What stepper motor should I use thread - Page 3

1. Motor related calculations and realistic performance

I need some guidance regarding realistic feed rates, accelerations, cutting forces etc. for stepper motor sizing calculations.

I'm also hoping someone can give me a reality check on the results of my initial calculations.

** Seeking typical values for the following **
-What is a realistic rapid rate
-Typical cutting rate for router in ¾ mdf
-Typical cutting rates for 60watt & 100watt lasers cutting cotton fabric (bed sheet weight)
-Typical cutting rate for plasma torch cutting 16 gage steel.
-What are realistic accelerations for the weights indicated below?

** The machine **
The machine will be a multi-purpose XYZ table. Initially, it will direct the beam from a 60-100 watt CO2 laser for cutting cotton fabric. Down the road, it will also do plasma cutting and light router work.

** Controls being used **
Gecko G203V stepper drivers
PDMX-122 breakout board
Mach 3 software

** General parameters **
Gantry weight: 70 lbs
Cross slide weight 30lbs
Table size: 4’x 8’
Motor resolution 1.8 degrees per full step
Motor resolution .18 degrees per microstep
Desired linear resolution of .001”
The X & & will be driven by belt. The Z will be ball screw.

** my attempt at the drive calculations **
Assuming 1.194 pitch diameter final linear drive pulleys for both axis, the necessary ratio between the motor and final drive shafts should be 1.875 to 1 to get the desired linear motion per micro step

I calculate that, at this ratio, the driver will need to receive 16,666.7 pulses per second to run at the rapid rate of 1000ipm while the motor will be turning at 500rpm.

Both the X and Y axis are linear belt driven with reduction between motor and final drive. I have not gotten to the z – axis calculations yet.

The x axis which will move the gantry has the following specs:
Mass to move: 70lbs
Motor pulley: 1.194” Pitch Diameter
Intermediate pulley: 2.387 Pitch Diameter
Final linear drive pulley: 1.194” Pitch Diameter
This axis needs 432 oz – in of torque to accelerate at 2 G’s

The Y axis which will move the cross slide has the following specs:
Mass to move: 30lbs
Motor pulley: .637” Pitch Diameter
Intermediate pulley: 1.273” Pitch Diameter
Final linear drive pulley: 1.194” Pitch Diameter
This axis needs 198 oz – in of torque to accelerate at 2 G’s

How close am I?

Roger

2. Hello all,
I finally went off the deep end and ordered the parts to build my first machine.

The plan is a gantry style machine made of aluminum (80/20 and plate) with
46" of x axis travel, 2 48" 10tpi acme leads
22" of y axis travel, 1 24" 10tpi acme lead
6 " of z axis travel, 1 9" 10tpi acme lead

all axis will be running on Thomson Accuglide 25 series rail and blocks, probably mass overkill but the price was right.

I have a Porter Cable 690 router I will be using as a spindle with precision collets.

I want to use it as an all purpose machine to cut wood, aluminum and brass using tooling from .5mm up to .5". I will be doing some jewelery type stuff with the metals and mostly sign work with wood.

The question is... What is the recomendation for a 4 axis Nema 23 based stepper system kit that would handle my wants with an good accuracy, durability, and speed. Price is as always a consideration but from what I have read here you get what you pay for and I only want to pay once...

Thanks all
DC

3. Good Day Everyone.

I'm also new here and as such a little curious about how to determine the most appropriate Stepper Motor specifications. What I would like to do is convert my existing Mill (Craftex B1976 Mill - http://busybeetools.ca/cgi-bin/picture10?NTITEM=B1976) to a CNC Mill. As such, I have visited various website and vendors and have found lots of interesting means to calculate the required specifications, the Parker Hannifin one was by far the easiest to use, but they all give me numbers and ratings which sound too low to be true! When I read that people are typically using Nema 34 and larger framed motors with torque ratings above 1200 oz-in and then these softwares tell me that all I am required to buy is a motor with 64 oz-in to drive a pulley system attached to my leadscrew assembly with a mass of 400 Lbs (worst case scenario); I’m not sure if I’m missing something from here or not. Even if I change the mechanical efficiency settings to make it the worst machine out there such as steel on steel with no lubrication and an efficiency of only 65&#37;, I only get 64 oz-in motor required?

If any of you know how to do this, I would appreciate some help in this regard. The specs of my machine are as follows.

TPI = 10
Length of Leadscrew = roughly 33”
Density of Steel = 0.28 Lb/in^3
Friction Coefficient = 0.58
Table Mass = 400 Lb
I’ve said maximum velocity = 300 rpm
And the pulleys are:
Motor Pulley Diameter = 1.46 in
Motor Pulley Thickness = 1.063 in
Density = 0.096 lb/in^3
Load Pulley Diameter = 3.73 in
Load Pulley Thickness = 1.063 in
Density = 0.096 lb/in^3

Thanks for any help/advise you folks can offer to me and Cheers…

4. If your going to direct drive the screws with the stepper motors, I would use 600oz/in ones. Speed will be around 200ipm with a 10 TPI lead screw.
It would be alot easier however, to belt drive the axis and give it a 2:1 at the same time. Then you could use 400oz/in steppers and a Gecko G540 to run the whole thing. The 2:1 will slow it down a bit but the table isn't that big so there's really no reason to go 300ipm. Accuracy will increase and you won't likely have to use micro stepping.
Currently I have 100ipm on my DynaMyte 4400 and its not that bad, as long as the controller doesn't get stuck at 12ipm.

Timothy

Hold on, you said 300rpm... with a 10 TPI thats 30ipm.
Is this correct?

5. Hello, good people!
I just got a question. There is photos in my gallery of my project. This is going to be a 4'x8' 3 axis cnc router.
Now, the question is, how do I do the x-axis motion? should I use 2 steppers with lead screw on each, or one stepper with 2 lead screws chain bonded, or use linear gears on both tracks and rod bonded pulleys with one stepper?
p.s. Sorry for my English

6. 1 Motor per axis. XYZ

Why would you need more?

7. more...

On the pictures in my gallery you can see the "skeleton".
Bad thing when you don't know something to begin with and then forget it... (russian joke
I have seen other people make x-axis with two steppers.
Is it possible to operate two steppers in parallel mode? And also I am not sure if it is a good idea to have lead screws diameter 3/4" and almost 10 feet long. I am afraid of vibration, almost wobbling around... This is why I am considering having a linear gears and stuff.
It is you know... may be I need a little push in right direction. some advise, thoughts.
Thank you.

8. Bipolar or Unipolar? That is the Question

Hey Yall,

I am thinking of building a CNC router to cut out aircraft instrument panels and I have been reading a bit on the different types of stepper motors and controllers. I have read that unipolar steppers and controls are easier to work with, but the article didn't explain why. I understand the difference from how they operate, but I don't know which best for me. Uni or Bi? I see a product by Novakon that seems to have enough muscle (370 in/lbs.) to do the job of cutting .090 2023-T3 aircraft aluminum, but the rated current is 3.7 amps/phase, which is higher than the maximum 3 amp/phase supplied by the Hobby CNC Pro Chopper driver kit I wanted to use. If I select this combination, I worry that I will not get the full utility from the motors, and the controllers that Novakon offers are out of my budget. Does anyone know where I can get an affordable unipolar controller that will drive up to 4 amps or so? Or should I even worry about it and set up a bipolar system?

Kris

9. 2 motors

Originally Posted by robotek
On the pictures in my gallery you can see the "skeleton".
Bad thing when you don't know something to begin with and then forget it... (russian joke
I have seen other people make x-axis with two steppers.
Is it possible to operate two steppers in parallel mode? And also I am not sure if it is a good idea to have lead screws diameter 3/4" and almost 10 feet long. I am afraid of vibration, almost wobbling around... This is why I am considering having a linear gears and stuff.
It is you know... may be I need a little push in right direction. some advise, thoughts.
Thank you.
2 motors are better. One on each side of the gantry. One will be a slave. I dont know what software your going to use, but 2 motors certainly are better in your sretup.

10. Can Any one suggest an equivalent NEMA 34 size motor to superior electrics M091-FD-6217 150oz 200 step 1.8v 4.7a. . . I have an old gerber system48 and one of the steppers has gone down.. . I appreciate that I will have to replace both the x and y axis. . but after loads of searching I can't seem to find anything similar.

11. Here's a good link with a ton of info.

Stepper Motors

12. Hallo there

Hi everyboady, this is the first time I write something on cnczone forums, and I'm not here to help as I'm a novice, I'm here to get helped :-) (and sorry in advanced for the bad english)
I'm building my second cnc mill, it has a 1,3 m/ 0.8m working area, and as it is preaty big I'd like to place two leadscrews for the X axis - one on each side. so far so good... I have some 4 nema stepper motors rated at 2 amps and a driver board (3 axis) rated at max 3 amps/phase. My plan is to link in parallel the stepper motors (phase by phase) on the x axis , but I don't know how to limmit the current so that I don't burn up my driver board... Any sugestions?? (besides buy another driver/steppers)
I thought of linking in series with each lead from the motors a resistor to limit the current to the desired value... I have no Ideea how this would work and how it would affect the performance of the motors (especially)
If anyone has any ideea please let me kow, or send me a link to where I can find something related
Thank you and may your projects live forever ;-)

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