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Topics - chrisjh

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I have had a problem with Mach3 for years now in that sometimes at the end of a program the feed rate override goes to maximum (1500%).  What this means is the next time I run the program, the feed rate is not correct.  I can manually cancel the feed rate override with the Reset Button or reboot Mach3 or manually type in the desired feed rate.  What I want to do is put a feed rate override command at the beginning and the end of all my programs in an attempt to overcome this annoying problem.  I note that there is an OEM Code for Feed Rate Override Cancel Button (1014) but I don't know how to integrate this as a command into my programs.

If this can be done it will solve another annoying problem of Spindle speed going to a initial speed higher than the commanded speed which can also be corrected with a manual press of the Override Reset Button.

What I have in mind is:

M3 S500 (Spindle goes to 640rpm)
Issue Reset Command here (Spindle drops back to 500rpm)
Perform cutting tasks until Program End
Issue Reset Command here (to cancel any spurious Feedrate Override that may occur)

Is there an easy way to do this?



Hi All,

I see a lot of queries, especially from novices, regarding methods of Spindle Control.  There are a lot of topics covering this but most do not give a full explanation with examples in one place.  

What I have tried to do is put a lot of scattered info and the benefit of my own personal experience into one document.

Please take advantage of my experiences at www.cjh.com.au//PWM Spindle Control using Mach3.pdf



I made some extended wheel nuts so I could mount tools like a shovel, an axe and a high lift jack on the spare wheel on the rear of my Toyota Prado.

I used my cnc lathe to make the wheel nuts.

The video tells the story http://www.youtube.com/watch?v=gsw5JtYMGSI&feature=channel



I use NFS wizards (I have V2.79) all the time.  Great CAM generator!!

Is there a way to specify the Approach Arc Start Position for external cuts on circles.  The default is approx +90 degrees (3 o'clock).  I am writing a step and repeat routine to machine multiple parts (a 50mm Fluted Knob) from a single block of material.

Problem is I have to waste a lot of material because the approach arcs are at the +90 degree position which means that my G52 offset for successive parts needs to be further to the right (+X) to allow for the arcs.

What I would like to be able to do is to specify that the start of the approach arcs somewhere near the 12 o'clock position (outside the +Y extremity of my material) to minimize wastage.

I could cut up my material to 51mm square blocks and do them one at a time but I would really like to be able to be 3 at a time with G52 step and repeats.



SmoothStepper USB / G4 Dwell Setting _Smoothstepper
« on: January 01, 2010, 03:50:09 AM »
Hi all,

Can someone confirm what I suspect?

When using Smoothstepper (any Plugin Version) the G4 Dwell units of time in milliseconds is ignored regardless if the setting in Mach3 "General Config" is checked.  I have been forced to express everything in seconds in my lathe G codes, which is not a problem, but annoying.

G4 dwell commands expressed in mS on my mill computer which uses a parallel port, behave as intended when mS is checked.

Just curious.



General Mach Discussion / G73 Pullback Setting in Mill Options Tab
« on: November 07, 2009, 05:52:21 PM »
I have tried to change the G73 Pullback from the default 0.1 (presumably inches) to 1mm ( My units are set to metric) and get to stick at that setting.

I can get it to change from 0.1 to 1 by entering "OK" not "Enter".

Problem is when I reboot Mach3 the pullback reverts to 0.1.

Can this be fixed?



General Mach Discussion / Lathe G83 Peck Drilling Problem
« on: October 17, 2009, 07:52:35 PM »

I cannot get the G83 Peck Drilling routine to work.  I have read "Topic: couple of things I have noticed with mach /g83 problem " and it appears that some can get it to work albeit with reported bugs relating to minimum peck distances. 

I have tried in vain with the codes attached.

In desperation I hand coded the Centre Spot Drill Template_B which uses simple G01 and G00 movements.  This works fine.

Where have I gone wrong with the G83 routines?

I am using the latest lockdown release of Mach3 Version R3.041 and SmoothStepper Plugin.



I have a mill controlled by a PP  and a lathe controlled by a Smoothstepper.

All is well except that there is a distinct hissing noise that comes from both stepper motors on the lathe when there is no motion (idle condition).  The mill under idle conditions is silent.

The hissing noise changes pitch and intensity if I jog one of the axis slightly.

The hissing noise is not present if the smoothstepper is not powered up.

I am not worried about this but am curious if anyone else has noticed this?



General Mach Discussion / G76 Threading Depth of Thread - M8x1.25
« on: September 08, 2009, 06:27:29 AM »
I am trying to cut my first thread M8x1.25.

The pitch is OK but the thread depth is not deep enough. ???

I am using dia 7.9 as x start diameter and 6.446 as the minor diameter.

The x axis is calibrated by doing a skim cut and entering the resultant diameter into Mach3 as detailed in the documentation and Tutorial Video.

Attached is my G code and a photo of the end result.

I could cut deeper by specifying the minor diameter as less than 6.466, however I am reluctant to specify the minor diameter as less than the recomended 6.446mm.

Where have I gone wrong?



Show"N"Tell ( Your Machines) / Chrisjh Home Built CNC Lathe
« on: September 04, 2009, 06:39:25 PM »
Hi All,

I thought that since I got inspiration from this forum I should share what I have acheived so far.

The design started 12 months ago and the actual build started 3 months ago.

Specs as follows:

38mm spindle bore using a Chinese Spindle (bought as a spare part for my manual lathe)

Spindle has a D1-4 and 5MT Chuck Interface so I can use all my Chucks and 5C Collet System from my manual Lathe.

20 x 5 x 640 Z axis ball screw and nut (Hiwin)

16 x 5 x 320 X Axis ball screw and nut (Hiwin)

20mm Linear Rails and Bearings (Hiwin)

Danfoss 0.75KW VFD (240VAC Single Phase I/P, 3 Phase 240VAC O/P, 0-200Hz) with Rototech 3 Phase Motor wired in Delta configuration.

Approx 3:1 Pulley Ratio and Powertwist Belt. (The 150mm pulley is from my old 1968 Datsun 1600 from years ago.  I cut out the centre and replaced it with my own designed and manufactured Taperlock Clamp on to the spindle.)

The current spindle speed is continuously variable from 250 to 1200RPM under Mach3 PWM control.

Smoothstepper and C23 BOB. (I didn't like the PWM to Analogue tacho chip on the C23 BOB, so I built my own much simpler and linear PWM to Analogue Converter and piggybacked it on to the c23).

Spindle Speed Feedback is supplied with an OPB960 IR Opto/Schmitt Trigger through an 8mm Slot Index Pulse generator mounted on the Spindle (CSS works flawlessly).

Meanwell 500W 48VDC PSU adjusted to 42VDC for the Steppers and Stepper Drivers.

Meanwell Dual 5/12VDC PSU to power everything else.

Leadshine M542 Stepper Controllers with 430oz/in Z Stepper and 311oz/in X Stepper.

Leadshine M542 Stepper Drivers.

Most parts are machined or fabricated from Mild Steel including the 1 metre bed (200 x 75 C Section Steel).  Headstock is 16mm thick Steel including a stiffening plate on the underside of the bed.

The bearing blocks are Aluminium treated with Alochrome 1200S machined on my X3 CNC Mill.

Spindle Bearings are 110mm Tapered Roller (Front) and 100mm Double Row Angular (Rear).

Axis bearings are simple Single Row Sealed on the leadscrew support end and angular contact on the motor end.

The stand is 65 x 65 x 5 RHS with adjustable levelling feet.

A slide out chip tray stainer located under the bed and below that is coolant return tray.

The cross slide has plenty of M6 threaded holes for all possible combinations of tooling.  My plan is for gang tooling all designed by yet to be fabricated.

I plan to use a fishtank submersible pump located in a heavy duty plastic bucket (I fed up with the problems I have had with Chinese coolant systems in my cnc mill and cutoff saw).

Here is the first cut done with much trepidation and fear!!!




Brisbane Australia

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