I’ve printed envelopes a few times on my Windmill, but I’m looking for a little input on how to do it better. I’m usually just printing on the flaps.
I typically lay the envelopes flat and feed them bottom side first (flap trailing). This works, but about 15-20% of the envelopes aren’t perfectly flat and the flap side (which is slightly bowing outward) misses the bottom guide and I get slanted prints.
I can’t use the guide pins to guide the envelope onto the guides because envelopes don’t have any trim area.
Any thoughts on getting a higher percentage of acceptable prints? I’ve tried spending more time making them lay flat with no luck.
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If you are only printing on the flaps,and you are feeding to the bottom edge, surely there is plenty of room for lay pins.
If casmit is printing with photopolymer plates and a base, the pins will leave a mark on the bottom edge of the envelope.
right on. pins leave marks on the envelope.
If you’re not doing multiple colors, why can’t you just run them without guides? I just did a 1-color envelope job this way. Gripped it on the short side.
Alternatively, can you move your base high enough in the chase to not be in the way of the guides? Then they shouldn’t leave marks on the envelope.
Are you opening the flaps, then running them through.
If not give that a try
I used a drill press to make a groove in one of my bases for the lay pins. If your base is too wide to allow your stock to hang over its edge where the sliding left guide would be, it works well.
I can usually flex or “work” the stack of envelopes to lean into the giudes, but we also often use what we have coined “the flapper-dapper”.
Basically it’s a brass guide, with a little flap of mylar or paper, and clear tape, attached to the outer (form) side of the guide. I make it about the height of a lay pin, maybe 2 inches, and go about as wide as the guide. If you build it right, and keep an eye on it during the run, it will work great, catching the envelope like a pin, but won’t mark the paper, because it is soft, flat, and flexible.
If you can get the envelope to land on the lay gauges, you can run flawless registration. I have run envelopes back through the press this way, with perfect registration.
Play around with the construction of it, to see what works, i like something slightly rigid, like mylar, but with a thin profile, and watch it during the run,so that it doesn’t slowly bend or fold towards the platen, allowing the envelope to skip the guide.
You can also cut away some of your packing beneath the tympan, to reduce the amount of pressure against the flapper or pin, against the envelope.
Play around, but you should be able to run envelopes with great success on the windmill.
Oh, and I always try to run my envelopes, with the base of the envelope on the guides, flap pointed up. Its always best on the windmill to try and run your widest length along the guides, if you can.
Thanks for the all the input! I think running commercial may be the answer on the one color jobs. For the two color jobs I’ll just have to try some of the things you all suggested when the time arrives.
My flaps are open when I print. I’ve tried to feed the envelopes so the bottom of the envelope sit on the lay guides, but if the envelope flap isn’t perfectly flat, my gripper was damaging a lot of the flaps.
I also like your idea natron for building my own guides. That would actually work on thinner envelopes.
Once again, thx everyone for taking the time to respond!