One other thing I'm generally not happy with is that my lathe has two speed ranges and to switch between them I have to move the belt from one pulley to another. So I'm wondering if there are ways to modify the lathe, so that it can be avoided altogether or some sort of a lever that moves the belt without the need to open the cover and loosening the tensioner. Any ideas?
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PM-1130V - switching between speed ranges?
- Thread starter javaduke
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A treadmill motor and controller or a 3 phase motor/vfd combination could be employed to mitigate the pulley change conundrum.
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You could perhaps build some type of toggling adjuster for the tensioner that would enable belt changes without any tools
Some form of over-center mechanism. Or maybe just replace the current bolt and washer with a large knob of some type?
Some form of over-center mechanism. Or maybe just replace the current bolt and washer with a large knob of some type?
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Short answer is probably no for a single belt speed. The belt offers a 4:1 speed reduction, which is a very large step, you are starting out with a 1.5 Hp motor that comes with the lathe, so if you wanted to run a single motor over that range, as a minimum you would need a 3Hp inverter vector motor, and run it something like 10-200 Hz for a 100-2000 RPM range. Big cost, and not enough space. You give up a lot of the low end torque from not having a 4:1 pulley ratio reduction. Better to sell the lathe and get something bigger with a gear head. The belt change uses a belt tensioner, you could add something like a Kipp lever instead of an Allen bolt, and spring load the tensioner, add an arm to release the tensioner (or pull back on the pulley) and then lock it with the Kipp lever. Make the the belt change and then release the tension, the spring will set the tension the belt and lock it with the Kipp handle. The whole process would be quick, you could also change how the belt cover comes off to speed its removal, something like a hinge and clapse.
I see, so the motor and VFD that come with the lathe is the limiting factor. I'm wondering though if it would be possible to keep it on the high gear and maybe fiddle with the electronics to have at least 100rpm on the low end. I might ask the PM support as well...
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Power delivery from a motor does not mean you can turn it down that low and get any appreciable torque at the spindle. it would likely stall with any degree of load. That is why you will see 2 or 3 speed lathes with factory VFD's, you never see a single speed lathe. There is no adjustment or programming on this lathe, VFD's you can usually program, but the whole point moot if the motor is just going to stall out.
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It's typical of lathes this size and in this price point. Unfortunately there aren't any affordable or simple ways to remedy the problem. If there were, they'd be factory options.
What are the high and low of the two speed ranges?
What are the high and low of the two speed ranges?
The low is 75 to 500 RPM and the high is 300 to 2000.
I'm thinking since there are two pulleys, small and large, would it be an option if I made a pulley that is between the two, and that would give me something like 100 to 1000 RPM range - is this an option?
This is what it looks like now, as you see, the small pulley is really small and the large one is almost the three times the small one, so what if I make an intermediate one?
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A compromise? Why not give it a try if you can live with the compromise RPM range? You can also shoot for other ranges. Looks like your VFD frequency range ratio is from 2000/300=500/75=6.66. So figure out what the high and low speeds are that you use the most and then choose your pulley dia. to suit this and then try to leave the VFD programing alone. You may still have to change the pulley, just less offend. Obviously if you change the pulley diameter to 2x the current smaller pulley diameter, then the lower speed will change to 2x75=150 and the upper speed will then be 6.66x150=1000. On the other hand if you set the pulley so that you have 100 RPM at the lower end then the max will be 666.6RPM.
If you really want 1000/100 =10 range ratio then you are still going to have to figure out if you can use the VFD over this larger range (programing?) and if it and the motor then has sufficient power and torque for your jobs.