Re: Eliminating the step pulleys
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They are dual v-belts.? The crown is still there. They tend to stay in the middle until heavy load is applied.? The flange will hit the top of the v and yes will occasionally wear the outer belt edge, but the bottom is doing the driving. ?It doesn’t get a lot of use right now. Rick ?
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From: [email protected] <[email protected]> On Behalf Of eddie.draper@... via groups.io
Sent: Monday, October 14, 2024 6:48 AM
To: Rick Swineford <terrapinsystems@...>; [email protected]
Subject: Re: [SouthBendLathe] Eliminating the step pulleys? Rick, if you add a flange to stop the belt wandering off, it will chew the edge of the belt, and the belt might even climb onto it. ?Flat belts need a crowned profile on the pulley, and you should check whether yours still has this. ?Compare the step in use with the others. ?If only one of the speed pulleys has been used for an extended period and there has been some slippage, it is possible that the pulley is worn hollow. ?So long as there is some metal left, you can machine the crown back onto it. ?I've never tried it, but a coat of hard epoxy filler might make up any material shortfall. ? All counter intuitive, I know, but that's how they work. ? Eddie
? ------ Original Message ------
From: terrapinsystems@...
To: [email protected]
Sent: Sunday, October 13th 2024, 23:19
Subject: Re: [SouthBendLathe] Eliminating the step pulleys
? 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 ? ? ??? 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 ?
? 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.
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Rick Swineford