R4ZZ bearing ID size

Bearings/Motors/Belts/Gears/Etc.

R4ZZ bearing ID size

Postby dirktheeng » Tue May 10, 2011 2:41 am

All,

I was wondering if you could check the bearing ID size with a calipers and post them. Some reviewers on the VXB site said that they recieved undersized bearings. Bart also mentioned this, but I am not sure that this isn't a fluke. I was wondering if this was a fluke of bad bearings or if VXB is not a reputable source. The R4ZZ bearing is supposed to be 0.2500" to 0.252" in size on the ID. That is a measured standard for the R4ZZ bearing. I am going to check mine too when I get my calipers back from work. This is somewhat important if we ever want to switch from threaded rod to a more precise shaft. If we have bearings that are undersized, then we have to replace them too to upgrade. Mcmaster also sells the same class of bearing for $4.60 a piece (really pricy but known to be right on and reputable). At most this means an additional $45. I have found other dealers who sell the same class of bearing as cheap as $1.90 a piece, but now I am afraid to order if they are undersized too. I have some emails out to ask about this and see if we can get measured confirmation of the id from another inexpensive source.

-Dirk
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Re: R4ZZ bearing ID size

Postby bdring » Tue May 10, 2011 2:54 am

Calipers are not the tool for this. I have calibrated gauge pins at work. By the way, I do not buy my bearings from VXB, but I did when I initially measured them. It is possible that this is just a VXB issue. I will measure my latest batch tomorrow.

gagepins.jpg
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Re: R4ZZ bearing ID size

Postby bdring » Tue May 10, 2011 11:52 am

The gauge pins I have are in 0.001 increments. The 0.249" was able to go on, but the 0.250" would not. I measured a little less than that with a caliper. Calipers don't go down to a perfect point so they have trouble with round inside diameters, especially small ones.

A 1/4" end mill might be a good test. They are usually pretty accurate.
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Re: R4ZZ bearing ID size

Postby dirktheeng » Tue May 10, 2011 12:36 pm

ok. That is good to know. I may be able to press the shaft into the bearing or maybee polish the shaft down with like 3000 grit paper to get the bearing in.
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Re: R4ZZ bearing ID size

Postby bdring » Tue May 10, 2011 4:38 pm

I am going to have my screw machine parts supplier quote a smooth idler pulley. I think I might be able to get the part for the same price as the pulley. It would go through the bearings and screw on from the back side. It would have a shoulder that sets the distance. I need to make it work for both X and Y. This would be a future enhancement to the design. The idlers could be egg shaped and not have too much influence on the accuracy. They only come into play with smoothness of the operation.

Untitled Project 43.jpg


Untitled Project 44.jpg
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Re: R4ZZ bearing ID size

Postby dirktheeng » Tue May 10, 2011 9:36 pm

bdring wrote:I am going to have my screw machine parts supplier quote a smooth idler pulley. I think I might be able to get the part for the same price as the pulley. It would go through the bearings and screw on from the back side. It would have a shoulder that sets the distance. I need to make it work for both X and Y. This would be a future enhancement to the design. The idlers could be egg shaped and not have too much influence on the accuracy. They only come into play with smoothness of the operation.


Let me know about what they say.
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Re: R4ZZ bearing ID size

Postby bdring » Wed May 11, 2011 12:17 pm

This is the drawing that went out. I will probably tweak the dims a tiny bit before I commit, but it is close enough to quote. I should hear back before the end of the week.

b18015_rev_1.pdf
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