Lathes with 0-2500rpm speed control? (how smooth etc)

[HankMcSpank]

I'd like to buy a mini lathe, but to make it earn its keep, I'd like to be able to also use it for coil winding. For this role, I'd need a lathe that starts at 0RPM & can be ramped up smoothly right up to 500RPM.

Now I see a lot of lathes advertised as variable speed, but some only show the speed starting at 100RPM.

I have found one 'candidate' that is marketed at variable speed 0-2,500RPM (it's a SPG/0618B ...by the way I live in the UK, but don't let that get in the way of chiming in ...even with feedback about US variants) ...but I was just wondering how easy it is to use the variable speed aspect?

Alternatively, can these lathes be retrofit with some form of speed controller which would allow from say 0-500RPM to be adjusted up slowly?

Many thanks in anticipation.

PS In case you're wondering how it can be used as a coil winder, well a lathe has all the right parts....a chuck that turns & a tailstock to press up aganst the turning bobbin held by the chuck... here's what the Chinese are selling as a dedicated coil winder http://www.tinyurl.com/n8zv2k - so I reckon a lathe could easily be used for coil winding duties (I've already got encoder disc & optical pickups that could be added on to the chuck to count windings, etc)

[ibuildstuff4u]

In my opinion I would say yes they have a smooth speed control and I could slow my lathe down to a few RPM. This was on a 7 x 10 lathe from Harbor Freight. These small lathes also have a high low speed selector which would help you even more and allow you to slow the spindle down while keeping more RPM on the motor.

Good luck with your project.

Dale P.

[MechanoMan]

But does it have a regulated speed?
If the speed is unregulated, even if the slide runs down the coil at a constant rate, the turns per inch on the coil will be unregulated since the spindle speed will change with load from the wire pulling force and inertia from starting and stopping.

[HankMcSpank]

Originally Posted by MechanoMan But does it have a regulated speed? If the speed is unregulated, even if the slide runs down the coil at a constant rate, the turns per inch on the coil will be unregulated since the spindle speed will change with load from the wire pulling force and inertia from starting and stopping.

I've got that one covered! I'd put an encoder disk on the chuck (somehow or other!), I've already written a little pulse counting PIC program, which sends a pulse to a stepper motor every 'x' plulses. The stepper traverses back/forward & feeds the copper wire onto the coil...so not matter how unregulated the speed, the stepper will still lay copper wire onto the coil core uniformly.

iS the speed control a knob/dial - in othger words, how is the speed actually set in practise?

[Al_The_Man]

For zero to 2500, I would tend to go with a DC motor, preferably with a tach for speed regulation, the controllers are relatively simple as they can be SCR control types, no DC power supply per-se.
In non-CNC use, these are typically controlled by a Potentiometer.
In N.A. KB and Baldor make different models, there are two quadrant, which is uni-directional or 4 quadrant which gives you fwd.rev with the pot and dynamic braking.
Large servo motors make nice spindle motors as they generally come with a tach.
Al.

[ibuildstuff4u]

Yes the speed is controlled by a dial.




dale P.