G0704 Milling Machine Spindle Bearing Upgrade: How to Install

This video covers the installation of angular contact bearings in the G0704 milling machine.

VXB.com
9537 (6007ZZE)
9569 (6209ZZE)
8891 (7007B)
8889 (7005B)

McMaster-Carr
98055A346 (35x45x1 Shim)
98089A404 (25x36x1 Shim)

Kluber ISOFLEX NBU 15

3ml Luer Lock Syringe w/15 gauge blunt fill needle

[jmbstudio]

Big help taking mine apart. I pulled the headstock off and the spindle bearings were shot. Thanks for the vid!

[howardblinder]

Hi Franco- thank you for this video. I have watched it several times, and now feel very comfortable beginning my own spindle rebuild. I did notice one thing that you did that may be a mistake. After you seated the lower spindle you installed the pt# 247 spindle ring loosely. You called it a dust cover, but I believe that it is actually the lower bearing retainer. Next you installed the upper bearing using the pt#251 adjustment nut to seat the bearing, then gave it a bit of preload, followed by fighting the bottom pt #247. I think that the pt #247 should be tightened 100% before installing the upper bearing, or attempting to pre-load. Because if the (bearing retainer) is not locked down, and stack up is slightly off, you won't be able to achieve pre-load, and could possibly press the lower bearing down, out of its seat. Now when you tighten the lower pt#247, you don't have any idea how much pre-load you may be inducing. Great, presentation, thanks again, Howard

[howardblinder]

Hi Franco- just a quick note to let you know that I did my bearing install per your video. All worked great. Once I got a look at the old taper bearings I could see why they were running hot, by the wear marks, bearings were dry as a bone. I am going to make a reminder/note to open up the spindle every few months and grease the bearings. Thanks again for the instructional Video. Howard PS. Spindle runout is less than .0001. Yes, I couldn't believe it, under 10th of a thou. I setup and checked several times with my .Mitutoyo 0005test indicator

[furbarator]

Thank you for doing this video. As a by product of your how to video I was able to figure out how to replace the nub screw that index's the R8 arbors & collets. The best part is not having to tear down the head to replace that screw. Thank you.

[kentowakai]

You totally earned your MacGyver badge on this one.

[DougHanchard]

It will be interesting to see how long the angular ball type bearings last. They are generally not designed for perpendicular loads, which your quill will go through every time you've engaged Z and load is applied to your part. An angular bearing is used to support radial loads. The Z runout (backlash) will be a great indicator when they are worn out.

The use of Angular ball type bearings are superb for high speed RPM, between the two race grooves but when loaded to one side (down or up) wall loads become uneven, the life of the balls will decrease and the high speed centrifugal forces will likely become distorted, allowing the quill to become unbalanced (harmonics).

There's a reason why the drive was rated for a maximum RPM and of course, why the OEM bearing specs would have been satisfactory for their intended use. One option would have been to have been to replace the OEM bearings with higher grade conventional bearings (SKF, Timken, etc) and have them chemically hardened with a heat treat, sometime known as EDM. That would allow higher rpm as you desire. There are models of bearings that use different bearing steel as well, further allowing more loads, temperature and speed.

We use angular ball style bearings in race cars and routinely have to replace them due to wear from perpendicular load characteristics and we use a bath oil system, which still has a difficult time keeping them within temperature range specification. They do significantly reduce parasitic drag (by as much as 30%) - but at the cost of increased wear rates and routine replacement. The RPM of our bearings is actually lower than you planned speeds of up to 5, 000 RPM but have perpendicular axial loads of up to 4, 000 lbs.

Let us know how they perform over the life of your machine!

[paulcotto]

If you heat the bearings before you install them its much easier to press them on a shaft. You might might not even need a press. You also can used canned air to freeze the outer race before you press them into the case.

[bs]

Just as an FYI not sure if its a difference in newer model or difference between clones but I am currently doing the same bearing upgrade on my PM25-MV which is a clone of the G0704. However the smaller deep groove ball bearing in the upper spindle housing is not a 6007ZZE, but a 6009ZZE everything else seems to be the same so far.

[tobyw]

Take care with ball bearings, the inner race can be expanded by a tight inner shaft and the outer by a tight outer race depending on how rigid they are. You need to have perfectly round shafts and bores and enough clearance for the film thickness of the lube you use. Insufficient clearance causes heating from shearing of the lube. Balls are sensitive to load since they have point load, not line load like rollers. The tight adj on your rollers may have been the cause of the heating. I have seen new and greased tapered wheel bearings in a car blued or yellowed by over tightening - no cheater bar required!

[arvakes]

So runout after.. but runout before? Because I understand that if bearings get so hot in there then either there is no oil, wrong oil or too much preload since tapered bearings need proper preload. Also as long as bearing temp stay below 100c it should be fine.

[wmcrash]

I have the same HF snap ring tool. If you install the attachment at 90 degrees to the body, you will have enough travel to open that snap ring. I forget which pins and which holes I used, but you get the travel. You will still have a HF tool, not a Snap-on, but you will get the travel.

[danielmorgan]

Nice job! You made me break down and buy that grease for my Smithy Granite! Lol

[theman-jorr]

Well done sir! those homemade tools are usefull.

[coffeeisthepathtovictory]

Thank you for this, 1000x likes if I could

[euroman]

Did your spindle got hot after running with no load before changing the bearings? Does it get hot now?

[kentvandervelden]

Interesting video. Why were the bearings replaced? To tolerate the higher speeds? What the mill quieter after replacing the bearings?

[tobyw]

With a needle, you can lube neoprene shielded bearings.

[mabgfounder]

Great video. Thanks for sharing. How well have the gears held up to the higher speeds?

[imetrr]

I wish you had showed more detail in the disassembly.

[makosharkcnc]

are these spindle bearings the same for the PM-25MV? and the same spindle as the G0704?