Bearing preload on Drill press spindle?

[rrgg654]

I am assembling the lower spindle assembly on my Delta press. I found taper pins that worked well. Thanks to those that answered my post about that.

When I install the assembly up into the quill, I can fell play in the spindle nose. It rocks back and forth ever so slightly. Unacceptable.

I pulled it out and clamped one bearing between wooden jaws in the vice. I can see it moving between the inner and outer races of the bearings.

I stated looking at the assembly and wondering why they have that big tube on that sits between the inside faces of the outer races of the bearings. SKF site says that for machine tool spindles, a preload is required to remove play. when my spindle cartridge is assembled it is not tight. That outer sleeve, while touching the outer races, is not forcing things tight together.

I'm thinking the purpose of that outer sleeve is to be slightly longer than the inner spacer to preload the bearings. In my case, perhaps the previous owners made their own spacer or something and now I don't have proper tension on the bearings.

Thoughts? Anyone ever dealt with this?

As always, any insights are greatly appreciated.

 

[A_Pmech]

What bearing number and ABEC class are those?

You'll want a 7000 series angular contact bearing to be able to take up the internal radial clearance with preload.

 

[rrgg654]

These are NTN 6203ZZ

 

[Packard V8]

Either you're overthinking this or you're missing a piece. I've got a similar Delta and the only preload is a light duty threaded collar which screws into the bottom of the quill and would touch only the outer race of the lower bearing.

Thinking about it, downward pressure of the feed handle and resistance from the drill bit loads the inner races, so what you're feeling when it is loose may not be present under operation.

SKF site says that for machine tool spindles, a preload is required to remove play.

Another thing to remember is a drill press is a relatively crude and inexpensive machine tool. It's just designed to make holes in approximately the desired location and diameter. It doesn't have the large adjustable tapered bearings present in lathes, mills and heavier, more precision equipment.

jack vines

 

[rrgg654]

Either you're overthinking this or you're missing a piece. I've got a similar Delta and the only preload is a light duty threaded collar which screws into the bottom of the quill and would touch only the outer race of the lower bearing.

Thinking about it, downward pressure of the feed handle and resistance from the drill bit loads the inner races, so what you're feeling when it is loose may not be present under operation.



Another thing to remember is a drill press is a relatively crude and inexpensive machine tool. It's just designed to make holes in approximately the desired location and diameter. It doesn't have the large adjustable tapered bearings present in lathes, mills and heavier, more precision equipment.

jack vines

I have a newer Delta less than 10 years old. The spindle in that press is rock solid. NO discernible play, and zero runout.

 

[marinusdees]

Preload typically applies to roller bearings, not ball bearings. That said, I'm no bearing expert, so let the experts come out.

 

[A_Pmech]

I would begin by sourcing new 7203 angular contact bearing. 6000 series radial contact bearings are not the right bearing for the job. Their low contact angles even when preloaded in the axial direction make them unsuitable for this application.

Once you get your bearings, reassemble the spindle. Maybe you get lucky. You're unlikely to find match ground race edges, so if not, disassemble the spindle and begin lapping the inner spacer a thou or so. Then try again. Keep it up until you get a small amount of resistance to turning and stop.

 

[454ragtop]

Still think you should ask over on OWWM.org, I'm sure a few guys over there have been down this road. When you checked it with the new bearings, did you install and tighten the retainer in the bottom of the quill? Maybe cut a shim out of sheet shim stock to tighten either the inner or outer spacer sleeve?

 

[Packard V8]

I would begin by sourcing new 7203 angular contact bearing. 6000 series radial contact bearings are not the right bearing for the job. Their low contact angles even when preloaded in the axial direction make them unsuitable for this application.

Once you get your bearings, reassemble the spindle. Maybe you get lucky. You're unlikely to find match ground race edges, so if not, disassemble the spindle and begin lapping the inner spacer a thou or so. Then try again. Keep it up until you get a small amount of resistance to turning and stop.

FWIW, the Delta DPs I've disassembled all came with the unsuitable bearings as OEM. The very light weight adjusting nut at the bottom of the quill will not accept much pre-load application without being destroyed. Will be interesting to see the results if OP follows this advice to change bearings and apply pre-load.

I have a newer Delta less than 10 years old. The spindle in that press is rock solid. NO discernible play, and zero runout.

Agree, my three Delta DPs are from thirty to seventy years old and are solid. However, look around here and you'll find those with a hard-used DP having #2MT spindle, using an adapter to then mount a JT33 chuck. The tip of the drill bit is hanging out about a foot below the bearings and the complaint is about runout. When precision is needed a collet in a mill will have the cutting edge 2-3" from bearings several times as large and precise as a DP.

Bottom line - well-designed and maintained DPs will drill good holes. They aren't mills and aren't used when sub-thou precision location and diameter control is expected.

Since the OP has asked this question here, as well as over on OWWM and also over on PM, he'll get a plethora of conflicting advice

jack vines

 

[Cruiserguy]

I second that , unless you find an a very high quality (and expensive) production drill press don't expect any TIR numbers below about .020" - that's not easy with a light duty machine . Bearing upgrades are where you start - then it's proper spindle adapters (MT spindles rock, btw) and good quality chucks , all of which add up to some serious cash .

Need a solid base to start from - upgraded bearings will help establish a decent base and from there you can do some adjustments to get a better result , it's really worth the time when you see how well drill bits work when they actually run true...

Sarge

 

[Packard V8]

(MT spindles rock, btw)

Explanation?

jack vines

 

[Cruiserguy]

Morse taper - industry standard for mounting chucks , accessories and some bits have that shank .

https://en.wikipedia.org/wiki/Machine_taper

Sarge

 

[Packard V8]

Morse taper - industry standard for mounting chucks , accessories and some bits have that shank .

https://en.wikipedia.org/wiki/Machine_taperSarge

Your opinions and results may vary, but the old machinist who taught me would curse at the sight of a drill press with a Jacobs chuck mounted on a #2MT spindle via an adapter. His logic - "Look at a mill or a lathe. Because they want it rigid, the taper in the spindle is internal and cutter is up as close to the bearings as they can fit it. On a drill press, where the taper is already external, several inches below the bearings, hanging a Jacobs chuck that far down on a small diameter adapter like that, it's gonna wobble. If you need a Jacobs chuck, mount it on a spindle with a Jacobs taper and right up under the bearings. Why start with a #2MT spindle if you're not using #2MT shank drills?"

jack vines