John, I do not own a knee mill as mine is a bench top model. I had a similar problem on the Z axis and ended up using heavy duty air shocks which float the head/motor assembly. Now it takes a lot less torque to move it up or down.
Bob?
On March 19, 2020 at 1:48 PM John Dammeyer <johnd@...> wrote:
Oh and I'm running 3:1 toothed from motor to knee handle.
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What I did was put vise, rotary table, faceplate and some metal onto the X table and then a torque wrench on the handle to see what was needed to move the table in the upwards direction to overcome static friction.
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That's why 3:1 and initially 600 oz-in. ?But again at speed torque falls off too much.?
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You can buy a bicycle for $100 but if you want 60 miles per hour the cost of the wheels to do that is way more even if it's just a VESPA scooter. ?Same with CNC.? You can do stuff with steppers open loop but for real performance it's all done with servos.
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John
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Gecko.
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This is what I'm using on the knee of my mill.? I started with the 3A driver and a 600 oz-in motor wired in series.? The ELS was the power drive for the knee and it was certainly better than hand cranking with a cast handle that kept falling off.
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But, not really as fast as the hand cranking.? I upgraded to the 1200 oz-in motor but even with series wound the current rating was such that at 3A my speed wasn't any better.? Series has too high an inductance for fast anyway. Lots of torque.? But not fast.
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So then I procured a 60VDC toroid and a Gecko.? Now I'm limited to 25 IPM which is faster than hand cranking but still not quite there for fast peck drilling.?? That 25 IPM is basically 300 RPM on the stepper which is where the stepper torque falls off to about 4 Nm from the rated 8.5 Nm.? So switching to a AC Servo with 4 Nm all the way up to 1500 RPM will theoretically give me 125 IPM.?
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My mill XY has a pivot capability since it could have a horizontal boring feature for doing helical gears.? If I throw on the heavy vise and 4th axis the whole works is pretty heavy.? So it's not surprising so much power is needed for that part.
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John
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John, what driver is used for 7 amps? My Microstep Driver max is 4 amp.
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On Thu, Mar 19, 2020 at 12:57 PM John Dammeyer <johnd@...> wrote:
My foundry is like my table saw, band saw and ELS driven lathe.? It's a tool.? ?In the case of the foundry I have a small ATMEL processor module, pre-dates Arduino, that does PWM drive to a treadmill motor that turns the blower and a circuit with ignition coil that runs a spark plug.? ESTOP button.? ON button and a DC controlled valve from marine applications for shutting off the gas at the tank.? Propane being heavier than air could collect in the bilge of a boat.
So I press the start.? The fan comes on slowly, the spark plug starts sparking, the gas is turn on and whomp!? Flame billows out the top of the furnace (it's open for this reason).? Then the fan automatically speeds up, the flame retracts into the proper mixture and I close the lid.? 12 minutes later I have 4 to 6 pounds of melted aluminium.
When I'm done I switch it off.? Gas solenoid is closed.? Fan drops to low speed for 10 seconds to clear any left over gas and fumes.? I open the lid and pull out the crucible.
I then put the crucible back in and switch the main switch over to circulate which runs the fan at a very low speed slowly cooling the furnace interior.? And if it's in the shop in the winter, warms things up nicely without fumes.
Eventually I'll reroute the air and gas so I have a direct view into the flame past the spark plug and I'll mount the UV flame detector.? The software is there for it.? Just not the mechanics.? It's been running like this for about 20 years.
Wow! 20 years...? where did the time go...
John
> -----Original Message-----
> From: [email protected] [mailto:[email protected]] On
> Behalf Of Richard
> Sent: March-19-20 9:28 AM
> To: [email protected]
> Subject: Re: [digitalhobbyist] #LATHES Spindle Encoder Update
>
> Exactly my sentiments. I have a 3Nm driving 2:1 to a 3mm pitch screw and
> have no problems even though I am using an encoder!
> BTW I love your casting capability. I have no outside space suitable or
> I would be casting myself.
> Richard
>
> On 19/03/2020 16:08, John Dammeyer wrote:
> > Hi guys.
> >
> > The Z axis motor on my South Bend Heavy 10L with the 8 TPI lead screw is
> using the max 3A drive current from the internal micro-stepping driver inside
> my ELS.? I found that 2:1 is more than adequate for power.? I've never
> bogged it down for any turning or threading operation in the 10 years.? As
> seen by the dust on the motor surface the one pulse per spindle rev ELS has
> worked perfectly just like the thousands of MACH3 systems out there.
> >
> > The motor mount is a simple casting used twice so the motor would clear
> the bed at the back and the base would still fit on the drip tray.
> >
> > I bought a surplus lead screw end bracket and milled some of it away so I
> could mount a shaft extension for the pulley.
> >
> > If you want 1:1 for this size of lathe generally a size 34 motor drawing
> about 7A tends to be what others are using in the MACH3 and ELS world.
> >
> > John
> >
> >
> >> -----Original Message-----
> >> From: [email protected] [mailto:[email protected]] On
> >> Behalf Of Richard
> >> Sent: March-19-20 12:13 AM
> >> To: [email protected]
> >> Subject: Re: [digitalhobbyist] #LATHES Spindle Encoder Update
> >>
> >> I feel that you are seriously underpowered. If using a 3Nm stepper I
> >> would run it at 2 to 1 or more with an 8tpi screw.
> >> Richard
> >>
> >> On 18/03/2020 17:33, Ralph Hulslander wrote:
> >>> That was a first try at getting something to at least hold the motor
> >>> close to where it might go. I have other mounting ideas also.
> >>>
> >>> The leadscrew is ??-8 Acme here is thestepper motor
> >>> <
> >> Shaft-3-1Nm-439oz-in-3-5A-CNC-Reprap-
> >>
> Robot/232528913835?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2057
> >> 872.m2749.l2649>?439
> >>> <>
> >>>
> >>> Ralph
> >>>
> >>> On Wed, Mar 18, 2020 at 1:10 PM Richard <edelec@...
> >>> <mailto:edelec@...>> wrote:
> >>>
> >>>? ? ? I should think so when you have it mounted on a bit of thin sheet!
> >>>? ? ? What
> >>>? ? ? Torque motor is that? and what pitch leadscrew?
> >>>? ? ? Richard
> >>>
> >>>? ? ? On 18/03/2020 16:00, Ralph Hulslander wrote:
> >>>? ? ? > Oh did you see I have a rough prototype mounting for my Z stepper
> >>>? ? ? > motor. That needs a lot of work.
> >>>? ? ? > I can feel the motor binding when I turn the leadscrew.
> >>>
> >>>
> >>>
> >>>
> >>>
> >>> --
> >>> Clausing 8520, Craftsman 12x36 Lathe, 4x12 mini lathe, 14" Delta drill
> >>> press, 40 watt laser, Consew brushless DC motors and a non working 3D
> >>> printer
> >>>
> >>
> >>
> >
> >
>
>
>
--
Clausing 8520, Craftsman 12x36 Lathe, 4x12 mini lathe, 14" Delta drill press, 40 watt laser, Consew brushless DC motors and a non working 3D printer
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