Amatuer question about registration on a semi-auto
So I picked up this American Tempo cheap a couple months ago, I know nothing about running a semi-auto as I have always done everything by hand with homemade vacuum table setup. So I had to do a bunch of wiring to get it running well again and got the pressure settings perfect on the squeegelizer, off-contact, etc. I was thinking this is going to be great having a micro registration table but then I go to print and I'm puzzled...obviously for the first layer you lay down marks on a a test print (registration print, whatever you want to call it) and line it up as close as possible...now here is what got me, when I line it up on my hand table I turn on the vacuum before I lift the screen so it doesn't move and I can tape down my bumper registration card stock. On the semi-auto the vacuum is running all the time but only engages the suction when it is in a print cycle and not a flood stroke. So I can line it up perfectly on the next layers when the head is down and the vacuum is on, but the dilemma is you have to lift the head back up to tape down bumper card stock and the vacuum turns off, so how the hell do I know if my paper just moved when the head lifted? Really there should be a switch to turn on the vacuum when the head is up (obviously this is not possible on my machine I opened it up and the vacuum is in a box with a port that slides open and closes with the action of the head going up and down). Anybody got a good suggestion. All I can think is line it up as close as possible, tape down your registration print, then micro it, and tape down your bumper stock.
i disengaged my vacuum on off port. there was a chain that closed it and opened it, i just unhooked it, cause i like the vacuum on all the time or not on at all.
another way is to attach an "arm" or strip of chipboard to the back of your print so it extends beyond the screen. attach your film to the print, stick it on the table, lower the screen, and use the arm to register your print looking through the screen (old school style)
same here - we have a tempo - disengaged the 'blow'. now it just 'sucks'.
also avoid taping chipboard on the table. great advice from andymac - get a shitload of bumber stickers or stickers, stick together 8-10, then cut with at least one edge being super clean. we reuse them all the time and they work great - no stoopid goo gone for us anymore.
Place the paper within 1/8" of the registration marks. Raise the head, tape down the registration tabs. Lower the printhead w/ screen, micro into place. Lock table, print. It's super duper easy . . .
you dont need to flip on and off. if you use those sticker tabs i was talking about - just slide the paper into the 2 main tabs (one on the side, one on the bottom - each about 1.5" from the corner of your paper) while holding up the opposite area of the paper. then slide the bottom down to hit your other bottom tab, then release. vaccuum sucking it, paper against it's 3 tabs.
Yeah after finishing up my other colors today, I think it would be nice to run the vacuum all the time and place the paper like your talking about (which I already use three tabs setup how you are talking). After you hit the paper with a color or two it starts to curl a little and the screen smashes it down on the table before the vacuum even engages, which in essence can shift the paper ever so slightly and f'up the registration (and I was running 4~color process so hitting it spot on is pretty important, man did those micros come in handy!). It's a never ending learning process!
Good thread. I'm a clamshell virgin as well and we have a Tempo and Cameo waiting to run in our new space.
I like the idea of having the vac flip off and blowback to ease moving the stock off the table, especially larger stock, but I see how this could screw with the integrity of your registration and that tight reg is, to me, a huge part of why I'm excited to print posters on these machines instead of throwing them on our shirt platens. And if your running 4cp, yeah, the possibility of the stock getting nudged out of place isn't very appetizing.
I know the old American presses are simple but it seems to me that you could rig something up to have the vac turn off for a few seconds after the print to let you pull the stock and then stay on the rest of the time. Does leaving the vac bed constantly on make pulling more of a chore?