Messages

6521

General Mach Discussion / Re: s curve

« on: November 01, 2010, 01:57:48 PM »

Bill,

It can just be added and selected, or not, on startup (full instructions in thread).

I must admit that I don't understand all the in's and out's but it certainly seems a lot better with 3D (.stl) files.

Tweakie.

6522

General Mach Discussion / Re: s curve

« on: November 01, 2010, 12:24:43 PM »

Bill,

Have you read all the stuff on the Tempest Trajectory Planner, adjustable 'Jerk' etc. ?

Tweakie.

6523

General Mach Discussion / Re: Maxnc

« on: November 01, 2010, 09:55:12 AM »

I suppose this thread will wind up deleted as well? Buyer beware!

Somehow I don't think so.

Would be nice to know what went wrong with Max because they were, relatively speaking, a good company with a good product at a good price.

Tweakie.

6524

General Mach Discussion / Re: Slave axis problem

« on: November 01, 2010, 09:24:47 AM »

What is the ratio of one to the other as far as steps are concerned, is it a whole number ?

Tweakie.

6525

Show"N"Tell ( What you have made with your CNC machine.) / Re: A golden anniversary wedding gift

« on: October 31, 2010, 11:51:42 AM »

Excellent work Mike, thanks for sharing.

Did you do the casting yourself ?

Tweakie.

6526

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.

6527

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.

6528

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.

6529

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.

6530

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.