Messages

8281

General Mach Discussion / Re: Drifting in the Y axis

« on: December 17, 2009, 06:50:32 AM »

Just a thought but if you are using stepper motors then it could be that you are loosing steps. One of the most common causes of this is binding or tight spots on the axis travel coupled with insufficient drive torque from the stepper motor.
As it is only occurring on the this one axis and only in one direction I suggest you look for a mechanical cause before suspecting anything else.

Tweakie.

8282

Show"N"Tell ( What you have made with your CNC machine.) / Re: A Short Video.

« on: December 17, 2009, 03:28:37 AM »

Hi Len-Tik,

Cutter is a standard carbide engraving bit 30 degrees angle.
Spindle speed was 3000 rpm.
The cut depth was -0.2 mm.
And the material is Traffolite (a standard engraving laminate).

Glad you enjoyed the video - There is another one here http://www.flickr.com/photos/tweakie-cnc/4174280038/ this time it's a PCB.

Tweakie.

8283

Tangent Corner / Re: Basic electrical questions

« on: December 16, 2009, 11:32:17 AM »

If you have the SSR before the transformer then the transformer is the load and no addition is necessary.
Good fortune with your project and I look forward to perhaps seeing a pic or two of the apparatus in operation.

Tweakie.

8284

Share Your GCode / Re: Spindle speed increaser for engraving...

« on: December 16, 2009, 10:45:37 AM »

You have got me thinking about this now.

Early radio sets used a ‘slo mo’ drive on the tuning knob using the differential between two circumferential tracks bridged by ball bearings.

Standard ball bearing races are designed to have a differential circumference ratio between the inner and outer tracks of around 2.6 to 1 therefore by holding the outer ring and driving a modified cage, the inner ring would rotate at 2.6 times the driving speed.

I don’t know the driving torque requirements yet but the cutter loading for engraving tools is extremely small (never stalled one yet).

This may achieve similar results to the proprietary item but without gears.

More thought is needed, but I might just build one to see the result (after I have completed all the other outstanding projects of course).

Tweakie.

8285

General Mach Discussion / Re: Tool probe macro

« on: December 16, 2009, 10:06:05 AM »

Two things come to mind here Mark.

Firstly you appear to be moving the Z axis a max of -9 units which means that if it starts more than 9 units away it will not get there.
Secondly I think you should zero your Z axis DRO with 'DoOEMButton(1010)' before making the move as this will prevent possible moves in the wrong direction.

Hope this is relevant or else I have totally misunderstood the original question. 

Tweakie.

8286

Share Your GCode / Re: Spindle speed increaser for engraving...

« on: December 16, 2009, 09:46:52 AM »

Thanks for posting the link Bill that is an interesting little tool.
How deep is it, or should I say how much Z Axis does it take up please ?.

Tweakie.

8287

Tangent Corner / Re: Basic electrical questions

« on: December 16, 2009, 09:37:49 AM »

Just another thought on your 50% duty cycle......

If you are thinking about switching 1/2 wave rectified AC through an SSR then it will not switch on reliably unless you provide a small load prior to the rectification (the SSR needs to see both the positive and negative going parts of the waveform to detect the zero crossing point).

Tweakie.

8288

Tangent Corner / Re: Basic electrical questions

« on: December 16, 2009, 09:10:35 AM »

It will depend on the AC frequency and design of the armature (shaded pole etc.) but basically DC is quiet, AC is noisy.

Tweakie.

8289

Tangent Corner / Re: Basic electrical questions

« on: December 16, 2009, 08:38:02 AM »

You could, of course, always use the SSR output to switch a transformer with rectified DC output for your existing solenoids. The possibilities are endless 

Tweakie.

8290

Tangent Corner / Re: Basic electrical questions

« on: December 16, 2009, 03:36:32 AM »

Hi Russ,

If it was me I would use an SSR or two SSR's.
The switched load must, of course, be AC but the low drive current (optical isolation), long life and extremely low noise (zero crossing point switching) make SSR's the preferred choice.

Tweakie.