Bearings

[Pevehouse]

I would stay with a better quality tapered bearing than swap to an A/C in a lower end machine. There are lots of unknowns when going to an entirely different type of bearing, as mentioned above. you really need someone who knows the design on the machine, and spindle to recommend the appropriate conversion and the benefit vs cost isn't all that great on that machine. Dave

Yea, that’s kind of the consensus so far. I would like to upgrade the bearing though. Maybe a teen or something similar. Got to figure out what the preload should be on them as well. I assume I will have to measure the rotating torque on the spindle when I go back with it. At least that’s how I measure preload on rear differential’s when I build those

 

[Ischgl99]

First of all, Thank you. Your knowledge is invaluable. This is exactly the kind of information I needed. I guess I just assumed that a higher precision bearing would yield higher precision as far as spindle runout goes. I’m certainly not opposed to going back to a taper bearing if that’s what would be ideal. I would like to put a better quality bearing in there while I’m here. The bearings that were in there were already discolored and starting to fail, I assume due to excessive preload. As far as the boring goes, it seems that what I was looking at was all wider than my taper bearings by a few millimeters. I will post up some numbers and pictures of what I have when I get home this evening, so that you can see what I’m working with. I am also not opposed to spending the money required to get some decent bearings in there.
If you could please guide me in my decision , I would be forever grateful.
I will say, that I’m not planning on running any additional speed outside of what the machine will currently do. Again Thank you for all your help

You’re welcome. I was a bit hasty last night with my statement you shouldn’t need to machine your quill, it will depend on how it is designed, and that may be necessary. What mill do you have? Having the parts diagram for the spindle would be helpful. Converting to ACBs is going to get complicated and might require some precision machining to get them to fit, since you don’t plan on increasing the speed, the best bang for the buck is going to be a higher quality version of what is in there now.

Here’s what I was looking at

Now I see why you thought you needed to machine the quill, those are double row bearings. You want single row for a spindle.

Once you get the tapered roller bearing numbers, then we can see what is available in that size as far as precision classes, but any of the major brands would be a step up from what was likely in there from the factory.

 

[Pevehouse]

You’re welcome. I was a bit hasty last night with my statement you shouldn’t need to machine your quill, it will depend on how it is designed, and that may be necessary. What mill do you have? Having the parts diagram for the spindle would be helpful. Converting to ACBs is going to get complicated and might require some precision machining to get them to fit, since you don’t plan on increasing the speed, the best bang for the buck is going to be a higher quality version of what is in there now.


Now I see why you thought you needed to machine the quill, those are double row bearings. You want single row for a spindle.

Once you get the tapered roller bearing numbers, then we can see what is available in that size as far as precision classes, but any of the major brands would be a step up from what was likely in there from the factory.

It’s one of those Chinese Bolton mills. I got it dirt cheap is the only reason I own it. It was part of a package deal with the Enco lathe I wanted. I figured I would work with it till a Bridgeport style came along within my reach. I will post what came out of it as soon as I get home this evening. Thank you

 

[Pevehouse]

Ok, here’s what I got

 

[Ischgl99]

I don’t see any indication of those being precision classed bearings, so they are likely standard precision. A name brand standard precision will probably be a noticeable improvement over those, or you can step up to a P6 or P5. P6 is one step above standard precision, and P5 is more suitable for mid level machine tools, but a lot more $$. FAG X-Life bearings are sold as standard precision, but many of the tolerances meet P6, so that is a cheap way to get a better bearing. The X-Life bearings will have an XL in the part number.

I took a look on the Grizzly website and they have a mill that looks like what Bolton sells, and uses these size bearings, so might be the same machine. Grizzly says the bearings are P5, but a member here bought some bearings from Grizzly claiming to be P5, they were NSK, but there were not any indications of a precision class that NSK puts on P5 bearings, so we concluded they were not precision bearings. This mill does not look to be worth modifying, so I would stick with the TRBs from a reputable manufacturer. If you modified the quill to take ACBs, you could make it worse than it is now.

 

[Pevehouse]

I don’t see any indication of those being precision classed bearings, so they are likely standard precision. A name brand standard precision will probably be a noticeable improvement over those, or you can step up to a P6 or P5. P6 is one step above standard precision, and P5 is more suitable for mid level machine tools, but a lot more $$. FAG X-Life bearings are sold as standard precision, but many of the tolerances meet P6, so that is a cheap way to get a better bearing. The X-Life bearings will have an XL in the part number.

I took a look on the Grizzly website and they have a mill that looks like what Bolton sells, and uses these size bearings, so might be the same machine. Grizzly says the bearings are P5, but a member here bought some bearings from Grizzly claiming to be P5, they were NSK, but there were not any indications of a precision class that NSK puts on P5 bearings, so we concluded they were not precision bearings. This mill does not look to be worth modifying, so I would stick with the TRBs from a reputable manufacturer. If you modified the quill to take ACBs, you could make it worse than it is now.

I follow what you’re saying. No point in spending a lot of money on this particular machine. I will see what I can find in a P6 class bearing. For that matter, the ones from grizzly would probably be an upgrade. Do you have a model number by chance?

 

[Ischgl99]

I do not recommend the Grizzly bearings, they are charging 3x standard precision prices without any evidence they are anything other than standard precision. You would be better off going to bearing distributors like Motion Industries, BDI, AIT, Kaman etc. that get you exactly what you order, and you know it is not counterfeit like is possible with some of the gray market distributors.

Here is the Grizzly link to the parts list if you want to take a chance with them https://cdn0.grizzly.com/partslists/g0761_pl.pdf

These are a few of the distributors I mentioned.

www.bdiexpress.com
www.motion.com
www.kaman.com

 

[Danzo187]

late to the conversation, I would replace with the original bearing. With class 7 angular type contact precision bearings, usually everything else is machined to very tight tolerances, and entire spindle is then balanced throughout the spindle assembly motor and all, I think you'll gain very little with an expensive angular bearing,
just my thoughts

 

[Pevehouse]

late to the conversation, I would replace with the original bearing. With class 7 angular type contact precision bearings, usually everything else is machined to very tight tolerances, and entire spindle is then balanced throughout the spindle assembly motor and all, I think you'll gain very little with an expensive angular bearing,
just my thoughts

Thank you, I appreciate your input. So something like a timken or a good skf would work?

 

[Danzo187]

Thank you, I appreciate your input. So something like a timken or a good skf would work?

yup