Hi Everyone,

I need to make a small .1875" OD X .125" ID X .1875" long, plain sleeve
bushing. I will be using the bushing as a small cam-follower roller.
The bushing will oscillate or pivot on a hardened steel dowel pin
(RC60) having a surface finish of 8 micro-inch or better.

I found that I cannot use a plastic roller (www.igus.com), because the
plastic is so slippery that there is sliding between the cam curve and
the bushing OD. This wears a flat spot on the bushing OD. I cannot use
a split or wrapped bushing, ( FB series www.peerinc.com) since the
bushing seam makes a noise when it rolls on the cam curve. The cam
curve also spreads the bushing apart when the seam lines up with the
cam.

The average load on the bushing (90% of time) is about 100 pounds
(4,266 PSI), but it will intermittently have a maximum load of 168
pounds (7,160 PSI). I can only lubricate the bushing ID once at
assembly (even this is difficult) , and then never again. I also have
to be careful not to get any lube on the bushing OD.

The cam is oscillated manually by hand via a small lever. The cam
follower roller has a pivot sweep angle of 42.25 degrees (42.25 degrees
in one direction, then back to the start point = 1 cycle). The bushing
oscillation or pivot cycle speed is about 1 cycle per second on average
but can go to 3 cycles per second. This translates to a bushing sliding
speed of about 0.46 FPM to 1.4 FPM. The device is only activated about
1 to 3 seconds at a time, once or twice per minute, over the course of
about 1 or 2 Hours per day. The rest of the time the device is stopped
with a static load on the bushing of 100 pounds.

The bearing engineers tell me I should not use an oil impregnated
bronze bushing because this type of bushing generally does not do well
in slow, heavy load, oscillating or pivotal motion applications. This
is because heat from rotational friction is needed to draw the oil out
of the bushing wall and into the space between the bushing ID and shaft
OD.

I have decided that making the roller from 3/16" OD drill-rod may be
the most viable option.

I would love to get some feedback from anyone who has had some "real
world" experience using drill rod as a roller and/or bushing,. I am
interested in what type of loads, speeds, motion, lube, and wear rates
were experienced. Also, what grade of drill rod did you use & how hard
did you make it ? I hear A2 wears fairly well, and D2 wears even
better, but I don't know how hard these two steels are to machine
and/or harden. My machinist recommended W-1.

Any bushing experence with pivotal motion, you can share with me, may
be a big help.

I can only tolerate about .005" of wear off of the thickness of the
bushing wall over the life of the product, so I need something that
wears well, but I need the material to be reasonably easy to machine
and harden.

I would appreciate any feedback, comments, suggestions, experiences, or
advice, from anyone.

Thank you very much for your help.

Sincerely,
John

On 8 Sep 2005 10:38:17 -0700, wrote:

Hi Everyone,

I need to make a small .1875" OD X .125" ID X .1875" long, plain sleeve
bushing. I will be using the bushing as a small cam-follower roller.
The bushing will oscillate or pivot on a hardened steel dowel pin
(RC60) having a surface finish of 8 micro-inch or better.

snip lots of facts

Sounds to me like you need a roller made from the drill rod and the
bushing made from something else. UHMW poly or the like for the
bushing would be my first guess but you do need to research it since
the load might be a little high with such a small axle.


Wayne Cook
Shamrock, TX
http://members.dslextreme.com/users/waynecook/index.htm

Hi Wayne,

Thanks for your reply.

Would the drill rod roller by itself (with no liner on the ID) not wear
OK for a slow moving hand operated device ?

The part is so small, the bushing wall is only 1/32" thick, and that is
without any type of liner on the ID, that's just making the bushing out
of solid drill rod. It seems machining or making a thin walled liner to
go on the ID will be very difficult.

The bushing OD cannot be any larger than 3/16".

Thanks
John

In article 1126201097.584262.69570
@z14g2000cwz.googlegroups.com,
says...
Hi Everyone,

I need to make a small .1875" OD X .125" ID X .1875" long, plain sleeve
bushing. I will be using the bushing as a small cam-follower roller.
The bushing will oscillate or pivot on a hardened steel dowel pin
(RC60) having a surface finish of 8 micro-inch or better.


The average load on the bushing (90% of time) is about 100 pounds
(4,266 PSI), but it will intermittently have a maximum load of 168
pounds (7,160 PSI). I can only lubricate the bushing ID once at
assembly (even this is difficult) , and then never again. I also have
to be careful not to get any lube on the bushing OD.


With a 1/32" wall the bearing is going to deform and you're
not going to see uniform pressure on the entire bearing
area. In other words, the max pressure is going to much
higher than you've calculated. I'd be willing to bet that
the pressure distribution between the pin and follower will
be closer to that you'd see between the pin and cam if the
follower were not present. The formulae for calculating the
pressure between two curved surfaces account for the
deformation of the two bodies in the contact area.

Googling-
bearing "hertzian stresses"
-turned this up among plenty of other promising links.

http://212.90.7.34/shigley/studenti/tutorial/6177-4
_Hertz_Contact_Stresses.pdf

Do you have to use a rolling follower? Depending on the
shape of the cam, you might do better with a sliding
follower that spreads the load over a larger area.

Ned Simmons

John,
Have a look at this nickel based, high heat resistent alloy made by
Haynes International. It's called HASTELLOY=AE S alloy. You can see it
at this Haynes Web site:
http://www.haynesintl.com/Salloy/HastelloyS.htm

Haynes makes exotic alloys & was originaly founded by a man names
Elwood Haynes who was the inventor of the following:
1=2E) Stainless Steel.

2=2E) The 1st internal combustion powered car.

3=2E) slot car racing.

4=2E) An alloy called stellite.

I only know all this because he hailed from my home town of Kokomo,
Indiana which is where Haynes still manufactures many of it's alloys
today. Hope this helped...
-Wayne-

Hi everyone,

Thanks for your replies. I will check into the Haynes site Wayne. If
the founder of Haynes invented stainless steel, I am a fan of His.

Ned, I may be able to use a "non rotating" 3/16" OD hardened steel
dowel pin for a follower, If this is what you meant by "sliding
follower". Would I probably need to put a hard chrome plating on the
pin ?

The main problem I would be worried about with a non-rotating pin as a
follower is that I think the sliding noise may be too great. I need to
keep the device as quiet as possible. I want the product to be
maintenance free, and I could only lube it once at assembly. I had
planned on making the cam from 4140 steel, hardened to 20 to 32 RC.

If there is a way to make it quiet for the life of the product, and
wear well, a non-rotating pin may be the way to go. I found a chrome
plating http://www.armoloy.com/ that looks interesting, if it can be
cost effective.

Thanks
John

Hi everyone,

Thanks for your replies. I will check into the Haynes site Wayne. If
the founder of Haynes invented stainless steel, I am a fan of His.

Ned, I may be able to use a "non rotating" 3/16" OD hardened steel
dowel pin for a follower, If this is what you meant by "sliding
follower". Would I probably need to put a hard chrome plating on the
pin ?

The main problem I would be worried about with a non-rotating pin as a
follower is that I think the sliding noise may be too great. I need to
keep the device as quiet as possible. I want the product to be
maintenance free, and I could only lube it once at assembly. I had
planned on making the cam from 4140 steel, hardened to 20 to 32 RC.

If there is a way to make it quiet for the life of the product, and
wear well, a non-rotating pin may be the way to go. I found a chrome
plating http://www.armoloy.com/ that looks interesting, if it can be
cost effective.

Thanks
John

In article 1126233070.845089.200900
@o13g2000cwo.googlegroups.com,
says...


Ned, I may be able to use a "non rotating" 3/16" OD hardened steel
dowel pin for a follower, If this is what you meant by "sliding
follower".

Sort of, but I was also suggesting that you try to increase
the contact area between the cam and follower. I don't know
what the shape of your cam is, but the ideal situation
would be if the cam were an eccentric circle, the follower
could have a concave face that approximates the curvature
of the cam. This would reduce the contact pressure
drastically. If the cam is more complex, which I expect is
the case, the shape of the follower would have to be a
compromise.

Would I probably need to put a hard chrome plating on the
pin ?


A carbide pin would probably be cheaper, unless you're
talking about large quantities, and assuming impact isn't a
problem.

Ned Simmons

wrote in message
ups.com...
Hi Everyone,

I need to make a small .1875" OD X .125" ID X .1875" long, plain sleeve
bushing. I will be using the bushing as a small cam-follower roller.
The bushing will oscillate or pivot on a hardened steel dowel pin
(RC60) having a surface finish of 8 micro-inch or better.

I found that I cannot use a plastic roller (www.igus.com), because the
plastic is so slippery that there is sliding between the cam curve and
the bushing OD. This wears a flat spot on the bushing OD. I cannot use
a split or wrapped bushing, ( FB series www.peerinc.com) since the
bushing seam makes a noise when it rolls on the cam curve. The cam
curve also spreads the bushing apart when the seam lines up with the
cam.

The average load on the bushing (90% of time) is about 100 pounds
(4,266 PSI), but it will intermittently have a maximum load of 168
pounds (7,160 PSI). I can only lubricate the bushing ID once at
assembly (even this is difficult) , and then never again. I also have
to be careful not to get any lube on the bushing OD.

The cam is oscillated manually by hand via a small lever. The cam
follower roller has a pivot sweep angle of 42.25 degrees (42.25 degrees
in one direction, then back to the start point = 1 cycle). The bushing
oscillation or pivot cycle speed is about 1 cycle per second on average
but can go to 3 cycles per second. This translates to a bushing sliding
speed of about 0.46 FPM to 1.4 FPM. The device is only activated about
1 to 3 seconds at a time, once or twice per minute, over the course of
about 1 or 2 Hours per day. The rest of the time the device is stopped
with a static load on the bushing of 100 pounds.

The bearing engineers tell me I should not use an oil impregnated
bronze bushing because this type of bushing generally does not do well
in slow, heavy load, oscillating or pivotal motion applications. This
is because heat from rotational friction is needed to draw the oil out
of the bushing wall and into the space between the bushing ID and shaft
OD.

I have decided that making the roller from 3/16" OD drill-rod may be
the most viable option.

I would love to get some feedback from anyone who has had some "real
world" experience using drill rod as a roller and/or bushing,. I am
interested in what type of loads, speeds, motion, lube, and wear rates
were experienced. Also, what grade of drill rod did you use & how hard
did you make it ? I hear A2 wears fairly well, and D2 wears even
better, but I don't know how hard these two steels are to machine
and/or harden. My machinist recommended W-1.

Any bushing experence with pivotal motion, you can share with me, may
be a big help.

I can only tolerate about .005" of wear off of the thickness of the
bushing wall over the life of the product, so I need something that
wears well, but I need the material to be reasonably easy to machine
and harden.

I would appreciate any feedback, comments, suggestions, experiences, or
advice, from anyone.

Thank you very much for your help.

Sincerely,
John


Personally, I'd use 52100. I'd rough the rollers, heat treat them to, say,
58/60Rc, then hone and grind them.

Harold

wrote:
I need to make a small .1875" OD X .125" ID X .1875" long, plain sleeve
bushing. ...
The bushing will oscillate or pivot on a hardened steel dowel pin
....

Instead of a bushing pivoting on a stationary pin, could you have a
..1875 pin that pivots in outboard supports? E.g., ball bearings. Or a
pin whose outboard diameter is larger to lessen the psi load? Bob

Hi everyone,

Thanks for your reply Bob, but I'm afraid I don't have room to put
bearings on each side of the shaft. I have a very, very, confined and
limited space to work in. This is why the cam and cam-follower roller
are so small.

Thanks
John

In article 1126361485.686908.11060
@z14g2000cwz.googlegroups.com,
says...
Hi everyone,

Thanks for your reply Bob, but I'm afraid I don't have room to put
bearings on each side of the shaft. I have a very, very, confined and
limited space to work in. This is why the cam and cam-follower roller
are so small.


Unfortunately at this point you've got a design problem
rather than a materials problem. Until you've got a better
model of the pressures involved in your mechanism you're
shooting in the dark trying to select materials. You can
either use the materials on Hertzian stresses I pointed to
before and go thru the admittedly ugly calculations, or
change the design to something that's easier to analyze.

I've designed my share of cam operated machinery, and my
gut feeling is that the design is not practical as
conceived.

Ned Simmons

Hi everyone,

I think I have found a suitable solution and/or compromise.

Ned, thanks for your reply. I would especially appreciate your comments
& thoughts on the following, since you have designed cam mechanisms.

After Bobs reply, I did not think I had enough space to have the
cam-follower roller "rotate with" the shaft, & put a bearing on each
side of the shaft. I had thought of this before, but the available
space is so small, I just did not think there would be a stock bushing
small enough.

However, I found a self lubricating plastic bushing from www.igus.com
(part # GSM-0203-03), 2 mm ID X 3.5 mm OD X 3 mm long. I do have "just
enough" space to put one of these miniature bushings on each side of
the shaft. I used the online computer program at the Igus site, their
"expert system" under "online tools" to calculate bushing life under
the most severe conditions, and even with shock loads and "edge
loading" selected in the program, they showed excellent life. Since the
cam-follower load is in the center of the two plastic bushings, the
maximum cam-follower load of 168 pounds is reduced to 84 pounds per
each of the plastic bushings. The bushings are only 0.32 cents each in
quantities of 500, so its cost effective.

I will still use some 3/16" OD, W-1 or D2 drill rod as a cam-follower
roller, but now, the roller ID will have a press fit on the 2 mm OD
shaft, so the roller rotates with the shaft. The shaft will then be
supported by a miniature Iglide self lubricating plastic bushing at
each end.

I think the cam-follower should roll well using this method, since the
Iglide bushings have very low friction. Plus, I still have a 3/16" OD
roller with a smaller shaft. This also eliminates the problem with the
roller having a thin wall, since the roller ID is now pressed onto the
2 mm OD shaft, and it's really like a solid roller having no wall.

With the previous method of just using a 3/16" OD hardened steel
bushing oscillating on a 1/8" OD hardened shaft, even if it had
acceptable wear, I just don't know how good it would actually "roll". I
tend to think it would not have reliably rolled well, and there would
have been sliding between the cam and roller OD.

I think this new method will work well, and seems to be about the best
solution I have found. However, I am interested what everyone thinks.
Since the cam is oscillated manually by hand and the speeds are slow,
using the new method where the cam-follower "rotates with" the shaft,
and the shaft is supported by a bushing at each end, do you think I can
get away with not hardening the drill-rod roller ? Perhaps I should
harden it anyway, in case there is still some small degree of sliding
between the cam and roller OD. I supose it's hard to get truly "pure
rolling action" 100% of the time.

I was thinking of possibly using some "belt dressing" on the cam curve
to increase friction between the Cam curve and roller OD, to insure the
roller always rolls in the shaft and there is no or very minimal
sliding between the cam and roller OD.

http://www.lpslabs.com/Products/Lubr...t_Dressing.asp

The belt dressing lasts for a long time on fast rotating & hot belts,
so perhaps it might last plenty long on a hand operated device that
pivots slow and never gets hot.

Does anyone have any other ideas for a friction coating on the cam
curve or roller OD that would last and handle high loads ? My machinist
suggested to "glass bead blast" the cam curve in increase traction
between the cam and roller OD.

Bob, thanks allot for your reply, because you got me thinking again of
having the cam-follower rotate with the shaft, & putting a bushing on
each side of the shaft. Then, when I was looking through the igus
catalog, I found the miniature bushing and put everything together. I
did not know they made bushings that small, that could support loads
14,310 PSI with a PV of 12,000 dry.

Thanks again to everyone that has replied, especially Ned and Bob. I
have so many constraints on this design, because of the limited space,
I was really starting to feel boxed in. It always helps to get feedback
from other people, and that's why forums like this are great.

Sincerely,
John

John2005 wrote:
.... It always helps to get feedback
from other people, and that's why forums like this are great.

In my experience RCM is one of the best. I discovered it about 5 years
ago and it amazes me what I learn here. From the help I get on
problems/questions that I have and from just listening in on others
posts. And not just metalworking, but all kinds of stuff.

Glad that I could help, even if it was just a nudge to your thinking.

Bob

In article 1126457224.121977.55810
@f14g2000cwb.googlegroups.com,
says...


Bob, thanks allot for your reply, because you got me thinking again of
having the cam-follower rotate with the shaft, & putting a bushing on
each side of the shaft. Then, when I was looking through the igus
catalog, I found the miniature bushing and put everything together. I
did not know they made bushings that small, that could support loads
14,310 PSI with a PV of 12,000 dry.

Thanks again to everyone that has replied, especially Ned and Bob. I
have so many constraints on this design, because of the limited space,
I was really starting to feel boxed in. It always helps to get feedback
from other people, and that's why forums like this are great.

Sincerely,
John


This sounds like a huge improvement. Igus = good, I
purchase a fair amount of stuff from them. Are you familiar
with drill jig bushings? I think it's quite likely you can
use them for your follower. They're very hard, usually made
of 52100 bearing steel, and can be had in a large range of
ID, OD, and length. 3/16 OD bushings are available as
standard from 1.6 to 2.5mm ID, and from 1/4 to 3/4" long.
You can specify any ID you please within that range.

Here's one source...

http://www.carrlane.com/Catalog/inde...025071F0B22111
8070C1C512D020609090C0015482013180B041D1E173C3B285 351435D

Ned Simmons

Hi everyone,

I just wanted to say thanks again for all your help and repies. I think
I have a viable solution now. Thanks for the drill jig bushing tip Ned,
I will check into it.

Sincerely,
John