Installing Variable speed motor on New Style 8x12 C&P

So after spending a lot of time trying to figure out how to put a variable speed motor on my New style 8x12 Chandler and Price I thought I might share my experience to help those with a similar need.


First I wanted to drive the press by the right side drive shaft (when facing it) just like it was intended to. But I didn’t have the original drive (flywheel) pulley.

Second I wanted to gear the motor down to the correct speed to achieve about 20 impressions per minute.


To replace the drive pulley I opted for a v belt style pulley because they are the cheapest and completely appropriate for this application. The drive shaft for the large pulley is 1.5” in diameter so I had few options on pulleys. I looked for a pulley that had a “finish bore” which meant I could just buy a bushing that would fit my 1.5” shaft size.

My perfered ratio was about 18:1 with a motor rpm of 1725. The drive shaft on the 8x12 needs 4 revolutions per impression so this works out to about 24 impressions at its fastest.

Short story- 18.75” (18” pitch angle) pulley for drive shaft and 1.5” (1.35 pitch angle) pulley for motor shaft. Note that the pitch angle of the pulleys is what you want to calculate if you are doing the math. NOT THE LARGEST DIAMETER. Therefore I ended up with 32 impressions per minute which was the best I could do with the parts available.

So without getting into the exact math for gearing to achieve 20 impressions per minute I decided to go with a bit higher impression speed and then control the speed with a variable frequency control. That means I would go with a three phase motor.

A note on three phase. It is not scary, it is easier to wire than single phase. I promise. My background is in refrigeration which involves all kinds of motors. If you are unfamiliar with wiring a motor this may be the better way to go. Connect the 3 wires up to any of the control output terminals on the speed control and you can’t go wrong. If you need the motor to spin the opposite way just reverse two of the wires and that is it. No capacitors or start windings or relays nothing.

Do yourself a favor and buy a motor with only one voltage then it will only have three wires to work with. Some have 9 wires for various voltages. If that is the case just follow the wiring instructions that come with it.

The Variable Frequency Drive that I chose has a single phase 120 volt input. Meaning a regular outlet that you plug anything in your house into. No electrician needed. The output on the VFD is three phase 230 volt. This is all A/C power.

I wired everything with 20 feet of 16 gage 3 wire cable, otherwise known as 16/3. Purchased by the foot at Home depot. The wire is stranded copper wire, not solid. The cable has a black flexible outside coating. This will handle 13 amps up to 25 feet long so don’t bother getting a larger gage.

I used a 3 phase, 1/2 (0.5) horse power motor. 1/3 is sufficient according to my research but I couldn’t find one with the specs i need. No need to over do it so go with the 1/3 if you can find it.

I finally added an inline switch with non resettable fuse. The VFD instillation instructions required it. I used the cheap one that was in the Home Depot electrical department. It is the little metal box in one of the photos that I will post. It has a screw in type fuse with a 6-1/4 amp time delay fuse.

So here is the exact pieces I bought as of 3/15/2012:

1. Baldor 3 phase motor, CJM345, 0.5HP, 1725 rpm, 60hz, with mounting base = $202.95 + shipping
2. V-belt Pulley, split taper, 18.75” OD by Browning = $113.90
3. Bushing split taper, 1.5” bore = $5.88
4. V-belt Pulley, 1.5” OD, 5/8 bore = $4.95
5. V-belt, A type, A84, 86” long = $25.95
6. Westinghouse (TECO) Variable Frequency Drive (motor control)= $127.95 + shipping

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Here are some photos to help with the visual.

image: VFD, Inline Fuse

VFD, Inline Fuse

image: 1/2HP, 3Ph, Motor

1/2HP, 3Ph, Motor

image: Drive shaft pulley 18.75"

Drive shaft pulley 18.75"

image: Pulley system

Pulley system

Here is a youtube video of it all running.

Very nice!

I did something similar, v-belt, driven by a DC motor with a variable controller/converter from 110 house current. Price range was about the same. I used a DC with a gear reducer to get from 2000 to 500 rpm at 100%.

Looks really nice, and the thread is really informative. Much appreciated.


I thought seriously about going with the gear reduced motor. I kept coming up with a higher cost to go that route. But that was this week and next week it could change.

I was looking for a gear reduced motor with about 80 - 85 rpms though and that is probably more expensive than the 500 rpm with control you used, I am guessing.

A couple of points on the wiring (the electrician in me has to speak up): The wiring from the 120V outlet to your disconnect should be #14 AWG (three conductor - one for ground), because it is protected by the 15A breaker in the main panel.
The cabtire cable from the VFD to the motor should be 4 conductor (not three as indicated), so that the motor can be grounded. Nice 18” cast pulley, kinda fits well with the machine! Over all I agree with your choice of V-belt drive and 3 phase motor with VFD. That’s much more flexible than a gearmotor, which would prevent you from turning the flywheel bey hand.


you are right about the 4 wire conductor going back to the VFD as being the right choice. I do have the motor grounded but it is not through the VFD. It is grounded back to the incoming power supply. I am not sure how kosher that is actually but it is grounded none the less.

On the other hand I am not sure I agree about the 14 gage wire feeding the VFD just because the outlet is 15 amp. As far as I see it only needs to be gaged based on what the amps the unit will draw. Otherwise every cord on any appliance would have to be 14 gage just because the breaker is 15 amps, right? What about a lamp or an extension cord that is 16 gage which is very common. Just a thought. It is true that I am not a licensed electrician so I will defer to those who are.

Due to inquiries, I am posting a schematic of the wiring. Hope this clarifies some things for everyone.

Note that this is representative of how I have mine wired. It can be done with other voltages of your liking if you have a different need. Just make sure that your VFD control has the correct input voltage that your wall outlet (supply voltage) has and that the output voltage on the VFD matches what your motor voltage is.

Often voltages for motors or supply varies in its stated rating. For example often motors are rated at 115 volts. If your voltage that you connect to it is 120 volts, that is fine, don’t let it confuse you. Motors are often rated below the maximum voltage from the supply voltage. This is to make the motor run more efficient and protect it if the supply voltage drops due to a number of factors.

By the way a household outlet is almost always referred to as being 110 volts. This is old terminology since, I believe, sometime in the 70’s the voltage was changed to 120 volts. Don’t let that confuse you either since it is the same thing.

image: Platen press wiring schematic  1.jpeg

Platen press wiring schematic 1.jpeg

Also on the inline fuse. The little silver box houses the fuse. It is under the smaller square box next to the switch. This has an “old style” screw in type fuse called an Edison base. It is very common and nothing special.

I attached some generic photos below. The fuse is not 25 amp as the photo shows but a 6 1/4 amp fuse.

image: 3W759_AS01.jpeg


image: 1DH49_AS01.jpeg


This thread gave me the push I needed. There are a few posts about this topic on Briar Press and around the blogosphere, but this one shared in a simple and specific enough way that I figured, “I can do this.”

The motor that came with my press, a Golding Jobber #6 was set up with a series of pulleys to reduce the impression cycle, but ultimately was more than I was comfortable running at. I too wanted a variable speed, but the easy options seemed expensive and of the few people that dealt with it first hand lacked the how to steps. Additionally, it became clear that there are lots of ways to go about it, which only adds to the complexity. Half the battle was simply selecting the parts. Putting it all together was pretty easy and very educational.

My setup is a little different than Caleb’s in that I decided to use a circuit breaker instead of the fuse switch and all of the goodies are nicely hidden in a wall mounted enclosure. I picked up on Hugo’s point and ran a continuous ground wire which is why I ended up feeding everything through a conduit to clean up the run. An interesting note, the 6 amp fuse was only going to work for my VFD if it were a 230v input unit. The 120v to 230v unit I purchased required a 16 amp protector.

Thanks for the thread folks!

image: 10-16 amp circuit breaker on the left and the VFD on the right. The box is large enough to allow for heat dissipation and small enough to not make it the focal point which is why I decided not to mount it on the press.

10-16 amp circuit breaker on the left and the VFD on the right. The box is large enough to allow for heat dissipation and small enough to not make it the focal point which is why I decided not to mount it on the press.

image: This is the enclosure I decided to mount everything in. Power on the left and cable runs to the motor on the right.

This is the enclosure I decided to mount everything in. Power on the left and cable runs to the motor on the right.

image: This is a rear view of the motor, showing how the pivoting attachment was a good idea to make the conduit run more flexible.

This is a rear view of the motor, showing how the pivoting attachment was a good idea to make the conduit run more flexible.

image: For the motor mount I laminated two pieces of finished plywood together and drilled screws from the bottom to mount the motor from the top. I attached that platform to the base(s), which were cuts form the prior owner's lumber, with larger bolts.

For the motor mount I laminated two pieces of finished plywood together and drilled screws from the bottom to mount the motor from the top. I attached that platform to the base(s), which were cuts form the prior owner's lumber, with larger bolts.

image: A much cleaner setup than the prior owner. Those extra gears need space and the older motor was huge!

A much cleaner setup than the prior owner. Those extra gears need space and the older motor was huge!

Here is a link to pictures of a variable speed setup on a C & P
10 X 15 I did a number of years ago.


that looks really great. I would love to have that Golding Jobber. I must say that your set up is very clean and I think taking Hugo’s suggestion of running a continuous ground is worth doing.

Thanks for sharing.

It’s been a while since I visited here. Regarding your comments on the extension cord. The reason there is so much 16 gauge cabtire and household extension cord sold is that it’s for lamps and hand tools that draw much less. If you install a flexible cord without a plug it must be rated 15A. And when you power a motor with a cord there is another factor at work. A smaller wire causes voltage drop to the motor. As you mentioned, that’s why manufacturers rate the motors at a lower voltage than nominal. As the voltage drops at the motor terminals, the current drawn increases. So if you want the most power at startup and the coolest running under load use 14 gauge.


Finial thought… I follow you but for those reading that don’t understand electrical stuff this is what you do to decide. How far is your cord going to have to go to reach the outlet. If it is more than say 6 feet then you can play it safe and go with the 14 gage. If it is less, then the 16 gage will do you just fine. I am making this suggestion based on practical experience.

This suggestion has nothing to do with code. That is something else. I do have a plug on the end of my cable unlike Brian which appears to change the code requirements as Hugo notes.

Hope this ends that discussion and everyone has a successful motor installation.

Best wishes!

Caleb et al, I did a double take reading this thread. My set up is virtually identical, fuse switch and all. My only addition is that I have been really happy with some of the coded settings in my variable frequency Drive. One setting provides a self adjusting torque setting which provides enough torque to start the belt and then eases off as the wheel comes up to speed. Discovering this setting eliminated a rash of overload codes that had me worried. I am sure that you ran into similar problems if you are using a VFD, but my advice to anyone considering using this method, read the manual cover to cover. VFDs can be robust tools for controlling your motor.

This was an extremely helpful post. I’d like to motorize my 8x12 C&P but I do have a couple of questions. Where did you purchase the 18.75” OD V-belt pulley, and what are the dimensions of the hole? Also, where did you get the split taper bushing? Thanks again for sharing!

I bought one recently at Grainger on clearance for much less than retail.

They sell the hub you want as well. Look through the clearance section for pulleys in the 16-20” range, and get the hub that is the correct size for your shaft (probably 1.5”)

I came across this company while researching Chandler & Price. They do press restorations and motor kits for C&P presses..

The motor kit looks to be well designed.


Great thread! thanks

Careful with gear reducer drives on our old presses, you loose what I consider a very important safety feature: You can no longer turn the press over by hand, before starting the motor. So if something is wrong, you get the full force of the motor, (with flywheel inertia) to jam or brake it.

I have a C&P 10x15 NS which I am planning on motorizing. After reading all of the archives here (thank you all so very much for adding your experiences and insights) I am planning to go with this combination:

G.E. CAT#: S2802 (5KE143AC205C)
1 HP
RPM: 1800
VOLTS: 230/460

1 HP

My questions is about adding an emergency stop switch. I have read that there are two terminals for this switch, however, when the switch is engaged, the press will “coast” to a stop.

My thinking is that if I need the press to stop immediately, I want it to stop right now… not in a couple of seconds.

I have read that some kind of braking resistor is needed. Does anyone have any experience with this component? Where do I get it, how to wire it in, does it work????

Thanks, I’m asking because I’d rather put this together once and be happy knowing it is as safe as I can make it without resorting to just running it with a foot treadle.

I am about to update my press with VFD and new motor and I have found this post very helpful.

The one question that I have though is:

If I already have 230v 3phase installation power here at my shop, would it make more sense or would it be more beneficial to use that instead of hooking the 3phase motor to a 115v 1phase line via the VFD?
Am I looking at substantial power savings or increased motor efficiency?

So in short, should I get a “3phase in — 3phase out” VFD?

Thanks a lot.

What type of press / size motor?

Assuming we’re talking a typical C&P / maximum 0.5-1hp range - Three-phase VFDs are typically more expensive than single-phase VFDs, and you’re not getting much by way of improved efficiency or performance. The three-phase VFDs also take more space, require more wire, more costly breakers, etc. There are benefits to a three-phase - a more balanced input (split across the three phases), for example - but in my opinion it isn’t worth it unless you have access to an inexpensive three-phase VFD. Using a single-phase VFD also allows you to move the press to a location without 3-phase power.

By the way, I bought my VFD/motor locally from these guys - they were pretty helpful and stock surplus equipment.


Thank you Mike. It clears up a lot of my initial questions.
The VFD was meant for a Kluge 10 x 15.
I don’t plan on moving anytime soon, since we just moved here, but you never know.
I’ll save the 3phase for a machine that truly would benefit from it.
Thanks a lot.
That’s exactly the website I was looking at.

One final question: I also have 230v 1phase. And 110v 1phase.
Should I get the VFD for 230v ?

It usually requires less amps, right?

That’s right. Higher voltage means lower amps for the same load. However for small motors, higher voltage really isn’t necessary. A hair dryer or toaster pull more amps at 120 Volts than the press will.

If you use 120 Volt single phase you’re using one hot leg and a neutral. If you use 240 Volt single phase, you’re using two hot legs. In this case, the equipment described above will need to be modified (for example - you would need a 2-pole fusible disconnect rather than the single in-line fuse).

Also, verify your service voltage. It is not common to have both three-phase 240 Volt and single-phase 240 Volt service in the same building.

I would suggest sticking with 120 Volt (lower voltage = safer) and making sure you consult an electrician regarding your electrical system and intended VFD wiring to play it safe.


Thank you Mike, that makes a lot of sense. Will go with the safer route and have someone help me determine the exact specs of my installation.