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Thost truck transmission mods were pretty popular back in the day as the kids say . I always wondered if there was a article in a old,old Popular Mechanics or like mag showing the mod . animal

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

9A has a listed speed of 1270 rpm. I have a tach on my SB13. ?If I run the VFD at 60 hz in high gear, it shows within 10-20 rpm of the factory listed speed of 940 rpm. ?I have turn the frequency up

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

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.

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

So some of this is being overthought.? If you have a good motor don't worry about overheating it.? My 16" has a 3hp motor just like it came with.? It does have an industrial cast iron frame motor

The point isn't just torque. Reduced RPM will reduce the air flow through or around the motor and the motor will overheat unless you install a separate cooling fan for the motor.? Also, the

Eddie has it exactly right. Power is the product of torque and speed, and cutting engineering says that material removal rate is proportional to power. Anecdote: My 1 HP dc drive is totally inadequate

But you don't want constant torque at all speeds. ?The whole point is, you want MORE torque as you reduce the speed. ?Lower speeds are used for machining or drilling bigger diameters. ?Applying a

specs on the VFD are telling me this; " Yes, a variable frequency drive (VFD) can maintain constant torque at any speed" If that is true, doesn't it eliminate the low speed torque concern?

The problem is that the pulleys give you a speed reduction and torque amplification. To run your motor that slow and to expect the torque you need you will most likely overheat it. For light stuff it

Why eliminate the step pulleys?? To just simplify the whole shebang.? I know changing the belt to another speed is quick and easy, but why have to do it at all if you can get around it?? You see, I

Keep the belt and pulleys. The VFD won't give you the same low-speed torque as the belt and pulleys. When you slow down the motor with a VFD, so does the cooling fan. Unless you add some kind of fan,

Don't do that! ?The speed change pulleys don't just change speed, they maintain constant power so you get more torque at low speeds. ?You wouldn't try to start your car from traffic lights in top

I'm not sure why you would want to do that. ?I run my SB13 on a VFD, and use that for most speed changes, but I do change the belt occasionally. ?You would also have to rig something up to hold the

Has anyone eliminated the undercarriage step pulleys on a heavy 10L by using a VFD and motor to drive one of the spindle pulleys directly?

A change of circumstances means I need to sell my 9a lathe, I'm not sure how many folks here are from the UK, but I thought the decent thing to do would be to offer it here first before heading to

https://www.youtube.com/watch?v=Q77vIrbdJWs animal

FWIW In the files section are copies of the 3rd edition, the 56 edition and the 58 edition. Jim B,