O-Rings, Drive belts etc

[Gopher]

Not in anyway affiliated with them but, recently needed some new feeder belts and acquired them from http://www.polymax.co.uk/ pricing seems good even compared with what I could find on the bay (& significantly less than DC used to ask for) and they came next day. Wasn't entirely sure what size would work best so tried 84mm ID 2.5mm CS nitrile rings, so far its quite clear these work much better than the 3mm CS belts I was using before and tbh I suspect may well have been what was originally supplied on the machine. Could possibly be worth trying a smaller inner diameter however, I arrived at 84mm by chopping an existing belt and measuring it on a ruler which clearly won't have given the best measurement.

[Mike]

Thanks for the info - I'm getting tired of having to 'help' some of my feeders so maybe time for a re-belting session.
Platenclene spray (for cleaning print rollers) can give some temporary respite but hard to get all round the belt.

BTW I think DC got them from http://www.bearingtraders.com/

[spiyda]

I am having trouble getting the feeders to drive plastic tape...
I assume this is a lack of friction between the belt and the tape..

I have tried platenclean which helps a bit but I guess I will have to rebelt at least one feeder

Has anyone tried any other belt materials than nitrile ?

Urethane seems to be popular for small drive belts, but I have no idea what the difference in co-efficient of friction would be.

Chris

[Mike]

The nitrile ones seem to last pretty well, and work well during their life - you'd need to test over quite a while to see any difference (unless alternates are particularly poor).
If yours are slipping maybe you should try rebeling with different types to see how they compare?
A possible issue is they are under high static pressure when not moving, so some materials may be prone to flat-spotting. 
Rebelting is a pain to do, but afterwords everything just works with no fiddling.
Remember to slacken off any previous excessive tension used to squeeze life out of old belts!

[phonoplug]

I've replaced nearly all of mine with silicone (orange) belts. They tend to have a bit more tack that doesn't age, and don't crack and break within 12-24 months. One particular feeder design, one of the older ones I think, came with silicone ones as standard I believe.

And on that subject I recently found out there were at least 4 different designs of feeder! Not talking 10x8, 3x12+5x8 etc, but different designs in terms of the mechanism. All seem to have their own good and bad points.

[Jason]

Yes, I have a feeder that has what appears to be original orange belts on them and they are still very grippy.
The problem with that feeder is that is only works well with paper (not plastic) tapes and they all need to be the same thickness.
I also need to service a number of black-belted feeders and was going to ask about materials too, so this discussion has been helpful.

[phonoplug]

Jason - the feeder you describe is the one I was thinking of. Its actually one of the most reliable ones I've found, though loading it is a pig. Indeed you do really need to use roughly the same thickness tapes in all the lanes, but you can adjust it so you can use plastic tapes by 'whacking' the levers at the side that hold the pin that is the axle for the roller wheels. Sounds crude - it is - but I think that is how it was meant to be!

That said, when set up right, its pretty reliable, so set it up with things you won't be unloading much (100N, 10k etc..)

[spiyda]

Well,

I'm sure most folks with RVs have done this but
I bit the bullet and stripped the offending feeders down (as far as the mechanicals go)
I ultrasonically cleaned the mechanicals that are involved in stripping
and cleaned the moving carriage parts with an air line..
The belts (which appear to be nitrile) were soaked in platenclean rubbed and dried.

I found a variety of SMD parts..  as well as several short lengths of cover tape..!
I think it may have been the cover tape wound round the take up spindle that was causing the issue.
It probably increased the load the friction between the belt and cover tape needed to overcome.

For the moment the feeders seem to be working OK even on plastic tape..

One question..  the pins operated by the solenoids appear to be running in oilite bushes..

After 15 years they may be a bit dry..  has anyone attempted to relube in this area ?

[phonoplug]

Ha - fatal mistake to oil the pins! It sounds like a good idea, but what will happen is that the oil will absorb tape dust and you'll soon end up with 'sticky pins disease' where the feeder drives the tape forward then immediately retracts it again because the pin doesn't drop out of the hole in the tape. Very annoying.

[Mike]

The belts (which appear to be nitrile) were soaked in platenclean rubbed and dried.

If you're going to the trouble of stripping down it's silly to not put new belts in - they're only 30p each!

[spiyda]

The belts all seem to be working OK now,
I reduced the tension on many of them and they work better.

as for lubrication, I was thinking more like washing out with solvent then using PTFE dry lubricant...

Even after cleaning out with an airline, I have a few pins that seem a bit slow to retract..
the odd tape does not line up exactly with the others after indexing..

I have enough to avoid using the iffy ones, but it would be nice to have them all working..

[Mike]

While I have the packet to hand - the ones I use are stock code 84X2.5N70 from Polymax
http://www.polymax.co.uk/o-rings/rubber-nbr-oring/2-5mm-cross-section-nitrile

[Jason]

I measured up the old belts and went for 3mm rather than 2.5mm and they seem to work ok.
A renewal was forced on me after a number of my unused feeders were left in bright light for a while
and I cam back to find all the belts on one feeder had broken.
Interestingly, the only one that had suffered this appeared to be populated with Nitrile whereas
the rest seemed more like traditional latex.
The new Nitrile belts deffinitely have more grip but I suspect the are more prone to aging.

[Gopher]

The reason I went for 2.5mm belts back then was because 3mm ones get ever so slightly pinched by the neighbouring pulley and this seemed to be affecting feeder performance. YMMV

[Mike]

The O-rings for the head are 8x1mm - I have Nitrile and EPDM ones from Polymax, and The Nitrile are definitely better - the EPDM ones are too stiff so the nozzle doesn't load well.
Order code 8X1N70.