# The turbocharged 14.5



## RandyWilson (Mar 28, 2017)

Does anyone know off hand the primary pulley ratio for a 14 1/2"? And motor speed? I assume a 16 would be the same.  I put a handheld tach on my spindle last night, it's running more than double what my documentation says.  The slowest direct drive measures 460, should be 215.  The motor and pulleys have been changed, long ago by appearances. The math says it's a four pole motor.


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## tq60 (Mar 28, 2017)

Is yours single or 3 phase?

Original motor?

Ours is 3 phase 2 hp and we could measure if needed but it is a bit difficult. ..junk in the way...

Suspect if single phase possibly a 3600 rpm motor may have been used resulting in the double speed maybe.

We have a photo someplace of the motor plate as we needed it to search for vfd and it was in a spot we could not see...

Seems to be 1700 or similar common standard speed but being 3 phase could be other general low speed.

Others may have better data handy or later we could look.

Normal speed motor would require substantial change to double end speed.

Sent from my SAMSUNG-SGH-I337Z using Tapatalk


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## RandyWilson (Mar 28, 2017)

No no, don't go to that kind of trouble. I was just hoping someone had the specs at hand to appease my laziness.


 The motor and pulleys have been changed. That is obvious because it has a single large/wide belt.   And the flame-cut a notch in the pedestal to clear. It is 3 phase.  By marking the spindle and motor pulley, I eyeball counted 3.8:1 motor to spindle with the flat belt on the slowest pulley. Based on the 460 spindle speed, this gives a nominal motor speed of 1750, which sits within error margins of calling it a four pole motor.

 Then to make matters more complicated, these alternate pulleys appear to be variable speed; looks like an old F440 (aka snowmobile) drive. So it's very possible that loaded speed will be different than free-running.

 I just ordered a pulse tach off alibaba.


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## Bob Korves (Mar 28, 2017)

The ratio of the diameters of the pulleys determines the change in speed.  Two inch motor pulley and four inch drive pulley with a 3450 rpm motor gives a 1725 driven pulley speed.  With V belts the measurement is to about the center of the belt inner and outer diameters.  You are trying to slow it down to 215 from 460. If you make the motor pulley .47 the size it is now, or  make the driven pulley 2.14 times larger, you will be there.  Changing the motor to one with half the rpm would do the same approximate job.


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## woodtickgreg (Mar 28, 2017)

Or just run a vfd to slow it down. If it runs ok at the higher speed and doesn't appear to be heating up that could be a good thing as it might run carbid tools better. Dunno?


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## RandyWilson (Mar 28, 2017)

Thanks Bob, but that didn't answer my question. I asked what is supposed to be there because I'm curious what is supposed to be there.  This isn't because I'm going to change anything. I just want to learn about the machine.   It's certainly not important enough for someone to spend time digging in and measuring their machine.


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## woodtickgreg (Mar 28, 2017)

You have not been able to find an original parts break down?


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## RandyWilson (Mar 28, 2017)

The South Bend parts manual just says to measure the current pulleys when ordering new. 

Like I said, this is just a curiosity thing. Unless this variable drive does strange things under load, I'm not going to change anything. The only place there would be trouble is if I needed slower than it will allow. While the VFD will drive the motor at 30hz, even 20hz, I'm a bit skeptical of the durability that far out of designed operating parameters.


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## RandyWilson (Mar 28, 2017)

It's definitely a variable pulley.  I may be able to slow things down a bit by adjusting it, though it is pretty much at the minimum radius already. Before that can happen, I will need shorter belts. Both the v-belt and flat belt adjustments are maxed.... the motor touches the floor when the cam goes over-center.


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## woodtickgreg (Mar 28, 2017)

Well that definitely is not a stock set up. I can see why it is running so fast. Do your bearing caps for the spindle get warm when it is running? Kind of a shame someone hack the cast base like that to get that set up to work. Maybe a shorter belt would have been all they needed to do to install that instead of hacking the casting. Do those 2 pulleys move in and out like a variable or are they now fixed in place?


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## RandyWilson (Mar 28, 2017)

So far I've only run it 460 and whatever the next step up is. As long as I stay within the design limits, I don't see a problem. The issue will be if I can't get it slow enough to turn a large object.

 The driven pulley is fixed. The drive pulley has a large internal spring, the belt tension wedges it open. Adjust the motor down, the pulley opens, and you get a lower ratio. But I have to get the motor off the floor before I can try more.

This seems to be what I have, if a bit shinier. 

http://www.speedselector.com/

http://www.speedselector.com/engineering/index.htm


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## woodtickgreg (Mar 28, 2017)

Ah I see, so it's an internal spring. Well that belt looks like it has seen better days, try getting one that is shorter. That would allow more range to lower the motor


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## RandyWilson (Mar 28, 2017)

The flat belt is pretty knackered also. I'm going start there with a belt at my measured 62.5". Current is 65".  we'll see what happens from there.... might end up replacing the pulley set, as I just thought of one issue with the over drive. I may be running with the back gears constantly in.


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## tq60 (Mar 29, 2017)

The driven pulley looks too small so someone trashed it.

A shame they torched the door so you now have a shopping list.

Suspect some clown wanted higher speeds and murdified it.

Do pull bearing caps to inspect.

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## Glenn Brooks (Mar 29, 2017)

AHa!  You have the venerable "Reeves Drive" type variable speed control.  You adjust speeds by changing the diameter of the lower pully with a small motor and gear attached to the lower shaft.  The pully opens and closes, changing the diameter and pully ratio.  Looks like you are missing the lower drive motor to change speeds.  I think you could buy the drive motor and retrofit.

These are very common in industrial settings, such as conveyor systems that need to be slowed and speed up for different work loads. Not so much on lathes.  Google " South Bend Fourteen" lathes.  These were built with the same style VS system in the 70's and 80's, but I suspect SB made their own proprietary drive, as mine at least is not a Reeves brand drive.

Also there is a SB Fourteen rebuild thread either here on the SB thread, or over on .Chaski that will give you some info on the drive unit.  My SB Fourteen turns from around 50 RPM to somewhere near 2000+, however, the upper drive pulley connects to a two speed transmission, and has a Hi/low lever for switching between the two basic speed ranges. Because these work with a transmission, I doubt you will be able to find different size pulleys, if you wish to alter the speed range. Do you have such a transmission?  This is how you would achieve a full range of speeds.

The belts are actually not flat, but thick and wide v belts.  The edges of the belt are cut at something like 22 degrees to grip the countours of the pully.  Readily available online from gates and several other respected manufacturers.

One other thing - change out the belt if it makes noise, or doesn't hold RPM whilst turning.  particularily listen for a vague thumping sound, like a bearing starting to go bad deep inside the machine, or pre load on the spindle out of adjustment. It's not.   It's the belt.  ( As I found out after weeks of trouble shooting). The rubber and biase eventually gets stiff and inflexible and impedes performance. New belt makes a world of difference.

Glenn


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## woodtickgreg (Mar 29, 2017)

For what it's worth, this is how my heavy ten is set up from the factory. Your 14 should be the same just bigger.

You can see that the lower pulley on the motor is a "V" pulley. It has 2 sizes for High and low speed. The upper pulley is also a 2 sized pulley but it's flat and the inner part of the "V" belt rides on that flat. I have never had it slip.



Here it is with the belt installed. I put a new cloth wrapped power equipment belt on it and it works well. I think as it is now that it's on the high speed position.


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## RandyWilson (Mar 29, 2017)

Great!!!  Thanks!

 The flat belt I'm replacing is the original SB drive, not the v-belt on this primary drive.  I'm used to this style drive from my days at the track. Old F440 (440cc snow mobile engine) used an inertia controlled variable drive; basically a very primitive CVT.   Little old two stroke screaming at 7000rpm from 0 to 140mph. I'll dig further into this drive when I get time. Way to many irons in the fire right now. As long as I can get the speeds needed for the jobs at hand, it functions.

BTW, the hack that did this modification was the engineering department at Penn State.


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## woodtickgreg (Mar 29, 2017)

Here's what I did for the flat belt. There's lots of options but I chose this because I can source an automtive serpentine belt cheap and cut it to the needed length. They don't slip either, run quiet too the way that I joined it. I have not had much luck with any kind of glue, but this has held up well. I even had to cut the stitching and remove the belt to move the lathe when I moved, just put it back on the same way. 

I used this braided picture hanging wire because it was cheap, available at the local big box store, and it flexes without breaking or kinking.


I tinned the end with solder so I could pull it through the holes I drilled in the belt without fraying it.


I drilled the holes far enough away from the edge that they won't tear out. I did it so the wire would lay in the grooves and not make contackt with the pulley's


Flipped it over and put a drop of solder on it to secure it.


And this is how it looks on the pulley's.


Again, your 14 is just bigger with 4 pulley's instead of my 10L's 3, but you can still source a belt that is wide enough for your pulley's. Just measure the width and loop a string around the pulley's and measure it to get the length. Really easy and it works great. Pluse if you ever need to remove it you won't have to buy a new belt, just re stitch it.


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## woodtickgreg (Mar 29, 2017)

Funny about the hack, lol. I work a part time job in a power equipment shop as a counterman. Ever try and sell parts to a engineer!


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## RandyWilson (Mar 29, 2017)

Thanks Greg. Right now I am seriously time-poor. Cleaning out the in-laws estate, building amother-in-law suite, moving into said estate and building the shop. And a full time job and a home business. So I went with a flat belt off ebay for right now. I have a bunch of turning coming up, all in the 1.5-2.5 range. I should be fine for right now.

And conversely, ever tried to get useful concrete engineering data out of the salesman?


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## woodtickgreg (Mar 29, 2017)

I totaly get the moving and no time thing.


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## Rustrp (Apr 1, 2017)

What's the rated RPM on the motor and the amperage ratings? I read you're busy so this is just an important bit to look at when changing pulleys.


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## RandyWilson (Apr 2, 2017)

I tried before to read the motor. Unfortunately the plate is against the floor. No amount of camera-phone work and mirror inspection would get a clear view of it. I can say the motor is old. The plates are embossed brass, not stamped tin.  The shorter belt arrived, installing should lift the motor 1-1.25 inches off the floor. I'll post if I can get it read.


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