[Jamming] RP3700 Main Drive Gear Replacement?

[mixedfeelings]

Hello all,
I have a pretty serious timing issue with my RP3700 and can no longer print. The pressure roller seems to lift at the wrong time and stops the drum from spinning properly. They only way I can resolve it is by using the test mode to release the pressure spring and manually rotating the drum to a position where the drum can be pulled out. When I press the normal drum release button, it rotates the drum into a position where it can not be pulled out (master clamp is at approx. 5 o'clock), and I again have to manually turn it to get it into a position where I can remove the drum.


When I opened up the back of my machine - there were little black plastic flakes, which makes me think that it's possible that one of the main drive gears have blown - causing my timing problems. My machine never got the upgraded main drive gears. It had about 3.6 million impressions when I got it, now its at about 3.9.

I called my local techs today and they seemed really convinced that it wouldn't be worth repairing this obsolete machine with so many impressions - but looking at other threads on this forum, I think that it still has some life in it after I get these gears upgraded. So how hard is that? Is it a total fools errand? I have read that instructions for the timing holes aren't in the tech manual? are they published anywhere else? Does anyone have any tips? I have the tech bulletin about the upgrade, but it just tells you what new parts are needed - not how to actually do it.

I have successfully realigned my second paper feed area, is this much more complicated than that?

This all said, I am also open to a replacement used RP3700 in the upper midwest (I'm located in Michigan) if anyone has any leads on that too.

Thanks in advance!

[20gaugeO/U]

Re: RP3700 Main Drive Gear Replacement?

Some machines went 2 million, some went 5 without breaking. Most would break sometime in between. If you have all 3 updated metal gears already you might as well go for it. I can't say it's the most fun to do because when you aren't looking one gear will slip a tooth and you get to realign again. Check page 3-2 of the tech manual, that what it should look like when going back together. Follow the steps for removing the Main Motor Unit (Page 3-6) but when you get to step 9, stop and you should be in the area of the 3 gears.

Tips: 1) Have the drum in the machine in home position
2) Put a dowel rod in the Position-B alignment hole Cam Gear (marked on page 3-7, upper right) so when you take off the gears it doesn't spin out of time. There are timing marks all over the frame pieces to make sure everything is "in time."

RP's are obsolete and I would rather work on a Z any day. Half the parts in them to break and still run run run. RP's were over complicated for the tech's and end users.

That's all I remember. No more in the field for me.

Good Luck

[mixedfeelings]

Re: RP3700 Main Drive Gear Replacement?

Thanks! 20Gauge0/U!!

I really appreciate the advice. The dowel is a genius idea. I am hoping to work on this all weekend, if the gears arrive in time. I will definitely be studying those pages until then.

One thing that is kind of throwing me: isn't the machine currently already out of time? it seems like i shouldn't put the new gears on exactly the same way that the old broken ones are coming off?

[20gaugeO/U]

Re: RP3700 Main Drive Gear Replacement?

When the drum is in the machine and at home the Position B alignment hole (Cam Gear) mark should be at 12 o'clock. Dowel it and replace the 3 broken plastic gears with the metal one's. Take note of all timing marks as you are putting back together. One tooth off and you get to do it again, and again, and again. Sounds like fun??? Have a great weekend

[mixedfeelings]

Re: RP3700 Main Drive Gear Replacement?

OK! I finally got the parts, and I have them installed, and I have all of the timing marks lined up (That dowel tip is genius, 20gauge!). Positions A and B are now in the appropriate place, it can make masters and the drum ejects properly.

But, I can't for the life of me get the paper to feed past the guide / timing rollers. No matter what I do it just stops there. It seems like I must be off a tooth or something - but is there a way to know which direction i should be turning it? It also seems like if i take it a tooth off, the b position holes on the main gear and the timing cam won't each line up properly anymore? Is there anyway to know what I should be doing at this point?

Thanks!

[20gaugeO/U]

Re: RP3700 Main Drive Gear Replacement?

Without seeing it I can't say. How was it feeding before the gears broke? Maybe take some pics and post, could see if we spot something out of time. I traded my last one in 6 months ago, so all I have is the manual and my memory. There are so many timing marks and things to keep aware of on this model it's easy to miss something if you don't know to look for it.

[Iowatech]

Re: RP3700 Main Drive Gear Replacement?

There are timing holes that align the gear train to the frame in the paper feed drive area. So you should be able to see which way to go.
On the other hand, it sounds a little like the cam on the guide roller is out of adjustment or bad, or maybe the spring that keeps the cam follower on that cam is disconnected?

[feak2012]

Re: RP3700 Main Drive Gear Replacement?

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[mixedfeelings]

Re: RP3700 Main Drive Gear Replacement?

Well, the issue here was that I am an idiot. When taking out the timing roller to clean a while back I lost the e-clip somewhere in the machine, and i guess the one I replaced it with isn't an exact fit (i think maybe just a little too thick to sit properly in the groove) and the whole roller had some how gotten dislodged while i was retiming the machine. Because I hadn't been working down there, I never thought to double check that it was still in place, until, well, i did! Thanks again for helping work through that problem. of course, there is another (well several).

I had it all running well enough to print 2 60-page multi-color (2 and 3) books. But I realized that I didn't bother to get the smallest new gear perfectly aligned, so I decided to take it all apart and redo the timing for good measure - just in case. what a nightmare that has been. Now I can only get two impressions before the third wraps around the drum without fail - This is happening with the test mode prints (i've tried 50, 52, and 53) and with about 1/4" of white space at the head. Is something like that caused by the ejection air flow coming on too late or too early?

[jermyth]

Re: RP3700 Main Drive Gear Replacement?

Ussally not the air seperator, mostly timing or feed timing or too much ink at lead, but it sounds like you covered that. Try running a confidental and run some prints to see what and where it jams.
Good luck.

[20gaugeO/U]

Re: RP3700 Main Drive Gear Replacement?

I agree with Jermyth, 1/4" inch isn't very much. It's a good idea to have a 1/2" lead edge void and that's what I tell all my customers. Anything less and you are asking for jams especially with cheap paper. I'd test with another job or flip the paper over if it's curled or twisted.

[mixedfeelings]

Re: RP3700 Main Drive Gear Replacement?

Normally I have a much bigger margins - i was just using the TM test modes because, well, I was in test mode... I thought the dots would be light enough. I'll try something more "real" when I get the masters feeding reliably!

Thanks!

[mixedfeelings]

Re: RP3700 Main Drive Gear Replacement?

I got the master flowing again and made my own test sheet that is essentially just 2 2pt lines and some boxes to help me determine the alignment of my images in printing (yep, still skewed), and it is feeding just fine! the image is even centered. I guess the test modes laid too much ink after all!

It's been a hellish couple of weeks - but I have learned A LOT and I am feeling a lot more comfortable working with these machines. Thanks so much for everything!