Replacement bearings for this block grinder?

[larryq]

Related to this thread, I've got the bearings out of the block grinder and want to replace them.

With the dial caliper I get 40 mm OD and 17 mm ID and 12mm thickness. Reason I went with the mm measurements is those appear to be exact on the caliper-- in terms of inches it read 1.57 in, some strange value like that.

I looked at the McMaster Carr section and was a little overwhelmed. They have double-shielded and double-sealed bearings there, for $6 - $10 per bearing that match my dimensions and RPM limits, but I'm not sure which is preferred for this application. The one in the picture I've attached is double shielded, so...

And, when I reinstall these should I put them on the shaft first, then into the body? Not sure about best procedure for that.

Thanks!

 

[paul2112]

is there a number on it? next to the made in USA? just google that and it will tell u..other thank that any bearing shop should fit it right up

 

[A_Pmech]

It's a 6203 bearing by dimensions and by the number on the inner race.

Shielded or sealed will work fine in that application. A bench grinder is well within the speed limitation of a sealed bearing that size.

5972K2 or 5972K44 would be my choice.

 

[softailgarage]

There should be a bearing number on the face, usually starts with a "BR" or "CR". This is where I go...http://www.applied.com/site.cfm/bearings_new.cfm?WT.ac=Bearings_Home

 

[softailgarage]

Should be a Ball Bearing #77503 on the shield & 3203 on the race. You can also go to searspartsdirect.com, punch in the model # without the decimal and get a complete parts list.

 

[A_Pmech]

Should be a Ball Bearing #77503 on the shield & 3203 on the race. You can also go to searspartsdirect.com, punch in the model # without the decimal and get a complete parts list.

That's interesting, using an double angular contact bearing in a bench grinder... Beware the 3203 is quite a bit wider than the bearing he removed!

 

[benjamintmiller]

Most of the ideas that revolutionized bearings came from Europe, so metric bearings have always been the norm. You can find imperial bearings, but bearings are often metric, even in older machinery.

That is a New Departure bearing, and they haven't been around for many years. I agree with A_Pmech that either shielded or sealed will be fine... a bench grinder really isn't a critical application.

McMaster-Carr sells decent quality bearings. You don't get to choose the brand, but the ones I've received have all been Fafnir or ***.

 

[larryq]

Great advice here, thanks everyone.

 

[softailgarage]

That's interesting, using an double angular contact bearing in a bench grinder... Beware the 3203 is quite a bit wider than the bearing he removed!

OK, you got me. I looked at one grinder with NDH (New Departure Hyatt) showing 3203. After your post, I found another Craftsman grinder, same model #397.19580 and those bearings were *** #6023 clearly. Now, is it possible that the 3203 converts to 6023 depending on manufacturer? I know sometimes an obsolete or discontinued bearing will cross over to a different #.

 

[scw1991]

+1 on the 6203 generic bearing p/n. You can purchase the China bearings for a few bucks or spend a little extra and get a good quality NSK, Fafnir, or SKF bearing. For your application, the bearing can be either sealed (designation RS) or shielded (designation ZZ).

 

[older=better]

Since you have the old one you can simply take it to any good auto parts guy and get the right one.
I don't like buying things like that online. Its to much trouble when it doesn't work out.

 

[benjamintmiller]

Now, is it possible that the 3203 converts to 6023 depending on manufacturer?

Yes, New Departure used different model numbers. These bearings predate modern numbering schemes. New Departure became New Departure Hyatt (NDH) in 1965, and they stopped making non-aerospace ball bearings entirely in 1986.

Measure the bearing, order one from McMaster-Carr, and be done with it. You can also get a 6203 from absolutely any bearing house, but it will be more than twice the price of McMaster.

 

[SMKS]

It's just a 6203 bearing, as others have said. It's a very common size. But that's assuming your measurements are accurate.

Go to ebay, Amazon or your local bearing house.

It looks from the pic like that is a metal shielded bearing. I'm assuming both sides are the same? Bearings with non-removable metal shields often have the suffix "ZZ" on the part number.

There are bunch on ebay, but I would personally avoid the no-name Chinese ones.

Here's an affordable one that should be a good choice. Nachi bearings are made in Japan:
http://www.ebay.com/itm/6203ZZE-Nac...=BI_Heavy_Equipment_Parts&hash=item5d28681785

I used Nachi bearings on this project and they're holding up great:
http://www.garagejournal.com/forum/showthread.php?p=2169922

 

[catalytic]

Related to this thread
...

And, when I reinstall these should I put them on the shaft first, then into the body? Not sure about best procedure for that.

Thanks!

As a general rule, yes -- put them on the shaft, then install the motor housing.

Heat the bearings in the oven to 215° or so (NOT hotter). Heat helps more with bigger bearings, but still helps a noticeable amount with your size. Line them up carefully and slide them on quickly. They often will not go on all the way, so have a piece of wood with a hole drilled for the shaft that you can slide behind the bearing and push. You want to push on the inner bearing race, not the outside of the bearing. Or just press them on with your press, making sure that the pressure is focussed on the inner bearing race.

The motor housing fits over the bearing, but not nearly as tightly as the shaft/bearing connection. It's supposed to be loose enough so that the bearing rotates extremely slowly over time in the motor housing.

 

[NotStock]

3/4 schedule 40 pipe is what I used to drive similar 6204 bearings on my grinder. Fits nicely against the inner race of that size bearing and it's probably laying around your shop somewhere.

I replaced the bearings in my grinder with rubber sealed units from SKF that I got on ebay. Good for the dirty application, inexpensive, and ok at the rpm.

 

[larryq]

Here's an affordable one that should be a good choice. Nachi bearings are made in Japan:
http://www.ebay.com/itm/6203ZZE-Nac...=BI_Heavy_Equipment_Parts&hash=item5d28681785

Funny enough, I got 40x17x12mm Nachi bearings from that eBay seller, 15 minutes before reading this!

Thanks again to everyone on the thread, much appreciated.

 

[benjamintmiller]

The motor housing fits over the bearing, but not nearly as tightly as the shaft/bearing connection. It's supposed to be loose enough so that the bearing rotates extremely slowly over time in the motor housing.

The bearing really shouldn't be spinning in its housing. Bearings are usually a slip fit on the fixed part to allow for thermal expansion. When they get up to temperature, they expand ever so slightly and both races stay put on their respective part.

Remember, "the fixed part rotates and the rotating part is fixed." The shaft rotates here, so it's fixed to the bearing (through an interference fit). The housing is fixed, so the bearing is able to rotate, though as noted above, this is for thermal expansion.

 

[catalytic]

The bearing really shouldn't be spinning in its housing. Bearings are usually a slip fit on the fixed part to allow for thermal expansion. When they get up to temperature, they expand ever so slightly and both races stay put on their respective part.

Remember, "the fixed part rotates and the rotating part is fixed." The shaft rotates here, so it's fixed to the bearing (through an interference fit). The housing is fixed, so the bearing is able to rotate, though as noted above, this is for thermal expansion.

The first part of this is correct. The fit of the outer race in the motor housing should be tight enough to prevent wallowing and to allow heat transfer. However, it's still supposed to be loose enough to allow the outer race of the bearing to creep/rotate slowly over time. This creeping allows the load to be distributed at different parts of the raceway.

See for example this reference for example from "Ball Bearings on Electric Motors" by F.E. Rogers, JR in Electrical Review and Western Electrician Vol. 68, No. 11: Note the paragraph:

"It is important that ball bearings be mounted properly. The inner race must have a tight fit on the shaft and should be permanently seated by means of a locknut or distance piece in a fixed position against the shaft shoulder. The outer race, on the contrary, should seldom be held rigidly in the housing. A sucking fit within the housing will permit the outer race to creep and insure a more perfect distribution of the load over the whole circumference of the race" (p. 562).

http://books.google.com/books?id=BU...page&q=bearing outer race creep motor&f=false

 

[torqueman2002]

I checked to see if I had any bearing numbers for the 1/3 HP CM rebuild I did, but nope.

Here's something that might help however.
A thread about ordering bearings online.
http://owwm.org/viewtopic.php?f=1&t=93322
+++++++++++++++++++
A local shop helped me out with the old & discontinued bearings from my CM Block grinders, with replacements that are commonly used.

BTW - they use metric measurments.

Bearing Service
13400 Newburgh Rd.
Livonia, MI 48150
734-591-0400
FAX 734-591-1688
800-929-0200
http://www.bearingservice.com/

 

[catalytic]

I checked to see if I had any bearing numbers for the 1/3 HP CM rebuild I did, but nope.

Here's something that might help however.
A thread about ordering bearings online.
http://owwm.org/viewtopic.php?f=1&t=93322

^^ +1 for Accurate Bearing Co. Ask to speak with Lynn. I am not affiliated with them but have ordered bearings from them and they have been very helpful.