How accorate is a Riso?

[Risotto]

I got a RN 2500 and got a 2nd drum for colour now.

I am asking me how accurate is the riso in printing 2 colours?

Are there tricks to get better results in colour-fitting? In the printer menue I can place the printing screen in 0,5mm steps, but it looks like the 2nd colour is spreading about +/- 2mm within a printjob.
Is this normal or is there something that I should check?

It looks a litt like the 2nd print goes more out of accuracy than the first one.


And another question: is there a trick for adjusting the output? I got the problem that the sheets are often "jamming" or turned around when I print A5. Best result so far is to make the paper basket much bigger than A5 but even then can it happen that sheets are turned upside down....

(PS: sorry for my english I am learning another foreign language at the moment and it is often like english, so I got it mixed up, as I speak more often this 2nd language then english...)

[Iowatech]

Re: How accorate is a Riso?

If I remember correctly, +/- 2mm is the standard for Risos. Plus you have to factor in the age and wear on your machine. The RN line has been around for a while, after all.
You might try letting the first print dry for a while, wet ink will cause the rollers to slip more than they should.
One guess for the receiving tray problem - if you are not a particularly patient person it will be in your best intrest to make sure the "flappers" (the twelve kind of triangular plastic pieces that extend from the front and rear guides) are retracted. To adjust the guides properly with the "flappers" extended takes time, patience and experimentation, otherwise they are not worth the trouble. Just pull up on the green plastic piece above the "flappers" and they should retract into the guide.

[Risotto]

Re: How accorate is a Riso?

If I remember correctly, +/- 2mm is the standard for Risos. Plus you have to factor in the age and wear on your machine. The RN line has been around for a while, after all.
You might try letting the first print dry for a while, wet ink will cause the rollers to slip more than they should.

Sh***
I have to print much A5 and +/- 2mm is much for such a small sheet of paper.
I will test it with letting the sheets dry first. How long will it take?
Maybe using 100g paper instead of 80g will help too?

One guess for the receiving tray problem - if you are not a particularly patient person it will be in your best intrest to make sure the "flappers" (the twelve kind of triangular plastic pieces that extend from the front and rear guides) are retracted. To adjust the guides properly with the "flappers" extended takes time, patience and experimentation, otherwise they are not worth the trouble. Just pull up on the green plastic piece above the "flappers" and they should retract into the guide.

I got the flappers out and the position on A5+ (maybe even little more) now. I tried with flappers in, but it was the same problem. If I put the position closer, the sheets are sometimes flying with a corner into a gap of the side of the tray and jamming.

It looks a little like broken design for me as the paper has a long distance to "fly free" before it is landing in the tray. Maybe I should try to give the tray some "wings" to get this gap smaller?

[Iowatech]

Re: How accorate is a Riso?

Fifteen minutes is usually enough time for the ink to dry.
As far as the receiving tray troubles go, it sounds like the paper you are using has too much curl, and the aerodynamics of the paper is causing the problem. If running the machine at it's slowest speed doesn't help, you might need better paper. Sometimes adjusting the right hand guide of the receiving tray so that it holds the trailing edge of the proof print very close to the machine can help, as it doesn't allow the paper the time to dive that dramatically. Sometimes flipping the paper over in the feed tray helps. Some people found that putting things under the receiving tray so that it is parallel with the machine helps.
Sorry for being so unhelpful.

[Risotto]

Re: How accorate is a Riso?

Fifteen minutes is usually enough time for the ink to dry.
As far as the receiving tray troubles go, it sounds like the paper you are using has too much curl, and the aerodynamics of the paper is causing the problem. If running the machine at it's slowest speed doesn't help, you might need better paper. Sometimes adjusting the right hand guide of the receiving tray so that it holds the trailing edge of the proof print very close to the machine can help, as it doesn't allow the paper the time to dive that dramatically. Sometimes flipping the paper over in the feed tray helps. Some people found that putting things under the receiving tray so that it is parallel with the machine helps.
Sorry for being so unhelpful.

15 minutes were not enough, but I proved to dry about 1-2 hours. I also put the speed down to minimum and it became better, not perfect, but about factor 5-10 better. Now i have one flipped/folded paper in maybe 70-100 prints, before....

I tried different angles of the tray before, it became better sometimes, but still not perfect an I am not sure which angle is the best.

Seems like I will stay with the following solution:
Cheap paper only for one sided prints best with one colour or only a little 1st colour, let it dry and then 2nd colour.
120g paper for the 2 sided prints, best to let it dry between every colour/print. (The 120g was as expensive as the 100g. But it is more than 2 times more expensive as the 80g :-( )

You helped me to be sure not to have forgotten something to try to make the printing better, that is quite much help ;-)

I read a little in the forum, for the colour drifting problem I will check if the paper-silk-screen is moving on the drum. Is there a tip for material to replace the "sticky rubber" on the drum, that one that is placed under the clamp? Taping the silk on the drum looks not like the best solution for me...

[mixedfeelings]

Re: How accorate is a Riso?

Really? 15 minutes?

Is that on a special kind of paper?

I have found that paper with vellum finish tends to dry the fast - but even after letting a print dry over night I still get roller marks when applying the next layer the next day. I try to give a minimum of 8 hours between layers, but often it is closer to 12 or 24 - all with marks.

I have also discovered that I need to print red and fluro pink last no matter what because they will NEVER dry. (well not never, but definitely seem to take much longer)

[Iowatech]

Re: How accorate is a Riso?

15 minutes were not enough, but I proved to dry about 1-2 hours. I also put the speed down to minimum and it became better, not perfect, but about factor 5-10 better. Now i have one flipped/folded paper in maybe 70-100 prints, before....

I tried different angles of the tray before, it became better sometimes, but still not perfect an I am not sure which angle is the best.

Seems like I will stay with the following solution:
Cheap paper only for one sided prints best with one colour or only a little 1st colour, let it dry and then 2nd colour.
120g paper for the 2 sided prints, best to let it dry between every colour/print. (The 120g was as expensive as the 100g. But it is more than 2 times more expensive as the 80g :-( )

You helped me to be sure not to have forgotten something to try to make the printing better, that is quite much help ;-)

I read a little in the forum, for the colour drifting problem I will check if the paper-silk-screen is moving on the drum. Is there a tip for material to replace the "sticky rubber" on the drum, that one that is placed under the clamp? Taping the silk on the drum looks not like the best solution for me...

If I understand correctly, the sticky rubber is actually a fairly strong magnet that holds the clamp shut. If that is correct, replacing it wouldn't be advised. Try cleaning it with alcohol.
Or better yet, after you've made a new master for a one color print, make a mark on the master next to where it goes under the clamp plate (felt tip marker works best, but anything that won't puncture the master that you can easily recognize will work), make some prints (at least twenty, one hundred or so is better) then pull the drum out and see if the mark has moved away from the clamp. An easy way to tell if the master is moving or not.

[Iowatech]

Re: How accorate is a Riso?

Really? 15 minutes?

Is that on a special kind of paper?

I have found that paper with vellum finish tends to dry the fast - but even after letting a print dry over night I still get roller marks when applying the next layer the next day. I try to give a minimum of 8 hours between layers, but often it is closer to 12 or 24 - all with marks.

I have also discovered that I need to print red and fluro pink last no matter what because they will NEVER dry. (well not never, but definitely seem to take much longer)

Sure, fifteen minutes works. But then again the vast majority of places I've been to are printing four to six percent coverage text documents. So that is the minimum time that I've seen. And also the best I could come up with for my comprehension of the information provided.

[Risotto]

Re: How accorate is a Riso?

Sure, fifteen minutes works. But then again the vast majority of places I've been to are printing four to six percent coverage text documents. So that is the minimum time that I've seen. And also the best I could come up with for my comprehension of the information provided.

I will see, new paper is ordered and will be tested soon.

I also got a 2nd RN2500 now very cheap with two extra drums. It is a 2500 EP now, what is different from the normal 2500? The new one has some xtras, but I think they are build in afterwards (LAN2LTP adapter, job seperator IV)

I have to clean it first, the smartguys have run a drum with a broken gasket and now there is lots of ink on the bottom of the drumslot. Any Idea where to buy gaskets for the drum? As I cleaned my old black drum one gasket was too long because of aging, I cut a little out and it is OK now, but I fear that the new black hasn't a gasket at all so much paint as I find in the drumslot.......

[Iowatech]

Re: How accorate is a Riso?

If you have an auto supply store nearby, buy a tube of RTV gasket material. If you are careful and patient (it needs some time to set up), you can use that to plug leaks in the front and rear seals of the drum. Just make sure to use only enough to seal the leak. Try to get the smallest tube you can, too, the stuff tends to go bad if you don't use it up in time.
We used RTV gasket material to seal up leaks in the RA and GR line drums a lot. Smells a little like vinegar. But it worked really well.
Make sure to use RTV gasket material, though. RTV remains flexible after it sets up, other types of gasket material set up rock hard, which is undesirable in this application.

[Risotto]

Re: How accorate is a Riso?

If you have an auto supply store nearby, buy a tube of RTV gasket material. If you are careful and patient (it needs some time to set up), you can use that to plug leaks in the front and rear seals of the drum. Just make sure to use only enough to seal the leak. Try to get the smallest tube you can, too, the stuff tends to go bad if you don't use it up in time.
We used RTV gasket material to seal up leaks in the RA and GR line drums a lot. Smells a little like vinegar. But it worked really well.
Make sure to use RTV gasket material, though. RTV remains flexible after it sets up, other types of gasket material set up rock hard, which is undesirable in this application.

RTV gasket is some sort of fast drying silicone if I see this right? If I let it dry little longer I could sure use simple silicone form sanitary handcrafting?

And there is no problem to disassemble the drum once more after you have sealed it with this stuff?

I have to check the drum first I hope the Ink comes out on the drum "silk gasket" and not near the pump.

[Iowatech]

Re: How accorate is a Riso?

RTV stands for room temperature vulcanizing (rubber). It stays flexible and resistant to chemical degradation once it cures.
While it will adhere to both the drum end frame and the drum shell, it is soft enough that you should be able to remove the drum shell without damaging it, at least I could every time I used it.

[Risotto]

Re: How accorate is a Riso?

RTV stands for room temperature vulcanizing (rubber). It stays flexible and resistant to chemical degradation once it cures.
While it will adhere to both the drum end frame and the drum shell, it is soft enough that you should be able to remove the drum shell without damaging it, at least I could every time I used it.

OK, Thanks! So I better buy this stuff, even if common silicone sure will do it too...

Do you have a clue what is different between the "EP" Risos and the "non EP"?