Squeegee & Floodbar position

[cclaud3]

On multiple color jobs, do your floodbars in the other heads exert downward force into the screen pressing into the pallet? Or do both the floodbar & the squeegee hover above the screen until the shirt gets to that head?

Example: I have a two color job using 1 & 7 print heads. The non-printing (as in the shirt hasn't made it to it yet) head's floodbar exerts it's full pressure into the screen, into the pallet. This happens anytime another head is printing. It's really annoying if I'm setting up test prints and don't have shirts on every board yet. The pressure on the shirtless boards causes the floodbar to press the screen into the pallet and plucks emulsion off. This happens even with minimal flood bar pressure to properly flood the screen. It also causes the image area to bleed if the flood bar is resting in the image area--even if I'm 6 inches from the top of the screen.

I'm using a electraprint. it appears that it's the simplistic design of the press that has all head's squeegees & floodbars move up and down into the screen while one head is printing. Not a problem if there isn't a screen in one of those stations.

I've been watching youtube videos to see if other makes do this. Maybe it's for stability of the machine? Maybe it's not supposed to do this? Just curious on other makes or if anyone else with a automatic electraprint has some insight.

Thanks

[ebscreen]

Short answer, no. Each head is individually driven, yes? Is there no way to turn individual heads on and off?

[cclaud3]

No, there's a bar that rotates in each head that drives the parts up/down, actuated by an electric motor. Also, the non-printing heads don't stroke until they are ready to print--it's just the up & down part that's aggravating. I believe the bars connect inside the center of the machine--moving in synchronization. Can't see without disassembling. Machine is all electric. Was just curious if any other brand makes contact with the pallet in the non-printing heads that have squeegees & floodbars loaded.

[alan802]

Many machines have their floodbars in the down position when the printhead isn't on or printing.  If you use a really hard flood stroke then it will cause the bottom side of the screen to come into contact with the pallets when they raise assuming your off contact isn't really high.  On some presses like ours you can raise the floodbar chopper up individually to keep this from happening and once a shirt gets to the printhead it will then drop down and start it's stroke.  The squeegee is always in the up position until it does it's print stroke. There are a few entry level machines that have both of their flood and squeegee choppers going up and down even when they aren't actually printing and that is to cut the cost of the machine down due to not having to have all the additional air valves that it takes to separate the airflow.

Now I'd say that maybe you're flooding too hard, and your off contact is too low and if your emulsion is being ripped off due to that contact then you got too much tack on your pallets.  Lot's of times if I have a screen on printhead 10 and I'm beginning the job, the pallets will come up and kiss the bottom of the screen where the floodbar is slightly pressing down, but we use a hard flood with very low off contact so it's normal.  Our emulsion does not come off when this happens.  I do have the option to lift that floodbar but I don't normally worry about it.

[Prosperi-Tees]

Maybe I am wrong here but isnt the Brown mechanical in the print head instead of electrical? I dont know if I am asking that wrong but from my understanding of the Brown is that it is controlled by mechanical (like gears and chains) means which would not allow a printhead to be turned on and off like an AC head. Shoot me if I sound stupid.

[cclaud3]

It's mechanical but each head has it's own motor for the stroke. It seems like the up/down mechanical parts are connected to each other inside of the core. I just confirmed with the manufacturer that they will always move up/down (but not stroke) together around the machine. Didn't confirm if they are connected or if it's just a software or electrical command. Meaning if they are not connected together then possibly the software could be modified to cut out the all-together up down. At least they all don't stroke together.

[Prosperi-Tees]

I believe they are all connected.

[cclaud3]

Yeah bummer. Life would be better if they weren't.

[blue moon]

actually, the simple solution to this is to load all the plattens with the shirts before starting to print!
You will still need to run an inlet mode so everything is printed correctly, but at least the floodbars will not be hitting a bare platten.

pierre

[cclaud3]

Yep, I've had to start doing that. The other floodbar down pressure issue I mentioned is when it sits in the flooded image area towards the top of a taller print. I have to keep my art at least 4.75" from the inside edge of the frame so the bar doesn't touch the art. Even if I clear it by a little, the down pressure is still pressing the flooded screen into the platten on that end. It looks like I need to keep art 6 or 7 inches from the inside edge of the frame so the floodbar doesn't transfer ink from the screen.

[blue moon]

Yep, I've had to start doing that. The other floodbar down pressure issue I mentioned is when it sits in the flooded image area towards the top of a taller print. I have to keep my art at least 4.75" from the inside edge of the frame so the bar doesn't touch the art. Even if I clear it by a little, the down pressure is still pressing the flooded screen into the platten on that end. It looks like I need to keep art 6 or 7 inches from the inside edge of the frame so the floodbar doesn't transfer ink from the screen.

on our MHM we have to go about 6" from the edge to prevent the floodbar line. I have heard that the other presses need less, but somebody else will have to chime in here. . . . my guess, yup, limitation of the system and you have to find a workaround.

pierre