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Dumb question on R8 (i think) spindle
- Thread starter r-mm
- Start date
- Joined
- Jan 6, 2017
- Messages
- 1,214
It's generally done by temperature. A setting that results in the bearings warming up after 30 minutes and fill speed, but not too hot too hold your hand on. For mine, I like it to reach about 130-140f after 30 minutes of use.
That said, unlike a lathe, these preload nuts are a pain to be adjusting multiple times, on the fly.
For my cnc mill, I went as tight as I could get the nut with my bare hands, then picked a spot on the outside edge of the nut and tapped it about another 1/16” in the tightening direction.
After 30 minutes @4000 rpm, it was at 130°. I could have got a little tighter, but runout was under a ten thousandth, so I left it alone.
You’ve gotten a lot of great advice here. One more thing to check is the spacer. It needs to be flat and parallel to 0.0001” otherwise the bearings might not remain parallel and maintain the proper preload.
If you decide to get your spindle checked out, there is company up here in New Milford called Cavco that rebuilds machine tools and would be able to bring it back to specs. I have no idea how much that would cost, but an option for you.
If you decide to get your spindle checked out, there is company up here in New Milford called Cavco that rebuilds machine tools and would be able to bring it back to specs. I have no idea how much that would cost, but an option for you.
- Joined
- Mar 25, 2013
- Messages
- 4,617
I am confused about the spacer. I always thought spindle bearing had to be "matched ground". My understanding was that once matched, they would be correctly preloaded if they were placed face to face without any spacer? In this application it seems like the spacer will hold the inner races apart and preload would be established by tightening the nut which pushes on the inner races? That seems unreliable at best. It works well for bicycle headsets! Am I interpreting this correctly? Would it be better to use a matched ground set? I have never built a spindle but please enlighten us if you have experience.
See this:
principle-eng.co.uk
Robert
See this:
Duplex bearings | Principle Engineering
Duplex Bearings provide accurate alignment in both radial and axial directions. Vibration can be eliminated and higher load capacity achieved.
principle-eng.co.uk
A matched ground set is only needed when the bearings are mounted without a spacer between them, or a spacer on the inner AND outer rings. You would need to order them with the preload you want, light, medium, heavy, etc.
The way these mills are designed, the bearings are spaced apart to increase the rigidity of the spindle, it also helps with heat dissipation. The spacer provides the spacing between the bearings on the outer ring, as well as keeping them parallel. You can adjust how much preload you want by how tight you make the nut against the top bearing inner ring. If there was a spacer on the inner ring as well, it would either have to be precision ground to the amount of preload you wanted for the bearing set, and then you would just tighten it down until it stops and not worry about adjustment, or you would have both spacers the same height but use bearings with the appropriate preload ground into the rings. It’s a lot cheaper to do it with a single spacer and manually adjust the correct preload.
The way these mills are designed, the bearings are spaced apart to increase the rigidity of the spindle, it also helps with heat dissipation. The spacer provides the spacing between the bearings on the outer ring, as well as keeping them parallel. You can adjust how much preload you want by how tight you make the nut against the top bearing inner ring. If there was a spacer on the inner ring as well, it would either have to be precision ground to the amount of preload you wanted for the bearing set, and then you would just tighten it down until it stops and not worry about adjustment, or you would have both spacers the same height but use bearings with the appropriate preload ground into the rings. It’s a lot cheaper to do it with a single spacer and manually adjust the correct preload.
Hey everyone after focusing on some other projects I finally got my spindle and quill assembled and ready to install back into the head.
I am presently stumped by two things. First is that the quail absolutely will not start at the bore on the head. I gave the edge a light deburring on both parts but it still will not budge. What is odd is that I can get it started upside down. Are parts like this is known to be a tight fit that requires heating and cooling and light press action possibly from the knee?
The other thing is that it looks like the male splines on the spindle are slightly crowned meaning they are wider at the very end. I do not have enough experience to know if this is damage or intentional but they will need to mate with the female splines while I am inserting the quill.
I
I am presently stumped by two things. First is that the quail absolutely will not start at the bore on the head. I gave the edge a light deburring on both parts but it still will not budge. What is odd is that I can get it started upside down. Are parts like this is known to be a tight fit that requires heating and cooling and light press action possibly from the knee?
The other thing is that it looks like the male splines on the spindle are slightly crowned meaning they are wider at the very end. I do not have enough experience to know if this is damage or intentional but they will need to mate with the female splines while I am inserting the quill.
I
- Joined
- May 23, 2017
- Messages
- 109
The spindle outer bore should fit tight, if you can start it from the top, then it too was mushroomed by a hammer.
That spline damage looks like hammer damage. That should be filed to the same diameter as the rest of the shaft.
That spline damage looks like hammer damage. That should be filed to the same diameter as the rest of the shaft.
