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Messages - chrisjh

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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 / Re: G76 Threading Depth of Thread - M8x1.25
« on: September 08, 2009, 11:52:31 PM »
I nailed it!!!

I checked the real diameter with a cut from the insert and found it to be very close to 7.9mm.  I ran a light cut in the cnc lathe to be sure, remeasured and recalibrated the x Axis.

I checked the specs on the index thread insert and found it was 0.4mm.  I entered this into the tool table and ran the program again.  Slightly better but still not cutting deep enough.

After running more unsuccessful tests with varying OD,  I bit the bullet and decided to decrease the Minor (Root) diameter in small steps. :-\

The test nut fitted on at a root diameter of 6.4mm (down from the recommended 6.466mm) ;D

Thanks for your help.  I am very new at programming cnc lathes.  It took me 3 weeks to stop thinking in cnc mill mode where the tool tip position is clearly defined in X, Y, and Z coordinates to thinking in terms of diameters in the X coordinates.  I am a slow learner :'(

Below is a link to a poor quality video of the successful threading routine.




General Mach Discussion / Re: G76 Threading Depth of Thread - M8x1.25
« on: September 08, 2009, 06:55:09 AM »
Hi Hood,

I am using a carbide tipped fully formed index threading tool.

You raise a good point, I should try a light commanded cut using the threading tool itself and measure that.

The method I used was to turn the 7.9 diameter in my manual lathe first, then use a 3mm drill shank to set the tip of the threading tool to diameter 13.9.  Maybe this where I am going wrong.



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

General Mach Discussion / Re: Front & rear toolpost in Turn 42.020
« on: August 27, 2009, 10:04:09 PM »
Hi Hood,

The bed is 200 x 75 C Section steel.  It is only 6mm thick across the wide part so as a precaution I have added a 16mm thick steel plate under the headstock end to ensure that all is stiff.

I had to machine the linear rail and headstock contact faces in one set to ensure that everything was in the same plane.

The bed is 1m long (too long for my manual mill so I had to get it machined by some blokes I know who have a HAAS VF5 with extended bed.  That machine is huge. See Photos.

Everything else I machined myself using my manual lathe and Mill + my Syil X3 cnc mill.



General Mach Discussion / Re: Front & rear toolpost in Turn 42.020
« on: August 27, 2009, 09:15:19 PM »
Thanks Hood for checking my code.

My dyslexia kicked in once more.  I typed G52 X-2 instead of G51 X-2. >:D

After correcting my error, the code then wanted to cut all around the full circumference of the ball. ???

My lathe is actually designed to take gang or tool plate tooling so I thought "What if I pretend to use a real toolpost when in fact I have the tool mounted in a front toolpost like Hood does?"

I set the tool table to tell Mach3 that the tool was mounted in a rear toolpost and voila, it worked!!!  ;D

I am now one step closer to actually cutting metal (Still trying to build up the confidence and courage). :-[

Attached is a photo of my home designed and manufactured lathe.

Basic Specs:

Spindle Bore 38mm with D1-4 chuck interface. (I purchased a spare spindle for my manual Chinese lathe and used it rather than make one from scratch.  I couldn't make one for the price of the spare part - $260AUD).

Danfoss VFD controlled through PWM in Mach3 with my own PWM to Analogue Converter with OPB960 through 8mm Slot Index Pulse generator mounted on the Spindle (CSS works flawlessly).

.75KW 3 Phase motor with approx 3:1 Pulley Ratio and Powertwist belt.

Smooth Stepper

Hywin Linear Rails and Linear Bearings and 5mm pitch ball screws and nuts.

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

My own bearing housings with Dual Row Angular bearings where it counts.

12months of research and design and a lot of blood sweat and tears inc lots of good Aussie dollars.

Hopefully I can post a video soon.

Kind Regards and once again, Thanks.

Chris Humphris


General Mach Discussion / Re: Front & rear toolpost in Turn 42.020
« on: August 27, 2009, 07:25:10 AM »
Hi Hood,

I have just finished building my own designed lathe and now the battle begins.

Currently I am using a front toolpost.

I used Mach 3 turn wizards to generate G code for a 24.5mm ball.  I hand edited the code to add such things as CSS.  The air cuts work fine except that the the X cuts are on the positive side of centreline rather than negative.  I tried your trick of using G51 X-2 in diameter mode but my code simply ignores the intended result, that is, cut on the negative side of centreline.

Can you have a look at my code to see where I have gone wrong?


Brisbane Australia

LazyTurn / Re: LazyTurn
« on: July 13, 2009, 07:20:37 AM »
Hi Budman,

I too am not a Solidworks pro.  I use SW 2007 and have no formal drafting or CAD training, hence my ignorance of quadrants and origins.  Thanks to Rich I am now better informed.

The method I used is as follows:

1.  Create the model in Solidworks.

2.  Create a drawing of the model showing only the top or side view ensuring that the scale is 1:1.

3.  Save the drawing as a dxf.  (SW gives you the option to save in various dxf fromats including ACAD 11/12)

4.  Close the dxf in SW and open it again in BOBCAD (I do this because I don't know how to move origins in SW or DWG Editor.  I tried to follow the help but gave up!!!)

5.  Use BOBCAD to move the origin to the correct quadrant and trim the drawing to show the upper half of the profile only.



LazyTurn / Re: LazyTurn
« on: July 12, 2009, 05:47:54 AM »
Thanks Rich,

I am kicking myself for missing the obvious.

Kind Regards


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