mid-'50s shopsmith disassembling and cleaning -- help

bucksaw · Post by **bucksaw** » Fri Mar 20, 2009 10:35 am

[quote="dusty"]Bill Mayo suggested that the position of the relay might cause the clicking (relay drop out). Has that possibility been confirmed]

My replacement relay does not click while the motor is running. I haven't had time to play with old relay yet to see if I can "repair" it.

bucksaw · Post by **bucksaw** » Fri Mar 20, 2009 11:41 am

edward wrote:My bearing supplier is saying that there's no quality difference between C1 and C3 -- those are just date designations. Does anyone know what this is about?

Source: AHR International ( See article that explains radial clearance)

The total internal clearance is the amount that one ring can be displaced relative to the other ring, either radially or axially. The radial clearance is the total clearance between the raceway and the rolling elements - measured normal to the bearing axis. The clearance changes with the expansion or contraction of the bearing rings. The axial clearance is the total amount that one ring can be displaced relative to the other in an axial direction.

In ball bearings, as the radial clearance increases, the axial clearance increases as well. The more room between the balls and the rings (radial clearance), the more the elements can shift in relation to each other. Generally, internal clearances are designated from C1 (the tightest) through to C5 (the loosest or largest). The 'normal' clearance is CN, a range sitting between C2 and C3. It is worth noting that if the bearing clearance is not stated in the bearing reference it can be assumed to be normal clearance. With a higher clearance there is more tolerance of thermal expansion effects on the rings and rolling elements. When noise and vibration must be restricted, lower clearances are necessary. Ultimately the specific application and operating conditions determine the appropriate internal clearance. For example, paper-drying machines that operate under hot conditions usually need C3 and C4 clearances. The severe vibration in vibrating screens normally means that C3 and C4 clearances are required. Selection of the correct radial internal clearance group is by calculation and you should refer to your bearing manufacturers handbook. Factors to be assessed include:

Expansion of the inner ring due to interference fit on shaft

Contraction of the outer ring due to interference fit in the housing

Differential temperature between the inner and outer rings

Differential expansions due to non-ferrous mountings
In addition to the ISO clearances, manufacturers such as NSK also offer specific clearances for electric motors known as CM clearance. This class includes a tighter noise specification. The CM clearance falls within the range of the CN clearance. Some motor manufacturers specify CM clearance where closer radial internal clearance helps reduce noise. C3 clearance, which is frequently used in the aftermarket, is greater than the CN and CM clearances.

dusty · Post by **dusty** » Fri Mar 20, 2009 12:03 pm

bucksaw wrote:Time for a new bearing supplier.

Source: AHR International ( See article that explains radial clearance)

Help me, please. Where in the reference provided did you find information that makes you say it is time for a new supplier.

I am unable to determine that there is a significant difference between C1 and C3 bearings (for use in a Shopsmith type environment).

bucksaw · Post by **bucksaw** » Fri Mar 20, 2009 12:20 pm

dusty wrote:Help me, please. Where in the reference provided did you find information that makes you say it is time for a new supplier.

Sorry...the original post was from "edward" that stated "...C1 was a date code". See pose #113

JPG · Post by **JPG** » Fri Mar 20, 2009 1:03 pm

[quote="dusty"]Bill Mayo suggested that the position of the relay might cause the clicking (relay drop out). Has that possibility been confirmed]

See #113:)

Sorry Dave! I was reading while you were posting. I missed #133 b4 I posted #134.

JPG · Post by **JPG** » Fri Mar 20, 2009 1:16 pm

bucksaw wrote:"internal clearances are designated from C1 (the tightest) through to C5 (the loosest or largest). The 'normal' clearance is CN, a range sitting between C2 and C3"

In your previous post you stated that your bearing supplier thought that C1 was a date code. That would indicate the supplier is not real familiar with bearing specifications. I believe normal bearings (somewhere between C2 and C3) are what is shipped with Shopsmiths. It has been suggessted by Billmayo that C1 is a better choice if you can find it, especially for a quill bearing. As long as you are buying name brand (Fafnir, NTN, etc) you should be fine with a "normal" clearance bearing if that is all your supplier handles. It is assumed that a bearing is has "normal" clearances if the "Cx" designator is not attached to the bearing part number. At least this is my understanding, and I am no bearing expert by any stretch of the imagination.

This IS consistant with my 'research' last night through ntn/nsk/fafnir etc. web sites. I could not find ANY which make a 6203 ZZ C1 (17x40x12mm double steel shield tight clearance) Best I could find was C2.

bucksaw · Post by **bucksaw** » Fri Mar 20, 2009 1:24 pm

edward wrote:My bearing supplier is saying that there's no quality difference between C1 and C3 -- those are just date designations. Does anyone know what this is about?

Your supplier needs to read up on radial clearance specs.

See #131

edward · Post by **edward** » Fri Mar 20, 2009 1:34 pm

I was the one with the bearing issue. You're right about my supplier, or, at least the clerk doing the supplying. He measured the bearing incorrectly, twice, which should have been an indication of something. Anyway, I can get a C3 for $10 (not Fafnir) or a C1 for $25 (and I have to wait longer). Alas. I am of two minds.

JPG · Post by **JPG** » Fri Mar 20, 2009 3:40 pm

edward wrote:I was the one with the bearing issue. You're right about my supplier, or, at least the clerk doing the supplying. He measured the bearing incorrectly, twice, which should have been an indication of something. Anyway, I can get a C3 for $10 (not Fafnir) or a C1 for $25 (and I have to wait longer). Alas. I am of two minds.

WHICH bearing???

bucksaw · Post by **bucksaw** » Fri Mar 20, 2009 3:42 pm

edward wrote:I was the one with the bearing issue. You're right about my supplier, or, at least the clerk doing the supplying. He measured the bearing incorrectly, twice, which should have been an indication of something. Anyway, I can get a C3 for $10 (not Fafnir) or a C1 for $25 (and I have to wait longer). Alas. I am of two minds.

If he had the old bearing in hand, I'm surprised he couldn't do a cross-reference look up. The NTN website has that service.