Dumb question on R8 (i think) spindle

[DavidR8]

Here is a long boring bar in a 5c collet block.

Now I need to replace the bearings and have at.

View attachment 355289

Looks good though you will want to keep the tool stick out to just what is necessary to perform the operation.

 

[rwm]

I gotta think that boring bar is too long and too narrow for this operation.
R

 

[Ken226]

It'll have to be long enough to reach the top of the upper register in his R8 spindle.

That is to say, he will need 4" of boring bar to reach the top. About 4-1/4" ish, to keep the collet block from rubbing the spindle nose.

He shouldn't need to take much, if any, depth of cut. Just knock down any high spots from whatever damage is there.

With 4.25" of stickem-out and light cuts, he'll probably be ok.


Most likely, someone in this machines past under-tighted an end-mill holder, sheared the index pin, and kept a pushin while the holder was galling out the spindle.

 

[DavidR8]

Based on the photos of collets that were modified I don’t think the problem is damage. I think the internal bore is not large enough, far enough up the spindle.

 

[r-mm]

Hi all. Here's a photo mocking the boring bar up, positioned to the rearmost surface that needs material removed. Yes I will fine tune stick out when I'm ready.

 

[r-mm]

Regarding the bearing replacement - McMaster has good options for all besides the two angular contact bearings at the bottom of the spindle.

McMaster-Carr

McMaster-Carr is the complete source for your plant with over 595,000 products. 98% of products ordered ship from stock and deliver same or next day.

www.mcmaster.com

McMaster-Carr

McMaster-Carr is the complete source for your plant with over 595,000 products. 98% of products ordered ship from stock and deliver same or next day.

www.mcmaster.com

The angular contact bearings are 7207b. I removed the old ones which are Made in Japan NSK brand and look/feel to be in good condition. Mcmaster lists 7207 for $86 each. https://www.mcmaster.com/6680K18/

This is my first hobby machine and I do not want to spend a huge amount on bearings. I do realize their importance, but everything is a balance. I want to get to know the machine, make some parts - which I never have - and see how I feel from there.

 

[DavidR8]

Regarding the bearing replacement - McMaster has good options for all besides the two angular contact bearings at the bottom of the spindle.

McMaster-Carr

McMaster-Carr is the complete source for your plant with over 595,000 products. 98% of products ordered ship from stock and deliver same or next day.

www.mcmaster.com

McMaster-Carr

McMaster-Carr is the complete source for your plant with over 595,000 products. 98% of products ordered ship from stock and deliver same or next day.

www.mcmaster.com

The angular contact bearings are 7207b. I removed the old ones which are Made in Japan NSK brand and look/feel to be in good condition. Mcmaster lists 7207 for $86 each. https://www.mcmaster.com/6680K18/

This is my first hobby machine and I do not want to spend a huge amount on bearings. I do realize their importance, but everything is a balance. I want to get to know the machine, make some parts - which I never have - and see how I feel from there.

You may want to check out Bearings Canada. I picked up Nachi angular contact bearings fro my mill for less than expected.

2 Bearing 7207B 35x72x17 Angular Contact

2 Bearing 7207B 35x72x17 Angular Contact

www.bearingscanada.com

 

[Ken226]

How is the spindle end-play and preload for AC bearings set or controlled on that spindle? It didn't have threads nor an adjustment nut, right?

Ha! Nevermind. I see the threads in your pic.

The cheapest precision bearings I can find are abec4 7207 on Amazon for about 86$ each.

Just get the best you can afford. Having a thousandth of spindle runout is better than not having a mill. If that means 20$ truck axle bearings, it's still better than no mill at all.

 

[r-mm]

I see well priced Nachi bearings on ebay then questioned if they may be counterfit. The price on Bearings Canada suggests maybe not - but I don't see anywhere on the link posted that those are in fact made in japan.

NACHI 7207 B JAPAN ANGULAR CONTACT BEARING 35x72x17mm | eBay

These bearings are non-separable. Since the balls are inserted utilizing counter-bore construction, a larger number of balls can be installed than in the case of Deep-groove ball bearings. Standard cage materials may be pressed steel, high-strength brass, or synthetic resin.

www.ebay.com

 

[DavidR8]

I see well priced Nachi bearings on ebay then questioned if they may be counterfit. The price on Bearings Canada suggests maybe not - but I don't see anywhere on the link posted that those are in fact made in japan.

NACHI 7207 B JAPAN ANGULAR CONTACT BEARING 35x72x17mm | eBay

These bearings are non-separable. Since the balls are inserted utilizing counter-bore construction, a larger number of balls can be installed than in the case of Deep-groove ball bearings. Standard cage materials may be pressed steel, high-strength brass, or synthetic resin.

www.ebay.com

The ones I linked to are not Nachi, but they do have several varieties of Nachi 7207.

Search Results, Bearings Canada, The Ball Bearing Canadian Online Store

www.bearingscanada.com