Messages

21

General Mach Discussion / Re: Can't raise feedrate past 50 in./min. without messing up... suggestions?

« on: March 13, 2012, 03:50:37 PM »

Mike,
What is the max Kernel Speed you can use?
What are your steps per unit?
Post a pic of your machine.

RICH

My Kernel Speed set in mach 3 is 35k, I wouldn't know how to determine my max?  
My steps per in mach 3 are around 32000 for y-axis and roughly 25000 for the x-axis.
My machine pics are below(having a bit of trouble so may take a bit).

Thanks again,
Mike

22

General Mach Discussion / Re: Can't raise feedrate past 50 in./min. without messing up... suggestions?

« on: March 13, 2012, 03:15:08 AM »

I just think you need different motors since the ones you have are 160 in oz motors. Have a look at the motors on Kelings site
and you will find some 360 to 500 in oz that can be run at 3 amps and should be able to almost triple your speed.
Review the motor curves to compare if they list a curve for the motor.

RICH

I had a feeling all along these motors were my problem.  I've been to their website and found the biggest 8-wire NEMA 23 stepper motor:

2:        NEMA 23 BIPOLAR STEPPER MOTOR 425  oz-in
KL23H286-20-8B (1/4” shaft with a flat)   Specification  or Specification Price: $49
425 oz In. Hybrid Motor
1.8° /200 Steps Per Rev.
2.8 Amps Current Per Phase ( Bipolar Parallel)
8-wire  Bi-polar or unipolar,  NEMA 23 Frame

Compared to the ones I have now:

5:   NEMA 23  BIPOLAR STEPPER MOTOR  156 oz-in KL23H251-24-8B ( ¼” dual shaft with a flat) $26.95
Specification , Torque-Speed-Curve
156 oz In. Hybrid Motor
1.8° /200 Steps Per Rev.
3.4 Amps Current Per Phase ( Bipolar Parallel)
8-wire  Bi-polar or unipolar,  NEMA 23 Frame

Do you think the bigger motor listed above would be enough to make the machine as fast as I need it(150-200 in/min)?  

Thanks for the help,
Mike

23

General Mach Discussion / Re: Can't raise feedrate past 50 in./min. without messing up... suggestions?

« on: March 12, 2012, 02:51:17 PM »

Can you give some info on your machine?
For a CNC router your usualy interested in fast feedrates so you won't burn the wood with the router bit. Stepper motors are somewhat limited in how fast they can rotate.
At  higher motor rpm's you have less torque so even if the torque requirements for moving the axis are low  you still need enough to take care of the machining and reserve just for the sake of reliability.  The higher feedrates are achieved by using multi start screws or gearing. So have a look at comparable machines and make note of components used along with feedrates achieved. You need to look at the whole system and what you want to do with it. There are plenty of post's about routers and certainly worth some searching.

RICH

Machine:
Travel: X-24",Y-36",Z-5"
X & Y Axis uses precision ground cnc linear rails.
Z Axis uses 2 linear bearings on .75 DIA 440 hardened Stainless Steel Round Bars.
X, Y, & Z Axis Stainless Steel Acme Lead Screws
Anti-backlash Acetal Nut on X, Y, & Z.
Uses 2 paired motors(Y & A axis-one on each side of table) to run the Y axis.


Right now my Geckos have 55 Volts running to them and Idk what my motors max Voltage spec is or how to find it.

24

General Mach Discussion / Re: Can't raise feedrate past 50 in./min. without messing up... suggestions?

« on: March 10, 2012, 03:26:21 PM »

What is the power supply VOLTAGE to the drives That more than anything will set the max speed of the motor. What are your motors rated for?

(;-) TP

I didn't set it up so I'd have to test it to know the Voltage.  My motors specs are in the link in my post at the top of this page.

25

General Mach Discussion / Re: Can't raise feedrate past 50 in./min. without messing up... suggestions?

« on: March 10, 2012, 02:07:38 PM »

Bump... sorry, would like to get this figured out quick, losing money.

26

General Mach Discussion / Re: Can't raise feedrate past 50 in./min. without messing up... suggestions?

« on: March 09, 2012, 05:09:26 PM »

Well I need some help. Right now all four of my geckos have 68k ohms resistors which puts the current above 4 amps.  The motors on my CNC machine(http://www.kelinginc.net/KL23H51-24-8B.pdf have a max amps rating of 3.4A in bipolar parallel(which I don't know if mine are hooked up this way?). So should if I were to replace the resistors on the Geckos with 45k ohms resistors(which would put the current just under 3.4 amps), would I be able to go with higher feed rates?  Or should I invest in bigger motors that can take the 7 amps possible with no resistors?

27

General Mach Discussion / Re: Can't raise feedrate past 50 in./min. without messing up... suggestions?

« on: March 09, 2012, 04:50:56 PM »

The G201's are capable of 7A and 80 volts max. If you don't use a resistor to set / liimit the amps then the drive can output the max current.
The amps and volts available to the drives are determined by the power supply. You need to look at the motor rating since they may limit current and
volt use.
RICH

Exactly what I needed to know. Thanks a lot!

28

General Mach Discussion / Re: Can't raise feedrate past 50 in./min. without messing up... suggestions?

« on: March 09, 2012, 09:48:21 AM »

Can you increase the amp's and voltage with in the range of the stepper and driver?
If below allowable then you are not taking full advantage of your motors capability.

You can get bigger steppers that for the same given voltage and amp settings you will get more torque / acceleration / and also more usable velocity.

RICH

Well, I don't really know how and where I need to check the amps and volts.  I found out I have 4 G201 10 Ustep Gecko drives.  How would I know whether I'm using them to their full capabilities and if not, how would I increase the power supplied to them?  I'll post a pic of my drives, stepper, etc. if needed.

29

General Mach Discussion / Re: Can't raise feedrate past 50 in./min. without messing up... suggestions?

« on: March 06, 2012, 09:59:29 PM »

Can you increase the amp's and voltage with in the range of the stepper and driver?
If below allowable then you are not taking full advantage of your motors capability.

You can get bigger steppers that for the same given voltage and amp settings you will get more torque / acceleration / and also more usable velocity.

RICH

That makes sense.  It makes me understand picengravers post better too.  I'll have to check it out tomorrow.  Thanks for the advice. 

Mike

30

General Mach Discussion / Re: Can't raise feedrate past 50 in./min. without messing up... suggestions?

« on: March 06, 2012, 08:17:59 PM »

Could be that you just don't have the torque available  from your steppers to do the short fast moves that are being demanded by the code. 
RICH

This sounds promising.  How would I go about getting the torque needed from my steppers.  Would I have to just upgrade my steppers?