Intermittant duct control - good or bad idea???

[Disappointed]

Hi all,

On all of our previous machines the ink vibrator roller contacted the duct roller once for every sheet on a fixed cycle, nice and simple and has work for countless years.

We now have a Presstek 52DI which has the default option of intermittant ink vibrator control based on a set of figures that can be adjusted. It is broken into three bands of ink coverage - 0-20% will get 4 out of 10 contacts, 21-50% will get 7 out of 10 and 51-100% will get 10 out of 10 as in the older machines.

What i am tryng to find out is if this is a sound idea or not. What we are seeing is that because the roller on ly contacts maybe 4 out of every 10 sheets, any duct key adjustment takes a long while to have effect on the sheet. Is anyone familiar with this or could it be better to just switch it off and go for 10/10 as in older machines?

Does an SM52 have this feature or is it a Ryobi quirk?

Dave

[Cornishpastythighs]

This feature is also on our new Komori press. In another life I had these retrofitted onto 3 older Komoris. On very low coverage jobs it allows the operator to have his ink keys open a bit more and ink duct a little less instead of trying to grind metal on metal (figuratively speaking). When you get the hang of them they work fine, if they serve no purpose to you then hit the off button.

[Erik Nikkanen]

Originally Posted by Cornishpastythighs

This feature is also on our new Komori press. In another life I had these retrofitted onto 3 older Komoris. On very low coverage jobs it allows the operator to have his ink keys open a bit more and ink duct a little less instead of trying to grind metal on metal (figuratively speaking). When you get the hang of them they work fine, if they serve no purpose to you then hit the off button.

Yes, the advantage is with very low coverage but this again is a solution that is only half way effective. If one has a job that has both high coverage in one location and low coverage in other areas on the same plate, this method is not effective.

My view is that the press should be designed so that it will provide accurate ink feed for all conditions. This can be done with different and better technical approaches.