I apparently suck at this. I thought that using a vac bed and a semi-auto would make this a cake walk but here's the deal:
I use 3 point reg- dymo labels. It feels good and solid to me.
I use an old Model T as andymac calls 'em, a Cameo 22x30 or something. It's old and banged up but works.
Today I had to print some plastisol transfers for trucker caps. Pretty straight ahead deal- basic orange going onto dark caps. I layed down some 174c through a 110 first. Looked good, but when I hit it a second time after tack curing in the dryer it was always off. I load carefully and keep my index fingers on the paper until the vac kicks on and I pull them away like hot hands. I use good transfer paper, I think it's the best you can get for dimensional stability but maybe I'm wrong there. I mask for extra vac suction to hold down the slightly curled sheets. I pre run all the sheets through the dryer and avoid stoppage or letting the sheet cool off significantly. Basically I think I follow all the rules on this. This was a short run of about (50) 12.5x12.5 cold peel sheets.
To better gauge how far off things were, I did a color change and loaded white into the exact same screen and printed. It was pretty damn far off too, just like the second hit of orange. This is same everything- screen squeegee, blade, speed -so the parameters there are static.
I ran 300 pcs with TW inks on 12.5x19 70lb text French Speckletone last week and it too walked around on the reg. The art was forgiving with it though and, for some reason, everyone likes to see that so they "know it was screen printed" which still seems weird to me as a printer that people would like off-reg prints. Anywho...
Leads me to conclude:
- I'm either throwing the paper on there incorrectly
- The press can't hold reg.
- Both of the above.
- I definitely need some advice.
I can't even fathom printing 4cp or something at this point. Frustrating b/c we do fine as textile printers with tight registration. Thanks for reading and thanks in advance for any help.
I can't tell what your problem is.
It's off consistently in the same way?
It's wandering all over the place?
It can't be made to register at all (has distorted)?
You need more black magic and acid.
with reg issues, or if you are having problems, pull one of your first prints and hit it again later in the run. should be dropping right on top. if it isn't then fix that first. Colour to colour won't be any better if it isn't consistent within each run.
Dan's right, you need to be more specific if anyone is going to help you figure this out.
For the trucker caps, could you be heat curing for a little too long? Maybe the heat is warping the substrate and making it impossible to register. I have had this happen before.
Did that, and she was off. So there's the problem I guess. It was wondering all over the place when I tried just dropping a second orange.
Originally Posted by Andymac
Paper is T105 "Dimensionally stable paper for cold peel, litho, or crystal transfers only. Quillin release. This is the same great paper as the industry standard, Trans 75, only in a heavier weight... more stable than ever!"
Sheets are ran through before first down. Each color is gelled at about 275˚F surface temp reading with the ray gun.
This does cause curling but I'm not aware of what else is out there for trans paper that is thicker/more stable.
Here's pics of how far off a print using the exact same screen is and of how I'm regging on the vac bed. I did the ink color change to white on the identical screen without pulling it off the press and put that down on the orange for a solid visual on how far off it is. I knew it was off just from hitting the orange the second time already.
We've been pumping out transfers for trucker caps for years and the process is nailed down pretty well on that end. Previously we used clean shirt boards and print/flash/printed them on the manual shirt press. Accuracy will deadly tight from color to color there as the paper wasn't being removed and replaced. That's why I think it's something to do with how I load paper on the vac bed.
Yes, black magic and lsd would be very helpful.
On the press. Note curling (natural for the process with this paper) but also note the vac is off and I had masked during the print run so the suction was there when I actually printed.
Example of how far off things are, using the white to show. And this was one of the ones that "looked good" from the sheet.
In the end, I ran 4 passes of orange to get opacity and then culled all the junk ones out and was able to complete the job. They actually look great this way and came out fine as the offset from orange to orange wasn't noticeable on the finished cap like it is with the white underbase in this pic. But I need to fix this issue so I can run these properly with an underbase next time and so I'm not printing off reg on this thing all the time.
I know you guys like to stick heavy duty knowledge stuff in the premium forums, is that correct? It would be cool to see videos of how people load stock.
Ok, I was doing exactly like these dudes are at 19 sec. Paper down to the bottom two guides, slide across to left guide. Masked all around on the bed.
First think I would do, is to lay the film over top of the prints, and see if the actual substrate has changed shape. If not, then you have eliminated that option.
Then determine if the registration issue is caused by badly loaded paper or screen distortion. If it's badly loaded, you will notice the mis-registration will be on the same side of each design element. If 80% of the image is in register, and 20% is out of register, you might have distortion in the screen. That can be anything from slack mesh, to too much off contact, to too large a squeegee etc.
You probably won't get 100% perfect register, so choke those underbases . . .
Film to print looks about as close as it gets to my eye. I was running a 110 tpi, standard thread, 20 n/cm, 2/2 coat of emlusion using the round edge of the coater. 18" 80 or 90 duro, brand new blade and matching winged flood. Off contact is just the standard on the cameo with the clamps resting on the bed, about 1/8". Flood pressure was fairly hard, you could feel the flood edge depressing the screen when it was down. Squeegee pressure I started with it up high and brought it down bit by bit until the image cleared. You can only adjust the flood and squeegee up or down on the left or right with the Cameo, no angle adjustment and no air.
Originally Posted by Fools Gold
I noticed the mis-reg all over, it was different between sheets and different within the sheet as well.
I did tune up the eccentric bearings on the press and ensured they were adjusted properly in the front gate before printing.
I defintely intend(ed) to choke the UB, I always do that a little but wanted to test things out and see how much was needed. If the first color isn't holding to itself though...
Did you prerack your paper or just pull it straight out of the box. How new was the box it came in? Fresh off the truck?