Messages

7411

Show"N"Tell ( Your Machines) / Re: The Laser Project.

« on: October 31, 2010, 11:33:03 AM »

The banding I am referring to consists of many lines and can probably be seen best in this image http://www.machsupport.com/forum/index.php?action=dlattach;topic=12444.0;attach=22163;image which consists of just two shades (black & white).

Not sure if I should show this because it may confuse the issue but the image below is a good example of color depth banding (similar but not the problem I am referring to) where the background consists of more shades than the eight which the Mach plugin can handle. As a result the background is stepped into bands that best match the true shade. The dithered image itself is unaffected by this procedure.

Tweakie.

7412

Show"N"Tell ( Your Machines) / Re: The Laser Project.

« on: October 30, 2010, 07:49:16 AM »

That's a thought Dave - thank you - I think that may work.

De- focusing a little may also have the same result of smoothing things out a little I suppose but it has become a real challenge now and I have just got to find the actual cause of this phenomenon.
It is so strange that, in the laser world, everybody seems to know about it, nobody admits to it and the cause has just not been defined. If this was the plot for a book it could be a best seller.  

So far, I have checked my Y axis for backlash / slack and also for unequal step size (looking at the line scan spacing under magnification shows no problem). I have measured the time taken to complete each line (feedrate) from the X axis direction signal and they are as equal as I can measure on a chart recorder. I have recorded the incoming mains voltage and there is some fluctuation, but not much, certainly not in steps like the images show however I have a UPS voltage conditioner coming for a trial. And finally, for the test sample, I have matched the vertical image size and stepover exactly to the number of vertical pixels.

The saga continues.

Tweakie.

7413

Show"N"Tell ( Your Machines) / Re: The Laser Project.

« on: October 30, 2010, 04:41:52 AM »

Is it your girlfriend

In my dreams, along with 10 million other guys. 

A BIG problem
I have an issue with, what is commonly termed, ‘banding’. It can just be seen on this image but is perhaps better seen on this one http://www.cooperman.talktalk.net/files/27_files/image762.jpg .
This is not the same thing as encountered with some colour printers etc where there is insufficient colour depth for the image it is a distinct band of some 10 – 50 lines having a different contrast or brightness. I have run 5 identical images, one at a time, with the same settings, side by side, on the same material and the banding is different on each – it appears to be quite random in nature.
I have been doing a lot of reading and various forums searching to try and find an answer but it just seems to be a mystery.
Some have suggested that it is a mismatch between stepover and vertical pixel count, plausible but this should then produce a repeating pattern.
Different laser machine manufacturers disagree about the cause and almost all say their machines don’t exhibit banding but their competitors machines do.
Glass tube (DC excited) lasers seem to be more prone to this problem than RF excited lasers.
There is undoubtedly more than one type of ‘banding’ therefore there is obviously more than one cause and cure.

If any of you Guys have any suggestions for things I can try to eliminate this problem I would be more than grateful – I really must get to the bottom of this one.

Thanks,

Tweakie.

7414

Show"N"Tell ( Your Machines) / Re: The Laser Project.

« on: October 29, 2010, 12:41:51 PM »

Thanks Sam.

I never seem to be able to take the best photographs of a lot of stuff so I had another crack at this one, this time without the flash.

Tweakie.

7415

General Mach Discussion / Re: replacing manual valves with electric valves?

« on: October 29, 2010, 11:57:26 AM »

Dan,

If you decide to use one of those valves then to switch it (open/close) an SSR, similar to this would be ideal. They are opto isolated and can be driven direct from the BoB (M8/M9 etc) and they switch ac loads with extremely low electrical noise.

Tweakie.

7416

Tangent Corner / Re: How to check your airbag

« on: October 28, 2010, 08:05:10 AM »

That is real wicked Jeff. 

Tweakie.

7417

General Mach Discussion / Re: problem mach3 nide help

« on: October 28, 2010, 07:45:53 AM »

Hi komar1970,

Welcome to the forum.

You could try following the optimization steps towards the bottom of the page here http://www.machsupport.com/downloads.php

Tweakie.

7418

Promote and discuss your product / Re: Mach3 as 3d printer software

« on: October 28, 2010, 05:01:52 AM »

I will soon share the information so that you can build a kit by yourself (or buy one) and screw it to your mach3 cnc and start using it as a 3D printer.

This I am looking forward to, thanks for the info Nuri.

Tweakie.

7419

Promote and discuss your product / Re: Mach3 as 3d printer software

« on: October 27, 2010, 11:07:05 AM »

what I am trying to do is easy switching from a cnc to 3d printer. Mach3 will be the software. You will plug a extrusion head instead of a spindle and you will begin to print. A arduino based circuit board will control all the stuff like extrusion temperature, extrusion speed and build platform heating. I prefer to separate the 3d printer requirements from mach3 software. This will not disturb the mach3 to run the cnc code and will help people to switch between cnc and 3d printer.

This is a brilliant concept Nuri - I am following this with great interest.

Tweakie.

7420

Show"N"Tell ( Your Machines) / Re: The Laser Project.

« on: October 27, 2010, 07:16:32 AM »

Hi Russ,

Total time probably about 20 minutes, the image is just 90mm x 60mm and the vertical step size was 0.06mm.

As soon as I lay my hands on a decent gloss finish piece of black anodized I will try and make a better job of this, larger image and smaller step size perhaps. 

Tweakie.