longitudinal axis to a minimum, whether the deviation comes from shaft deflection or bearing misalignment. However, I need to be sure that the dowel is not going to be stressed past it's yield point, so that it springs back to it's original position when the housing load is removed, and does not take a permanent set. Thanks for your help. John |
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Request for advice regarding cantilevered mounted bearing housing, deflections and shaft stresses
I would like to ask for some advice regarding a cantilever mounted
bearing housing. We might be able to guess at a generalized answer with little real certainty, but I suspect to get the level of detail you desire you are really going to have to either: 1. Go with a finite element model--there is some cheaper software out there to do this, but it's been a while since I've looked so I don't recall names or sources, or even if any of the entry level packages would do this detailed an analysis. If you go this route, try to run as many different scenarios as you can, not just the one or two designs you like most. There may be other factors affecting your design, and once you have the software, computer run time is cheap. 2. Mock up both ways and measure. Be meticulous and keep notes. It's what everyone has resorted to when they don't have enough data for a pen and paper calculation. Be sure to double check by plugging your experiment results (deflections, for example) back into your paper model so you can at least get a better pen and paper estimate for your other datapoints (like stresses) than the one you had without the experiment. If this is for a production device involving personal safety and not just a one-off for your own use, consider doing both, or better yet, hiring a licensed engineer to sign off on it (CYA for lawsuits). My $0.02, --Glenn Lyford |
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Request for advice regarding cantilevered mounted bearing housing, deflections and shaft stresses
Personally, I wouldn't hang 200lbs 1-1/2" out on a 3/8 shaft, but that's
just me. Where I come from, we thumbnail engineer, then test. You can engineer until you're blue in the face. Go get your hands dirty. =) "John2005" wrote in message oups.com... Hello everyone, I would like to ask for some advice regarding a cantilever mounted bearing housing. Due to various design constraints, I have two choices as to how I implement a cantilevered mounted bearing housing. I have uploaded two simple dimensioned jpeg images for reference, at the following site. You can Save or print the images as needed. http://www.ice9.zoomshare.com The housing has two drawn-cup needle roller bearings pressed into it, and the housing oscillates rotationally on a stationary shaft (i.e., a hardened steel dowel pin). As shown in the drawings, I can use a 7/16" OD dowel with the bearings spaced closer together, or I can use a 3/8" OD dowel with the bearings spaced further apart. 1. I mainly need to know the correct way to model how the bearing forces act on the shaft, due to the housing load, so I can determine how far the end of the shaft & housing will deflect, and whether the dowel can withstand the stresses without taking a permanent set. The maximum load on the housing will probably be about 130 pounds, but I would like for the dowel to be able to withstand a 200 pound housing load if possible, for a safety factor. I can calculate the force at each bearing, but I am not sure exactly how the force actually acts on the dowel. It seems to me that the load on the bearings will almost be a torque moment, where the the shaft is being bent between the contact points of the two bearings, with bearing #2 pushing down, and bearing #1 pushing almost upwardly. Here is the formula I used to calculate the bearing loads, the letters are shown with the corresponding dimensions, on the two drawings. Where (LA) = the housing load Load on bearing #1 = (LA) * B / A Load on bearing #2 = (LA) * C / A 2. The bearing shaft is a hardened steel pull dowel pin, made from C1541, 4037, or 4140 steel (thats all the info I can get from Mcmaster Carr). The single shear strength for the pin is 130,000 PSI. The pins have a core hardness of Rockwell C47-58, and a surface hardness of C60 (they meet ASME B18.8.2 standards). Since the dowel is hardened I am not sure what the maximum yield strength is, I know tensile goes up with hardening but I don't have any information on the yield strength of the hardened dowel pin. I am hoping someone can shed some light on this issue. I have a beam design program I can use to help determine stress and deflection of the dowel, but I am not sure If I should model a torque moment with the rotation axis between the two bearings, or perhaps a combination of a torque moment and vertical forces. Using a housing load of 130 pounds, the formula given above, and a downward force on both bearing #1 & #2, it seems the 3/8" OD dowel has slightly less stress than the 7/16" dowel, but it deflects about .001" further. The end of the dowel is 1.26" from the cantilever support. The loaded end of the housing is 1.48" from the cantilever support, and there is a .031" space between the housing and the cantilever support. I have a 3/8" OD, lever "connection socket" that screws into the bearing housing, perpendicular to the housing, right next to the cantilever steel support. The advantage of housing #1 is that I can "step" the bearing bore in the housing so that I have a little more housing material to thread the connection socket into, since bearing # 1 is moved out from under the connection socket, and closer to the load end of the housing. The advantage of housing #2 is that the bearings are spaced further apart, and this helps reduce housing deflection due to bearing misalignment. The trade off is that I have a little less housing material to thread the connection socket into, since the socket threads in, right on top of bearing #1. The housing is oscillated by hand, and never gets hot. The radial clearance between the bearing ID and the shaft OD will be .0002" Min. to .002" maximum. If there is no way to model this to get a close estimate, I would appreciate your gut feelings as to which method is best, as far keeping the deflections at the load end of the housing to a minimum, and avoiding overloading the dowel so that it does not incur a permanent set due to the housing load. Obviously, if the dowels had the same OD in each case, then housing #2 would be best, since the bearings are spaced further apart. I think that either arrangement could take 130 pounds, but I am not sure about 200 pounds. I would like to be able to estimate the maximum housing load the dowel pin could withstand without taking a permanent set, and make a close estimate on the deflection of the dowel and housing. I want to keep the deviations of the housing end from it's longitudinal axis to a minimum, whether the deviation comes from shaft deflection or bearing misalignment. However, I need to be sure that the dowel is not going to be stressed past it's yield point, so that it springs back to it's original position when the housing load is removed, and does not take a permanent set. Thanks for your help. John |
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Request for advice regarding cantilevered mounted bearing housing, deflections and shaft stresses
"John2005" wrote in message oups.com... | Hello everyone, | | I would like to ask for some advice regarding a cantilever mounted | bearing housing. | | Due to various design constraints, I have two choices as to how I | implement a cantilevered mounted bearing housing. I have uploaded two | simple dimensioned jpeg images for reference, at the following site. | You can Save or print the images as needed. | | http://www.ice9.zoomshare.com | SNIP Model it both ways as a stationary device, but for worst case scenarios and see which works out better. Since a load is a load, regardless of whether its rotating, I think this would best be done thinking about it as static. Oh, and stop trying to think about this is such complex ways, if you do the math using simple and/or summarized numbers, you'll get the safety factor you're looking for. As to my opinion, housing two is likely the stronger of the two. You have the load more evenly distributed, despite the difference in shaft size, and this way the housing can act as a load path around the section between the two bearings, assuming they are as secure as you'd like them to be. How possible is it for you to provide a light duty thrust bearing where the housing nears the support? It could be roller or brass (better roller, I suspect, because of less wear and slop,) but either way it will pass some of the load around the pin, letting you focus more on the shear load rather than the cantilevered beam loading (you have to have a tight fit or that will be a part of it, though.) Can you provide snug or interference fit bushings on the pin between the first bearing and the support, inside the housing? This would also take up most of the bending load, and reduce the load on the pin to much closer to shear load. |
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Request for advice regarding cantilevered mounted bearing housing, deflections and shaft stresses
Hi everyone,
Thanks for your replies, Carl Mciver wrote: How possible is it for you to provide a light duty thrust bearing where the housing nears the support? It could be roller or brass (better roller, I suspect, because of less wear and slop,) but either way it will pass some of the load around the pin, letting you focus more on the shear load rather than the cantilevered beam loading (you have to have a tight fit or that will be a part of it, though.) John2005: I was thinking along the lines of using a thrust washer as well. A needle bearing thrust washer would be ideal, but it's really kind of expensive for a product like this. Brass or steel would be OK if it can be quiet over the life of the product, and wear OK with no additional lubrication beyond lubing at assembly. I was thinking of using a plastic thrust washer like Delrin or PEEK. I have a couple of choices with regards to how I mount the housing. The dowel / shaft is a "pull dowel" with a tapped end. I was going to hold the housing on with a screw going into the end of the dowel. I could put a thrust washer between the housing and the cantilever support, and put another thrust washer between the screw head and the loaded end of the housing. I would put a little dab of loc-tite on the end of the screw threads, then just snug the screw down to take up any axial play in the housing, but without any significant drag. When the loc-tite dries, the screw would never back out due to the oscillation of the housing. I had also considered using some "long-lok" screws or some screws with the nylon patches in conjunction with the loc-tite, so I would not have to keep the parts setting completely still until the loc-tite dries, i.e., the nylon patch or long-lok screw keeps the screw from backing out while the parts are being handled during assembly, and then when the loc-tite dries, the screw should never back out during use. Otherwise, I could just wait for the loc-tite to dry. It may be possible that a long-lok screw or a screw with a nylon patch on the threads would work by itself without loc-tite, I would have to test to see. I would not think there would be much force or friction on the screw head to cause it to loosen and back out. I think the thrust washer would stiffen everything up, "until" it wears, and then when you get play, you are right back at square one. If I can find a material that will be quiet and work well in a situation where re-lubrication is not possible after assembly, it may go a long way to making everything stronger, because then I would have the stiffness of the shaft, and also the .905" OD housing, which I would think would hold a very large force, since the overhang is fairly short. It's just a matter of getting a thrust washer that will be quiet and last, and be cost effective. I used my beam program to model a torque moment between the two bearings, in the middle of the span, and the stresses and deflections were much less than with vertical forces. If the forces of each bearing are purely vertical, both pushing down, then the 3/8" OD shaft deflects about .001" further than the 7/16" OD shaft, but with slightly less bending stress. However, if the forces are a pure torque moment, with the rotation axis in the middle of the two bearings, then the 7/16" dowel deflects .002" less than the 3/8" dowel, and with about 10 KSI less stress. Probably testing is the only way to find out, I don't think the bearing load will be a pure torque moment, or a pure vertical force, and I am not sure how to divide the load up between vertical and torque forces. Thanks again, John |
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Request for advice regarding cantilevered mounted bearing housing, deflections and shaft stresses
Hey John,
This is advice from strictly empirical knowledge. Looks OK, probably either way, and there should be no noticeable deflection of the "dowel" assuming the "support" is truly "fixed".....but...... If the "load element" will be of an oscillating nature, rather than rotational beyond 45 degrees, then use of Torrington style needle bearings will EVENTUALLY lead to "tracking" on the shaft, flattening of the needles and then seizing on the shaft, as the needles will always be tracking and loading only in a repeating pattern. Even worse if the force is not constant (eg..it "bangs") I would consider using a plain or oil-lite bushing if that is the case. At least when they wear, they don't "jam", and with the sizes and weight shown will easily do the job. In either instance, what is the purpose for "two" bearings. Even with the needle type, there is no sense reducing the available contact area is there? Why not a bearing or bushing that is of maximum allowable size, projecting form the bearing housing at least a few thous towards the fixed support, to provide a "rub point". And you also have not indicated at all what will keep any of this from "walking off" the shaft/dowel. Take care. Brian Lawson, Bothwell, Ontario. On 8 Nov 2005 16:52:19 -0800, "John2005" wrote: Hello everyone, I would like to ask for some advice regarding a cantilever mounted bearing housing. Due to various design constraints, I have two choices as to how I implement a cantilevered mounted bearing housing. I have uploaded two simple dimensioned jpeg images for reference, at the following site. You can Save or print the images as needed. http://www.ice9.zoomshare.com The housing has two drawn-cup needle roller bearings pressed into it, and the housing oscillates rotationally on a stationary shaft (i.e., a hardened steel dowel pin). As shown in the drawings, I can use a 7/16" OD dowel with the bearings spaced closer together, or I can use a 3/8" OD dowel with the bearings spaced further apart. 1. I mainly need to know the correct way to model how the bearing forces act on the shaft, due to the housing load, so I can determine how far the end of the shaft & housing will deflect, and whether the dowel can withstand the stresses without taking a permanent set. The maximum load on the housing will probably be about 130 pounds, but I would like for the dowel to be able to withstand a 200 pound housing load if possible, for a safety factor. I can calculate the force at each bearing, but I am not sure exactly how the force actually acts on the dowel. It seems to me that the load on the bearings will almost be a torque moment, where the the shaft is being bent between the contact points of the two bearings, with bearing #2 pushing down, and bearing #1 pushing almost upwardly. Here is the formula I used to calculate the bearing loads, the letters are shown with the corresponding dimensions, on the two drawings. Where (LA) = the housing load Load on bearing #1 = (LA) * B / A Load on bearing #2 = (LA) * C / A 2. The bearing shaft is a hardened steel pull dowel pin, made from C1541, 4037, or 4140 steel (thats all the info I can get from Mcmaster Carr). The single shear strength for the pin is 130,000 PSI. The pins have a core hardness of Rockwell C47-58, and a surface hardness of C60 (they meet ASME B18.8.2 standards). Since the dowel is hardened I am not sure what the maximum yield strength is, I know tensile goes up with hardening but I don't have any information on the yield strength of the hardened dowel pin. I am hoping someone can shed some light on this issue. I have a beam design program I can use to help determine stress and deflection of the dowel, but I am not sure If I should model a torque moment with the rotation axis between the two bearings, or perhaps a combination of a torque moment and vertical forces. Using a housing load of 130 pounds, the formula given above, and a downward force on both bearing #1 & #2, it seems the 3/8" OD dowel has slightly less stress than the 7/16" dowel, but it deflects about .001" further. The end of the dowel is 1.26" from the cantilever support. The loaded end of the housing is 1.48" from the cantilever support, and there is a .031" space between the housing and the cantilever support. I have a 3/8" OD, lever "connection socket" that screws into the bearing housing, perpendicular to the housing, right next to the cantilever steel support. The advantage of housing #1 is that I can "step" the bearing bore in the housing so that I have a little more housing material to thread the connection socket into, since bearing # 1 is moved out from under the connection socket, and closer to the load end of the housing. The advantage of housing #2 is that the bearings are spaced further apart, and this helps reduce housing deflection due to bearing misalignment. The trade off is that I have a little less housing material to thread the connection socket into, since the socket threads in, right on top of bearing #1. The housing is oscillated by hand, and never gets hot. The radial clearance between the bearing ID and the shaft OD will be .0002" Min. to .002" maximum. If there is no way to model this to get a close estimate, I would appreciate your gut feelings as to which method is best, as far keeping the deflections at the load end of the housing to a minimum, and avoiding overloading the dowel so that it does not incur a permanent set due to the housing load. Obviously, if the dowels had the same OD in each case, then housing #2 would be best, since the bearings are spaced further apart. I think that either arrangement could take 130 pounds, but I am not sure about 200 pounds. I would like to be able to estimate the maximum housing load the dowel pin could withstand without taking a permanent set, and make a close estimate on the deflection of the dowel and housing. I want to keep the deviations of the housing end from it's longitudinal axis to a minimum, whether the deviation comes from shaft deflection or bearing misalignment. However, I need to be sure that the dowel is not going to be stressed past it's yield point, so that it springs back to it's original position when the housing load is removed, and does not take a permanent set. Thanks for your help. John |
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Request for advice regarding cantilevered mounted bearing housing, deflections and shaft stresses
Hi Brian Lawson,
Thanks for your reply, The reason I used two bearings instead of one, is because two bearing engineers from two different companies recommend two bearings instead of one. This is because using two bearings spaced apart, reduces the edge loading, as opposed to using one long bearing. This is true whether you use bushings or needle rollers. This thing is just oscillated manually by hand, 1 or 2 seconds at a time, once or twice per minute, over the course of a couple of hours per day. The sweep angle is only about 10 degrees, i.e., 10 degrees in one direction and then back to the start point equals on cycle. Timken used a computer program to estimate the bearing life with the bearings spaced further apart as shown in the housing #2 drawing at the website link. At that time, I had a different housing and I was able to use a little larger OD bearing that worked on a 1/2" OD shaft, but timken's Eng. department estimated a life that was far beyond what I needed. The life was so much more than what I needed, that I figured the 3/8" and 7/16" bearings would work OK as well, even with the different spacing of the 7/16" bearings. The static load rating of all the bearings is plenty in any case. I will be using "full complement" needle rollers, packed with a high pressure grease. I checked into bronze bushings, but most bearing engineers say bronze bushings don't do well for slow moving high load oscillation or pivoting applications. I need to keep the clearance between the shaft OD and bushing / bearing ID to a minimum. With a bushing, this clearance will only open up with time, with a needle roller, the clearance will basically remain the same as it is at assembly (which is smaller than it is with most regular steel or bronze bushings) . I was going to use plastic bushings from www.igus.com, they show good wear, and tolerate misalignment, but they have clearances that are a little too large. Therefore, I chose the needle rollers. As far as what keeps the housing from walking off the shaft, please look at the post I made right before yours, where I explain the use of loc-tite on a screw that threads into the end of the dowel, i.e., the dowel is a pull dowel with a tapped end. Thanks again for your feedback, John |
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Request for advice regarding cantilevered mounted bearing housing, deflections and shaft stresses
On 10 Nov 2005 15:35:40 -0800, "John2005"
wrote: Hi Brian Lawson, SNIP This thing is just oscillated manually by hand, 1 or 2 seconds at a time, once or twice per minute, over the course of a couple of hours per day. The sweep angle is only about 10 degrees, i.e., 10 degrees in one direction and then back to the start point equals on cycle. Hey again John, I may well have missed the service life expectancy part of your earlier post. If it less than say 10 years, then no problem-o. If it is hoped for longer, than I suggest that you set up a maintenance routine whereby the bearing sees a series of relatively rapid (as fast as your hand can swing it) full rotations for a minute or so, preferably while GENTLY re-lubing, say twice yearly. Of course, it goes without saying that this would follow only if practical.... bearing like this are easy to replace and at such low cost (for materials). Take care. Brian. |
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Request for advice regarding cantilevered mounted bearing housing, deflections and shaft stresses
Hi Brian Lawson,
Actually, a product life of about 10 years is about what I have been shooting for. I want the product to be maintenance free, and Timken's Eng. department seemed to think that as long as the environment was clean, and the bearings were sealed fairly well in the housing to avoid any type of contamination, that a one time grease lube at assembly would be fine. The bearings and shaft are cheap, and easy to replace, the only thing I don't like is that I have to pack the bearings with grease myself, unless I buy a large amount that would justify a special order where Timken could do it cost effectively. I'm thinking about some type of jig I could use to pack many bearings at one time, perhaps using dowels to push the grease into the bearings. I need to give some thought to keeping the "mess" to a minimum, and avoid wasting grease in the process. Brian Lawson wrote: This is advice from strictly empirical knowledge. John2005: Empirical Knowledge is the best kind as far as I am concerned, I really appreciate the feedback of someone who has some real world experience. I will take experience over textbooks & theories anytime. Thanks again, John |
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Request for advice regarding cantilevered mounted bearing housing, deflections and shaft stresses
On 10 Nov 2005 19:05:17 -0800, "John2005"
wrote: The bearings and shaft are cheap, and easy to replace, the only thing I don't like is that I have to pack the bearings with grease myself, unless I buy a large amount that would justify a special order where Timken could do it cost effectively. I'm thinking about some type of jig I could use to pack many bearings at one time, perhaps using dowels to push the grease into the bearings. I need to give some thought to keeping the "mess" to a minimum, and avoid wasting grease in the process. Never seen a bearing greaser? The various types are dead simple to make. If you only have a couple sizes..making one for each is easy..and with some designs...you can stack a bunch of bearings and do them all at one time. http://www.columbusmaskiner.se/smorjapp_engelsk.htm http://www.americanhog.com/Garysgreaser.html Just a couple examples Gunner "Pax Americana is a philosophy. Hardly an empire. Making sure other people play nice and dont kill each other (and us) off in job lots is hardly empire building, particularly when you give them self determination under "play nice" rules. Think of it as having your older brother knock the **** out of you for torturing the cat." Gunner |
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Request for advice regarding cantilevered mounted bearing housing, deflections and shaft stresses
"John2005" wrote in message
ups.com... | Hi everyone, | | Thanks for your replies, | | Carl Mciver wrote: | How possible is it for you to provide a light duty thrust bearing where the | housing nears the support? It could be roller or brass (better roller, I | suspect, because of less wear and slop,) but either way it will pass some of | the load around the pin, letting you focus more on the shear load rather | than the cantilevered beam loading (you have to have a tight fit or that | will be a part of it, though.) | | John2005: | I was thinking along the lines of using a thrust washer as well. A | needle bearing thrust washer would be ideal, but it's really kind of | expensive for a product like this. Brass or steel would be OK if it can | be quiet over the life of the product, and wear OK with no additional | lubrication beyond lubing at assembly. I was thinking of using a | plastic thrust washer like Delrin or PEEK. SNIP Have you looked at using a wave washer? While it reduces the load factor you can use, if you find one stiff enough to resist the pressure, it can accommodate for wear of a solid wear surface. You also might look for preoiled bearings, such as DU bearing or similar, and either make or buy something that works. That's really good stuff, too, and handles high pressures really well. |
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Request for advice regarding cantilevered mounted bearing housing, deflections and shaft stresses
Hi guys,
Thanks for the additional feedback. The DU material would probably work well as a thrust washer. I also found a similar self lubricating material at www.peerinc.com (FB material) that has a PV rating of 140,000 PSI * FPM completely dry. I considered using the peer "FB" split bushings in the housing, instead of needle rollers, but they don't tolerate misalignment as well as needle rollers, and the radial clearances are larger. I should be able to find something that acts as a decent and cost effective thrust washer. I don't think there would be much axial force on the thrust washer. Thanks for the links on the bearing greasers, I should be able to rig something up for these small bearings. Sincerely, John |
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Request for advice regarding cantilevered mounted bearing housing, deflections and shaft stresses
On Fri, 11 Nov 2005 07:08:11 GMT, with neither quill nor qualm, Gunner
quickly quoth: On 10 Nov 2005 19:05:17 -0800, "John2005" wrote: The bearings and shaft are cheap, and easy to replace, the only thing I don't like is that I have to pack the bearings with grease myself, unless I buy a large amount that would justify a special order where Timken could do it cost effectively. I'm thinking about some type of jig I could use to pack many bearings at one time, perhaps using dowels to push the grease into the bearings. I need to give some thought to keeping the "mess" to a minimum, and avoid wasting grease in the process. Never seen a bearing greaser? The various types are dead simple to make. If you only have a couple sizes..making one for each is easy..and with some designs...you can stack a bunch of bearings and do them all at one time. Stacking usually allows too much to escape from the end closest to the pump, thus wasting too much grease, so take your pick. Either waste some time or some grease. http://www.columbusmaskiner.se/smorjapp_engelsk.htm I had a little 6" coned aluminum job similar to this which worked well when I didn't feel like hand-packing bearings. http://www.americanhog.com/Garysgreaser.html BAD idea. Always clean the bearings and check them for wear, period! No ifs, ands, or buts. Your life is at stake. ================================================== ============ Like peace and quiet? Buy a phoneless cord. http://www/diversify.com/stees.html Hilarious T-shirts online ================================================== ============ |
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