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screen printing => Equipment => Topic started by: rmonks on January 09, 2013, 09:04:58 PM
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Slow Season = Maintenance time. I am going to take a look at my plattens and level them if needed. I know on a previous board that Alan802 had developed a method of leveling and would like for him to post the pics if he has them here for all to see. If anyone has a system for leveling 3 point systems please share .
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Good metal ruler and pick a viewpoint or angle that you view the platen at that you can eyeball the height consistenly at any position you measure from.
Tried feeler gauges, dial indicators, etc and like this best.
Better yet, get a press with four point leveling- vastly superior, in my humble opinion.
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what kinds of press are we leveling the plattens on?
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what kinds of press are we leveling the plattens on?
M&R Gauntlet
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M&R Gauntlet
Those are easy.
The rear two are for left and right and dual up/down while the front is for up/down.
It's best if you have some slim line open end wrenches (cheap harbor freight with the face ground down) as the area you're working in is pretty tight under there and normal wrenches don't fit in there so well.
I think m&r has white papers or some kind of instruction sheet on the entire process. You can always PM 244 and ask em.
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Assuming the press is level starting with one of the pallets place a torpedo level at the back edge of the pallet left/right and adjust to center bubble. Rotate that pallet under head one and raise the pallets. Put a flood bar in, align it with the back edge of the pallet and adjust the height to just touching the pallet or place a quarter in each corner of the pallet and adjust the flood bar to touch the quarters. Pull the flood bar forward (by the carriage not the flood bar) and adjust the pallet front/back until the flood bar has the same amount of clearance front/back and left/right. Then adjust the remaining pallets left/right, front/back to the flood bar on head one. Make sure the flood bar is not directly over the pallet when indexing, if one of the pallets is high it may hit the flood bar knocking the setting out then you would have to start all over again. I usually use a business card as a feeler gauge so the flood bar isn't dragging across the pallet or with the quarters if the flood bar hits it then the pallet is too high etc.
Like John said using a thin or tappet wrench makes it a lot easier.
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Also on leveling. After doing all of that. You may want to check you off contact with you print heads. I don't know how long it's been since you've done that. Bit it's prob a good idea to check your heads with the first pallet you leveled. You can use a level with a quarter stuck to one end (that will lay on the pallet) and just lay one part of the level in the print carriage and other on pallet, adjust till level. And make sure your central off contact is at its lowest setting if the quarter is how low you want it. Please correct me if I am wrong on this info gents!
Prob not the best explanation. But you may catch what I'm trying to say!
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Like Pat said do the screen holders also so everything is the same.
I use two steel rules both 1/8" thick. I lay one on the pallet front to back and slide the other on its edge to the screen holder and adjust so it is flat on the other ruler and on the holder.
I may just be too anal about it but once everything is adjusted I always make sure the same pallet stays with the same arm.
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Like Pat said do the screen holders also so everything is the same.
I use two steel rules both 1/8" thick. I lay one on the pallet front to back and slide the other on its edge to the screen holder and adjust so it is flat on the other ruler and on the holder.
I may just be too anal about it but once everything is adjusted I always make sure the same pallet stays with the same arm.
I just re-leveled all my pallets and hangers as well. I used the flat steel ruler out of the framers square laid flat on the pallet like you do to set the screen hanger height at each station from the same (leveled) pallet.
So level all the pallets first to ONE head, then level the hangers to ONE pallet.
Only difference in the methods above is I level/clearance to the print arm/linear rail itself via the Roberto Barney youtube method.
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Mine are due as well anyone have tricks for levelling a Sportsman?
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Should be about the same croft. Three point leveling. And I would assume around the same type of heads
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Here is my latest tool for paralleling the pallets. It can also work to parallel the screen holders by putting in a screen but I'm using a straight edge sitting in the screen holders like most everyone else does for that part. I used this tool and got all the pallets damn near perfect over the holiday break and I must say that it's been the best tool I've used to parallel the pallets, no doubt about it. I don't show what I did to move the pallets in the video but basically all I did was raise the rear of that pallet up since the front of the pallet was at the correct off contact that I was trying to achieve (which was true 0.00"). So the dial indicator needle basically stays the same as I run the print carriage back and forth once I calibrate my pallets correctly. I bring the next pallet over and set it to read the exact same numbers on the dial indicator as my baseline pallet.
Remember if your press has central off contact you need to take that into acount. If you have your press set to a high central off contact when paralleling and you move all your pallets down to match your baseline pallet then you're not going to have as much off contact adjustment to play with. I set my central OC to zero, and then paralleled everything so that when I have it set to 0.00, the mesh is just touching the pallets when the table is up. When I set my OC to .25", it's a true .25" of OC between the mesh and pallet. Those numbers could not have been accurate if I didn't take that into account when doing this. So if I was to have had the central OC at .10" when I did all this, if I did it the same way, then the setting of .10" would have actually been 0.00 and I have lost .10" of off contact movement. I could then set the OC to 0.00" and my pallets would have been pushing up through the mesh on my screen, with a true off contact of -.10", on contact really. Hope that makes some sort of sense because it's hard to explain.
Press Parallel Tool Vid 1 (http://www.youtube.com/watch?v=-axn7C1cX2s#ws)
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Hey Alan thats pretty cool but from my reasoning that will only parallel all the palettes to that particular head. What do you do about making all the other heads match the base one? For instance on my press none of my print heads are identical some are way way off so the only option I have is paralleling the hangers to the palettes.
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Once all your pallets are the same in relation to that one head's floodbar/linear rail, then you adjust your screen hangers to one pallet (or theoretically any pallet because they should all be at the same exact and level height).
I think a dial indicator setup on most presses would cause more headaches than necessary. My pallets were brand new a year ago and now that they've been warmed and flexed for a year, the corners don't necessarily match the overall pallet. Get it as close and consistent as you can across the whole pallet, then set your screen hangers.
Using squeegee pressure instead of the physical depth stop stop knobs can also aid in minimizing the whole "printhead linear" issues. Pallets and arms will still flex and deflect under downward pressure.
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Hey Alan thats pretty cool but from my reasoning that will only parallel all the palettes to that particular head. What do you do about making all the other heads match the base one? For instance on my press none of my print heads are identical some are way way off so the only option I have is paralleling the hangers to the palettes.
I'm just using a straight edge to parallel all the other printhead's screen hangers to the baseline print head and pallet, just like you would be doing and what most everyone else is doing. The tool is perfect for pallet paralleling but using it to adjusting other print heads hangers is a bit difficult. I know how to accomplish it but it means adding some things to the tool and I haven't gotten that far yet. Basically I'll have to add a better dial indicator (I'll leave it at that for right now) to use it for the printheads. You'll essentially put a screen in the screen holder/hangers and use the tool much the exact same way you do for the pallets, but you have to tie up a few loose ends to make sure things are right from head to head. There is a slight difference in print carriage rail height on this press that you have to account for so a better dial indicator and some math skills and you'd have an absolutely parrallel press that could handle just about any tension level you can achieve. We're talking about at least .005" or better tolerance between carriage rail, squeegee blade edge, screen mesh and pallet from pallet to pallet and head to head if I have the tool done the right way.
I don't encourage using shims unless things are that far out of whack, but hopefully the manufacturer has gotten the carriage rails within a good tolerance so you don't have to worry about it. Our press is fairly tight in that area with only a very small difference from head to head.
For your problem, I just hope you have enough adjustment with the screen holders/hangers to adjust for the difference in carriage rail height. Then enough squeegee and floodbar height adjustment to account for that. Is that an issue with your press?
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Assuming the press is level starting with one of the pallets place a torpedo level at the back edge of the pallet left/right and adjust to center bubble. Rotate that pallet under head one and raise the pallets. Put a flood bar in, align it with the back edge of the pallet and adjust the height to just touching the pallet or place a quarter in each corner of the pallet and adjust the flood bar to touch the quarters. Pull the flood bar forward (by the carriage not the flood bar) and adjust the pallet front/back until the flood bar has the same amount of clearance front/back and left/right. Then adjust the remaining pallets left/right, front/back to the flood bar on head one. Make sure the flood bar is not directly over the pallet when indexing, if one of the pallets is high it may hit the flood bar knocking the setting out then you would have to start all over again. I usually use a business card as a feeler gauge so the flood bar isn't dragging across the pallet or with the quarters if the flood bar hits it then the pallet is too high etc.
Like John said using a thin or tappet wrench makes it a lot easier.
Is this something you can do with a servo press? if I raise the pallets on my air sportsman I cant move the flood bar without doing a test print stroke?
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Assuming the press is level starting with one of the pallets place a torpedo level at the back edge of the pallet left/right and adjust to center bubble. Rotate that pallet under head one and raise the pallets. Put a flood bar in, align it with the back edge of the pallet and adjust the height to just touching the pallet or place a quarter in each corner of the pallet and adjust the flood bar to touch the quarters. Pull the flood bar forward (by the carriage not the flood bar) and adjust the pallet front/back until the flood bar has the same amount of clearance front/back and left/right. Then adjust the remaining pallets left/right, front/back to the flood bar on head one. Make sure the flood bar is not directly over the pallet when indexing, if one of the pallets is high it may hit the flood bar knocking the setting out then you would have to start all over again. I usually use a business card as a feeler gauge so the flood bar isn't dragging across the pallet or with the quarters if the flood bar hits it then the pallet is too high etc.
Like John said using a thin or tappet wrench makes it a lot easier.
Is this something you can do with a servo press? if I raise the pallets on my air sportsman I cant move the flood bar without doing a test print stroke?
You will need to disconnect the air hoses from the cylinder so the head can move freely. Bend the air hoses over and tape so air is not blasting.
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Thanks , I went back to the owners manual and reread the set up section and got it figured out.
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Spent yesterday evening and this morning paralleling (and leveling for giggles and to have a starting point). I'm on a manual Rototex, so it's a bit different.
My best logic process so far - get the base near level.
Designate one platen and one head.
Test a static aluminum for true flatness on the exposure glass.
draw back the OC bolt to zero, tape a nickel to the lover part of the OC (on this press that's the camed roller-bearing arm). This gives a standardized OC and makes it so the screen would go LOWER than the surface of the platen when the nickle is removed.
use the three platen support bolts to make the surface of the platen come up and just barely meet the bottom of the screen.
[one thing I only picked up this time - THE LOCATION OF THE BOLTS RELATIVE TO THE SPACE THE PLATEN OCCUPIES - my rear bolt is past the tail by about 2" and the front 2 are almost in the middle - so you can't just think "back, front left, front right as adjusting back changes the pitch of the front too, etc.]
This may require adjusting the 2 bolts that adjust the screen arm back near the central bearing (you can adjust the tilt up, down and side to side) as well.
That's good enough, but I went a step further and made the platens level to reality as well to keep printing stresses even.
From there, add a nickel to each remaining OC base, true up each platen to the FIXED IN PLACE designated main screen arm, using ONLY the platen bolts.
Then adjust all the arms to sit flat to any given platen (at this point they should be truly interchangeable).
The only part of the logic I haven't yet solved is - is the nickle spacing a relatively good starting place to
A) be sure the screen can sit flat on the platen to register and
B) not go too far out of tilt withing the range of OC settings we mostly use (without needing to reset all 6 arms to flat).
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i always used a flood bar..