Machine Make a precision spindle.

[mjautek]

incredible work, mcguyver, very inspiring... thanks for taking the time to write-up and share your knowledge with us!


maybe a stupid question but did you ever consider remaking the spindle with plain bearings? do you think that would have been any easier (or just different)?

 

[Mcgyver]

incredible work, mcguyver, very inspiring... thanks for taking the time to write-up and share your knowledge with us!


maybe a stupid question but did you ever consider remaking the spindle with plain bearings? do you think that would have been any easier (or just different)?

Thanks!

I'm a big fan of plain bearings. The can deliver excellent performance. Consider the humble watchmakers lathe, tons of them around, plain bearing, 100 years old, zero wear and virtually no run out. One of the top of the line DSG lathes, the T17 had as a option plain bearings for the lowest possible runout and few rolling element bearing lathes match the performance of say the Holbrook B8, Rivett 608, many of the Schaublin 70 and 102's (and many more, those are just what came to mind).

Nothing wrong with plain bearings, but .....

1) I'm not sure it would have been easier. You still have to create the accuracy in the parts and now you're adding the complication of tapers. I just finished reconditioning a Schaublin 70 including regrinding the shaft and making a new bearing - the double taper style. THAT was a job I vowed not to repeat. Without designated fixtures and grinders like the manufactures had, it was next to impossible to get the male and female each with two adjacent tapers mating perfectly. This is assuming the double taper (3 and 45) is how to come at it. It has had incredible success so I probably would have thought that's the preferred arrangement and it is just really hard to create.

2) secondly, in a mill, you have to have to deal with thrust in both directions. That adds complications. The way lathes do it is ok, often just with a plain bearing thrust washer/bearing, but I figure a mill would have more force pulling on the spindle (for the helix on cutters) than a lathe. Arrest things up top via the original AC's could be problematic as the shaft will expand when warmed up. That doesn't matter with the needle bearings that could move a bit within the housing, but its quite an issue for a conical bearing where you're then pushing the shaft out of contact with the bearing.

Once I figured out I could fit low profile AC's I didn't spend much time on plain bearing arrangements, although it is a worthy approach to consider. Maybe it could work, the above are just my thoughts on why I went toward cartridge bearings.

I had this fantasy of owning a machine like that some day. Not I'm much less certain. HaHa.

I hear you. Who am I to criticize the likes of Deckel and Aciera ..... but nevertheless, imo, its a horrible spindle design. The rest of the machine is just so bloody nice its worth it. Mine is silky smooth with no discernible wear, something that is a factor in deciding how much effort to put into them. What I'm unclear on is why the rest of the machine seems to have no wear, but the spindle was gone. They are highly sought after, asking prices of like 10,000 eros.

I wonder how many check and understand the potential spindle complication? Maybe I just got unlucky and most others are good? Everybody indicates the tapered bore which checking out a machine which in this case had very little runout ..... but this was because of the AC's at the top of the spindle. A bit of lateral force moved the business end of the shaft .003"!

 

[Dan Dubeau]

Great machining and problem solving. Thanks for taking us along for the ride.

I didn't really realize how small these mills were until some of your photos showing the sense of scale.

 

[Susquatch]

I hear you. Who am I to criticize the likes of Deckel and Aciera ..... but nevertheless, imo, its a horrible spindle design.

I simply can't resist commenting on this......

They would have paid you a king's ransom to go and work for them....... But you would have said no because you had more important dreams and prolly couldn't tolerate their work culture anyway. And that is why it's a horrible spindle design..... It's all your fault! LOL!

 

[Mcgyver]

When were you talking to my wife?

j/j, she's great and never does stuff like that lol

 

[mjautek]

Nothing wrong with plain bearings, but .....

Thanks again for your thoughts! come to think of it, it's pretty incredible that you've rebuilt both a plain bearing spindle and this one with roller bearings.


As for why deckel did what they did (and also why plain bearings came to mind) - the fp1 had plain bearings in both horizontal and vertical spindles from 1933(?) - 195x (?) so I wonder if the ground-in bearing races was done to keep the same form factor.

Also I wonder if it's not really a problem if people keep up to date on maintenance. the deckel manual says to dismantle and regrease the spindle every 3-5000 h, I'm sure most people never did...

one could argue that the design is good enough - with some care it will last the "lifetime" of the machine. I wonder if the designers and factory workers ever considered that their creations would be cherished by people like us 50-70 years after the machine was built...