Issue with VS640 buckling vinyl media – help please?

[Chris Wool]

We run our vs on the high head setting most of the time the standard height in my opinion is too close for general use
.
even the slightest buckling was causing slightly smudged prints let alone the increased risk of head damage.
Some manufacturers of vinyls are worse for it than others as the backing paper absobing moisture
I would check the actual bed temperature compared to the read out and that media roll holder only has a small resistance.

[Hugh Band]

Sure you’ve tried everything but we had this problem in early days with our VS640 and eliminated it with a combo of adjusting vacuum, adjusting heating and drying temps and reducing number pinch rollers used on 1600mm wide vinyl. Biggest improvement was to preheat before clamping vinyl as it seemed that bringing vinyl up to temp when clamped caused these tunnels between rollers.
What is your print room temp like? Does it maintain good temp and humidity? We bought four cheap little temp/humidity meters lcd meters and placed them round the room surprised at differences across room with windows and doors playing factor (rotated meters to eliminate any inaccuracy) Reorganised layout and heating and got good results. First thing in our new print room was to set up consistent temp control and all printing fine. Heating/drying at 38/45 on metamark.
Good luck.
Hugh

[Richard Harris]

Thanks for reply, we have had this issue over a year now. Main material printing on that isnt quite so temp dependant is usually fine but anything vinyl, with a liner is generally the biggest issue. We originally got the issue though with a wallpaper. Roland have previously been unable to find the problem, temp readings of the bed were taken and they varied approx 5 degrees within a 100mm spacing. This apparently is normal? We generally printed on metamark 1600 wide but occasionally have used various other media. Tend not to use cheap vinyl as our clients are not usually on tight budgets and are more quality orientated.

The machine has been in three locations over the time , all residential property with central heated room temp controlled although just via a usual heating system.

What is the best way you would recomend pre heating?, we generally clamp then rum the start of a job across width the relaease and start again. The buckling show had a bed temp of 35. We have increased vacuum to 100% as well with no change of result.

We also have a VS300 in the same room. Although narrower we have taken the same media and set up and printed on both. Even the 720 media buckles on the 640 but not the 300. Roland have replaced everything possible, control board etc.

We did increase head hight but buckling still has issue and quality is compromised on some jobs.

We have had an issue with the temp setting, to test we would set the temp on machine to off or 30 and once the print was underway check it. it would climb over a number of minutes to 35. No temp info was being supplied by versaworks. Roland still have not managed to come up with an anwser.

Any more thoughts welcome please currently the machine is an expensive door stop!

Thanks

[Hugh Band]

Hi Richard
Some interesting points there.
Have Metamark given an opinion? Is it on same media batch numbers?
Re roland test was the variation +/-5 degrees across the whole bed and any pattern to it correlating with the tunnels/pinch roller layout? Would be interested in metamark view on +/-5 degrees in 100mm variations

One thought – if on central heating is it on 24/7 or goes off at night. Media anywhere near door/window? Radiator or warm air heating? Might be worth checking on the Humidity levels and/or temp drops. Has it been worse this winter?

I’ll check on our VS640 re temp consistency – we have an infra red laser thermometer, don’t know if it will be as accurate as a touch probe one but interesting to see consistency across bed and read out.

With preheating for s/a vinyl we put some waste media in then when up to temp. feed required media through – time taken to scan media doesn’t seem to give time to form tunnels.

Will let you know re our own correlation with temps on panel and bed.

That’s some door stop! 😀
Cheers
Hugh

[Richard Harris]

Thanks Hugh, will be interested in seeing heat variation. in one location temp was constant as controlled via a ground source system. Media next to printer most of the time away from doors or windows. Changed pinch rollers today and made a 80% inprovement but still get issue so talking to roland tomorrow. Ideally need a second vs640 on loan, put side by side and see if happens on both machines.

Will keep updated on progress and yes bloody expensive door stop!!!

[Hugh Band]

Hi Richard
Did some measurements today – only one set and rough spacing of measuement points so not totally scientific but interesting results! Measurements with infra red laser reader held about 4" from printer bed, measurements across 1600mm but not at ends of bed. Ambient room temperature @ 19.6C (not relevant but post readings ran media and checked media temp which was @19.5C for job and no buckling whatsoever).

Heater at 38C and Dryer at 44C
Results: Dryer
41 / 45.3 / 44 / 39.2 / 40 / 38.9 / 35.7 / 38.5 Dryer at 44
Results: Heater
39.1 / 40.4 / 39.9 / 41.4 / 40.5 / 40 / 41.1 / 41 Heater at 38

so 9.6C variation in Dryer and 2.3C variation in Heater. Heater also reading higher than panel setting. Heater more consistent than dryer so could be why your buckling is occurring with a bigger variation. Wouldn’t be happy with +/- 5C in 100mm on heater.

Hope this is of some comparative help. How did it go with your Roland visit?

Cheers
Hugh