Gummy Repair

[teenix]

Hi all,

I've repaired a few gummy wheels now and I am starting to get convinced the 1/4" outer diameter o-rings are not quite the right ones to use.

I may have missed this earlier on, but I am finding that when these are fitted, the o-ring outer edge butts up against the little nylon idler roller and causes drag on the drive wheel.

If you make a repair with o-rings, then it is best to check how well the drive wheel turns without the motor installed and with no card in the slot. If it doesn't spin freely, then it is likely the o-ring diameter is too great. The drive wheel should slide into position without drag either, or the o-rings are too wide.

I tried some 3mm silicon tubing but this is just a fraction too small although it works on maximum pressure adjustment.

Looking around, there are some o-rings with 2.57mm hole and 6.13mm outer diameter. This is somewhere in between 3mm and 1/4 inch. These look like they are easily available, bags of 50 for a few dollars.

I also came across an old post which mentioned the same thing, so maybe there is something in this, although I am yet to try them.

https://archived.hpcalc.org/museumforum/...50207.html

Its interesting that the inner o-ring on the repaired wheel is almost useless. It doesn't look like it touches the card, but it does serve as a spacer for the outer one :-)

cheers

Tony