Hi guys. I have a unique garage business selling hardware to builders and repairers of upright basses. Check bass capos dot com for details. One thing they need is a small but strong pulley wheel with a 1/8" dia. round belt race. The ones I supply are brass with a sealed bearing and are a bit overbuilt and expensive for the application. I want to arrange for a run of a few hundred which would be more fit for purpose, and hopefully a bit cheaper.

The plan is for a 7/8" dia. x 1/4" wide brass pulley with a 1/4" brass axle and without the sealed bearing. There is a constant force of about 120 lbs.. on the shaft, but almost no rotation. Maybe +/- 1-2° a few times a day for tuning, and no adjustments at all sometimes for weeks or months, and it must be usable for decades. I think that simple brass on brass should work if both parts are well machined/polished/lubricated, but there have been anecdotal failures. So, I need to do something more if only for marketing, but also I stupidly offer a ten year warranty. So, I must be very careful about how I design and produce my wares!

Anyway, what are some options?

1. A polished SS shaft instead of brass? Good, but the customer needs to cut the shaft to length and polish the ends. Not practical for most violinmakers /repairers. They can always special order the needed length, so not out of the question, but extra pain.

2. A bearing-grade bronze shaft with brass pulley? Seems like the most cheap and practical, but how durable?

2. A greased bronze or SS sleeve between the brass shaft and the pulley? Sounds good except that afaik it would have to be machined from solid round, upping costs. Anyone know of bushing sleeve available in small diameters like this?

3. Delrin bushing sleeve? This seems available in the size I need, but some customers really don't want any plastic on their bass. I know. It's just something you have to deal with in my world.

4. SS or bronze Pulley? sounds expensive.

Anyway, I hope there is someone out there with interest and understanding of the specific issue I discuss, and who has the time to give advice.

Please do not post if you wish to warn me of:
A - the risks to life and limb of using metalworking machinery, or anything else which uses electricity or has sharp cutting edges.
B - the liability risk of altering something without UL approval, or using it for a purpose not described by the manufacturer.

wrote:
Hi guys. I have a unique garage business selling hardware to builders and repairers of upright basses. Check bass capos dot com for details. One thing they need is a small but strong pulley wheel with a 1/8" dia. round belt race. The ones I supply are brass with a sealed bearing and are a bit overbuilt and expensive for the application. I want to arrange for a run of a few hundred which would be more fit for purpose, and hopefully a bit cheaper.

The plan is for a 7/8" dia. x 1/4" wide brass pulley with a 1/4" brass axle and without the sealed bearing. There is a constant force of about 120 lbs. on the shaft, but almost no rotation. Maybe +/- 1-2? a few times a day for tuning, and no adjustments at all sometimes for weeks or months, and it must be usable for decades. I think that simple brass on brass should work if both parts are well machined/polished/lubricated, but there have been anecdotal failures. So, I need to do something more if only for marketing, but also I stupidly offer a ten year warranty. So, I must be very careful about how I design and produce my wares!

Anyway, what are some options?

1. A polished SS shaft instead of brass? Good, but the customer needs to cut the shaft to length and polish the ends. Not practical for most violinmakers /repairers. They can always special order the needed length, so not out of the question, but extra pain.

2. A bearing-grade bronze shaft with brass pulley? Seems like the most cheap and practical, but how durable?

2. A greased bronze or SS sleeve between the brass shaft and the pulley? Sounds good except that afaik it would have to be machined from solid round, upping costs. Anyone know of bushing sleeve available in small diameters like this?

3. Delrin bushing sleeve? This seems available in the size I need, but some customers really don't want any plastic on their bass. I know. It's just something you have to deal with in my world.

4. SS or bronze Pulley? sounds expensive.

Anyway, I hope there is someone out there with interest and understanding of the specific issue I discuss, and who has the time to give advice.

Please do not post if you wish to warn me of:
A - the risks to life and limb of using metalworking machinery, or anything else which uses electricity or has sharp cutting edges.
B - the liability risk of altering something without UL approval, or using it for a purpose not described by the manufacturer.

If you have a premium product, why not stick with the bearings and brag
about them?

is your product just functional or something you and the buyer will be
proud of owning?

On Mon, 01 Apr 2013 09:15:51 -0700, lostfrom68jay wrote:

Hi guys. I have a unique garage business selling hardware to builders
and repairers of upright basses. Check bass capos dot com for details.
One thing they need is a small but strong pulley wheel with a 1/8" dia.
round belt race. The ones I supply are brass with a sealed bearing and
are a bit overbuilt and expensive for the application. I want to arrange
for a run of a few hundred which would be more fit for purpose, and
hopefully a bit cheaper.

The plan is for a 7/8" dia. x 1/4" wide brass pulley with a 1/4" brass
axle and without the sealed bearing. There is a constant force of about
120 lbs. on the shaft, but almost no rotation. Maybe +/- 1-2° a few
times a day for tuning, and no adjustments at all sometimes for weeks or
months, and it must be usable for decades. I think that simple brass on
brass should work if both parts are well machined/polished/lubricated,
but there have been anecdotal failures. So, I need to do something more
if only for marketing, but also I stupidly offer a ten year warranty.
So, I must be very careful about how I design and produce my wares!

Anyway, what are some options?

1. A polished SS shaft instead of brass? Good, but the customer needs to
cut the shaft to length and polish the ends. Not practical for most
violinmakers /repairers. They can always special order the needed
length, so not out of the question, but extra pain.

2. A bearing-grade bronze shaft with brass pulley? Seems like the most
cheap and practical, but how durable?

2. A greased bronze or SS sleeve between the brass shaft and the pulley?
Sounds good except that afaik it would have to be machined from solid
round, upping costs. Anyone know of bushing sleeve available in small
diameters like this?

3. Delrin bushing sleeve? This seems available in the size I need, but
some customers really don't want any plastic on their bass. I know. It's
just something you have to deal with in my world.

4. SS or bronze Pulley? sounds expensive.

Anyway, I hope there is someone out there with interest and
understanding of the specific issue I discuss, and who has the time to
give advice.

Please do not post if you wish to warn me of: A - the risks to life and
limb of using metalworking machinery, or anything else which uses
electricity or has sharp cutting edges. B - the liability risk of
altering something without UL approval, or using it for a purpose not
described by the manufacturer.

How polished do the ends need to be? You can cut a 1/4" piece of music
wire to length with a cutoff wheel in a Dremel tool and a bit of patience
-- is this not an expected tool in your customer's shops?

I would think that a hard alloy steel shaft would be way better than
stainless -- stainless isn't known for being low friction, and I'm not
sure if the grease would stay in place over months.

Does the pulley have to be free to turn no matter how small the rotation
demanded of it, after a month of sitting still? What kind of torques are
involved? You may have some stick-slip issues to contend with.

It may be that the bee's knees for this is a hardened steel shaft that's
been hard chromed and polished, with a bronze bearing surface on the
pulley -- but that may be even more overkill than you have now.

--
My liberal friends think I'm a conservative kook.
My conservative friends think I'm a liberal kook.
Why am I not happy that they have found common ground?

Tim Wescott, Communications, Control, Circuits & Software
http://www.wescottdesign.com

On Mon, 1 Apr 2013 09:15:51 -0700 (PDT),
wrote:

Hi guys. I have a unique garage business selling hardware to builders and repairers of upright basses. Check bass capos dot com for details. One thing they need is a small but strong pulley wheel with a 1/8" dia. round belt race. The ones I supply are brass with a sealed bearing and are a bit overbuilt and expensive for the application. I want to arrange for a run of a few hundred which would be more fit for purpose, and hopefully a bit cheaper.

The plan is for a 7/8" dia. x 1/4" wide brass pulley with a 1/4" brass axle and without the sealed bearing. There is a constant force of about 120 lbs. on the shaft, but almost no rotation. Maybe +/- 1-2° a few times a day for tuning, and no adjustments at all sometimes for weeks or months, and it must be usable for decades. I think that simple brass on brass should work if both parts are well machined/polished/lubricated, but there have been anecdotal failures. So, I need to do something more if only for marketing, but also I stupidly offer a ten year warranty. So, I must be very careful about how I design and produce my wares!

Anyway, what are some options?

What's wrong with an oil+PTFE-impregnated bronze bushing bearing on
the 1/4" shaft? You'll need something like a 3/8" hole in the pulley.
It's a standard part costing less than $1.

1. A polished SS shaft instead of brass? Good, but the customer needs to cut the shaft to length and polish the ends. Not practical for most violinmakers /repairers. They can always special order the needed length, so not out of the question, but extra pain.

2. A bearing-grade bronze shaft with brass pulley? Seems like the most cheap and practical, but how durable?

2. A greased bronze or SS sleeve between the brass shaft and the pulley? Sounds good except that afaik it would have to be machined from solid round, upping costs. Anyone know of bushing sleeve available in small diameters like this?

3. Delrin bushing sleeve? This seems available in the size I need, but some customers really don't want any plastic on their bass. I know. It's just something you have to deal with in my world.

4. SS or bronze Pulley? sounds expensive.

Anyway, I hope there is someone out there with interest and understanding of the specific issue I discuss, and who has the time to give advice.

Please do not post if you wish to warn me of:
A - the risks to life and limb of using metalworking machinery, or anything else which uses electricity or has sharp cutting edges.
B - the liability risk of altering something without UL approval, or using it for a purpose not described by the manufacturer.

Watch out for paper cuts when you type out the P.O.

On Mon, 01 Apr 2013 09:15:51 -0700, lostfrom68jay wrote:

[snip]
The plan is for a 7/8" dia. x 1/4" wide brass pulley with a 1/4" brass axle and without the sealed bearing. There is a constant force of about 120 lbs. on the shaft, but almost no rotation. Maybe +/- 1-2° a few times a day for tuning, and no adjustments at all sometimes for weeks or months, and it must be usable for decades. I think that simple brass on brass should work if both parts are well machined/polished/lubricated, but there have been anecdotal failures. So, I need to do something more if only for marketing, but also I stupidly offer a ten year warranty. So, I must be very careful about how I design and produce my wares!

Anyway, what are some options?

1. A polished SS shaft instead of brass? Good, but the customer needs to cut the shaft to length and polish the ends. Not practical for most violinmakers /repairers. They can always special order the needed length, so not out of the question, but extra pain.
[snip]

Dowel pins might work. Click Dowel Pins, 1/4" diam, alloy steel,
etc at http://www.mcmaster.com/#standard-dowel-pins/=m4uuzx

A package of 25 each 1/4" diam by 3/4" long alloy steel dowel pins
appears to cost $5.24; other lengths that are multiples of 1/8" also
are inexpensive, eg $3.62 for 25 ea. 1/2" long. Odd multiples of
1/16" are available but several times as expensive; eg $14 for 10 ea
11/16" long. You could include one each of the 5/8", 3/4", and 7/8"
pins in your kit for a cost to you of about 60 cents. The user can
grind off 1/16" or whatever, if the needed length is between two of
the cheap sizes.

--
jiw

On Mon, 1 Apr 2013 09:15:51 -0700 (PDT),
wrote:

Hi guys. I have a unique garage business selling hardware to builders and repairers of upright basses. Check bass capos dot com for details. One thing they need is a small but strong pulley wheel with a 1/8" dia. round belt race. The ones I supply are brass with a sealed bearing and are a bit overbuilt and expensive for the application. I want to arrange for a run of a few hundred which would be more fit for purpose, and hopefully a bit cheaper.

The plan is for a 7/8" dia. x 1/4" wide brass pulley with a 1/4" brass axle and without the sealed bearing. There is a constant force of about 120 lbs. on the shaft, but almost no rotation. Maybe +/- 1-2° a few times a day for tuning, and no adjustments at all sometimes for weeks or months, and it must be usable for decades. I think that simple brass on brass should work if both parts are well machined/polished/lubricated, but there have been anecdotal failures. So, I need to do something more if only for marketing, but also I stupidly offer a ten year warranty. So, I must be very careful about how I design and produce my wares!

Anyway, what are some options?

1. A polished SS shaft instead of brass? Good, but the customer needs to cut the shaft to length and polish the ends. Not practical for most violinmakers /repairers. They can always special order the needed length, so not out of the question, but extra pain.
Not sure what's in a typical violin makers shop, but a 1/4" SS (303 or
304) round is easy to cut with a decent hacksaw.

2. A bearing-grade bronze shaft with brass pulley? Seems like the most cheap and practical, but how durable?
I doubt a bearing bronze will be much better than what you've got.
Though not ideal, you might get away with an aluminum bronze or other
hard alloy, but you may find they're not much easier to cut than SS,
and you may have trouble finding the shape and tolerances you need.
Ampco would be the place to look.
http://www.ampcometal.com/en/index.php?page=home

2. A greased bronze or SS sleeve between the brass shaft and the pulley? Sounds good except that afaik it would have to be machined from solid round, upping costs. Anyone know of bushing sleeve available in small diameters like this?
My gut is you could get SS bushings made for $1 or less in the
quantity you mentioned. There are thin steel bushings with various
anti-friction linings available, but they're generally not
inexpensive. A drill jig bushing would work, but also not cheap.

3. Delrin bushing sleeve? This seems available in the size I need, but some customers really don't want any plastic on their bass. I know. It's just something you have to deal with in my world.
Not Delrin, something from Igus. Probably less than $.25 in quantity.
http://www.igus.com/default.asp?PAGE=IGLIDE

4. SS or bronze Pulley? sounds expensive.

Anyway, I hope there is someone out there with interest and understanding of the specific issue I discuss, and who has the time to give advice.

Please do not post if you wish to warn me of:
A - the risks to life and limb of using metalworking machinery, or anything else which uses electricity or has sharp cutting edges.
B - the liability risk of altering something without UL approval, or using it for a purpose not described by the manufacturer.



--
Ned Simmons

On Apr 1, 10:15*am, wrote:
Hi guys. I have a unique garage business selling hardware to builders and repairers of upright basses. Check bass capos dot com for details. One thing they need is a small but strong pulley wheel with a 1/8" dia. round belt race. The ones I supply are brass with a sealed bearing and are a bit overbuilt and expensive for the application. I want to arrange for a run of a few hundred which would be more fit for purpose, and hopefully a bit cheaper..

The plan is for a 7/8" dia. x 1/4" wide brass pulley with a 1/4" brass axle and without the sealed bearing. There is a constant force of about 120 lbs. on the shaft, but almost no rotation. Maybe +/- 1-2° a few times a day for tuning, and no adjustments at all sometimes for weeks or months, and it must be usable for decades. I think that simple brass on brass should work if both parts are well machined/polished/lubricated, but there have been anecdotal failures. So, I need to do something more if only for marketing, but also I stupidly offer a ten year warranty. So, I must be very careful about how I design and produce my wares!

Anyway, what are some options?

1. A polished SS shaft instead of brass? Good, but the customer needs to cut the shaft to length and polish the ends. Not practical for most violinmakers /repairers. They can always special order the needed length, so not out of the question, but extra pain.

2. A bearing-grade bronze shaft with brass pulley? Seems like the most cheap and practical, but how durable?

2. A greased bronze or SS sleeve between the brass shaft and the pulley? Sounds good except that afaik it would have to be machined from solid round, upping costs. Anyone know of bushing sleeve available in small diameters like this?

3. Delrin bushing sleeve? This seems available in the size I need, but some customers really don't want any plastic on their bass. I know. It's just something you have to deal with in my world.

4. SS or bronze Pulley? sounds expensive.

Anyway, I hope there is someone out there with interest and understanding of the specific issue I discuss, and who has the time to give advice.

Please do not post if you wish to warn me of:
A - the risks to life and limb of using metalworking machinery, or anything else which uses electricity or has sharp cutting edges.
B - the liability risk of altering something without UL approval, or using it for a purpose not described by the manufacturer.

A ball-bearing isn't needed in this application, it's not in constant
rotation, a waste of money. You need a non-deforming shaft/sleeve
combination, hardened steel and cast iron would work, a bronze sleeve
might deform with constant load, depending on how large the shaft is.
Make your pulley of cast iron, use a hardened dowel pin and you're
set. Figure out your unit load pressure, I think you'll be surprised
since it's pretty much going to be a line contact.

Stan

Thanks everyone for the info so far. I find some of it very useful and I'm glad to see that the forum still has some real content.
Robobass

Excellent! I'll study this.

wrote in message
...
Hi guys. I have a unique garage business selling hardware to builders and
repairers of upright basses. Check bass capos dot com for details. One thing
they need is a small but strong pulley wheel with a 1/8" dia. round belt
race. The ones I supply are brass with a sealed bearing and are a bit
overbuilt and expensive for the application. I want to arrange for a run of
a few hundred which would be more fit for purpose, and hopefully a bit
cheaper.

The plan is for a 7/8" dia. x 1/4" wide brass pulley with a 1/4" brass axle
and without the sealed bearing. There is a constant force of about 120 lbs.
on the shaft, but almost no rotation. Maybe +/- 1-2° a few times a day for
tuning, and no adjustments at all sometimes for weeks or months, and it must
be usable for decades. I think that simple brass on brass should work if
both parts are well machined/polished/lubricated, but there have been
anecdotal failures. So, I need to do something more if only for marketing,
but also I stupidly offer a ten year warranty. So, I must be very careful
about how I design and produce my wares!

Anyway, what are some options?

1. A polished SS shaft instead of brass? Good, but the customer needs to cut
the shaft to length and polish the ends. Not practical for most violinmakers
/repairers. They can always special order the needed length, so not out of
the question, but extra pain.

2. A bearing-grade bronze shaft with brass pulley? Seems like the most cheap
and practical, but how durable?

2. A greased bronze or SS sleeve between the brass shaft and the pulley?
Sounds good except that afaik it would have to be machined from solid round,
upping costs. Anyone know of bushing sleeve available in small diameters
like this?

3. Delrin bushing sleeve? This seems available in the size I need, but some
customers really don't want any plastic on their bass. I know. It's just
something you have to deal with in my world.

4. SS or bronze Pulley? sounds expensive.

Anyway, I hope there is someone out there with interest and understanding of
the specific issue I discuss, and who has the time to give advice.

Please do not post if you wish to warn me of:
A - the risks to life and limb of using metalworking machinery, or anything
else which uses electricity or has sharp cutting edges.
B - the liability risk of altering something without UL approval, or using
it for a purpose not described by the manufacturer.

================================

I think if I were doing this, I would press-fit the shaft into the wheel and
have the bushings at the ends of the shaft. That would prevent the wheel
from wobbling due to any clearance in the bushing. Perhaps the shaft could
have just a short section of the larger diameter in the middle to make
press-fitting during assembly easier. For the bushing, if you can not find
the right stainless sleeve, you could drill out an unthreaded stainless
steel spacer to the right size (or size the shaft to match). You could also
use some stainless tubing and drill it out to the right size (often then
have a weld seam that protrudes on the inside). Although one problem with
this whole concept is you would need a step in the shaft at each end to keep
the shaft from moving laterally, so that would require specific lengths that
you were trying to avoid.

Here's another idea: The brass wheel rotates on a short S.S. shaft made from
an internally threaded spacer. The ends of the shaft are made from hollow
brass spacers held to the center portion with screws from both ends (perhaps
brass for aesthetics?). The OD of the brass spacers could be larger than the
center portion of the shaft to provide strength and some lateral support
against wobbling.

On Mon, 01 Apr 2013 14:41:47 -0400, Spehro Pefhany
wrote:

On Mon, 1 Apr 2013 09:15:51 -0700 (PDT),
wrote:

Hi guys. I have a unique garage business selling hardware to builders and repairers of upright basses. Check bass capos dot com for details. One thing they need is a small but strong pulley wheel with a 1/8" dia. round belt race. The ones I supply are brass with a sealed bearing and are a bit overbuilt and expensive for the application. I want to arrange for a run of a few hundred which would be more fit for purpose, and hopefully a bit cheaper.

The plan is for a 7/8" dia. x 1/4" wide brass pulley with a 1/4" brass axle and without the sealed bearing. There is a constant force of about 120 lbs. on the shaft, but almost no rotation. Maybe +/- 1-2° a few times a day for tuning, and no adjustments at all sometimes for weeks or months, and it must be usable for decades. I think that simple brass on brass should work if both parts are well machined/polished/lubricated, but there have been anecdotal failures. So, I need to do something more if only for marketing, but also I stupidly offer a ten year warranty. So, I must be very careful about how I design and produce my wares!

Anyway, what are some options?

What's wrong with an oil+PTFE-impregnated bronze bushing bearing on
the 1/4" shaft? You'll need something like a 3/8" hole in the pulley.
It's a standard part costing less than $1.

P.S. an SAE 841 sleeve bearing with a Pmax of 2,000 will have a
maximum load (zero RPM) of 125 lbs on a 0.25" shaft if it is 0.25"
long. A 3/8 long 1/4" bearing would be rated proportionally more.

They recommend shaft hardness Rb 85 for the shaft material.

http://www.capturedlightning.org/hot...rasssleeve.pdf


Best regards,
Spehro Pefhany
--
"it's the network..." "The Journey is the reward"
Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog Info for designers: http://www.speff.com

There is some food for thought! I just found some small oil impregnated bronze sleeve bearings which cost only 34 cents and could hold up to 250 lbs. This would allow me to stick with a 1/4" brass shaft, so I think I'll go with that.
Thanks everyone!

wrote in message
...
There is some food for thought! I just found some small oil impregnated
bronze sleeve bearings which cost only 34 cents and could hold up to 250
lbs. This would allow me to stick with a 1/4" brass shaft, so I think I'll
go with that.
Thanks everyone!


A bronze bushing on brass shaft is somehting that I have never seen and it
is certainly not how the bronze bushing was meant to be used. It is quite
possible there would be too much chemical affinity and they would start to
stick and gall.

On Tue, 2 Apr 2013 09:54:20 -0700, "anorton"
wrote:


wrote in message
...
There is some food for thought! I just found some small oil impregnated
bronze sleeve bearings which cost only 34 cents and could hold up to 250
lbs. This would allow me to stick with a 1/4" brass shaft, so I think I'll
go with that.
Thanks everyone!


A bronze bushing on brass shaft is somehting that I have never seen and it
is certainly not how the bronze bushing was meant to be used. It is quite
possible there would be too much chemical affinity and they would start to
stick and gall.

Absolutely. Do not use such similar materials for shaft and bushing
unless they are extremely hard and have low cohesion coefficients. No
way do you want to use two copper alloys together.

Music wire or other hard, high-carbon steel is the logical choice for
the shaft. If rust is an issue, then 440-grade stainless steel.

The ideal wheel would be a high-strength (over 100,000 psi compression
strength) bronze, but it probably isn't necessary. Even yellow brass
(~ 40,000 psi compression) probably is adequate. And impregnated
material will help with stick-slip.

A milder steel shaft probably would be Ok, too. If you go too soft on
the shaft, you'll eventually run into a stick-slip problem. But I
don't think it's likely to show up here, even with a mild-steel shaft.

--
Ed Huntress

On Apr 1, 12:15*pm, wrote:
Hi guys. I have a unique garage business selling hardware to builders and repairers of upright basses. Check bass capos dot com for details. One thing they need is a small but strong pulley wheel with a 1/8" dia. round belt race. The ones I supply are brass with a sealed bearing and are a bit overbuilt and expensive for the application. I want to arrange for a run of a few hundred which would be more fit for purpose, and hopefully a bit cheaper..

The plan is for a 7/8" dia. x 1/4" wide brass pulley with a 1/4" brass axle and without the sealed bearing. There is a constant force of about 120 lbs. on the shaft, but almost no rotation. Maybe +/- 1-2° a few times a day for tuning, and no adjustments at all sometimes for weeks or months, and it must be usable for decades. I think that simple brass on brass should work if both parts are well machined/polished/lubricated, but there have been anecdotal failures. So, I need to do something more if only for marketing, but also I stupidly offer a ten year warranty. So, I must be very careful about how I design and produce my wares!

Anyway, what are some options?

1. A polished SS shaft instead of brass? Good, but the customer needs to cut the shaft to length and polish the ends. Not practical for most violinmakers /repairers. They can always special order the needed length, so not out of the question, but extra pain.

2. A bearing-grade bronze shaft with brass pulley? Seems like the most cheap and practical, but how durable?

2. A greased bronze or SS sleeve between the brass shaft and the pulley? Sounds good except that afaik it would have to be machined from solid round, upping costs. Anyone know of bushing sleeve available in small diameters like this?

3. Delrin bushing sleeve? This seems available in the size I need, but some customers really don't want any plastic on their bass. I know. It's just something you have to deal with in my world.

4. SS or bronze Pulley? sounds expensive.

Anyway, I hope there is someone out there with interest and understanding of the specific issue I discuss, and who has the time to give advice.

Please do not post if you wish to warn me of:
A - the risks to life and limb of using metalworking machinery, or anything else which uses electricity or has sharp cutting edges.
B - the liability risk of altering something without UL approval, or using it for a purpose not described by the manufacturer.

Don't gamble with your quality. If the ball bearing you use has gone
up in price, then switch to a drawn cup needle roller bearing, full
complement, on a steel shaft. Easy to press into your brass wheel.
You've a high static load and want no compromises.
Needle bearings should be inexpensive enough for this application, and
may even be a marketing advantage. Add brass screw-on end finals to
the design, with your logo engraved on the ends perhaps. They can
support through the wood and screw onto the steel shaft to allow for
scroll width adjustment by the end user.

Good luck

--

PaulS

On 4/1/2013 12:15 PM, wrote:

Anyway, what are some options?


In that what you are selling has a marketing component as well as
engineering requirements, lignum vitae:

http://www.lignum-vitae-bearing.com/


Kevin Gallimore

Thanks. I think that LV or needle bearings would not work on this small size. I appreciate the advice against using brass and bronze together. I think I'll go with a delrin sleeve and brass shaft.

On Thu, 4 Apr 2013 02:34:25 -0700 (PDT), the renowned
wrote:

Thanks. I think that LV or needle bearings would not work on this small size. I appreciate the advice against using brass and bronze together. I think I'll go with a delrin sleeve and brass shaft.

Don't do that. Delrin is not strong enough (Pmax = 1000), IMHO.
(disclaimer: IANAME)

I would suggest trying a steel or SS shaft and oil/PTFE impregnated
bronze. Follow the bronze bearing recommendations on the hardness of
the shaft Rb 85+ or whatever it is. Test it at higher than expected
loads. SAE863 (oilite+) is stronger than 841 (Pmax 4,000 vs 2,000)



Best regards,
Spehro Pefhany
--
"it's the network..." "The Journey is the reward"
Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog Info for designers: http://www.speff.com

On Thursday, April 4, 2013 5:34:25 AM UTC-4, wrote:
Thanks. I think that LV or needle bearings would not work on this small size. I appreciate the advice against using brass and bronze together. I think I'll go with a delrin sleeve and brass shaft.

Lostfr,

Hate to be a pest but...

Needle bearings are compact enough to easily increase your shaft size to 5/16" in a 1" brass pulley. They come as small as 3/16" IIRC. Look at Timken's references.

Use drill rod for a 5/16 threaded shaft. 3/8" dia. brass screw-on end-caps for finals/width adjustment spacers. Saves customer's cutting & polishing work installing. A 3/8 hole is almost same as 9.5mm. Works worldwide, no need to send a 1/4" drill with the kit! That saves you cost.

Delrin on brass may creep over time under high static load. Keeping C-string in-tune may be harder. Hate to see your nice C-extensions compromised with a poor bearing choice.

How come this is such a cost-sensitive problem for you? A C-extension is many hundreds of dollars to install, no? You need lower-cost CNC machined parts? If so I may be able to help. I like interesting side work. Small runs are no problem on my gang-tool lathes.

Good luck.

--

PaulS

On Thu, 04 Apr 2013 07:45:57 -0400, Spehro Pefhany
wrote:

On Thu, 4 Apr 2013 02:34:25 -0700 (PDT), the renowned
wrote:

Thanks. I think that LV or needle bearings would not work on this small size. I appreciate the advice against using brass and bronze together. I think I'll go with a delrin sleeve and brass shaft.

Don't do that. Delrin is not strong enough (Pmax = 1000), IMHO.
(disclaimer: IANAME)

I would suggest trying a steel or SS shaft and oil/PTFE impregnated
bronze. Follow the bronze bearing recommendations on the hardness of
the shaft Rb 85+ or whatever it is. Test it at higher than expected
loads. SAE863 (oilite+) is stronger than 841 (Pmax 4,000 vs 2,000)


Which is why I mentioned Igus products in an earlier post. They offer
standard bearings and materials with Pmax from 7500 to 21000 psi.
Prices for a 1/4 x 1/4 x 5/16 bearing run from $.57 to $2.00 at qty
100, depending on material.

--
Ned Simmons

Take a look at B-24 drawn cup roller bearings. 1/4 OD X 1/4 inch long with a 1/8 dowl pin for a shaft. They are static load rated at around 200 lbs.

Am Donnerstag, 4. April 2013 23:12:33 UTC+2 schrieb d32:
Take a look at B-24 drawn cup roller bearings. 1/4 OD X 1/4 inch long with a 1/8 dowl pin for a shaft. They are static load rated at around 200 lbs.

Ned,
Sorry, I only checked out Igus just now. They're headquartered in my city! I need to get my head out of my yellow bible sometimes! I figure that a 1/4" wide x 1/4" bore sleeve would need a minimum P value of 1900. I found a MDS-FILLED Nylon Bearing from McMaster with a P value of 2900. I see that Igus offers way way stronger options.

As to needle bearings, sounds cool, but I really want to use a 1/4" or 6mm brass shaft. It's not only the comfort issue with the luthier, but a 1/8" shaft might compress the wood too much. Many extensions are made of solid ebony, which should be no problem, but some are maple or other softer woods.

On 05/04/13 16:44, wrote:
Am Donnerstag, 4. April 2013 23:12:33 UTC+2 schrieb d32:
Take a look at B-24 drawn cup roller bearings. 1/4 OD X 1/4 inch long with a 1/8 dowl pin for a shaft. They are static load rated at around 200 lbs.
Ned,
Sorry, I only checked out Igus just now. They're headquartered in my city! I need to get my head out of my yellow bible sometimes! I figure that a 1/4" wide x 1/4" bore sleeve would need a minimum P value of 1900. I found a MDS-FILLED Nylon Bearing from McMaster with a P value of 2900. I see that Igus offers way way stronger options.

As to needle bearings, sounds cool, but I really want to use a 1/4" or 6mm brass shaft. It's not only the comfort issue with the luthier, but a 1/8" shaft might compress the wood too much. Many extensions are made of solid ebony, which should be no problem, but some are maple or other softer woods.
If you sign up on the Igus site they will likely provide free samples of
potential candidate bushes. I did this on their UK site and ordered the
bushes I wanted and paid for them and got a follow up call wanting to
know the application and volume and I explained it was likely a one off
but the chap said they would still have provided the bearings as free
samples, I presume this encourages repeat business and may lead to
larger orders. I expect you would do well to talk to or email an
application engineer there and explain the design requirements and see
what they recommend and get some appropriate samples. They sent me a
welcome pack containing more information and a variety of samples of the
range of products types they do.

On Fri, 05 Apr 2013 17:38:59 +0100, David Billington
wrote:

On 05/04/13 16:44, wrote:
Am Donnerstag, 4. April 2013 23:12:33 UTC+2 schrieb d32:
Take a look at B-24 drawn cup roller bearings. 1/4 OD X 1/4 inch long with a 1/8 dowl pin for a shaft. They are static load rated at around 200 lbs.
Ned,
Sorry, I only checked out Igus just now. They're headquartered in my city! I need to get my head out of my yellow bible sometimes! I figure that a 1/4" wide x 1/4" bore sleeve would need a minimum P value of 1900. I found a MDS-FILLED Nylon Bearing from McMaster with a P value of 2900. I see that Igus offers way way stronger options.

As to needle bearings, sounds cool, but I really want to use a 1/4" or 6mm brass shaft. It's not only the comfort issue with the luthier, but a 1/8" shaft might compress the wood too much. Many extensions are made of solid ebony, which should be no problem, but some are maple or other softer woods.
If you sign up on the Igus site they will likely provide free samples of
potential candidate bushes. I did this on their UK site and ordered the
bushes I wanted and paid for them and got a follow up call wanting to
know the application and volume and I explained it was likely a one off
but the chap said they would still have provided the bearings as free
samples, I presume this encourages repeat business and may lead to
larger orders. I expect you would do well to talk to or email an
application engineer there and explain the design requirements and see
what they recommend and get some appropriate samples. They sent me a
welcome pack containing more information and a variety of samples of the
range of products types they do.

Igus is a class act. I spent about $8000 with them in the last year,
mostly cable carriers and flexing duty cable. But they've been just as
helpful in the past when all I wanted was $15 worth of bearings.

--
Ned Simmons

Am Freitag, 5. April 2013 20:11:31 UTC+2 schrieb Ned Simmons:
On Fri, 05 Apr 2013 17:38:59 +0100, David Billington

wrote:



On 05/04/13 16:44, wrote:

Am Donnerstag, 4. April 2013 23:12:33 UTC+2 schrieb d32:

Take a look at B-24 drawn cup roller bearings. 1/4 OD X 1/4 inch long with a 1/8 dowl pin for a shaft. They are static load rated at around 200 lbs.

Ned,

Sorry, I only checked out Igus just now. They're headquartered in my city! I need to get my head out of my yellow bible sometimes! I figure that a 1/4" wide x 1/4" bore sleeve would need a minimum P value of 1900. I found a MDS-FILLED Nylon Bearing from McMaster with a P value of 2900. I see that Igus offers way way stronger options.



As to needle bearings, sounds cool, but I really want to use a 1/4" or 6mm brass shaft. It's not only the comfort issue with the luthier, but a 1/8" shaft might compress the wood too much. Many extensions are made of solid ebony, which should be no problem, but some are maple or other softer woods.

If you sign up on the Igus site they will likely provide free samples of

potential candidate bushes. I did this on their UK site and ordered the

bushes I wanted and paid for them and got a follow up call wanting to

know the application and volume and I explained it was likely a one off

but the chap said they would still have provided the bearings as free

samples, I presume this encourages repeat business and may lead to

larger orders. I expect you would do well to talk to or email an

application engineer there and explain the design requirements and see

what they recommend and get some appropriate samples. They sent me a

welcome pack containing more information and a variety of samples of the

range of products types they do.



Igus is a class act. I spent about $8000 with them in the last year,

mostly cable carriers and flexing duty cable. But they've been just as

helpful in the past when all I wanted was $15 worth of bearings.



--

Ned Simmons

Sounds like a great outfit. The GLW series has a P value 6x what I need. I'll give them a call!