Pittman Scalecraft synergism

Rob, when you gonna use one of those CPR motors I machined the end caps on?…..those 12V motors we’re finding out are the cat’s meow, the bee’s knees,….they are super efficient, lots of low end torque, and super smooth……you need to try one

Pat  

Pat,

Yep, the CPR motors are the best of the best, but they require a fair amount of space.  They are slated to go in some USH 4-8-4s.  

In this case needed a smaller 9xx3 motor.

Rob

Pat,

I never heard of the CPR motors.  Please tell us more, torque, max rpm, diameters, lengths, etc. and where to purchase them.

Thanks,

Ed

@Ed Kelly posted:

Pat,

I never heard of the CPR motors.  Please tell us more, torque, max rpm, diameters, lengths, etc. and where to purchase them.

Thanks,

Ed

This is the CPR Pittman motor Rob & I are talking about. These motors are rare earth magnet, silver graphite brushes, and huge double ball bearing ends…..the only draw back is machining off the encoder housing, and with out specialized tools, and a knowledge of working with the end cap material, it can be a daunting task for some DIY guys……beings New Ametek Pittmans are way too high to purchase new, some of us seek secondary market alternatives……this little gem of a motor was found by my buddy Lou, and we never looked back,…….I don’t think I ever bothered to look up the actual specs, cause the darn thing performs the absolute best I’ve ever seen, IMO,…….they sip energy, and pull like a mule,…..about one of the only motors where we can say speed step one IS speed step one ….very smooth and makes good power at low RPM’s …..I believe it is a 6K RPM motor ….or in that neighborhood anyways…….hope that helps,…

Pat

@harmonyards posted:

This is the CPR Pittman motor Rob & I are talking about. These motors are rare earth magnet, silver graphite brushes, and huge double ball bearing ends…..the only draw back is machining off the encoder housing, and with out specialized tools, and a knowledge of working with the end cap material, it can be a daunting task for some DIY guys……beings New Ametek Pittmans are way too high to purchase new, some of us seek secondary market alternatives……this little gem of a motor was found by my buddy Lou, and we never looked back,…….I don’t think I ever bothered to look up the actual specs, cause the darn thing performs the absolute best I’ve ever seen, IMO,…….they sip energy, and pull like a mule,…..about one of the only motors where we can say speed step one IS speed step one ….very smooth and makes good power at low RPM’s …..I believe it is a 6K RPM motor ….or in that neighborhood anyways…….hope that helps,…

I've seen a few of these out there. I assume only the 12V ones are useful? Would the 24V ones be too weak-sauce with the voltages most electronics work at?

Pat,

I believe also that it is a 6k rpm motor.  Always enjoy your descriptions.

Rob

@rplst8 posted:

I've seen a few of these out there. I assume only the 12V ones are useful? Would the 24V ones be too weak-sauce with the voltages most electronics work at?

All motors/ engines have what’s called a power band, ….in the case of electric motors, it’s the combination of the sweet spot in voltage and RPM that makes smooth power, in our case of this hobby,…..although a lot of motors are rated 12/24, it’s where they make the best power that counts, ….I’d doubt you could rev up legacy, or DCS to match the consumption needs of a 24V motor,…I believe some Lionel’s used 24V motors, but the electronics are specifically designed to get the motor in that sweet spot…..clear as mud, right??….

Pat

Pat,

Thanks but what does CPR mean?

Ed

@Ed Kelly posted:

Pat,

Thanks but what does CPR mean?

Ed

CPR= Count Per Revolution……that has to do with the encoder housing on the end cap of the motor. It has absolutely nothing to do, and has no meaning in our hobby….If you see a Pittman, or anybody else’s motor for that matter, that has a CPR capability, that means it will have some sort of encoder housing mounted on the motor, or in the case of the above mentioned motor, it’s integral to the end cap, and must be machined off for use in our industry…..

Pat

@harmonyards posted:

CPR= Count Per Revolution……It has absolutely nothing to do, and has no meaning in our hobby.

Pat

Au contraire Mona Ami.  Pat, when you attach them around flywheels do these not produce CPR's?:

Mike

@Mellow Hudson Mike posted:

Au contraire Mona Ami.  Pat, when you attach them around flywheels do these not produce CPR's?:

Mike

The question that I replied to was in reference to the Pittman CPR motor and the CPR encoder housing mounted on the motor. Which has no use for us…….I can see where someone could misconstrue what I replied, …..

Pat

@harmonyards posted:

The question that I replied to was in reference to the Pittman CPR motor and the CPR encoder housing mounted on the motor. Which has no use for us…….

Pat

Agreed.

Mike

This topic really is interesting. While I know zero about how these motors work, what all the stats mean, I'm curious what are the best price ranges you all search for? I bet that some offerings out there are not the ideal motors, nor the right prices. Anything over $50-$75 outrageous? Guess that entirely depends on what the motor is though too?

@Dave NYC Hudson PRR K4 posted:

This topic really is interesting. While I know zero about how these motors work, what all the stats mean, I'm curious what are the best price ranges you all search for? I bet that some offerings out there are not the ideal motors, nor the right prices. Anything over $50-$75 outrageous? Guess that entirely depends on what the motor is though too?

As cheap as possible, and in the greatest quantities possible……😁

theres a blue million different Pittman motors,…you have to know what you’re looking for in order to be able to search second hand, which is what we have to do now that Pittman ( owned by Ametek ) said sianara suckers to the hobby industry …the general rule of thumb is to find 8000 & 9000 series 12V Pittmans ….the most common in our hobby,….they are out there, sometimes NOS, it just takes some digging around to find them….you need not worry about it Dave, ….I do all your Pittman swaps anyways!….🤣🤣🤣🤣🤣🤣

Pat

@harmonyards posted:

As cheap as possible, and in the greatest quantities possible……😁

theres a blue million different Pittman motors,…you have to know what you’re looking for in order to be able to search second hand, which is what we have to do now that Pittman ( owned by Ametek ) said sianara suckers to the hobby industry …the general rule of thumb is to find 8000 & 9000 series 12V Pittmans ….the most common in our hobby,….they are out there, sometimes NOS, it just takes some digging around to find them….you need not worry about it Dave, ….I do all your Pittman swaps anyways!….🤣🤣🤣🤣🤣🤣

Pat

Well yeah, I know about the swaps. I saw a site having some ranging in the $20's up to the most expensive at$75. All seem to be 12V that I can make out of it, dual shaft, with very little other information available. I figured that most likely these are probably not ideal even though they are under the "O scale" banner at that site. Don't know much else on that though, guessing that they have a manufacture date stamped on it, but hard to read it off the pictures provided as well.

@harmonyards posted:

it’s integral to the end cap, and must be machined off for use in our industry…..

Pat

Pat, is it vital to remove the encoder, or is it purely due to space considerations?

Paul.

@Woodsworks posted:

Pat, is it vital to remove the encoder, or is it purely due to space considerations?

Paul.

Purely out of space issues…..lemme see if I can dig up some before and after pics for a better comparison ….

So when we talk about the 9434 Pittmans found in a lot of O scale models, we tend to call that a 60 mm motor, right?, …more or less, add some change …..well, the CPR motor we’re discussing on Rob’s thread is a 9234 with a 500 count CPR encoder housing,….the motor itself without an encoder option would be a 60 mm,  same as 9434, ….but the encoder housing adds 20 mm, so now it’s 80 mm long,….but the silver lining comes when we machine off the encoder housing portion….now we have a motor slightly under 60 mm, but still have the larger armature and big can…..so now even some opportunities open up on locomotives that were just too tight to fit the big motor ( -34 ) ……I’ll get some pics up after this reply …..we’ll go ahead and make this thread as clear as mud…..🤣🤣🤣

Pat

So here’s the side by side comparison of the before and after,….you can see where that housing just gets all up in our way,…..

Pat

I don’t mean to rain on the 500 CPR motor parade, but I have not seen these things on a certain very popular and well known auction site for a couple months.  They used to be commonly found there.  These may be somewhat rare now.

@swrr posted:

I don’t mean to rain on the 500 CPR motor parade, but I have not seen these things on a certain very popular and well known auction site for a couple months.  They used to be commonly found there.  These may be somewhat rare now.

There were two fellas selling these Rob, ….one I know is sold out, the other fella may still have some left, ….I’ve seen his ad disappear, and reappear….

Pat

Due to the supply difficulties with Pittman motors being compounded several times over by distance (I am in New Zealand) I have been experimenting with can motors taken from Canon and Hewlett Packard desktop printers.  There is often three smaller and one larger motor in each printer.  Sizes run from 36dia x 57 long to 28dia x 37 long.  They run quite smooth, but their operating voltage could be as high as 32VDC, and at 12 volts the largest motors are only turning at 2000rpm - I checked with tachometer to make sure.  The smaller motors are more like 3600rpm.  This would make any steam loco with a 25:1 gearbox WAYYYY too slow.  Fortunately I haven't completed the loco I decided to try one of these motors in, and I'm using screw-assembly drivers made by Slaters in the U.K. so it's not a major chore to substitute a 12:1 or 10:1 gearbox, but this should serve as a warning to anyone thinking of remotoring a loco - check the RPM and do some sums before cutting metal!

Ye, I must admit Im a sucker for scavenging can motors too. The source, medical equipment and photo copiers. The cost was free, mostly! There mostly 24 volts, and I have boxes of them, still love scavenging them. The older KTM motor has rare earth magnets, you can see them sticking proud of the open frame. The loco is also Scale Craft Mikado, Behler motor is similar to the Pittman/Amatec motor, not sure of the magnets in the Behler, both stall at 2.5 amp's      cTr....( Choose the Right )

Working backwards, for something like a high-wheeled Pacific or Atlantic, (at 80 inches for the prototype) to run near 100 scale miles per hour:

For a typical PRR freight engine like a Mike, Decapod, or Consol with 62" drivers and a reasonable 50 MPH:

While it doesn't hold true for the later designs of steam locos, the general rule of thumb for many years was maximum speed in MPH was roughly the same as the number of inches of driving wheel diameter i.e. having 63" drivers meant roughly 63mph top speed - and a caveat before someone starts trotting out statistics; this is the maximum that a loco could run at comfortably, with a train under normal conditions....I am well aware that they could be pushed to do a lot more.  Also, the wheel arrangement played a major role in dictating top speed - trying to do 50mph in an 0-8-0 with 51" drivers would probably be a wild ride, if not downright dangerous due to its lack of guiding wheels up front.

When you do the math, this works out to be 336rpm at the wheels, but I am more interested in low-speed performance so I am aiming for something around 200rpm.  Using those slow-revving motors out of printers I mentioned above, the ratio of gearbox I need is in the range of 10:1 up to 18:1 depending on which motor I can fit.  This has come as quite the surprise, because I was expecting a figure much higher.  I am so glad my teenage son talked me into buying a digital tachometer; it has saved me a lot of bother with false starts on powering my Rivarossi 0-8-0 kits!

I noticed you are not far from Whangarei, my wife was a missionary there, many years ago. I must admit a tach would be very useful. I ended up using the red caped motor (scavenged again ) for my Indian Harbour Belt 0-8-0.      cTr...( Choose the Right )

For your convenience, there is a 8000 series Pittman with CPR encoder housing on that unmentionable sight now, …..I’ve used this motor for powering 0-8-0’s, Connies, and light Mikes……it has similar characteristics as the larger 9234 CPR motor, obviously on the lighter end of the spectrum, but it’s very smooth for it’s size in the lower rpm ranges….same deal as the bigger CPR, ….rare earth, silver graphite brushes, encased brush holder, ball bearings on both ends…

Pat

This thread has really morphed into something!  Bob Turner really likes the 8000 series motors, better size and RPM range, I think.  I use both but tend to favor 9000 series. The wider diameter generally means more torque from physics standpoint.

@swrr posted:

This thread has really morphed into something!  Bob Turner really likes the 8000 series motors, better size and RPM range, I think.  I use both but tend to favor 9000 series. The wider diameter generally means more torque from physics standpoint.

It’s your thread Rob,…..are we ok?, or do we need to change course?…..sorry if it got off your topic, …..clearly we’ve gone overseas, ……like wayyyyyy overseas….😳

Pat

Pat,

Everything is just great with this thread.  I’ve learned a lot.  Thanks to all who contributed!

Rob

Great thread, thanks to all.

For anyone is interested and that has a Google account, I've created a spreadsheet to calculate the required motor RPMs for a set of inputs.

It takes wheel diameter in inches, miles per hour, and gear reduction ratio and then calculates the RPMs at the motor shaft required to get that. Wheel diameter and miles per hour are for the prototype size.  The gear reduction ratio would be for the model, and is the total reduction from the motor output shaft to the axle gear.

https://docs.google.com/spread...nME/edit?usp=sharing

P.S. the green boxes are what are user editable.

@rplst8 posted:

For anyone is interested and that has a Google account, I've created a spreadsheet to calculate the required motor RPMs for a set of inputs.

It takes wheel diameter in inches, miles per hour, and gear reduction ratio and then calculates the RPMs at the motor shaft required to get that. Wheel diameter and miles per hour are for the prototype size.  The gear reduction ratio would be for the model, and is the total reduction from the motor output shaft to the axle gear.

https://docs.google.com/spread...nME/edit?usp=sharing

P.S. the green boxes are what are user editable.

99% of the larger 12V motors are gonna top out in the 6-7K range ….unless you use the wiper motors that early Williams used, then you might find some 9-10K motors ….like in the case of those lousy 42:1 gear boxes, which at any speed above a crawl they sound like a Censa getting ready to toss it’s cookies….it really boils down to cheap motors aren’t good and good motors aren’t cheap …..

Pat

@harmonyards posted:

99% of the larger 12V motors are gonna top out in the 6-7K range ….unless you use the wiper motors that early Williams used, then you might find some 9-10K motors ….like in the case of those lousy 42:1 gear boxes, which at any speed above a crawl they sound like a Censa getting ready to toss it’s cookies….it really boils down to cheap motors aren’t good and good motors aren’t cheap …..

Pat

"...sounds like a Cessna getting ready to toss it's cookies." That's a new one! LOL

Hopefully this will allow one to pick the right motor for the job given the other inputs. and if someone can live with a slower top speed but maybe more pulling power or vice-versa, there's that too.

@rplst8 posted:

For anyone is interested and that has a Google account, I've created a spreadsheet to calculate the required motor RPMs for a set of inputs.

It takes wheel diameter in inches, miles per hour, and gear reduction ratio and then calculates the RPMs at the motor shaft required to get that. Wheel diameter and miles per hour are for the prototype size.  The gear reduction ratio would be for the model, and is the total reduction from the motor output shaft to the axle gear.

https://docs.google.com/spread...nME/edit?usp=sharing

P.S. the green boxes are what are user editable.

FWIW I've used this CPR motor in several MTH Premier 80" driver steam locomotives with a 16:1 or 18:1 gearbox. None of them has had any issue hitting right around 100 scale MPH, but they won't go any faster than that.

I am a fairly practical guy.  I experiment with 12,15, 24 and 30Vdc Pittmans and they all seem to work fairly well with gearboxes in the 25:1 range. I try not to get too much into math of what should and should not work.   I do not run my stuff at 100 scale mph, however. While the 12 V motors seem less common, one can still get 24vdc cheaply ($20 or less) and still NOS. In this case the platitude, “Nothing ventured, nothing gained,” holds true.  I find the biggest constraints on motor swaps to be size, not voltage.

@harmonyards posted:

99% of the larger 12V motors are gonna top out in the 6-7K range ….unless you use the wiper motors that early Williams used, then you might find some 9-10K motors ….like in the case of those lousy 42:1 gear boxes, which at any speed above a crawl they sound like a Censa getting ready to toss it’s cookies….it really boils down to cheap motors aren’t good and good motors aren’t cheap …..

Pat