Lathe RPM

Is there a speed you just routinely find yourself using most of the time?
As I've said many times. I'm not a "real" machinist. I just play one on
the Internet, and I get paid for some work in a very narrow specialty.
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On Mon, 21 Aug 2017 10:52:57 -0700

I'm even less than that :)
I run my HF 9 x 20 spindle at 420 all the time. Maybe kind of slow, but I'm okay with that. That speed positions the belt on the smallest motor pulley and largest head pulley. Which skips the "back gear" jack shaft. The latter is still spinning but not being used to drive the head.
If I had a lot of turning that needed to be done or was using it to make $$$ for my living I would probably change speeds to suit...
I don't change my drill press speeds either. The larger one is set for as slow as it will go and the smaller two are set to spin much faster.
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Leon Fisk
Grand Rapids MI/Zone 5b
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"Leon Fisk" wrote in message wrote:

I'm even less than that :)
I run my HF 9 x 20 spindle at 420 all the time. Maybe kind of slow, but I'm okay with that. That speed positions the belt on the smallest motor pulley and largest head pulley. Which skips the "back gear" jack shaft. The latter is still spinning but not being used to drive the head.
If I had a lot of turning that needed to be done or was using it to make $$$ for my living I would probably change speeds to suit...
I don't change my drill press speeds either. The larger one is set for as slow as it will go and the smaller two are set to spin much faster.
--
Leon Fisk
Grand Rapids MI/Zone 5b
  Click to see the full signature.
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Bob La Londe wrote:

900 RPM on my 15" Sheldon. it will go to 1250 RPM, but that just seems too fast. I normally have an 8" adjustable chuck on it.
For larger work, or hard materials, I have to change down to a lower gear.
Jon
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On 21/08/17 18:52, Bob La Londe wrote:

I normally run at 800 rpm or 1200 rpm on my Harrison M300, it will go to 2500rpm but the fuse for the 3 phase converter doesn't like the start-up surge unless the gearbox oil is already warm. For some tougher materials I machine from time to time such as 310 stainless steel I'll drop down to 260 rpm, 370 rpm or 540 rpm depending on the operation and tool material.
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wrote:

Calculate the cutting speed :-) Turning an item, say a foot in diameter, requires a noticeably different speed than turning a 1/2" shaft :-)
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Cheers,

Schweik
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RPM is set for surface speed to cut with. Large diameters have more surface speed - inches/minute.
cutting steel or brass depends on the correct setup.
Martin
On 8/21/2017 7:25 PM, snipped-for-privacy@invalid.junk wrote:

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I try for a cutting speed around 80-100 feet per minute, using HSS bits on steel.
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I don't know the speeds I use. I have a 3-phase motor & a VFD for which I made a controller that has a dial for the FPM and another for the diameter. Dial 'em in & the controller takes it from there. On-the-fly adjustments as needed.
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