configure motor for C&P 10x15

Would the following DC motor specs be suitable for a C&P 10x15 New Series press?

I have a drive pulley on the right side of the press that is 15 inches in diameter and I’m trying to determine if this motor will provide adequate power for this press. The motor pulley that I have is 5 inches in diameter.

3/4 hp
90V dc
1750 rpm
5/8 inch shaft

Here are my numbers based on Gary Johanson’s informative article at

6 flywheel revolutions = 1 impression
1 impression every 3 seconds
flywheel rpm = 120 (20 impressions per minute, 1,200 per hour)
motor rpm (1,750) / press rpm (120) = 14.5ish
motor pulley to press ratio = 14.5 : 1

These numbers make sense to me but I’m trying to understand how the drive pulley diameter (15”) works into this equation.

Can I use the motor listed above with this 15” diameter drive pulley and achieve a reasonable impression speed? I see that the maximum impressions per hour for this press is 2,300. What would be considered a typical, usable speed?

Thank you for any assistance!


Log in to reply   6 replies so far


600 or so IPH is plenty for me. With a treadle. I don’t use motors anymore, they go too fast.

Can’t remember the last time I had a press run more than 500, and the difference between 600 iph and 2000 iph is pretty meaningless for short press runs. Also, I doubt many could continuously hand-feed at the higher rate. I certainly couldn’t I make way too many misfeeds when the iph goes upwards of my usual 600 or so.

Other factors get in the way when hand feeding a C&P. The upper feed table only comfortably holds so much paper, usually one stack no more than a couple hundred sheets at a time. Depending on how big a form you are printing, the ink table will need to be refreshed of ink before too many impressions—as few as every 10 and maybe as high as 100. Ink fountains might help with that, but they have their own series of issues. Finally there are only so many copies you can stack on the lower feed table before risking set-off; those need to be moved off to some safe place to dry.

You’ll spend much more time on setting type, cutting paper, cleaning the press, distributing type, and those miscellaneous tasks above than you will actually feeding the press.

BTW, I believe the 10x15 C&P only has 5 revolutions per impression, at least that’s what we experience on our 10x15OS at the University. A 12x18 OS I had briefly had 6 revolutions per impression.

josh, i will have to agree with Arie. 2,300 IPH is really quite a fast speed… even when i am just die cutting or foiling…. i really can’t see a safe senareo slinging ink rollers at this speed…. it is your stuff but,,,, slow it down….everything i use, for the most part, is auto feed, and 2300 is quite fast…i have run some jobs faster. but i don’t worry bout my arms, fingers, legs, etc…..

I run my 10x15 at 14 impressions per minute. That will produce 840 per hour. I’m a beginner and this speed is very comfortable for me. Inevitably there are misfeeds even at this speed but they are relatively few and I don’t have to race.

The excellent book Elementary Platen Press Operation reprints a study that shows that when a press is run either too fast or at a borderline speed for the pressman, even though technically more impressions and therefore printed sheets should be obtained than on a slower running press, in fact fewer sheets are actually printed over a longer period of time as a result of misfeeds and the extra time involved in throwing off the impression as a result. Sort of like the tortise and the hare. Naturally there are safety considerations also.

While in general the motor you have is fine in terms of horsepower and rpm, the problem you may have is that even though a variable speed motor varies the speed electronically, it has a range of speeds. That speed range is affected by the diameter of the pulleys. The pulleys you have may work to give you the range of speeds you want. But you will have to hook everything up and then determine what the fastest and slowest speeds are with that setup. If the press needs to run slower then you will need to either reduce the size of the motor pulley, increase the size of the drive pulley, or both. In other words, move the range of the variable speeds downward mechanically using the pulleys.


Front Room Press
Milford, NJ

Here is the formula
(motor pulley diameter) x rpm / driven pulley diameter = driven pulley rpm
so 5x1750/15=583.333 rpm
This is going to be too fast to hand feed will work out to almost 6000 ipm. Look into a gear reducers ac inverters,larger press pulley to slow your press down. I’m sure others will also add valuable comments and advice.

I made the assumption that since you are using a DC motor that you are using it as a variable speed motor since that is the usual reason to emply a DC motor on a machine. If however you’re using it at its fixed speed of 1750 rpm, the pulleys you have will not give you a speed at which you can operate the press as others have noted.

Even with a 2” motor pulley and a 24” drive pulley, the smallest and largest respectively you can reasonably expect to use, the press will run at 28 impressions per minute. You could belt the motor to the flywheel with a 2” motor pulley and get about 20 impressions per minute depending on the diameter of the flywheel. Not bad but perhaps still too fast for you; I know it would be for me.

The only other practical mechanical option to reduce the speed further is to use an intermediate shaft between the motor and drive pulley called a countershaft. By using the right combination of pulleys you can get the speed to wherever you want. This is the method I used on my first press, a C&P 8x12.

I use a vintage AC variable speed motor on the 10x15 I have now. I have a 2” flat belt pulley on the motoer and a 24” flat belt pulley on the press with a leather belt.

Sorry if my assumption caused any confusion.


Front Room Press
Milford, NJ

Thank you all for your insight. It is very appreciated! It’s especially helpful to know what “typical” impression speeds are. I’m guessing that somewhere between 600 (Arie) and 840 (Rich) per hour will be a good starting point. I’ll see what feels comfortable. Like Rich, I am a beginner.

The motor that I described previously was a motor that I have the chance to purchase at a great price. I was curious if that would work with the drive pulley (15 inch) and motor pulley (5 inch) that came with the press. It is not a variable speed motor.

I currently have a three-phase variable speed motor that came with the press but was considering purchasing the single phase motor (above) to motorize the press more cost effectively. It seems that the best approach will be to simply buy a rotary phase convertor for the three-phase motor that I already have. It looks like they run a few hundred dollars new.

The three-phase motor that I have has these specs.

3/4 hp
motor rpm: 1,800
rpm: 235
rpm max: 2,350

I’m guessing that this variable speed motor has an acceptable range for printing since it was used previously with this press (previous owner). Would the “rpm” be considered the minimum rpm? If that is the min rpm then that would equate to 783 impressions per hour (using Mike’s formula w/ 5 inch motor pulley and 15 inch drive pulley).

Sorry for the novice questions. :) Thanks again. I’ll keep you posted on my progress!