Roland RE-640 – media lifting

[Chris johnson]

I guess anyone with an RS640 might have had the same problem too if you can shed any light on the problem.

I can’t really use the take up system until I can sort this issue out.

Thanks

Chris

[Denise Goodfellow]

first I would try polishing the area where the media touches the machine, with anti staic polish. Static builds up and stops the meadia coming through nice.

The other thing, we never print banners without connecting it to the take up roller. this also helps pull the media through.

[Jamie Wood]

It is usually caused by heat – too much, and the banner will cockle. Our ways round it,
are to reduce heat (if possible), or raise the head to the higher position. As already said, attaching to the take up before starting will also help.

[Chris johnson]

I have used the take up system too and seem to get the same problem.
Maybe I will try the take-up system again.

The cockling doesn’t seem to run diagonally like it would if the media wasn’t straight. They are always straight between the rollers. I will try turning the heat down a little too.

It happened while my printer installation engineer was with me and his solution was to unroll some of the media so it wasn’t pulling, problem is if I am busy and don’t notice when the slack is used up I get major cockling as the media starts pulling off itself again. Ideally I was hoping to do some unattended printing but not confident I could leave it at the minute.

[Chris johnson]

Also something I realised the other day during printing of a large solid area was that it seemed to occur at regular intervals about a foot apart which is maybe the circumference of the roll.

[Jamie Wood]

Is it expanding into the gap between the rollers, causing a hump? If it is, it’s the heat causing it, as there is nowhere else for the material to expand into. Can you raise the
printhead?

[Chris johnson]

Yes it is always between the rollers. I will try lowering the heat, mine is set at about 35 I think. Will drop the heat and run some tests.

[Chris johnson]

yes I can set the print head to high, problem is I think that the printing would still have the same problem as the head would still lay different amounts of ink where the media is raised.

[Simon Worrall]

Chris ,35 degrees is not excessive. What media are you using? And how heavy is the ink going down?
Occasionally customers mistakenly use REGISTRATION black instead of black, which puts down about ten times as much ink which softens the media so much it balloons or melts. Watch for this. Otherwise, try a different profile.

[Chris johnson]

Thanks for all your help guys.

I turned the print heater off and much less cockling. The only thing I am finding is the occasional ripple right in the center of the media between the rollers. It does seem to disappear after the first few meters of media only reappearing very rarely.

I think the print heater was causing me problems because i’m not using the take-up system. So the media is sat over the heater while I send it the next print allowing it to heat longer than it would if it was continuously printing.

[Chris johnson]

Hi simon,

I checked the ink and seems to be as expected, I am hoping turning the print heater off will fix the problem.

Thanks

Chris

[Richard]

Is the roll itself straight?

Release the brake and see if the roll appears to be more or less in balance, if you let it spin.

Have a look in the middle of the roll and see if it appears to go up and down relative the media rollers as it rotates.

We had terrible problems with this trying to print an unsupported clear until we realised the problems that bent rolls can cause.

Richard

[Chris johnson]

I checked the current roll on the printer and it seems straight to me, although the media has only lifted a couple of times during the whole 30m.

I will check again the next time the problem appears.

The media I buy straight from the manufacturer based in the uk and has a very good reputation. Only ever had one roll that would just not print without crinkling up. Supplier replaced foc.

[Chris johnson]

Thanks for all your help.

I never got to the bottom of the problem.
I turned off both pre-heater and print heater and checked all the rolls and media loader for straightness.

Turning the heaters down did help to a certain extent. Also making sure the tension on the roll was constant was important, as I found when the roll went from lifting the media in with no friction to pulling it off the roll it caused the media to lift.

The media lifts always in the middle and always between the rollers which does suggest heat expanding the media but I can’t figure out where its coming from.

It doesn’t happen all the time but nearly always does if I print a solid colour.

Will let you know If i ever find what is causing the problem.

[Chris Wool]

how many rollers do you use if you are using full width banner its a lot for 2 rollers
even on my 540 i may use 4 rollers on banner thinking it fairer on the mechanics plus a more even pull, head height should be high on most banner material due to the thickness.
One other thing is don’t have the rollers too close to the edge s

[Chris johnson]

Just in case anyone else has had this problem, I found that one of my staff had heater under their desk which directed heat underneath the printer causing the media to expand. I do find that it still happens occasionally but again it is down to temperature of the media.

Hope this helps anyone that may have a similar problem.

Thanks

Chris