Hello Guest it is October 25, 2020, 08:50:00 PM

Author Topic: Gear Reduction question.  (Read 4000 times)

0 Members and 1 Guest are viewing this topic.

Re: Gear Reduction question.
« Reply #10 on: October 06, 2017, 12:46:35 PM »
The ballscrew will make a huge difference in speed and force. Since you are using a stepper I suggest you implement advance speed, press speed, and retract speed. Hydraulic presses all do this. Possibly a button that causes the advance speed when held, press when released, then when full stroke is reached you get fast retract to a settable starting height. This gives both high force and high speed.
Re: Gear Reduction question.
« Reply #11 on: October 06, 2017, 02:09:26 PM »
Eventually that is the plan. I'm new to Mach3 so maybe someone could point me in the right direction regarding these features of changing the speeds using I/O.
The press screw jack has 19.0" inches of travel , I'll only be using 8-10 inches of that travel. So retracting at a higher speed would be very desirable.
Couldn't I just write the federate into the NC code for the stroke ? like G0 (rapid traverse) ?

Thanks
Dennis
Re: Gear Reduction question.
« Reply #12 on: October 07, 2017, 11:37:50 AM »
Code like this:

G0 Z.25 (rapid approach)
F5
M1 (pause until start is pressed)
G1 Z-.25 (press stroke)
G0 Z2 (rapid retract)
M30 (rewind program top wait for start)
Re: Gear Reduction question.
« Reply #13 on: November 15, 2017, 07:47:07 PM »
Quick Update on the press build. Sorry its been awhile. So many other projects.
So after a lengthy build I attached the coupler to the  1600oz Nema 34 stepper and attempted to bend a 1.0in wide 16gage mild steel piece of material 90 degree.
The machine drives smooth and accurate but when it came to the actual grunt work of getting the tight radius in the bend it stalled and the stepper skipped steps. (big problem) !!!
I have heard of high torque steppers that have as much as 1800oz torque but I'm not sure this is my answer. ? I lowered the motor tuning velocity and accel to the min for max torque and
the results were better but not worthy of calling this machine a press. The downside to the settings change was a predictable slow as molasses pace.
I'm hoping someone has some insight or suggestions here please.   Hi-Torque ? Servo or DC motor , still needs to be programmable. Hoping to stay with the mach3 software as I'm really found of it now.

Thanks in advance.
Dennis
Re: Gear Reduction question.
« Reply #14 on: November 15, 2017, 07:58:27 PM »
Hi,
steppers are really good for torque at slow speeds, much better than a servo of the same size. The servo
comes into its own at speed.

1600oz.in is 8.3 ft.lb or 10.4 Nm. You are going to need a bloody big mega expensive servo if you wish to go that way.
The only other way is to gear  down your stepper and take the speed hit.

I have little 23 size steppers running through 10:1 low backlash planetaries and they max out at about 5 ft.lb or
960 oz.in....really really impressive for little motors...tad slow though!

Craig
My wife left with my best friend...
     and I miss him!

Offline ger21

*
  • *
  •  6,286 6,286
    • View Profile
    • The CNC Woodworker
Re: Gear Reduction question.
« Reply #15 on: November 15, 2017, 08:39:43 PM »
Have you calculated how much torque you actually need?
Gerry

2010 Screenset
http://www.thecncwoodworker.com/2010.html

JointCAM Dovetail and Box Joint software
http://www.g-forcecnc.com/jointcam.html

Offline ger21

*
  • *
  •  6,286 6,286
    • View Profile
    • The CNC Woodworker
Re: Gear Reduction question.
« Reply #16 on: November 15, 2017, 08:45:46 PM »
A 1.5-2Kw AC servo, with a 10:1 gearbox might work.
DMM sells a 1.8Kw servo with 11.5Nm torque. With a 10:1 gearbox, that would give you about 16,000oz-in at 150rpm. And up to 40,000 oz-in of peak torque for a short time.

About $700 for the servo and drive, and probably more for the gearbox.
Gerry

2010 Screenset
http://www.thecncwoodworker.com/2010.html

JointCAM Dovetail and Box Joint software
http://www.g-forcecnc.com/jointcam.html
Re: Gear Reduction question.
« Reply #17 on: November 15, 2017, 09:20:21 PM »
Hi Ger21,
thats pretty good buying really.

I had in mind a angle gear-reducer. I got one off Ebay 19.5:1 reduction, 2min arc backlash, 380 Nm output, including
airfreight to New Zealand $330NZD or about $250USD.

Craig
My wife left with my best friend...
     and I miss him!
Re: Gear Reduction question.
« Reply #18 on: November 16, 2017, 12:19:45 PM »
Hi , Thanks for the replies.
Current set-up is 6:1 gear reduction with 1600oz Nema 34 @ 75vdc. I was looking at the Screw jack with the single input shaft and thought what if ?
So I contacted Joyce Dayton and the friendly customer support guy said that I can remove the single input shaft and make my unit a double input shaft.
Now if I go with two HI-torque 1841oz Nema-34 steppers with 6:1 gear reduction that's twice the HP I may get the desired results (speed and power)
The addition of the two new steppers , another 80vdc power supply and one more stepper driver along with the Screw jack mod and coupler I'm looking
roughly $700 extra dollars.  Its a tough decision but I think this should do the trick.

Not sure why the pic is rotated , sorry.
« Last Edit: November 16, 2017, 12:30:15 PM by ddefocy »
Re: Gear Reduction question.
« Reply #19 on: November 16, 2017, 12:36:24 PM »
Hi,
that project looks good. The equipment the back ground of your pic suggests that you are an avid builder.

Quote
one more stepper driver along with the Screw jack mod and coupler I'm looking
roughly $700 extra dollars.  Its a tough decision but I think this should do the trick.

Seems like a lot of gold to spend without being  it will work. The advantage of the servo that Gerry mentioned is that it will hit its rated torque at 1500rpm,
no guessing involved.

Craig
My wife left with my best friend...
     and I miss him!