Messages

7731

General Mach Discussion / Re: Z Axis Drifting or Loosing Steps?

« on: July 08, 2010, 01:50:58 PM »

I think I am back to what I thought earlier - lost steps.

Tightness, binding, excess speed and electrical noise are all possible causes but electrical noise usually affects more than just one axis.
If you are absolutely sure it is not binding or excess friction on the axis then I would suspect the motor or possibly a loose coupling on the screw.

Tweakie.

7732

General Mach Discussion / Re: Maxnc 5

« on: July 08, 2010, 01:44:26 PM »

Bob,

I presume you have tried the MaxNC mode of operation within Mach - does that need a separate profile ?.

Tweakie.

7733

General Mach Discussion / Re: Z Axis Drifting or Loosing Steps?

« on: July 08, 2010, 01:39:17 PM »

What bothers me is that this seems to be a math error.

This is unlikely - there are so many users for so long, if this was the case it would have been discovered and corrected a long long while ago.

I can move the head up and down without cutting anything about 10 times and see that it is off.

Are you saying that just jogging the Z axis up and down produces this error ?.

Tweakie.

7734

General Mach Discussion / Re: Unipolar stepper motor with ULN2003?

« on: July 08, 2010, 07:47:53 AM »

You need to current limit the supply to each coil to ensure it doesn't exceed 500mA per driver (series resistors in line with pins 13 - 16). Also you may need to heatsink the ULN2003.

Remember - the computers printer port (LPT) is fragile and it is always best to use a buffered or opto isolated BoB when experimenting like this.

Good fortune and don't make expensive smoke 

Tweakie.

7735

General Mach Discussion / Re: Z Axis Drifting or Loosing Steps?

« on: July 08, 2010, 04:59:15 AM »

Bobby,

Sounds to me like a classic case of lost steps.
A common cause, when this happens with the Z axis only, is binding or tight spots in the screw or slides. Try halving the velocity and acceleration, in motor tuning, and see if it still happens (the effect of this will be to increase stepper motor torque). If this cures it then experiment to achieve the best reliable settings.

Tweakie.

7736

Show"N"Tell ( Your Machines) / Re: The Laser Project.

« on: July 08, 2010, 04:23:08 AM »

I get the picture Sam - but I'm going to keep reminding you 

Some people might ask if I have anything better to do with my time - answer NO, I am learning all the time and knowledge is everything.

Tweakie.

7737

General Mach Discussion / Re: stepper signals from breakout board

« on: July 07, 2010, 11:30:18 AM »

Sorry to keep asking all these questions but what stepper driver board are you using ?.

Looking at the bob instructions as long as you have the JN1 &JN2 connected and 5Volt power applied you should be getting an output.

Tweakie.

7738

Show"N"Tell ( What you have made with your CNC machine.) / Re: I'm in Hog Heaven

« on: July 07, 2010, 08:59:25 AM »

Excellent work,

I do like that raised arc effect - how do you do that ?

Tweakie.

7739

General Mach Discussion / Re: stepper signals from breakout board

« on: July 07, 2010, 08:28:33 AM »

Looks good John - that's exactly the same configuration as I am using.

You say you have the port address set correctly (0x378) I am wondering if your breakout board requires an 'enable' signal. What type are you using ?

Tweakie.

7740

Tangent Corner / Re: Gear cutting end mill search

« on: July 07, 2010, 05:40:28 AM »

Brian,

Thanks for explaining - I now see exactly what you mean, this method would be an excellent way to make gears (and even I could grind the correct shape cutter). 
This would simplify things a lot as only one cutter would be required for each D.P. of gear.

Tweakie.