# G3103 spindle bearings



## boostin53 (Apr 2, 2018)

I'd like to do some maintenance or just flat out replace the spindle bearings on my mill. I looked in the manual, but didn't see anything about maintaining them. I tried doing a few Google searches but no luck.

What I'm looking for is some type of guide, or any information as far as removing the spindle and bearings. I'm sure I could learn as I go, but I like to be able to look/read something for the first time. I'm also wanting to remove the R8 alignment pin in the spindle. How do I do this?


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## machPete99 (Apr 3, 2018)

I am in process of doing a Rockwell mill. It is similar to yours, although not exactly the same:
https://www.hobby-machinist.com/threads/rockwell-21-100-spindle-rebuild.67913/

Diagram for your mill:  
https://www.grizzly.com/products/g3103/parts

Spindle bearings are generally greased on assembly, and need to disassemble to regrease or replace.
Need to pull quill out of spindle, typically have to remove the feed mechanism and stop assembly first and it will drop out the bottom.
Once the retainer nut at base of quill (7) is removed the spindle with bearings should slide out the bottom (may also be a retaining clip on the top side that you need to pull).
You might be able to spray clean out the old grease and replace with new.
If bearings are pressed on you will generally need to replace as force to remove will damage them.

Ideally you want angular contact bearings at the bottom of spindle, with correct "back to back" orientation. they are typically purchased as a matched set. On my mill they used ball bearings here, custom ground for preload. I upgraded to angular bearings and added a grease seal since these bearings typically have none.

There are another set of bearings that support the drive pulley, these may be ball bearings. On my mill the originals were custom ground for preloading, but I am replacing with standard bearings and using a shim to preload. I'll be posting more on that in the Rockwell thread.


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## boostin53 (Apr 3, 2018)

machPete99 said:


> I am in process of doing a Rockwell mill. It is similar to yours, although not exactly the same:
> https://www.hobby-machinist.com/threads/rockwell-21-100-spindle-rebuild.67913/
> 
> Diagram for your mill:
> ...



And I'm guessing I can't get the collet alignment pin out without removing the spindle? If I can freshen up the bearings without removing the spindle, and they're still in great shape, I still would like to remove that pesky pin.


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## machPete99 (Apr 3, 2018)

Not sure about the pin, as they did not put one on the Rockwell. You could try sticking an appropriately sized (tapered?) piece of round bar to try to push it flush with the inside of the spindle.

If you don't want to disassemble it, people have been known to remove the depth stop and inject some oil or grease into the hole, which will work its way into the lower bearings. Ideally you would want something compatible with the original grease...


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## boostin53 (Apr 3, 2018)

I guess I should price out a set of new spindle bearings before I attempt to remove it. If they're a pretty penny, I'll just plan on cleaning and reapplying grease for the time being.


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## machPete99 (Apr 3, 2018)

In looking at the parts diagram, it appears that there is a single angular contact bearing (43) at the bottom of the spindle. The one above it (44) is a ball bearing but having somewhat smaller OD. That means you cannot use matched bearings, unless you were do some machine work on the quill.

Below are prices I saw on ebay for name brand bearings. You should consider changing ZZ (shielded) to 2RS (rubber seal) style. Otherwise I would stick with the current configuration. I wouldn't buy anything until its opened it up and sizes and condition verified. Anything thats pressed together probably will need replacement. If bearings aren't noisy and everything comes apart easily you could consider regreasing, although metal shields are pretty much impossible to remove intact. The more expensive angular contact bearing is likely to be open style, so could potentially be regreased.

Lower spindle:
43 36207 Angular (now called 7207C) 35x72x17 ($100-$150)
44 6007ZZ 35x62x14 ($10)

Upper Spindle
45 6206ZZ 30x62x16 ($10)

Drive pulley
48 6009ZZ 45x75x16 ($15)
4  6009ZZ


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## boostin53 (Apr 3, 2018)

I was going to wait until I pulled the spindle to being my bearing hunt, but you may have already did that for me! 

I will take your advice and not order anything until I pull it and verify what's in there. I should be able to simply remove the alignment pin when I pull the spindle as well. Thank you machPete99!


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## machPete99 (Apr 4, 2018)

Here's another thought...
If you have a decent lathe with a 4 jaw and steady rest, bore out the smaller bearing pocket to 72mm to match the larger one, and go another 3mm deep (make sure you have room and won't hit anything).
Then install matched 6007 bearings, for about $150 a pair:
https://www.ebay.com/itm/NSK-7207CT...ndle-Bearings-Matched-Set-of-Two/182903121251
You need to also make sure there is enough thread on the spindle to get the retaining nut on. If not might need to face it off behind the nose.


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## boostin53 (Apr 16, 2018)

Well I took the leap and started to take apart the spindle, which is a first for me. I got the spindle cartridge? out. The sleeve thing that stay stationary in the mill with the actual spinning spindle inside it. 

The bearings seem a tab bit rough to me. I will try giving them a thorough cleaning and fresh grease to see if they seem better. Now I have a question(s).

How do I get the splined spindle out of this sleeve, a long with the bearings? Which I assume would allow me to remove the R8 collet pin, correct?


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## machPete99 (Apr 17, 2018)

On my Rockwell there was a snap ring above the top bearing that had to be removed. Then you tap the top of the spindle and it should drop out the bottom of the quill, with lower bearings attached. Do not use a steel hammer directly or you will deform things. Use either lead or copper hammer or put a block of wood in between. Depending on the fit this may cause some further harm to the current bearings. You can also potentially use threaded rod and bushings/pipe/spacers (maybe PVC drain pipe?) to accomplish this, or use a hydraulic press. Try not to be too rough and see how willing it is to come apart.

If the bearings feel rough you really need to consider replacements. Fresh grease will not fix them.


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## boostin53 (Apr 17, 2018)

machPete99 said:


> On my Rockwell there was a snap ring above the top bearing that had to be removed. Then you tap the top of the spindle and it should drop out the bottom of the quill, with lower bearings attached. Do not use a steel hammer directly or you will deform things. Use either lead or copper hammer or put a block of wood in between. Depending on the fit this may cause some further harm to the current bearings. You can also potentially use threaded rod and bushings/pipe/spacers (maybe PVC drain pipe?) to accomplish this, or use a hydraulic press. Try not to be too rough and see how willing it is to come apart.
> 
> If the bearings feel rough you really need to consider replacements. Fresh grease will not fix them.



That was my thinking recently as well. I'll measure the bearings when I remove the spindle before ordering. 

I'll clean everything then check for any type of retainer when I get home.


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## boostin53 (Apr 18, 2018)

I removed the spindle @machPete99, there were no retainers or anything. A couple mild blows with a brass hammer dropped the spindle from the quill with no damage to the splines of the spindle. 

I cleaned the bearings and concluded that the two lower bearings are going to be replaced. The bearing that remained in the quill is perfectly fine. Now what is the easiest/safest way to remove these from the spindle, without damaging the spindle? The rubber seal from the top bearing reads "6007RS" the lower bigger bearing has "7207AC" etched on the outer diameter. 

I've included a picture to show the bearings on the spindle.


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## machPete99 (Apr 18, 2018)

Wow, that configuration differs from the parts diagram, in that there is no retaining nut holding the bearings on the spindle, so they must be pressed on pretty tight, and/or loctited on there. Likely a cost reduction on the spindle fab. The bearing numbers do seem to match up with the parts list, as listed in my earlier post.

You probably want to punch out the collet guide pin before playing with the bearings, in case it gets in the way.

You will need a short length of pipe (maybe 4" or so) that fits over the spindle nose, but contacts the lower bearing. Then ideally stand it up in a press and push the spindle down through the bearings. Its probably only a press fit for the last inch or so on the spindle.  If you don't have a press find the biggest piece of all-thread that will go through the spindle, and put plates and nuts on each end to apply the force, using the pipe over the spindle nose against the lower bearing. McMaster-Carr has some nice high strength all-thread if the hardware store stuff does not cut it. The forces here will likely damage both bearings, you will not be able to reuse them.

If the bearings do not budge there could be loctite holding them, which might require heating with a torch to get in the 450-500F range, at which point it should break down.

To install new bearings you will need a pipe that slips over the top portion of the spindle and contacts the inner race only of the bearing. (Can also use a combination of pipe and a turned bushing). Look at black iron or galvanized pipe sizes. Once again use a press or all-thread to bring them home. It would probably be best to press each bearing on separately, using the same procedure. (If the outer races touch and you did them both at once there could be some adverse forces on the races that might damage them). If the new bearings do not fit tight you may want to use loctite sleeve retainer on the inside surfaces.


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## boostin53 (Apr 18, 2018)

machPete99 said:


> Wow, that configuration differs from the parts diagram, in that there is no retaining nut holding the bearings on the spindle, so they must be pressed on pretty tight, and/or loctited on there. Likely a cost reduction on the spindle fab. The bearing numbers do seem to match up with the parts list, as listed in my earlier post.
> 
> You probably want to punch out the collet guide pin before playing with the bearings, in case it gets in the way.
> 
> ...



Thank you for the help and the tips! I don't have access to a press big enough, but I do have various lengths of all kinds of pipe on hand. 

I'll make the bearing puller/pusher you described tomorrow and have a go at removing them. I also sent you a private message regarding a specific bearing. 

Thanks again!!!!


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## FOMOGO (Apr 18, 2018)

Pack the spindle in dry ice and you probably won't even need the all thread. If you do use it, coat the threads with some anti-seize. Mike


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## boostin53 (Apr 19, 2018)

FOMOGO said:


> Pack the spindle in dry ice and you probably won't even need the all thread. If you do use it, coat the threads with some anti-seize. Mike



Might be a stupid question, but I'm going to ask anyways. Dropping the temperature of the spindle to shrink it with dry ice won't cause any type of warping when it comes back to ambient temp?

I know that metal can be warped if heated too much, didn't know if that applied to cold temps.


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## FOMOGO (Apr 19, 2018)

Not a stupid question at all. Should be no issue, as high accuracy parts are routinely submerged in liquid nitrogen for strengthening. I would try to make sure that it is cooled as evenly as possible, but I don't beleive it's really that critical. You might even get by just putting it in the freezer overnight, and measure the difference in size from room temp to fully cooled, and compare to your bearing id. Just install your bearings quickly. You could also preheat your bearings to around 200-250 degrees (rubber seals), but I think you will find the cooling adequate. Mike


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## boostin53 (Apr 19, 2018)

FOMOGO said:


> Not a stupid question at all. Should be no issue, as high accuracy parts are routinely submerged in liquid nitrogen for strengthening. I would try to make sure that it is cooled as evenly as possible, but I don't beleive it's really that critical. You might even get by just putting it in the freezer overnight, and measure the difference in size from room temp to fully cooled, and compare to your bearing id. Just install your bearings quickly. You could also preheat your bearings to around 200-250 degrees (rubber seals), but I think you will find the cooling adequate. Mike


I've done that very thing to install beading in small engines (atv and motorcylce). Freeze the bearings and warm the cases. Bearings dropped right it most of the time, then were nice and tight when the metals settled at room temp. 

I plan on doing the same thing with the spindle. Freeze it over night then lightly warm the bearings hoping they fall right into place. Now I'm considering your idea of using dry ice to shrink the spindle for bearing removal.


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## boostin53 (Apr 19, 2018)

Well the bearings came off the spindle with some persuasion. I had a pipe that fit the outer race of the lower bearing. I stood the pipe up on the bench with padding in it. Placed the nose of the spindle in the pipe, aligning it with the bearing. About 7 decent whacks with my brass sledge with a 1" aluminum between the spindle splines and hammer and the spindle dropped.

Both bearings came off with no damage to anything. I already ordered new bearings, they should be here Monday.


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## boostin53 (Apr 23, 2018)

Got the new bearings in today. Gave them a good cleaning then put in new grease. I did not fully pack them as I was told not to. Instead, they are packed about 20-30%.

I got the new bearings pressed on the spindle, which I put in the freezer over night. The new bearings went in with a little effort, nothing went wrong. Got the spindle in the quill, all thats left to do is put it back in the mill and everything else with it. 

I must say, just hand spinning the spindle in the quill and I can feel that it's way better.


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## machPete99 (Apr 24, 2018)

Good show!


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