HP 97 paper advance rollers

[Dave Britten]

I got a new idler gear installed in my 97, and the printer mechanism appears to be working fine, but the rubber paper advance rollers are shot (deteriorated much like the card reader roller) and need to be replaced. Has anybody found a suitable replacement for these? They look a bit bigger than the card reader o-rings.

[Dave Frederickson]

The rollers are the same as the ones used in the 82143, P/N 5040-9228. Perhaps the rollers can be salvaged from a for-parts 82143.

Dave

Edit: I did find them in Russia.
https://zipzip.ru/?state=prod&pid=459727

And while 205.2 rub might sound like a good deal, watch those shipping charges and availability dates.

[Dave Britten]

Found a possible match with GreyUser's assistance:

https://www.amazon.com/gp/product/B082WJ21RP

They only come in a 100 pack, and it looks like they'll take a couple weeks to arrive. But if they work, I'd be happy to toss a few in an envelope and mail some if anybody needs to repair a TopCat or 82143A (I've only got postage and envelopes suitable for mailing within the US).

[Paul Dale]

Sigh, not in the US and the sellers don't ship to Oz.

Oh well,

Pauli

[teenix]

(06-19-2020 02:36 AM)Paul Dale Wrote:  Sigh, not in the US and the sellers don't ship to Oz.

Oh well,

Pauli

This would be pretty close...
http://www.abseals.com.au/wp-content/upl...120606.pdf

Product Number 580-008

A problem might arise, because I think the roller beneath the worn material has a raised centre which will make the o-ring slide off one way or the other.

cheers

Tony

[Dave Britten]

(06-19-2020 05:33 AM)teenix Wrote:  This would be pretty close...
http://www.abseals.com.au/wp-content/upl...120606.pdf

Product Number 580-008

A problem might arise, because I think the roller beneath the worn material has a raised centre which will make the o-ring slide off one way or the other.

cheers

Tony

Correct, the original piece has a channel down the center that mates with the raised ring on the plastic shaft. It remains to be seen how well a pair of these will stay on, but I'm willing to give it a shot.

[Dave Britten]

I got the o-rings in the mail today. The results are encouraging, but it's going to need some tweaking to be usable. The inner and outer diameter seem perfect, but these rings are narrower than the original rollers. I was able to fit one ring on the outside of the center ribs on the plastic hubs, but there's not enough room on the inside of the rib to fit another o-ring. The originals would extend over this rib and cover nearly the whole plastic hub, as there was a channel inside the old rollers that would mesh with this rib.

As such, the replacement o-rings aren't providing as much grip, and not advancing the paper a full line with each advance (but they are moving the paper a bit). There also appears to be some tendency for the o-rings to "walk" toward the edges of the hub, though they don't fall off entirely, as other parts in the printer prevent them from having room to do so.

Maybe if I can find some small, non-metallic washers with a big-enough inner diameter, I could glue an o-ring onto each side and get them to straddle the rib properly. I also might need to slice the o-ring that goes inside the rib in half so that it doesn't hang too far past the inside edge of the plastic hub and bump the print head, or grip the ratchet teeth on the right hub.

[Raymond Del Tondo]

Also note that there exist at least three different incarnations of the axis.
The first version, much like that used in the 97, has a decreasing diameter from the outer edge to the raised center rim.
The second version, maybe from 1981 to late 1982, has a steady diameter from the outer edge to the rim.
The latest known (to me) version has a rising diameter from the outer edge to the rim.

If you think that the early version might suit best, since it prevents the O-rings from sliding off, be aware that if you use kinda O-rings like for the card reader, the total diameter might not be wide enough.

The result will be a print head which shreds the paper at the edges, or at least which will leave scratches at the paper edges.

Better use axes of the second or third incarnations, or use suitable O-rings with slightly bigger outer diameter.