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Topics - Tweakie.CNC

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Sometimes I find it necessary to intercept signals on my Parallel Port cable in order carry out some external processing, such as delaying a signal or extending a pulse width etc.
In the past it has been convenient to use one of the ready made, inline RS232 testers (removing the internal resistors and LED’s) then making breaks in the appropriate tracks and connecting my external circuit to the appropriate pins. Constantly changing technology has now made these RS232 testers harder to obtain so I needed to create an alternative.

Routing a strip of double sided PCB with the required pin spacing (ready made strip board is of little use here as the DB25 pin spacing is rather odd and they are staggered between the rows) then cutting off the required length and soldering on a DB25 plug and a DB25 socket produced exactly what was required.


Tangent Corner / Pyrography.
« on: June 07, 2013, 05:11:43 AM »
For those wishing to CNC reproduce photographic type images on wood (without the use of a laser) you may find this interesting. http://hobbycncart.com/forum/46-234-1

You may need to use Google Translate but the thread has links to a couple of Russian videos showing just how simply it can be done.

To enable this method, Zoli (one of the forum members) has written a beta program ‘G-ray’ which produces Mach3 compatible GCode which varies the axis feed-rate in accordance with the image pixel value and there is a download link for any that may be interested.

I think this should be regarded as a development project but for those who like to experiment it certainly has possibilities.


Tangent Corner / Missing steps.
« on: April 11, 2013, 04:29:40 AM »
The fitter tells me that the wiring checks out OK so the missing steps issue must be caused by a bug in the software.  ;D


Here is an interesting natural science experiment / project for children and others, like me, who never grow-up.

For Millennia the basic building block for nature has been observed and extremely well documented but only in relatively recent times (since the introduction of our Hindu-Arabic numbering system) could it be expressed so easily in mathematical terms.

The ratio 1 : (1 + √5) / 2  is all around us and because it occurs naturally we perceive it as being ‘pleasing to the eye’ so to this end we have duplicated it in our architecture, art and just about everything else. We call it the Golden Mean.

It should perhaps be emphasized that this ratio it is not a law, carved in stone, because there will always be exceptions it is merely a trend but, in nature, it occurs more often than not.

The infinite pair of  numbers in the Fibonacci series 1,2,3,5,8,13,21,34,55,89… are again in exactly the same ratio and if we look closely at our plants, fruits, trees etc. these numbers and the ratio are there.

Getting back to the experiment / project, the attached .dxf can be used to make a set of callipers whose points follow this ratio so that we can measure the things around us, learn from the experience and perhaps even inspire others.

(these callipers are perhaps not quite as accurate as I would like them to be but it’s a start).


Tangent Corner / A Microscopic view.
« on: February 16, 2013, 03:06:36 AM »
An interesting video showing what happens when we machine metals (and presumably other materials)   http://www.youtube.com/watch?v=mRuSYQ5Npek&feature=player_embedded#!


Tangent Corner / USB pendant.
« on: December 13, 2012, 03:11:30 AM »
Has anyone tried one of these pendants yet ??



When Isolation Routing double sided PCB’s I drill two holes in the PCB blank (one is the datum and one the reference) to locate the work on two pins in the spoil board on the machine. This method enables good location of the tracks when machining each side and also for hole drilling etc. (always using the same datum point for X zero /  Y zero).

After reading this post and watching the video http://www.machsupport.com/forum/index.php/topic,22555.0.html  I thought I would try visual location of the datum and reference holes (using my cross hair pointer) and use ‘Local System Rotate’ just to see if it was an easier method.

Then using 3 CB buttons (at the bottom of my Mach screen) it is as easy as ABC. Well it’s almost that easy.  :)
Obviously this was only experimental so it is bit of a ‘quick & dirty’ solution and it needs work to tidy up the user interface side of things but it works.


Button A turns on the cross hair pointer, sets slow jogging and brings up the status message ‘Locate Datum then click Button B’

Button B resets X and Y axis DRO’s to zero and brings up the status message ‘Locate Reference then click Button C’

Button C is where the calculation takes place – the current X and Y axis position (reference) is used to calculate ArcTan of the angle which is then used to set the Local System Rotate. The offset between the cross hair pointer position and the spindle position is factored in and the X and Y axis moved to bring the spindle to the datum position. Jog speed is reset to normal etc. and the status message ‘Complete’ is displayed.

As it turns out this method works very well and in operation is an equivalent to the system used in the aforementioned video. It can handle any rotation or position of the work (within + / - 90 degrees).
Although the accuracy I achieved is acceptable it could definitely be much improved by using a webcam for the hole location and Klaus’s video window (camera plugin). http://www.kd-dietz.com/klausphp/pages/ger/plugins/webcam/description/wcam_description.html

It is not a quicker method than my existing system of using the two dowel pins but it may have advantages with odd shaped circuit boards and possibly alteration of existing boards so definitely warrants further investigation.

My next step – fit a webcam to the Z axis.   ;D ;D

A short video of the result  http://tweakie.byethost10.com/rotate1.wmv


Show"N"Tell ( What you have made with your CNC machine.) / SkyFall.
« on: October 26, 2012, 05:53:54 AM »
Hi Guys,

I make no claims for originality but as ‘SkyFall’ was released this week it just had to be done. ‘M’ would not be amused.  ;D


Tangent Corner / Health and Safety ?
« on: October 17, 2012, 04:50:41 AM »
I am not disagreeing with Green Policies or Health and Safety etc. because they are essential for our ultimate survival but just as an observation much of our work is getting tougher to accomplish.

Rattle can paints don’t seem to be as good as when they used ozone unfriendly propellants.
Lead-free solder often makes a poor job compared with the old 60/40.
Halon fire extinguishers are far better to use when electrical & mechanical equipment is involved.
The list could go on and on.

Now I am heavily into re-cycling (living close to a re-cycling centre) and everything I dispose of is appropriately binned for presumably the best disposal method by the authorities.
I had to chuckle when I enquired what happened to all the old TV, electrical and computer equipment – “it is carefully placed into freight containers and sent to India, where it is re-used” I was told.
That’s one way of solving the lead disposal issue.


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