TSB
screen printing => Equipment => Topic started by: redwoodtees on July 17, 2017, 01:29:20 PM
-
I have a manual back-clamp press (Workhorse Mach). I'm starting to do jobs that require tighter registration, and I'm getting frustrated. I'm trying to get a feel for what kind of variance is normal or acceptable for my situation. Here is what I am experiencing: I register a screen, tighten everything, raise the screen, gently rotate the carousel back and forth to simulate normal operation, drop the screen back down, and I am out of registration by as much as 1/16". So I re-register and repeat, and again the registration is off. Is this to be expected on a back-clamp press, or does my press need adjustment? Or perhaps I am just doing something stupid (I am still relatively new at this). I'm also reaching out to Workhorse, but wanted to get some general feedback on manual presses holding registration.
Chris
-
I have a manual back-clamp press (Workhorse Mach). I'm starting to do jobs that require tighter registration, and I'm getting frustrated. I'm trying to get a feel for what kind of variance is normal or acceptable for my situation. Here is what I am experiencing: I register a screen, tighten everything, raise the screen, gently rotate the carousel back and forth to simulate normal operation, drop the screen back down, and I am out of registration by as much as 1/16". So I re-register and repeat, and again the registration is off. Is this to be expected on a back-clamp press, or does my press need adjustment? Or perhaps I am just doing something stupid (I am still relatively new at this). I'm also reaching out to Workhorse, but wanted to get some general feedback on manual presses holding registration.
Chris
Something is out of adjustment. You should be able to print dot on dot with no gain.
-
Are your registration gates allowing movement and slop? Those are the white nylon bolts.
Adjust and grease.
-
I have a back clamp press and it stays dead on, I would check the head that is off, and Frog is right check your gate bolts. Also it sounds like your screens aren't tight enough in the clamps, you might want to check that also, there so many things that could be wrong it's very hard to say because every brand of press is built a little different and have there own set of problems. What every brand of press you have I would ask if any has that press and compare notes.
-
Gate bolts were my first thought, too. But if that isn't it, go through every part that's adjustable, and make sure there's no play in anything.
Question: I assume you're having the problem after using micros, right? In which case, see above. But if by chance you're talking about it going out after registering manually , then it's not unusual (in my experience) to have screens shift when clamping. There are a few ways to compensate for that. One thing I've done is put some cut pieces of pellon between the clamps & screen, which allows the clamp surface to turn freely as it tightens, rather than biting in & moving the screen.
Another less-likely thing to look at is whether you are putting pressure on the screen in a certain direction when registering, and then not doing so when you pull the screen down for a check or test print. This might happen if you stand to one side during reg (I've done this, to reach micros) and push down one side of the screen; then when you're checking later, you stand straight on & pull down from the middle.
-
I have a Mach 6/6 and I had the same problem. Single colors jobs were fine, then got into multiple and 5-6 color gigs and had to figure out what was going on.
1. Make sure you register all screens to one station. Designate station one as your registration/setup. Each screen gets setup to that.
2. Check your registration nylon bolts. The screen should slide down in the gate with just a nudge of tightness. If too tight and you hear a squeak as it goes down, some screens may make it push out to the left, some to the right, ESPECIALLY if you have a unit that is not all-heads-down. These are the only bolts that don't have to be cinched down too tight.
3. Make sure your nuts and bolts are tightened. Micro registration x/y nylon bolts: the bolt/nut on each side must be very tight or there will be a bit of play regarding maintaining your off contact the entire squeegee length. Trust me, tighten them.
4. Once you get your off contact/tilt adjusted, tighten those bolts two bolts on the head that go left/right. If not tightened you will have some play. The play will go left to right putting you out of registration just enough to make you pull out your hair.
Doing these will help you gain registration success. I had COMPLETELY disassembled my mach 6/6 when I got it (very used) and didn't quite tighten things. Once I did, it was easy.
Also, I've had it for a year and didn't realize until 2 months ago that it was an all heads down until someone mentioned it. I had overtightened those screws not realizing what they were. All-heads-down is wonderful (if yours has it).
Oh, and finally. Make sure your pallets are tight enough on the bracket and the bracket is tightened enough and does not move. I spin my stations from the pallet (and sometimes with a bit of force when moving quickly) and I have nudged the pallet out of registration.
Let me know if I can help...
-
I have a workhorse 6/4. I've had to tighten up all the bolts on the arms where attach to the center plate. A slight shift in the platen arm will drive you nuts.
As others have said, check the nylon gate bolts.
How is the mesh tension? Loose screen mesh can affect registration.
Also thin wall aluminum frames can give and flex causing reg problems.
When out of registration, is it left to right, top to bottom, or a mix?
-
Glad I have a Kruzer... Haven't had to tighten or level or generally f with anything for almost a year. Pixel perfect registration all day every day. I hate the nylon bolts on every press I've tried them on.
-
Personally, I've never liked back clamps, though I know plenty of folks are successful with them. We just trashed a really old Rototex 6c, and kept all of the side clamps from it to use on a Hopkins we picked up years ago, but almost never use...
Steve
-
I don't care for back clamps either.
Wish I had known the issues before I bought the workhorse over 10 years ago.
Ya got what ya got until you get something better.
Maybe someday I'll be able to dump it and get me a Kruzer :)
-
With today's aluminum frames, I miss side clamps much less. Back when half of our wooden frames were warped, the side clamps really helped level things out.
-
Tons of excellent advice in here.
All I can think to add is to really make sure you have even level off-contact between the screens. Tight/new screens definitely makes a difference.
Make sure your platens and brackets are tight! That has driven me crazy before. Same with the nylon bolts, as mentioned.
Good luck!
Sent from my iPhone using Tapatalk
-
Thanks for all the great advice.. I plan to spend some quality time with the press this weekend and get everything dialed in. I'm happy to hear that perfect registration is an achievable goal!
-
Red,
I asked above if your out of reg was left to right, in to out, or something else. I don't think you answered.
IF it's "in to out".........to insure your off-contact is uniform for all screens......what I do, is break up an old yardstick and tape a 10 in. strip across the top of the screen and another 10 in. strip across the clamp end as close to the screen frame as possible and where they will set on the platten when you pull the screen down. What that will do, is maintain uniform off-contact and take any arm flexing out of the picture which can easily throw your registration off "in to out".
I use the "broken yardstick" method printing single or multi-color prints just to maintain a uniform off-contact to eliminate arm flex to leave part of a screen image to lay on the substrate and not allow it to "snap" to clear the ink from the screen.
I have found on my workhorse the nylon screws do the job for left to right, but arm flex raises issues for me and this seems to have solved my problems.
In my mind, this action emulates what the auto's do since they don't have a single arm and raise the platen to maintain correct off-contact for the squeegee.
-
It may not be your screens it may be your plattens that are moving when you rotate the press. We have a Vastex 2000 very heavy machine. When I first started out had the same issue and discovered the the energy I needed to rotate the press was more than the screws that held the plattens to the press arms could handle.
A tip from a board member suggested using non skid tape like the kind applied to stair steps to the arms and pallet brackets to gain some much needed friction to the assembly.
We also ditched the hand screws and replaced them with same size bolts that get tightened with a wrench....end of problem. As I said the Vastex is a very heavy press built like a tank and throwing the press around by the pallets initially was way more than it could hold with the OEM method of attachment.It has been years now and no movement there any more, in fact we almost always set our art for butt registrationand have no issues, tight roller frames, back clamps and some good luck I guess.
mooseman
-
He's got a Workhorse back clamper like I do.
I'm still curious whether his 1/16th movement is left to right or in to out.
-
Certainly many very good suggestions here. I have a workhorse 8/8 all heads down. Registration is a bit of an art. I don't over loosen my lock down handles a lot. Just enough to be able to move the screens easily with the micros. Then I lightly lift or kind of bounce the edge of the screen after I initially adjust the micros. What looked like a dialed in by micro setting will be off a little. I always attributed this to friction across the screen on my film creating tension (18x18 platen and film), but what do I know. After I have a pretty solid reg I'll tighten the screen in place with the lock down handles, raise the screen, swing back and forth once lightly, drop and check reg. Usually it is right on. Technique works for me. I'm using large screens and I print long runs with no issues.
Since it is a registration issue rather than a printing issue I would assume that you have the screen positioned flat on the positive. Make sure your print arm is fully down into the registration gate. Flush on the bottom. If it isn't you will get movement as the arm is depressed depending on how far down it goes each time. The screen deflects. It doesn't take much. Easy to miss.
-
He's got a Workhorse back clamper like I do.
I'm still curious whether his 1/16th movement is left to right or in to out.
Left-right. In-out registration is pretty stable, but I am intrigued by your yardstick idea. I spent the weekend filling potholes, so I did not have time to work on the press. I'm hoping my main issue is simply that the nylon gate bolts are out of adjustment. I'll report back either way. Lots of great info in this thread!
-
If the nylon and gates seem to be snug and you do not see any issues with the tightness of the arms bolted to the spinning platform, you could be experiencing some slight slippage of the screen frame in the back clamp. If nothing else comes to light, try putting some strips of the non-skid tape (black tape with embedded sand) in the top and bottom of the back clamp to insure no movement left to right when you tighten down on the screen.
Outside of that, I got nothing.
Let us know what you find.
-
I haven't been following this thread very closely.... but would like to add an observation about "back-clamp" manual presses:
I used a CAPS back clamp for about 10 years & if I got a little too aggressive spinning the screen carousel.. I could push the screens out of left/right registration.
I learned to push the screen carousel closer to the clamps when spinning it. That way you have less leverage to torque the screen out of reg.
I switched to a side-clamp Kruzer a couple years ago and have nothing but praise for it.
-
So I'm still struggling with this. I have adjusted the gate bolts as tight as possible without binding. I have followed the recommendations of Workhorse tech support (short version - "Tighten everything"). I'm still having this problem where I register the screen, tighten everything down, then simply raise and lower the screen, and it's out of registration by a 32nd to a 16th of an inch side to side. I can repeatedly raise and lower the screen, and the reg is consistently off -- it's not like its moving around. So all I can figure is that something is binding up when adjusting with the micros, and then that something is "releasing" when raising and lowering the screen. I'll put in another call to mfr. tech support in the morning.. I guess I am just venting my frustration here. Of course, if you have the solution, please do share! Thanks for listening.
-
You only mentioned the gate bolts, which I assume you mean the nylon guide bolts.
I don't see any mention of the bolts holding the screen arm to the carousel or the bolts holding the platen arm to the carousel. Unless that fell into the "tighten everything" category.
I don't think you answered by earlier question whether Newman frames, Aluminum frames or Wood frames.
Also, if the mesh is really low tension, the image could dance all over the place just by itself.
-
Yes, I mean the nylon bolts. They are adjusted so that it takes some force to lower the screen, but not so tight that it binds or squeaks. I have tightened everything between carousel wheel and screen. Standard aluminum frames with relatively new s-mesh. I don't have a tension meter, but I don't think low tension is the issue.
-
Thanks for filling in the blanks. Unfortunately, without seeing the press, I've exhausted any ideas. Sounds like you have done just about everything possible. But yet, something must be hiding and a real booger to find. Good luck and let us know when you stumble across it.
-
So I'm still struggling with this. I have adjusted the gate bolts as tight as possible without binding. I have followed the recommendations of Workhorse tech support (short version - "Tighten everything"). I'm still having this problem where I register the screen, tighten everything down, then simply raise and lower the screen, and it's out of registration by a 32nd to a 16th of an inch side to side. I can repeatedly raise and lower the screen, and the reg is consistently off -- it's not like its moving around. So all I can figure is that something is binding up when adjusting with the micros, and then that something is "releasing" when raising and lowering the screen. I'll put in another call to mfr. tech support in the morning.. I guess I am just venting my frustration here. Of course, if you have the solution, please do share! Thanks for listening.
With that head and that station, are subsequent strike-offs all in the same position, or does it jump differently each time? And always only side to side?
Also, I forget, did you say that this was a consistent problem on all heads and all stations?
btw, I use a 20 year old Mach VI (not an all heads down version)
-
So all I can figure is that something is binding up when adjusting with the micros, and then that something is "releasing" when raising and lowering the screen.
On mine, I have knobs to lock down the micro adjustment. Thought they all did. If yours is like that, how could it be anywhere in the macros once you tighten down those knobs? I think it's somewhere else. Frames slipping in the clamps?
-
@ Redwood: Once you've got the print registered except for this unwanted offset, is it possible to adjust with micros to compensate? Is it predictable so that if you go a little "out" in the opposite direction while registering, you'll actually be "in" and stay "in" once everything's locked back in place? I experienced a little of that with our manual. The screen didn't sit exactly the same when loosened for reg as it did when tightened for printing. But once I got used to it, I learned to compensate during reg, and it wasn't a big deal. And once locked in, it printed consistently.
-
@ Redwood: Once you've got the print registered except for this unwanted offset, is it possible to adjust with micros to compensate? Is it predictable so that if you go a little "out" in the opposite direction while registering, you'll actually be "in" and stay "in" once everything's locked back in place? I experienced a little of that with our manual. The screen didn't sit exactly the same when loosened for reg as it did when tightened for printing. But once I got used to it, I learned to compensate during reg, and it wasn't a big deal. And once locked in, it printed consistently.
Yes, this is exactly what I am experiencing. Thanks for providing a more concise description. The combination of my inexperience and the press being out of adjustment was causing me a great deal of confusion and frustration. I was able to register a job yesterday using the process you describe, and the press stayed in registration.
-
@ Redwood: Once you've got the print registered except for this unwanted offset, is it possible to adjust with micros to compensate? Is it predictable so that if you go a little "out" in the opposite direction while registering, you'll actually be "in" and stay "in" once everything's locked back in place? I experienced a little of that with our manual. The screen didn't sit exactly the same when loosened for reg as it did when tightened for printing. But once I got used to it, I learned to compensate during reg, and it wasn't a big deal. And once locked in, it printed consistently.
Yes, this is exactly what I am experiencing. Thanks for providing a more concise description. The combination of my inexperience and the press being out of adjustment was causing me a great deal of confusion and frustration. I was able to register a job yesterday using the process you describe, and the press stayed in registration.
Glad it helped. I wish I had the advice that would actually make the problem go away. But as said, I got used to just dealing with it. And as long as the prints are consistent & stay in reg once you've got it done, that's what really matters.
-
I'm back! Setting up a new job, and having issues again. Right now I'm working with one screen on one head, registering to a crosshair on one platen. I'm not moving the platen at all, so I think it's safe to eliminate any issues with the platen. All bolts from where the head mounts to the carousel to where the screen clamp mounts to the head are tight. The nylon gate bolts are as snug as they can be without binding. The screen clamp bolts are gorilla-tight. But still:
If I raise the screen and give it a *very* gentle tug to the right, to simulate spinning the carousel, and then re-center and lower the screen, the registration will be off slightly to the right. If I do the same, but give a gentle tug to the left, the registration will be off to the left. So something is still moving. I spent a couple hours last night trying to figure out what is moving, and I can't seem to figure it out. My best guess is that the screen is moving in the clamp. Earlier in this thread someone suggested applying anti-skid tape to the screen clamp.. That's probably my next move. I was also looking at the clamp design -- The jaw of the clamp on my press is about 3" wide, but the screen is only about 1 1/2" thick. So the clamp bolts have to extend pretty far into the clamp area to contact the screen. I'm wondering if the clamp would be more stable if I used a spacer block, so that the clamp bolts would not have to extend out as far.
Good times!
-
Yep, it was mentioned before that the frames themselves may be moving within the clamps. Assuming that they are really snug, adding something with a little friction can only help.
I have to say, that I don't seem to have this problem on my old Workhorse, but who knows? As I said, the addition of non-skid sandpaper tape can only help.
I'm less concerned about the bolts extending further than a fatter frame would have them.
-
I know on my workhorse, they only welded a nut to the top of the clamp and with no screen there is a noticeable wiggle in the bolts and bar that holds the screen if you wiggle the nylon knobs back and forth.
But, I put a wooden frame in the clamp, tightened it down and pushed it left and right and did not notice any deflection at all.
If it's moving both left and/or right enough to throw off registration, you have to be able to stand to the side, hold on to the clamp and bump (in the air) the screen forward and back and see deflection SOMEWHERE. If not, then don't hold the clamp and do the same thing. SOMETHING......is giving.
Since he said the screen is held in gorilla tight, I'd agree that it's probably not in the screen clamping.
I know this is off the chart, but.........there is a bearing in the middle that holds the carousal. Could the bearing be loose enough (or dry) to cause a shift? If there is, the very smallest of movement in the center would be a lot on the outer parts of the arm holding a screen. Workhorse has instructions for assembly and disassembly for removing the top carousal. It might be worth the effort to remove the center bolts, have someone help lift it off (it IS heavy) and inspect and lubricate the bearings. I know that's pretty bizarre, but might be worth a shot. Does the carousel turn easily? Any grinding sounds? Even if the center bolt is the slightest bit loose, there could be a deflection if it rides up and down.
Maybe the assembly never did get tightened down in the first place.
-
I think it is the screen moving in the clamp. If I put a screen in the clamp and tighten it partway, the screen obviously is easy to move around. I gradually tighten it, and it becomes more stable, but it will still move around slightly. I can see the clamp bolts pivoting back and forth as the screen moves. I think there is still a slight amount of movement, even when the screen is as tight as I can make it. Have you ever tried to clamp something small with a very large C-clamp? the c-clamp has a lot of strength in one axis, but it is downright wobbly in the other axis. Seems like the same idea with the clamp on the press.
So I heard the advice about putting non-slip tape on the clamp surface. My only concern with this is that it does not sound like it will be very good for the screen.
-
So I heard the advice about putting non-slip tape on the clamp surface. My only concern with this is that it does not sound like it will be very good for the screen.
Maybe try some of the non-skid rubber they make for kitchen shelves first? (Sold in rolls.) Cut to fit, and put it in loose, maybe above & beneath the screen frame edge. That might help the grip when you tighten down. And if it doesn't work, just take it off & try something else. (Never tried this myself, btw. But I do use the stuff under furniture to keep it from sliding on smooth floors.)
-
I think I was the one that mentioned the non-skip tape above. I did use that on an old POS press and it definitely improved the grip on the screen. Yes, it will dig in the points on the tape into the wood and leave some small impressions, but not sure what other options exist, especially if you are noticing movement when clamped down tight.
In my post yesterday I had clamped a wooden screen (1 3/8 frame) into my workhorse (does not have the non-skip tape). I tightened down but not what I would call gorilla tight and I cannot notice any movement.
This is a silly question, but after you adjust the micros, you are tightening down the back set of knobs to hold the adjustment, right? I'm sorry if that sounds insulting, but I can't think of much else going on.
Can you post a picture of your press so we can see what model it is? Workhorse has made several models.
-
I'm sorry to hear that, looks like you have a loose pair of nylon bolts, yes the white ones and you have to tight the micro registration head .This problem is so common with this brand of machines.
Do the same on all the machine's heads. :)
-
There are small Allen head bolts that secure the screen clamp to the tightening knobs/rods. Over time they back out and will do wonky things to how the clamp interacts with the frame. Try sticking a folded cleanup card between the clamp and the frame directly under the threaded rod of the clamp.
Sent from my SCH-I545 using Tapatalk