Angular contact bearings

[Kram]

On the list to make is a tool post spindle for lathe to use small milling cutters, 12mm shaft. Ive been trying to find small taper roller bearings, "30201" seems to be a real size, 12 x 32, but no where stocks it. The next one up, 30202, 15 x 35 is common.

Instead Im wondering if angular contact bearings would be just as good. There seems a few options, single row, used opposed like taper rollers would be, with a nut on shaft to pre load them?

Or double row for the front bearing, looks like a better option? In that case would I use a plain ball bearing rear, or a single/double row AC?
3201 looks like the type I want?

 

[Pete.]

Angular contact would be better most likely

 

[Misterg]

I used double row A/C for the front with a std ball bearing for the rear, but it didn't work as planned - I hoped that the double row A/C would locate the nose of the spindle, but there's a fair amount of play in them, so I had to preload it against the rear bearing to get rid of the play anyway.

FWIW, I would go single row A/C in opposed directions with preload. (I used an ER11 collet extension as the spindle and it was possible to drill and tap the end of it to take a screw to hold a preload cap.

(More here, if you haven't already seen it)

Mini Lathe Toolpost Spindle

I got asked about the toolpost spindle that I use in my mini lathe, so I thought I would post some info here. I'll describe it 'as it is' - there are improvements I've yet to make, and changes to the basic design that I'd make if I were to start again. One of the main limitations of mini lathes...

www.mig-welding.co.uk

 

[Kram]

That answers a question but raises another! If the double row still needs to be preloaded, doesnt that make the second row of the front bearing redundant as it will never be loaded?

I'll be using an er16 extension for the toolpost and I have an er11 to be a cordless die grinder - possibly adequate just with 6001's but AC should be better. I'll be using external threads for preload.

 

[Pete.]

There are a number of ways to use angular contact bearings. I don't have time to dig out the reference right now but there are a couple of good ways to do it - one is two opposed AC bearings at the front and a floating normal deep groove bearing at the rear. Another (superior arrangement according to the reference I remember reading up on) is one AC bearing at the front and the second opposing one at the rear with inside and outside spacers very closely ground to length for proper pre-load. tHe rear bearing will be floating on the OD to allow for expansion IIRC.

 

[Pete.]

Try this: https://www.schaeffler.com/remoteme...r_2/brochure/downloads_1/ac_41130_7_de_en.pdf

Check out page 194-upwards.

 

[Misterg]

That answers a question but raises another! If the double row still needs to be preloaded, doesnt that make the second row of the front bearing redundant as it will never be loaded?

Yes, I believe so - It would only act as a backstop to the loaded race. The way I have it set up, it ends up being the inner half of the double row A/C bearing that takes the load. It would have resulted in a stiffer arrangement if I had used a single row A/C bearing spaced closer to the nose of the spindle.

What I was seeking was a preloaded pair of A/C bearings to locate the nose of the spindle. These need to be separate bearings with carefully calculated shims between them, though.

If you want inspiration, have a watch of this:

 

[tigdlo]

That answers a question but raises another! If the double row still needs to be preloaded, doesnt that make the second row of the front bearing redundant as it will never be loaded?

Proper spindle bearings will have a pre determined preload once clamped together back to back or face to face or both if universal bearings.

https://www.ebay.co.uk/itm/304183880344 These may be suitable the part number can be decoded, 7003 is the size, I beleive U is universal, L is light preload, P3 is tolerance, the other letters will be for contact angle, cage and ball material, etc. Individual bearings will also be marked with ID and OD +/- in micrometers.

 

[RichardM]

In the Quorn book I have, they are fitted opposing with a spring collar to provide preload as outlined below.