TOS FN20 Grinding Sound in the Spindle Head

[TonyK]

I was making a bracket for my neighbour the last few days for his gas powered cut off saw that had broken. I could have tried welding it, but it was a light cast aluminum and didn't feel it would last very long on the machine with all of the vibration. Near the end of the machining I heard a grinding sound in the head of my milling machine. Today I took apart the right angle drive.

On the bench and cleaned are the parts in the head. The bearings are rough and over the years I have had a problem with the drive between the miter gear and the spindle. What was found was that the key had broken in two and fell into the bottom of the casting. My solution years ago was to make another key and thought until now that the key floated in the key way when positioning the Quill. Hence the long key you see here. What I found today was that the key was held in place by a pin so that it would not move up or down in the key way on the drive side.

The hole for the pin is behind inner bearing race that retains the key from moving up and down. All of the little bits of key have ended up in the bearings and they are shot.

The bearings are NSK 6008 and engraved is the letters "P5" on each bearing. I wonder if this means they are a matched set? The 6008 bearing is a deep groove bearing, possibly for higher radial loading?

So it looks like a trip to Canadian Bearings in Hamilton tomorrow. The right angle drive is not in an oil bath, but has an oiler on top ( spring loaded ball ). It also has a knurled ring that applies pressure to the brass cone to adjust the mesh of the miter gear. The spindle bearings are totally independent of the drive and power is transmitted to the spindle by 3/16" key. If I am looking at this wrong, please chime in. Thanks.

TonyK.

Grimsby Ontario Canada.

 

[RobinHood]

It’s a good thing you found what was causing the problem.

Your bearing experts will know for sure: I think the “P5” refers to the precision class. P5 ==> ABEC 5.

 

[Proxule]

Your bearing experts will know for sure: I think the “P5” refers to the precision class. P5 ==> ABEC 5.

Aye, that-ll be it. Could be pricey!
Matched sets normally have indications like dots or arrows or hash marks, Or a big V shaped marking from inner to outer race, Some thing.

Gluck

 

[TonyK]

It’s a good thing you found what was causing the problem.

Your bearing experts will know for sure: I think the “P5” refers to the precision class. P5 ==> ABEC 5.

Some searching shows that the P5 Precision class is middle of the range 4x to 5x more expensive than a standard bearing. So much for picking them up today, most likely will need to be ordered. That being said the miter gear and rotating boss has no affect on the spindle as it drives the spindle by the key. I will see how much the P5's are over standard bearings. If it was the spindle bearings, well that is another issue on it's own. I wonder how many milling machines have P5 bearings installed for drive line over standard bearings.

Thanks for the response.

TonyK.

Grimsby Ontario Canada

 

[TonyK]

Finally back at this. A two week vacation to Wisconsin Dells for a FIAT car show, then a trip to Radcliff ( Fort Knox )Kentucky to visit friends, 3200 KM of driving with the Ram 2500 Cummins 6.7, 6 speed manual to get back home again. Then my dad now 97 and will be 98 in August was moved from his nursing home of 7 years to a new facility and is totally confused. To add some more problems there was a respiratory out break and he ended up with pneumonia, fell, cut his head open and was hospitalized for a week. Liver function low, kidney function low, heart rate low, we were told to prepare for the worst. My dad was born on a farm in Manitoba and has a way of surprising everyone. A few days in the hospital and he is eating and resting and doing fine. Currently back at the nursing home using his walker, all is good.

The bearings came in to Canadian Bearings and were very reasonable for pricing $36 each. I asked if they were precision and was assured they replace the bearings that I took in for replacement.
While I was there I also asked for a length of 5mm key stock and was told metric key stock needed to be ordered. Imperial sizes only in stock. I just ordered from China and it arrived in 2 weeks when I got home from vacation.

This is how the drive assembles, but, the bearing race covered the holding pin for the 5MM key and I had to remove it.

These bearing appear to have one larger shoulder on the numbered side race for thrust applications.

A new pin was made to retain the 5MM square Key and a notch was filed into the Key. ( some how I forgot to take a picture of this ) The key is in the picture 5 down from this one. When assembled it has a thumb press fit on the spindle.

This is how the bearings are on the miter gear shaft, but I some how didn't assemble the bearing in the hub boss, so... once more I had to take this apart.

The Machine ( TOS FN20 ) is now back together and ready to work.

TonyK.

Grimsby Ontario Canada