How tight/closely do you parallel your press?

[jvanick]

late last week, I built a jig that holds 4 dial indicators in a screen frame to help parallel my press. 

I paralleled the print arm head to the screen holders (in my case 8.125 inches on my chopper head on the javelin... I know this is a bit higher than Workhorse's spec, but in order to get a good flood and chop height when running double-bevel squeegees, it's necessary).  (the rest of the heads are at spec 7.875").

Then I moved onto the platens...  I couldn't believe how far some were off... anything from .06" to .225"...  Since we print 99% Gildan Ultras, I picked right in between 1/8 (.125) and 3/16 (.1875) as my target (.165)...  relatively quickly, i was able to get them all with in +/- .002 of each other...

I then used that platen to level the rest of the screen holders in to the platen, as well as check the track to screen holder distances.

my next set of prints instantly showed a definite improvement (not unexpected)...

but it's getting me to thinking... what is close/tight enough?  should we strive for 1/1000 (.001") of tolerance, is .005 fine?  Obviously the closer the better, but where should the limit be.

Those of you that are using dial indicators to parallel your press.. what are you striving for?

[Printficient]

When I learned how to do this it was on a M&R Challenger in 1988 or do.  I was instructed to set it at .0057".  Also 5 points of contact.  All 4 corners and center.

[alan802]

I've done .005 the last few times I've calibrated and I think that is a good place to be.  I could have done better but the tighter you go the more time it takes to get things perfect.

[ScreenFoo]

I shoot for .01, but I'd think my head linear is at least .02-.03 off.

[blue moon]

last time I did it, we got EVERYTHING (platens, heads, arms . . .) within 0.015 and I though it was good enough. Platens were with 0.005" all the way around and couple of heads were out of parallel by before mentioned 0.015".
It is possible that with higher tension screens this might not be enough for super high end prints, but it worked fine for us.

pierre

[ScreenFoo]

One other thing--dial indicators only measure points, if that is all you use, and your platens are warped at all, or your rubber isn't flat, you could be WAY further off tolerance over the span of the platen than you think.   It's happened to me. 

[ZooCity]

We keep our '92 Gauntlet and the manual to probably about 0.016 since we parallel by eye with a steel ruler.  On this press, there's little need to work harder at it, it would just go out again before you can put the ruler away.  Especially if your press freewheels and is indexed by hand it can be pointless to get to tight when paralleling. No matter how careful the crew is in handling it's going to knock them out a bit.

With a fancy newer press with servo and no freewheeling, I might be tempted to get things uber tight though.   

[alan802]

I tried one time to get all 12 pallets to within less than a sheet of paper and had ok success.  There were a few pallets out by a little more but most of the 12 were within that spec.  Only bad part is it took me several hours just on the pallets, not including doing the print heads.

[Binkspot]

Keep in mind sometimes you get to the point you are just spinning your wheels. You always strive for 0 but if you are running a hot flash the alum pallets are twisting and warping, or a lot of squeegee pressure , might only be 0.001" but that's what your fighting to get on the adjustments. Add in the lint build up on the pallets, your loosing the hairs you were splitting leveling the pallets. The rubber squeegee makes up for these little changes.

I use the flood bar (I know your dealing with a Jav) and a business card, I look for the same drag across the pallet.

[tonypep]

Agreed.

[jvanick]

I did check the platens with straightedge, and by eye they look fine.

I agree with the print deflection and lint buildup, but I was more interested in where I should be shooting for, and what's good enough.

sounds like if I shot for .015 or so it wouldn't be too bad, and that gives me a lot of leeway before re-leveling...

can somebody describe/explain the floodbar trick to me.  head 1 on my Javelin is a chopper head... (not vsqueegee)... but when I lower the flood bar, there's adjustments on both the left and right side of it, there's no easy way to make sure that it's perfectly parallel to the track...so do I just lower it to one platen and then use that as my reference for all the rest???

[Binkspot]

Pallet 1, place a level across the back end of the pallet left to right. Adjust to zero bubble.
Index pallet under head one. Put the flood bar in the holder (May have to put it in the squeegee holder to reach the end of the pallet) and adjust it with the chopper stops until you have equal drag on a feeler blade like a business card on the left and right sides along the back edge of the pallet. Slide the print carriage fwd and adjust the front of the pallet then to the back to see if adjusting the front changed the rear. On the Jav you will have to disconnect and plug the air lines that work the stroke cylinder so it moves freely. This will also show any warping in the pallets, the feeler blade will be good on the outside edges and tight in the middle.

Slide the carriage back past the end of the pallet so the next pallet won't hit it and index to the second pallet and make adjustments, repeat.

Once the first pallet is set and the flood is adjusted you only have to drag the flood across each pallet.

[Action1]

Some of you may know - we do have a Leveling & Off-Contact Pallet that we offer. Consistent improvement on the design has yielded a current model that is very efficient and user friendly. They are available with Digital dial indicators and made using two pieces of honeycomb aluminum. The dial indicators are mounted on a piece of honeycomb that is the same size as your screens. The bottom reference pallet is also honeycomb aluminum. We use the honeycomb because it’s so flat. The dial indicators refer to an area on the edge of the pallet that has been machined to a thickness that’s the same as your aluminum and rubber.

[GaryG]

Pallet 1, place a level across the back end of the pallet left to right. Adjust to zero bubble.
Index pallet under head one. Put the flood bar in the holder (May have to put it in the squeegee holder to reach the end of the pallet) and adjust it with the chopper stops until you have equal drag

This is an important point- adjusting the choppers "evenly" -if not even across level pallet, it can look angled. And if looking
angled, may wonder if it's flood bar or pallet. Level pallet first then recheck after getting flood bar accurate.

Great timing, was trying to think this out actually last night!