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Re: Eliminating the step pulleys

 

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Just to throw another thought in the discussion.? I inherited a 1922 15”.? It came converted to top mounted 4 spd truck transmission driven by the original motor.? It has twin v-belts from the motor to the transmission input and twin v-belts to the step pulley, 2nd from the headstock.? Under very heavy loads the belts will walk off the step pulley (working on a collar to stop that) but it also adds a little safety.? I mounted a magnetic pickup on the change gear end of the headstock shaft and connected a digital tach.? Top rpm is 988.? I am attaching the speed chart and photo of setup.

Rick Swineford

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From: [email protected] <[email protected]> On Behalf Of mike allen
Sent: Sunday, October 13, 2024 2:35 PM
To: [email protected]
Subject: Re: [SouthBendLathe] Eliminating the step pulleys

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??? I think the top speed for my 9A was 1000 RPM . Pretty sure ya can set limits on the VFD .

animal

On 10/13/24 11:24 AM, Rick wrote:

On Sun, Oct 13, 2024 at 01:16 PM, Ron Goodger wrote:

Well, I have decided against eliminating the step pulleys.? It would be much more complicated than just replacing the motor and installing the VFD.? Then I will have full options available as to power.? With the VFD and three phase motor I will easily be able to overspeed the lathe.? Does anyone know what the physical speed limits of the lathe mechanism is?? At his point, I see no reason to ever do so.? Just wondering.

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My concern is the plain bearings in the headstock. I don't run either my SB9A or my SB13 much above the listed top speed of either lathe.

Spindle Speeds.pdf
Spindle Speeds.pdf
South Bend Lathe Drive setup.JPG

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