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10EE pulley sizes and RPM

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b335249

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Hi all,
I have a round dial machine that is missing the motor and drive guts. What I do have is the spindle pulley and gearbox. The pulley uses a flat belt and measures approximately 5-1/2" in diameter. The inverter motor I have selected for the VFD conversion is 5 h.p. rated for 1750, however the data plate says MAX RPM 6000.
So, hear is my question...What diameter drive pulley came standard on these machines and should I use that size going forward? The machine has a RPM dial that reads 0-4000.
 

Cal Haines

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The original DC motor would have had a base speed of 690 RPM and a top speed (with field weakening) of 2400 RPM. Use the pulley that you have see how it works for you.
 

Karl_T

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My round dial 10EE was different than cal's. It had a 1:1 ratio between the motor and spindle in high gear. Back gear chops it to 6:1. This machine also uses a flat belt, with teeth.

I use the same 1:1 ratio with my 5hp standard 1750 3 phase motor and VFD. I spin it up to 4000 RPM max.
 

b335249

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My round dial 10EE was different than cal's. It had a 1:1 ratio between the motor and spindle in high gear. Back gear chops it to 6:1. This machine also uses a flat belt, with teeth.

I use the same 1:1 ratio with my 5hp standard 1750 3 phase motor and VFD. I spin it up to 4000 RPM max.
So..is your pulley on the motor the same size as the spindle? (5-1/2)
 

Karl_T

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yep, that's what I mean by 1:1
 

Cal Haines

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You can trust me on this: all round-dial 10EE DC motors were 690 RPM base, 2400 RPM top speed. The machines could be ordered with either 2500, 3500 or 4000 RPM spindles, the only difference being the tachometer and the belt ratio. My machine is a flat-belt, 4000 RPM machine. The drive pulley is about 5-1/2 OD (just guessing, I don't time to measure it, but that's about right). The belt runs directly on the body of the collet closer and the OD there isn't much bigger than the OD of the spindle itself. I don't know if the gearbox is designed to handle 4000 RPM on the input.
 

b335249

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yep, that's what I mean by 1:1
Thanks for your answer. I have looked at a few pictures on the internet
You can trust me on this: all round-dial 10EE DC motors were 690 RPM base, 2400 RPM top speed. The machines could be ordered with either 2500, 3500 or 4000 RPM spindles, the only difference being the tachometer and the belt ratio. My machine is a flat-belt, 4000 RPM machine. The drive pulley is about 5-1/2 OD (just guessing, I don't time to measure it, but that's about right). The belt runs directly on the body of the collet closer and the OD there isn't much bigger than the OD of the spindle itself. I don't know if the gearbox is designed to handle 4000 RPM on the input.
Well ok...I believe you however on my machine the driven pulley(on the main spindle shaft) measures 5-1/2" approx. then that would mean my driver pulley would have to be massively larger to obtain the 4000 RPM of a motor RPM of 2400. You are saying that your belt runs on the collet tube. Maybe mine has been modified before me???? Please look at the picture.....and yes, I know the belt for the gearbox is not routed correctly..lol
Thank you for your help.
Ben

IMG_20180113_115409072.jpg
 

Cal Haines

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Thanks for your answer. I have looked at a few pictures on the internet

Well ok...I believe you however on my machine the driven pulley(on the main spindle shaft) measures 5-1/2" approx. then that would mean my driver pulley would have to be massively larger to obtain the 4000 RPM of a motor RPM of 2400. You are saying that your belt runs on the collet tube. Maybe mine has been modified before me???? Please look at the picture.....and yes, I know the belt for the gearbox is not routed correctly..lol
Thank you for your help.
Ben
I misspoke, sorry. It's my feed belt that runs directly on the collet-closer body. My driven pulley looks to be about the same size as yours. Here's a couple of photos:
IMG_0556.jpg
My original feed belt is gone. It came with a toothed belt, run inside out. I'll eventually change it to something else.

IMG14100.jpg
 

TheOldCar

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You can trust me on this: all round-dial 10EE DC motors were 690 RPM base, 2400 RPM top speed. The machines could be ordered with either 2500, 3500 or 4000 RPM spindles, the only difference being the tachometer and the belt ratio. My machine is a flat-belt, 4000 RPM machine. The drive pulley is about 5-1/2 OD (just guessing, I don't time to measure it, but that's about right). The belt runs directly on the body of the collet closer and the OD there isn't much bigger than the OD of the spindle itself. I don't know if the gearbox is designed to handle 4000 RPM on the input.
I heard an urban legend somewhere saying the spindle bearings were different for higher the RPM. I doubted it, but this post officially puts it to rest in my mind.
 

Karl_T

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I ran my round dial 10EE on the DC drive for years. It had a LOT more than a 3.5:1 speed range, or 690 to 2400. that would be a terrible performance out of a DC drive. My memory of 20 years ago, had it more like 8:1.

Sorry, do not have actual data or facts. Just really skeptical about the above statement. The 10EE was a wonderful machine with the DC drive, right up till it died. I am getting a 10:1 speed range or 400 to 4000 rpm out of the VFD 3 phase combo. But it does have less torque at low Rs than the DC drive. Approximately the same speed range though.
 

Cal Haines

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I ran my round dial 10EE on the DC drive for years. It had a LOT more than a 3.5:1 speed range, or 690 to 2400. that would be a terrible performance out of a DC drive. My memory of 20 years ago, had it more like 8:1.

Sorry, do not have actual data or facts. Just really skeptical about the above statement. The 10EE was a wonderful machine with the DC drive, right up till it died. I am getting a 10:1 speed range or 400 to 4000 rpm out of the VFD 3 phase combo. But it does have less torque at low Rs than the DC drive. Approximately the same speed range though.
I didn't say that it went from 690 to 2400 RPM. 690 RPM is the "base speed" of the motor, which is what you get if you apply the full 240 VDC to the armature and full voltage to the field (usually 115 VDC). Above base speed, the field voltage is reduced and the motor speed increases up to 2400 RPM (at the output to the motor). Below base speed, the field voltage is at 100% and armature voltage is reduced. The MG drive system allows you to vary the motor speed from about 30 RPM minimum to 2400 RPM. There's a 6:1 back gear unit that can be shifted in to further reduce the speed. My machine can turn at any speed between about 8 and 4000 RPM, using the back gear as needed.
 
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