IBM YD 360k Drive 'bouncy'

[falter]

Weird one - I'm trying to put this 5162 back together and away so I can finish rearranging my space, and I tried booting off the floppy drive, only to discover it wouldn't. As I looked at it, I noticed the disk was 'flexing' a lot more, the surface of it bouncing up and down, and the top 'spindle' wobbling a bit more that I thought it should.

For an experiment, I tried releasing the drive lock, letting the upper spindle up until it was just making contact with the motor spindle, and then observed that it was able to read the disk, with none of the flexing going on. I then lowered the handle all the way again, and it it carried on working until I ejected for the next disk.

I'm not sure why it doesn't lock in properly on first try, or why it locks in after my intervention every time.. is there any adjustment you can do with these? I noticed there was a screw that sort of sets the angle of the upper spindle, but adjusting that seems to make no difference at all.

This is a video of it bouncing. Many thanks if anyone has any advice.

https://youtu.be/ZLiqfVxveEs

[Chuck(G)]

I haven't grabbed one of my YE data drives off the shelf yet, but one thing to inspect is the nylon "cone" that's inserted into the hub and secures the floppy. Sometimes they crack or break.

[maxtherabbit]

I haven't grabbed one of my YE data drives off the shelf yet, but one thing to inspect is the nylon "cone" that's inserted into the hub and secures the floppy. Sometimes they crack or break.

It is exactly this. I've had this issue with the YD-580s as well. They don't usually crack or break but they do get stiff and create centering error. You can usually fix it by cleaning the cone and lubricating its bearing surfaces (not the part that bares on the disk but the part it rotates around).

Additionally you can loosen the screws and shift the upper bracket around a tiny bit to help make sure the cone is dead centered over the flywheel. You can test the fitment here without a disk inserted. Make sure if you lower the door latch slowly it smoothly engages the flywheel without "popping" into place

[falter]

Thanks maxtherabbit! You're referring to the shaft and spring between the 'plate' and the cone?

The cone looks like it goes down smoothly every time, no shifting. Only thing that seems to shift a bit when you lock the lever is the disk itself, it moves a tiny bit over to one side of the drive.

[Chuck(G)]

Believe it or not, floppy disk centering was a big deal back in the day. When the first 5.25" drives came out with DC controllable spindle motors, there was a huge problem with disk insertion when the motor wasn't running. Eventually, a switch was added to detect the drive door closing to give the motor a short period of spin so that the hub clamp could center the floppy. The 8" world at the time, didn't have to deal with this as most drives used line-operated motors that were always on.

So do check your drive to make sure that the spindle motor is running as you insert the floppy.

Before the drive manufacturers figured this one out, they introduced the hub reinforcing ring as a stopgap, albeit not very successful measure. You could get a kit to apply the rings to the disks you already had--IIRC, it was Dysan that first started this practice. Shugart had the patent for the "expanding cone" clamping method and not every other manufacturer licensed it. And that, my friends, is why DSDD 5.25" floppies have the ring, but high-density ones (1.2M) do not. By the time the high density media and drives were introduced, the problem had been solved.

[maxtherabbit]

Thanks maxtherabbit! You're referring to the shaft and spring between the 'plate' and the cone?

Yes

Believe it or not, floppy disk centering was a big deal back in the day. When the first 5.25" drives came out with DC controllable spindle motors, there was a huge problem with disk insertion when the motor wasn't running. Eventually, a switch was added to detect the drive door closing to give the motor a short period of spin so that the hub clamp could center the floppy. The 8" world at the time, didn't have to deal with this as most drives used line-operated motors that were always on.

So do check your drive to make sure that the spindle motor is running as you insert the floppy.

The YD-380 (HD) does indeed have that feature, but the YD-580 (DSDD) does not

[Chuck(G)]

Might be worth a shot to see if the drive is started and a disk inserted results in correct centering.

[falter]

What sort of oil/grease would be recommended for this sort of thing?

The disk doesn't seem to spin until you insert the disk and engage the drive. It does seem to center better when the motor is already running.

[Chuck(G)]

The motor, IIRC, should spin as you're closing the latch. I've got a 580 here and I'll check it out in the next couple of days to make sure I'm not talking through my blowhole.

As far as lubrication, the 380 manual doesn't recommend any, and I doubt that the 580 does either.

[maxtherabbit]

The 580 does not do that I promise, only the 380