Messages

6071

Show"N"Tell ( What you have made with your CNC machine.) / Re: Rack and Pinion Reduction Drives

« on: January 25, 2011, 02:25:38 AM »

Very nice work Michael.
How are you getting the tension on the drive belt ?

Tweakie.

6072

General Mach Discussion / Re: Power Supply +Se amd -Se sigal

« on: January 24, 2011, 12:12:22 PM »

Tweakie,

Thanks for your explanation.  I would assume then this is only useful if a voltage drop is anticipated. If not then one could just jump the +5V with the +Se and the -5V with the -Se terminals.  If this is incorrect please let me know about it.

Jorge

That's exactly what I would do.

Tweakie.

6073

General Mach Discussion / Re: Stepper driver chips

« on: January 24, 2011, 12:10:12 PM »

Hi Tony,

Although they both perform a similar function they are not interchangeable. The 3717 is essentially a single phase device and you would need two chips to drive one bipolar motor. Although they are OK for printers and scanners etc neither are really suitable for CNC use because the drive current is just not sufficient. (Most bipolar stepper motors require a minimum 24 Volts at 2 Amps to provide sufficient torque to drive a CNC). There are better Stepper Motor chips available – take a look at the Alegro range for starters.  http://www.allegromicro.com/en/Products/Categories/ICs/motor.asp

Tweakie.

6074

General Mach Discussion / Re: Power Supply +Se amd -Se sigal

« on: January 24, 2011, 11:43:56 AM »

Jorge,

It is usual on the quality, adjustable, bench power supplies to have Sense (Se) terminals which are link connected to the main terminals to complete the feedback loop for output regulation.

Tweakie.

6075

General Mach Discussion / Re: spindle speed control

« on: January 24, 2011, 06:19:10 AM »

Thanks Larry, I would dearly like to understand quilting machines and their setups. (although I read up as much as I can I think I will probably have to obtain / build a quilting machine before I finally get a grip).

Tweakie.

6076

General Mach Discussion / Re: spindle speed control

« on: January 23, 2011, 12:27:40 PM »

I have read this 10 times Larry and I still don't understand exactly what you are trying to achieve. 

Just as an example machines such as 3D printers often drive the material feed drums but because the material requirement or motion is not constant they use a micro switch or other sensor to check the position of a loop in the material then, when necessary, operate the drum drive a fixed amount then return to standby for the sensor to provide the next signal.
This idea could be made to drive both ways, is this of any use ?

Tweakie.

6077

General Mach Discussion / Re: Enlargement problem

« on: January 23, 2011, 04:55:17 AM »

Lou,

There are a few good tips for correctly setting up the 'steps per' in the 'members docs' area in particular you can download this calculator written by Al Lenz from here http://www.machsupport.com/forum/index.php/topic,16315.0.html.

Hope this helps,

Tweakie.

6078

Show"N"Tell ( Your Machines) / Re: 3rd try is the charm Mach3 Controllable PWM Spindle Motor Controller

« on: January 23, 2011, 04:45:38 AM »

Excellent post Zero Cool, very detailed and informative - don't know how I missed this post before.

If you haven't already seen it, this thread gives some details of pulse feedback which may be of interest to you. http://www.machsupport.com/forum/index.php/topic,995.10.html

Tweakie.

6079

General Mach Discussion / Re: s curve control board

« on: January 23, 2011, 03:39:18 AM »

A lot of work was done on the acceleration curve and slope in the excellent Tempest Trajectory planner which now appears to be an abandoned project. Shame really because it was much faster at 2.5D work and allowed higher accelerations without stall on my router.

From reading other threads I think Bill_O is on to this already.

Tweakie.

6080

General Mach Discussion / Re: cnc screwcutting???

« on: January 22, 2011, 07:16:59 AM »

Dale,

Try setting the 'pull up / pull down' jumper for pin 10 (input configuration) to the opposite of what it currently is.

Tweakie.