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.

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
  #1   Report Post  
John2005
 
Posts: n/a
Default 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

  #2   Report Post  
 
Posts: n/a
Default 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

  #3   Report Post  
Jon Grimm
 
Posts: n/a
Default 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



  #4   Report Post  
carl mciver
 
Posts: n/a
Default 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.

  #5   Report Post  
John2005
 
Posts: n/a
Default 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



  #6   Report Post  
Brian Lawson
 
Posts: n/a
Default 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

  #7   Report Post  
John2005
 
Posts: n/a
Default 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

  #8   Report Post  
Brian Lawson
 
Posts: n/a
Default 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.
  #9   Report Post  
John2005
 
Posts: n/a
Default 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

  #10   Report Post  
Gunner
 
Posts: n/a
Default 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


  #11   Report Post  
carl mciver
 
Posts: n/a
Default 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.

  #12   Report Post  
John2005
 
Posts: n/a
Default 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

  #13   Report Post  
Larry Jaques
 
Posts: n/a
Default 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
================================================== ============
Reply
Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules

Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On



All times are GMT +1. The time now is 11:04 AM.

Powered by vBulletin® Copyright ©2000 - 2024, Jelsoft Enterprises Ltd.
Copyright ©2004-2024 DIYbanter.
The comments are property of their posters.
 

About Us

"It's about DIY & home improvement"