TSB
screen printing => Equipment => Topic started by: Atownsend on September 18, 2016, 05:19:28 PM
-
We run one of the old Gauntlets here. A 1989 6/8 non revolver model to be exact. We fight with it on almost every setup, but once each head is dialed in and its registered, it actually prints fairly well. One problem that I have run into lately, is on images where its near max size (15"). The image will blur slightly at the very top of the image. It was only happening on certain pallets, which is why I am thinking that some of our pallets have come out of level We have some good size sim process runs coming up, so I am going to relevel all of the pallets and check off contact on all of the heads tomorrow to eliminate that variable. We usually level to nickels in the back, and dimes in the front to combat the pallet deflection (a tip I found here).
I am also thinking this might be a squeegee pressure issue. We use S-Mesh, and I think that the pressure is just too much and when the pallet deflects back we get the blurring at the top of the image. To control the squeegee pressure, we currently use the kip levers to raise / lower the cylinder. There is no regulator for the cylinder itself. I am not familiar with other autos, but from what I read here, modern presses with air heads are able to regulate the pressure to the cylinders much more precisely. Has anyone rigged up a inline pressure regulator to control the air inside the choppers? I am thinking I can pickup a few inline regulators from harbor freight, splice it into the plumbing, and rig up a mount for the head so I can dial in the PSI for the chopper cylinders more precisely. What i'm wondering is, has anyone done this before on an older gauntlet? Or is this just an unnecessary waste of time when I should just focus on the basics (pallet leveling / off contact / sq angle / pressure regulation via the kips).
thanks in advance!
-
Great idea!
on those older machines.. with some regulators, some new fittings and a helping of creative thinking, of course. get on it!
take some pictures along the way.
of course keep the platens level, that's always just a given.
-
You could try Double Bevel squeegees. They require very little pressure and no angle adjustments.
-
Don't discount your flood pressure either. I have had that problem with our
older Gauntlet of blurring at the top of a large print.
-
our number 2 press is a '94 6/8; yes it need some upkeep, but it has paid for itself many times over...
Steve
-
Thanks for all of the feedback! I will mind the flood pressure. I might also try some double bevel squeegee blades. I am running a mix of single angle 70/90/70's at the moment, along with some 60/90/60's. Any particular duro recommended for double bevels?
While I am messing with the head, I think I'm going to try to rig up a air dump valve so that we don't have to turn off air to the whole press to remove / insert squeegees. I picked up some air fittings / valves / regulators online. The most difficult part will likely be the mounting of the bracket for for all of this. But it really doesn't look that difficult. Will post pics once I get this rigged up & tested.
-
Success!
I removed the 5/32" hose coming from the press though the guide for the proximity flags, then a longer hose was spliced in and routed to the 1/4" harbor freight regulator. This required a 5/32 > 1/8"NPT quick connect to a 1/8" > 1/4"NPT coupler, > 1/4" close nipple > the regulator. From the regulator, if reduces back down to a 5/32 quick disconnect, and goes to a 1/8" npt switch that I picked up from mettle air. The outfeed from the switch, goes to where the original air line fed to on the head. I have a ton of 1/8" acrylic sheeting here, so I cut it down with a jig saw, drilled a few holes in it and mounted everything up so that there is no interference. If I had a bit more time / patience, I would totally make this out of metal, but I just don't have the patience for that right now. It isn't heavy, so I don't anticipate any problems using the acrylic. sheet.
It's not pretty, but it is a functional prototype. I am going to test this on a print run tomorrow, and if it goes well I will replicate this for the remaining heads. I can now control the squeegee pressure in the cylinders via the regulator, and I can dump the air with the switch so I can insert / remove squeegees without having to turn the air off to the whole press. I am pretty blown away. Hopefully test prints will go well tomorrow and we can get some shirts moving through here & break our backlog.
(https://i.imgsafe.org/1d1fe90cae.jpg)
(https://i.imgsafe.org/1d1f92e1f2.jpg)
-
So cool.... I love this kind of stuff!!! ;D
-
Looks great! Let us know how it works.
-
Great start!
I'd find the smaller regs and dials.. easier to work with the smaller air fittings and less reducers and threads. The more thread you have, the more chances of air leaks.
The huge benefit I see to this.. anyone who has ever worked on these older chopper styles.. adjusting those clip knobs is a pia and they strip out all the time.. it's this tiny thread with a long bolt.. ugh..
this way you can hard bolt them in and control pressure with a reg like the newer style choppers. Using S-mesh you don't need much pressure or squeegee angle anyway so using the machines air deficiency to your advantage, waaalaaa! squeegee air control.
modify and repeat.. again and again.
keep it up!
-
I feel that good squeegee pressure regulation via air is the only way to go.. presses that don't, or can't offer that are pretty much worthless to me.
same deal with presses that let the squeegee rock back and forth by a single pivot point. (like some certain green machines)
being able to have a consistent amount of force left to right and down lets you print and shear with much less effort, and in my opinion gives much better results for high-speed printing of plastisol.
when the squeegee is allowed to pivot or not conform to the surface of the garment you end up with differing ink deposits side to side of the shirt, and even hydroplaning of the squeegee when printing with minimal pressure and high speeds.
-
I feel that good squeegee pressure regulation via air is the only way to go.. presses that don't, or can't offer that are pretty much worthless to me.
same deal with presses that let the squeegee rock back and forth by a single pivot point. (like some certain green machines)
being able to have a consistent amount of force left to right and down lets you print and shear with much less effort, and in my opinion gives much better results for high-speed printing of plastisol.
when the squeegee is allowed to pivot or not conform to the surface of the garment you end up with differing ink deposits side to side of the shirt, and even hydroplaning of the squeegee when printing with minimal pressure and high speeds.
Interesting on the "self leveling" squeegees. We're moving one of our machines to those certain green ones. They do offer a dual chopper option fyi but it only appears to be needed for the larger jumbo or aop type prints. Self leveling makes far more sense to me for a number of reasons and MHM has always used it with excellent results but I admit I'm a bit nervous about having our main rig setup this way and doing some of our specialty, all over the front of a zip hood type of prints. Curious as to why you see this as negative. Sorry for thread derail! If one of our hosts would like to split this that might be best.
-
the issue is that you not only have a cantilever system where the pressure to the squeegee is coming down from one side, but also that the squeegee can 'float' side to side. when printing in a high shear, high speed method, you really want pressure on both SIDES of the squeegee, so that the platen and shirt can't cause the squeegee to lift up on either side. remember, you're just trying to kiss the top of the shirt.
I think that 'self' leveling print head designs like that are nearly as bad as a tuned up old Javelin... you have to print with so much pressure to overcome the rocking potential that now the squeegee is bent over.
-
If your only experience with floating squeegees is a Javelin then I can see where you are coming from.
But other than that, no. We've only had floating squeegees of two flavors for the last 8 years or so
and have never had a problem like you describe.
I can see where you would want double choppers if your screens or platens are out of parallel though.
-
I've used mhm for quite a bit of time and what you are describing does not happen. They're printhead technology is far superior to that of others and given the option would prefer to use their heads over choppers.
-
Oh, and to the OP, excellent work sir! I love seeing new life being brought to old machines.
-
the issue is that you not only have a cantilever system where the pressure to the squeegee is coming down from one side, but also that the squeegee can 'float' side to side. when printing in a high shear, high speed method, you really want pressure on both SIDES of the squeegee, so that the platen and shirt can't cause the squeegee to lift up on either side. remember, you're just trying to kiss the top of the shirt.
I think that 'self' leveling print head designs like that are nearly as bad as a tuned up old Javelin... you have to print with so much pressure to overcome the rocking potential that now the squeegee is bent over.
Not to derail the thread but I'd love see what you can do on your chopper heads that we cannot do here. Coming from running 5 chopper style presses to the single pin squeegee system I feel I have a great understanding of both systems and what they offer. What experience do you have with the single point squeegee system if I dont mind asking?
High sheer printing in my opinion has way more to do with the proper mesh, ink and blade then what your describing above.
-
I have no direct experience with the newer style machines.
however, I have heard reports from people that I trust saying that they're having problems clearing one side or the other side of a screen when printing with super low pressures on some single-point presses. The only working solution in some of these cases is to just add pressure and let the squeegee deflection act as a shock.
this would seem to indicate that the pressure isn't consistent side to side... which is what a dual-point chopper pneumatic driven system tries to solve.
the chopper presses down with X pounds of pressure on either side of the blade keeping the interface pressure between the blade and the screen (and thus the shirt) consistent.
having a system where the squeegee is free to rock back and forth means you're only pushing down with force in the middle. The force at either end can be different... the most apparent form of this would be a see-saw... the middle of the seesaw is like the pin/pivot... the ends are the ends of the squeegee... if one person pushes up, no matter how much pressure the middle has, the other end is going to go down, or vice versa.
-
I have no direct experience with the newer style machines.
however, I have heard reports from people that I trust saying that they're having problems clearing one side or the other side of a screen when printing with super low pressures on some single-point presses. The only working solution in some of these cases is to just add pressure and let the squeegee deflection act as a shock.
this would seem to indicate that the pressure isn't consistent side to side... which is what a dual-point chopper pneumatic driven system tries to solve.
the chopper presses down with X pounds of pressure on either side of the blade keeping the interface pressure between the blade and the screen (and thus the shirt) consistent.
having a system where the squeegee is free to rock back and forth means you're only pushing down with force in the middle. The force at either end can be different... the most apparent form of this would be a see-saw... the middle of the seesaw is like the pin/pivot... the ends are the ends of the squeegee... if one person pushes up, no matter how much pressure the middle has, the other end is going to go down, or vice versa.
Ok so no experience with the system, got it! ;)
I'm quite sure I know who your source is spreading this information out there, and while I can respect the individual I will say I have done tens of thousands more prints then this person on both single point and chopper style systems giving me a great understanding of what can/cant be done. This situation reminds me of when I was professionally racing cars in the aspect that when one manf was not getting the results they were looking for the easiest solution was to blame the next person in line - i.e if the car wasn't fast enough the engine builder would place blame on the chassis builder and vice versa. The same can be said for manufactures in this industry we are in. If an ink manufacture cannot get their ink to perform a certain way then blame is placed on the machine printing it when in reality the recipe might not be met. All machines are different and require different setups/recipes to make work.
We dont print at full speed a lot but when we need to we certainly can. Proper ink, mesh, tension, blade, off contact, etc as you know play a key roll in high sheer low pressure printing. If there are machines out there with single point setups that cannot do this then my thought is they are not calibrated correctly as mentioned we have absolutely no issues printing as fast or faster then any chopper setup out there. We've been there done that, and have done millions of prints with both styles.
-
This turned into some good reading and info from all ;)
-
... I can now control the squeegee pressure in the cylinders via the regulator, and I can dump the air with the switch so I can insert / remove squeegees without having to turn the air off to the whole press.
(https://i.imgsafe.org/1d1fe90cae.jpg)
(https://i.imgsafe.org/1d1f92e1f2.jpg)
I have been meaning to add this type of relief/air dump valve to my press. Could you add some more details on the switch you used? I assume it keeps the pressure in the rest of the machine when releasing pressure from the print carriage?
Great work on the DIY upgrade.
-
This has actually turned out to be the one of the best things I could have done for the press, and our shop, as this is our only auto. I went ahead and outfitted 5 of the heads with regulators and switches exception being the flash head. We put up a 5 color on press friday, setup is so much more streamlined. Being able to flip a switch on the head, to remove the constant squeegee pressure to adjust registration is a game changer for our setup time. Doesn't sound like much... but when you have to cut air to the whole press and wait for it to drain out to be able to move the micros on each head, that is a real time killer. Not to mention the extra frustration. This fixes that, and really improves my mental state. Still getting pallet deflection, but much less now that we can dial the pressure back. Registration, setup etc is 100% improved.
For the switch, I used this one https://www.mettleair.com/store/5-ports-3-way-2-position-toggle-valve-1-8-npt-detented.html (https://www.mettleair.com/store/5-ports-3-way-2-position-toggle-valve-1-8-npt-detented.html) It ended up being the most expensive part of the retrofit. Im sure I could have used a different one, but i really wanted one that was 1/8" npt so I didn't have to worry about other fittings and such. It is a 3 way switch, with two positions. When the switch is open, the muffler is closed and the chopper cylinders have regulated air pressure, when the switch is closed, the infeed from the press is closed and the remaining air in the cylinders / head is released through the muffler. The rest of the press keeps pressure, no constant bleeding or anything. Its super easy to rig this up, it took the better part of an afternoon to rig up the rest of the heads. Once you do the first, you can use the bracket as as a template for the others. Acrylic is easy to work with and seems to be pretty strong. You do need to extend the 5/32 air line that runs through the guide that holds the proximity flags. And then you'll need a bit of hose to run from the switch back to the manifold on the front of the head.
(https://i.imgsafe.org/69e85e2ffb.png)
I would have loved to get smaller regulators, and use less fittings, but harbor freight had these for $9.99 and it was local, meaning I could do it now. I may change them eventually, but for now i'm just stoked that it works! Best thing I could have done. If I get some time, i'll try to take a video of it in action.
The next thing on the list for me now... is to find a better way to clamp in roller frames. This may have been covered somewhere before, but we have the stock screw type clamps with the plastic feet, and have to use the metal shims from newman on all four corners.... which totally sucks. I haven't researched it much, but I'm pretty sure this can be upgraded with parts from the M&R store. Has anyone gone from the posts to a newman compatible bar type system on this press? Ive seen air lock upgrades on similar presses, but I don't think they'd work with rollers. I'm also a little hesitant to go the air lock route, unless I also rig up some kind of manual backup, because I routinely leave jobs on press overnight. But it would be nice to have them nonetheless.