Why aren't RP black drums compatible?

[mixedfeelings]

Hi All,
I was wondering if someone more knowledgeable explain the reason that RP black drums are not compatible between models (I have an RP 3105UI and a 3700) when color drums are?

Is there some key difference that I am not understanding?

Thanks!

[jermyth]

Re: Why aren't RP black drums compatible?

The 3700 is a HD machine. Uses different ink and master than the 3105. And is full 600x600dpi where the 3105 is 300x400dpi. That help?

[mixedfeelings]

Re: Why aren't RP black drums compatible?

That makes sense to me - to a point - wouldn't the color drums all need to be different as well? why just the black ones?

[jermyth]

Re: Why aren't RP black drums compatible?

The color drums are yet again different than BOTH the black and the HD black, making them compatable with all RP units. I think that Riso was having just too much fun with making drums at that time.

[mixedfeelings]

Re: Why aren't RP black drums compatible?

I suppose that makes sense! Thanks! But - what is the difference between an HD and non-HD drum black drum?

Also, does anyone have a Riso part number for the RP3700 / RP3790 Black HD drum - I have been scouring google for such a number and have not come up with anything.

I may have just made a grave ebay mistake :-/

[jermyth]

Re: Why aren't RP black drums compatible?

Riso stock # is S-3372B for the RP HD Ledger drum. Standard RP Ledger drum is S-3534.

[mixedfeelings]

Re: Why aren't RP black drums compatible?

Is it possible to use black ink in a standard s3534 ledger drum? The description of the drum I purchased indicates that it isblack and has been tested on an rp3700, but also that it is a s3534. So, I am confused.

Thanks for your help and info Jermyth! I couldn't find that number anywhere!

[jermyth]

Re: Why aren't RP black drums compatible?

I belive the 3700 unit would accept all drum types, being the top of that line. But I'd have to research that to be 100% sure.

RP has three different kinds of ink. Color, black and HD black. And they will work only in the respective drum types. Unless you want to physically modifty the ink tube to fix, which I do NOT suggest anyone to do. Many printers disagree with this but the inks are different and the drums and made a little different to run that ink. Screens and drum bodys and internal parts are manufactured to run with a specific ink formual. Happy New Year!

[mixedfeelings]

Re: Why aren't RP black drums compatible?

Thank you for all of this information! I really appreciate it!

What are the differences between HD black and regular black? Is there anything that is really going to make me regret purchasing a regular black drum rather than an HD?

Thanks again!

[ddude]

Re: Why aren't RP black drums compatible?

The HD stands for High Density, capable of printing at 600dpi - iirc, only the RP 37xx can print at 600dpi. I do not know what may happen if you use a non-HD black drum in the 37xx series, because the color drums seem to work fine between the whole line, the color does not differentiate between 400 or 600 dpi. The only trick will be getting the machine to recognize the drum.

EDIT- jermyth had explained this well earlier, sorry to repost-

The 3700 is a HD machine. Uses different ink and master than the 3105. And is full 600x600dpi where the 3105 is 300x400dpi. That help?

[mixedfeelings]

Re: Why aren't RP black drums compatible?

Ah, so does that mean that color drums do not print at 600 dpi? Only the HD black is capable of that?

How is the HD ink itself different? Is it thicker?

[ddude]

Re: Why aren't RP black drums compatible?

I would think the HD ink is thinner, allowing it to flow into the smaller pinholes burnt into the master.
I do not know if the 37xx will burn a different DPI master when it senses that a color drum is installed- That is a question best left to the experts??? IF- it does not burn a different DPI master, then we can deduce only two things:
1) that Riso color ink is capable of flowing through a fine,thinly burned 600dpi master, or-
2) that the whole HD concept put out by Riso is hooey.

[jermyth]

Re: Why aren't RP black drums compatible?

For whatever reason Riso does not make HD color ink only HD Black ink. Do color drums print better with a HD master on them? Most say yes. Personally...somewhat, it depends on the image.