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screen printing => General Screen Printing => Topic started by: mooseman on October 31, 2012, 08:30:59 PM
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what is the the typical amount of off contact on an auto?
mooseman
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we use a quarter for t-shirts. . if that helps?
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That's the thickness of a 25 cent coin, not a quarter inch! ;D (just in case, as you never know who is reading, and what they know)
Otherwise Moose, the distance varies with tension, just like on manual screens. Allan's 50 Newton screens can run a lot closer than my old cord and groove or tape and staple antique beauties!
This also assumes for plastisol, right?
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And don't forget rollers vs statics. We use rollers and a friends shop uses beat up statics and their off contact is twice if not more than ours. But I'm sure if you keep up on your statics you will be fine.
When we do some really big prints like 2 feet wide for piece printing before sewing those static screens that we have can and do loose their tension faster so we need more off contact. That's just us though so others might have it different.
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Then again if you don't keep up on your rollers same thing!
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about 1/16in , or about the thickness of a quarter here as well for Ts.
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Yep, we use quarters to set our off contact. Using rollers here
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Thanks all for the info.
We try on every job to mimic on our manual (as much as possible) the elements present for an auto.
I am really curious about many things and off contact and the way an auto squeegee addresses the screen are two of the bigger focus areas.
naturally my arms and energy are the greatest uncontrolable elements but fix what you can ..adapt to what you can't.
Our OC is about 1/16 of an inch on every job, i check and modify as necessary.
One of the great variables I am finding is the roller frame job to job, print head to print head all combine to address the platten differently each time a new screen is installed. We find not all of the rollers intersect the square bar exactly the same on each frame as the square bar is too weak (IMHO) where the side rollers bolt in on our newer frames. The square bar deforms slightly at the side roller footprint which modifies the angle of the fit . Also we find and not all frames interact with the print head the same depending how deep or shallow the square bar is inserted into the head.
As a result we are managing OC on every setup.
BTW we have only rollers, newer and older versions Newmans, run 230 @ 28 - 30n , 195 @ 36 - 40n and 155 @ 42 - 45n.
At any rate thank you all for the info and replies....mooseman is working hard to make screen printing easy ;)
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One of the great variables I am finding is the roller frame job to job, print head to print head all combine to address the platten differently each time a new screen is installed. We find not all of the rollers intersect the square bar exactly the same on each frame as the square bar is too weak (IMHO) where the side rollers bolt in on our newer frames. The square bar deforms slightly at the side roller footprint which modifies the angle of the fit . Also we find and not all frames interact with the print head the same depending how deep or shallow the square bar is inserted into the head.
As a result we are managing OC on every setup.
I've noticed that too. Didn't know what it was, but at least half the time I have to adjust the off-contact. Never occurred to me that it was differences in how the round bar ends engaged the square bar on my rollers.
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With screens that tight, you can be at 1/32" assuming your press is calibrated well. If it's not paralleled precisely then 1/16" or higher will have to do. I use metric :), so 1mm is close to where we are, sometimes half of that if I've got a bunch of 205N's on press at 55 newtons. I've seen shops using 12 newton statics at 1/4" and even witnessed a shop that had their screens at 1/2", double stroking navy ink on an ash shirt and it still looked like garbage. The guy got offended when I asked him if he wanted me to help them get away from having to do that, so when I see that type of stuff in other shops I just move along and try to talk shop without getting into all the problems I see.
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Alan runs some insane OC... barley visible. I didn't think his screens were clearing the first time I watched him print some white ink. It was just that it was clearing so well and the mesh was so close that you could easily see the ink like it was still in the stencil!
<super jealous>
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depends on the work load and if my pallets are level..lol somehow we get by..
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I've got to parallel our press again. It's been about 100K imprints since I did it last. It does no good to try to print with very little OC when your press isn't calibrated to a certain tolerance. If your pallets are 1/32" out of parallel with each other then you obviously need 1/16" OC to compensate. I tried getting our pallets to this ridiculous tolerance, .005" if I remember correctly, and putting 10lbs of pressure on some pallets can move the pallet 1/32" easily, depends on the press. Remember to take into account your press' deflection and how print pressure affects it.
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we use the same off contact we would use on the manual
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Moose, back when all I had was a manual press my biggest thing was trying to keep the same print angle....I was working on a tool to fit my squeege in so I could keep the same angle and pressure during printing never finish it though got an auto LOL
Darryl
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Moose, back when all I had was a manual press my biggest thing was trying to keep the same print angle....I was working on a tool to fit my squeege in so I could keep the same angle and pressure during printing never finish it though got an auto LOL
Darryl
Hey Darryl,
Funny you mention that we have been thinking about the same kinda thing. Realistically I will Rube Goldberg up something because at this stage in my life there is no way there is an auto in my future.
Not sure which way to go with this first i need to better understand the squeegee dance on an auto :P
mooseman
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It's called a one armed bandit and used primarily for flat stock. Also someone made a semi-automatic attachment air operated I believe. Never really caught on.
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It's called a one armed bandit and used primarily for flat stock. Also someone made a semi-automatic attachment air operated I believe. Never really caught on.
I have seen that somewhere i think it actually came up on the boards here some time ago...possibly by you then also.
Actually I am not looking to automate the process but to bring some constant / consistant load to my manual printing.
Stupid things like this happen when you are alone all day with just a pile of tee shirts and Ozzie , Van Halen, Zeppelin modfing my mood 8)
mooseman
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Do you want a video of an auto flooding and printing from different angles? I can do a vid of our press printing and just focus on the squeegee and floodbar from different points of view.
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I found that on super long runs I was eventually operating like an automatic.
The PrintMate was the attachment that controlled angle/pressure. Looked cumbersome
at best.
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Do you want a video of an auto flooding and printing from different angles? I can do a vid of our press printing and just focus on the squeegee and floodbar from different points of view.
AW GEEZE ....Alan, that would be great if you can carve out some time. any view of the squeegee would be great.
Primarily I am interested in the deflection on the squeegee blade as it contacts the screen then the blade profile as it travels up the screen.
Some time when you are running a typical job and can throw a camera down to look at it for me that would be great.
Thanks for the offer.
mooseman
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I'm waiting for the video shot with the GoPro, or similar camera, mounted on the carriage, giving a squeegee eye's view of the printing process up close and personal!
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I'm waiting for the video shot with the GoPro, or similar camera, mounted on the carriage, giving a squeegee eye's view of the printing process up close and personal!
hey Frog,
Funny you should mention that , with the new bag of ganja i have I have actually been thinking about printing on a piece of plate glass in the usual tee shirt manual way with a video camera mounted below looking up.
i know what manual printing looks like from the top but from below ....a mystery and I am curious ???
OK .....I have too much time on my hands :P
mooseman
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Moose, back when all I had was a manual press my biggest thing was trying to keep the same print angle....I was working on a tool to fit my squeege in so I could keep the same angle and pressure during printing never finish it though got an auto LOL
Darryl
Hey Darryl,
Funny you mention that we have been thinking about the same kinda thing. Realistically I will Rube Goldberg up something because at this stage in my life there is no way there is an auto in my future.
Not sure which way to go with this first i need to better understand the squeegee dance on an auto :P
mooseman
Guys I think this might be it. The M&R accu-stroke
[url]http://www.mrprint.com/en/ProductOverview.aspx?id=100[/url] ([url]http://www.mrprint.com/en/ProductOverview.aspx?id=100[/url])