OK, I seriously have the weirdest problem with one of my C&P’s.

The press is an 8 x 12 C&P Oldstyle converted with an electric motor.

I’ve only been using it for die-cutting and scoring, but I recently had my rollers recovered and decided to run some color on it.

After I inked up the press and started printing, the belt started to fly off! I’ve never had this problem before with this press. It kept doing it over and over, so eventually I just gave up.

Soooo, I took the rollers off, cleaned it up, and started die-cutting some labels. The press worked just fine.

Has anyone ever heard of this, where putting on the rollers on the press causes the belt to fly off, but leaving them off doesn’t?

Thanks in advance>

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The only thing I can think of is that the addition of the rollers causes some added resistance or drag on the motor and it may be that this is tweaking the belt just enough to cause it to slip off — I assume you are driving the flywheel with the belt — or is it a flat belt slipping off the motor drive pulley? Check that your motor mounting is solid and can’t shift under a bit more strain, because if it is twisting ever so little that would cause the belt to run off a pulley or the flywheel.


Your correct, Bob, I’m driving the flywheel with the belt. I’ll check the motor mounting, will let you know if this works.

Thank you!

Also check that the roller arm assemblies are clean and working smoothly for the length of travel — if the roller hook shafts are crudded up it would put a bunch of stress on the drive train.

maybe, IF you can see it, there is a “pulling side” to the belt and a “slack, or, return, side”
watch the belt on the slack side without the rollers installed. note what that side of the belt is doing. is it drooping at all during the press cycle?
then install the rollers and carefully notice any change in the behavior of the belt. Any extra drooping would indicate extra drag, or load on the machine. the extra slack in the belt may be allowing the belt to do what it wants. you can try changing the belt direction. flip it so the edge towards the press is now towards the operator.

It is reasonably well documented that with flat belt drive,either the Driven pulley (flywheel) or the driving pulley (Motor pulley ) has to be slightly *CONVEX* specifically to keep it Running On.
Generally there is no direction of travel with flat belt, perhaps mark with “Tippex” Arrow direction, flip it of, examine it flat, to observe for any default bow, through long use in one direction, and as an experiment replace running in the opposite direction.!
Corroborating the above, ericm & extra friction, flipping it just once may prove or disprove inherited *Warp*?

Apologies for potential rubbish,! may just trigger another angle/overview. . . Mick.

During the time that you have been using the press for die cutting the tension of the belt may have loosened and now the added pressure needed to start the press moving with rollers on it may be enough to throw off the belt. Have you tried turning the flywheel by hand to get it started and then cut on the motor?
Sorry if this is off target for your issue.

Belt dressing and conditioner might help.

Thanks for everyone who posted on this. I took all your comments to heart.

@Mick - Yes, the slightly convex shape was news to me, but I talked to some of my friends who are salty old dogs and they told me the same thing. Tried to get that shape.

@EricM - What up brotha! Nope, belt was good.

@Aaron - Never heard of belt dressing and conditioner; what is the purpose of this?

To everyone else - Roller arm assemblies are very clean, so, I think it was the motor mounting… there is some sort of base plate that sits below each side the track where the motor sits. Each base plate has two screw taps. (I forgot to take photos of the base plate).

The screws on the motor track were not mounted on the base plate at all, which explained why the motor wasn’t moving on the track when I tried to move the set screws.

I remounted the base plate, and the set screws were able to move the base plate now that they were in position. I also repositioned the track and motor about 2 inches up.

Sooo, the belt stopped flying off, but it still sits about 1/8” past the flywheel when the motor starts. I’m thinking about repositioning the motor over to the right a bit, but that’s another project for the future. :-)

It actually runs a lot better than before! The old girl moves with a beautiful hum. I’m pleasantly surprised, considering that the motor is at least 50 years old and has never been refurbished.

Thanks everyone!

AAAAhhh photo won’t load!

Check the filename of the photo — BP doesn’t like special characters in the file name. Make it simple, all lower case alphabetic and numeric, and it should work. It also has to be pretty small to be accepted.


D.C. to elaborate on Aaron,s *tip* above, if your belt is Genuine 100% leather, Here U.K. we would treat it exactly as Horse Tack or Saddlery, i.e. treated with Saddle Soap and/or Neatsfoot compound (hope this translates Stateside) to keep the leather soft and supple, for cranking round the tight circumference of the tiny pulley.!!

Plus it was/is fairly common practice to use either a tiny sprinkle of powdered rosin on the inside run of the belt to aid adhesion, & eliminate slip, especially if you have direct on start.? Corroborating A.L.P. and Ericm above.


As an alternative to *Rosin* and probably still available from your own Graphic Suppliers or Agricultural merchants , a Cardboard cased Stick containing a Tar like substance that you apply to the inside run of the Belt (with extreme care and caution of course) it deposits a fine layer on the inside run of the belt and both pulleys, to aid traction.

Applies to both traditional leather or more modern artificial leather with nylon laminate in the centre.

Makes a very interesting “Tacky Hiss”, akin to Auto tyres on a hot Tarmac road, or Dragsters doing *Burn outs*

As the order used to be *Passed for Press, RUN ON*

Good Luck. Mick

OK, try this photo again!

image: Motor.jpg


@Mick - Thanks for the advice, I’ll give it a shot!

@AdLib - Yup, renaming it worked! My original name of @#%$^&*(%^&*$@%$%^{]}{_C&P_Motor.JPG was no good, I guess. :-D