Oops, my obsession with computers from my childhood strikes again!

[PhilC]

Good luck with the drive @rubber_jonnie, I'm trying to think what would clean the rubber but not destroy it. Maybe carefully with some IPA? Might take the glazed surface off of it?

[Tomswork]

Are those litte spindles press fit on maybe you can find a donner drive just have to set the speed up again.

Tom

[rubber_jonnie]

Good luck with the drive @rubber_jonnie, I'm trying to think what would clean the rubber but not destroy it. Maybe carefully with some IPA? Might take the glazed surface off of it?

The rubber is actually just gone on the Seltron spindle, just a really thin brass drive spindle now, so I need to come up with an alternative rubber part to replace what is now missing, however at present I'm thinking superglue and a thick rubber band. don't think it needs much and I have some really thick bands that might just do it.

[rubber_jonnie]

Are those litte spindles press fit on maybe you can find a donner drive just have to set the speed up again.

Tom

They are press fit, but I don't have any that are spare, other than the 1050, which I am not willing to sacrifice as AFAIK that's a runner too, especially since I don't know 100% if the spindles are the same size.

I have a box of nitrile rubber 'O' rings as well, it may be possible to use a couple of those, I'll have to see.

Of course the difficulty is getting them on to the spindle as it has a large diameter lip around it:

IMG_20211001_170600.jpg

I think it'll be feasible but fiddly to do, especially since all of the wiring is soldered making motor removal rather more fiddly.

I just double checked the 1050 and it definitely has some sort of rubber component in the drive spindle, and that would totally explain why the drive belt is still slipping on the Seltron. Given it is a fibre reinforce belt, the likelihood of it stretching is much smaller.

It also explains when one of my other belts started driving it at nearly the correct speed when it slipped around the top of the drive spindle.

I'm hopeful here.

[PhilC]

@rubber_jonnie a couple of orange gets my vote if you've got any that will stretch over the flange on the pulley, good luck with getting it timed back up again.

[Tomswork]

You maybe able to put some rubber on the spindle with a glue as a last resort


Tom

[rubber_jonnie]

@rubber_jonnie a couple of orange gets my vote if you've got any that will stretch over the flange on the pulley, good luck with getting it timed back up again.

Timing is all good I can use Locksmith to get that sorted 😁

[rubber_jonnie]

You maybe able to put some rubber on the spindle with a glue as a last resort


Tom

That's what I'm hoping to do 😁

[rubber_jonnie]

A bit of success regarding the Seltron FDD today. I managed to get some rubber from a spare drive belt stuck to the spindle as below:

IMG_20211002_124349.jpg

And I am not having any drive problems now, in that the belt no longer slips on the brass spindle at all. I have tweaked a bit since this pic to ensure the brass lip is more prominent and the belt can't ride up.

A disk speed test with Locksmith actually registers now when before it did not, but as you can see, it is stuck way over at the far side of the graph on fast (It's the vertical line).

IMG_20211002_135833.jpg

Compared to my genuine Apple ][ FDD:

IMG_20211002_140301.jpg

It is however progress as I couldn't even get it to read on the speed test before.

Adjusting the motor pot down to the slowest speed (I can hear the motor note change) doesn't help, so I'm thinking I have 2 options:

1. Remove the rubber and re-apply and try to make it thinner.
2. See if I can change/augment the motor pot characteristics to give a wider speed range.

Option 1 is hard to do as I think I have it about as good as I can get it right now, so I'm thinking I need to try option 2, so I need to have a look at the pot value and see if it could be changed. The main problem I have is that it is an unusual FDD and I have no schematics yet.

All thoughts and suggestions welcome.

[stephen_usher]

I'd remove the rubber and just sand the surface to make it pretty rough myself. Are you sure that the belt that you're using isn't too long?