Messages

7661

General Mach Discussion / Re: New people welcome !! Come in here and introduce your self!

« on: August 15, 2010, 04:01:41 AM »

Hi Tony and Paul,

Welcome to the forum.
We all love pictures here so if you could post some pics of your machines etc perhaps under the 'Show n tell your Machines' section that would be really great.

Tweakie.

7662

General Mach Discussion / Re: Non-integrated Video Card with 32MB RAM

« on: August 15, 2010, 01:05:00 AM »

Glad you got it sorted Bob. 

Tweakie.

7663

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

« on: August 14, 2010, 01:53:07 PM »

Sam,

I don't know what to say - you are just awesome.

Tweakie.

7664

VB and the development of wizards / Re: What ready materials should I buy?

« on: August 14, 2010, 11:35:12 AM »

Hi Jim,

For a long time now I have worked on the principal that 'if you don't need to know it don't waste time learning it'. This has resulted in a 'hands on' approach of only learning stuff as I need it.
For what it's worth, my advice is, choose a project that you wish to achieve - jump in with both feet and write the VB, looking up what you need to know when you need to know it.
There are so many Mach specific routines that you won't find in any structured VB learning course which is why I recommend the practical experience approach. All the information on VB that you require is linked somewhere on this forum and if you can't find it just as the question and someone will point you in the right direction.

Sorry for rambling on a bit but I hope this helps.

Tweakie.

7665

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

« on: August 14, 2010, 09:54:04 AM »

Absolutely brilliant Sam.    just brilliant.

You have my full attention on this one - I have to know exactly how you did this - It is just about the best circle I have seen.

Don't suppose you could perform your magic on this foot or is that too much to ask ?.  

Tweakie.

7666

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

« on: August 14, 2010, 09:19:32 AM »

Dave,

That's exactly the way the parts come off my machine - there is no refinishing or flame polishing. (I have had a lot of practice now and if you look back a few posts you will see that some of my earlier attempts with acrylic were rubbish).

In a way this is the reason for my question regarding these striations.
Many (perhaps all, for all I know) of the commercial laser machines are operated via a 'machine manufacturers Printer Driver' with acts as the post processor from the design software, typically 'Corel Draw'. Now there is some doubts about the way in which these printer drivers handle arcs and the maximum resolution they will allow to pass through because, it seems, that those I am in contact with who have a GCC laser are unable to produce a curved surface in acrylic without the striations. I have carried out a lot of research on this now and it is perhaps obvious from what I have made that a dedicated cutting software, such as Mach, way out performs these Printer Drivers - at least as far as cutting acrylic is concerned.
I know how to cut stuff with the striations and I know how to cut stuff without the striations - what I didn't know, until now, is what caused the striations.
You have all been most helpful here and as a result I think there is probably no solution for the GCC owners as long as they continue to use a printer driver and unfortunately their machines would not support Mach without some modification. There is one US business who is offering a Mach compatible addition but it is still doubtful if it will offer any improvement on the resolution of arcs issue.

Waffled on a bit but hope this is of interest.

Tweakie.

7667

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

« on: August 14, 2010, 08:23:36 AM »

Hey look, an acrylic footprint (much more eco-friendly than carbon) 

Tweakie.

7668

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

« on: August 14, 2010, 08:19:33 AM »

Thanks for the magnification of the cutting path Sam - that looks pretty much like the striations.

So Guys, correct me if I am wrong, but would it be right to say that the striations are being caused by the lack of resolution in the exported arc ?.

Tweakie.

7669

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

« on: August 13, 2010, 11:36:41 AM »

Thanks Guys for your input, It is appreciated.

Dan and Richard,
You are, of course both quite right but...
The surface of the cut should appear to be a series of small flats (as you say a milling cutter path would produce) and there is really no reason why it should be striated - just a series of smooth flats. Unfortunately that's not quite what it looks like - for some reason.

Sam,
That's exactly what they look like - they weave left and right. They also get a whole lot worse if I increase the feedrate and subsequent laser power setting.

I did read, somewhere on the net, that they were caused by a reaction between the air-assist and the material vaporization but this doesn't hold true, otherwise both discs would look the same.

Tweakie.

7670

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

« on: August 13, 2010, 02:57:28 AM »

Hey Guys,

I wonder if you could help me out here.
I have just laser cut two 50mm diameter discs from 6mm acrylic - one has visible vertical striations one does not. The parameters (power, federate, air assist etc.etc.) are the same for both discs, the only difference is the GCode (disc 1 has been cut using a predetermined number of straight lines, whereas disc 2 has been cut using circular interpolation [GCode for each attached]).

Now this might sound like a daft question but “What causes the vertical striations to be made ?”.

Is it the fact that the cutting head stops and starts ?.
Is it the sudden change of direction ?.
Is it acceleration / deceleration of the cutting head ?.
Etc.

With circular interpolation the step size (or length of each flat that emulates the circle) is, obviously, a lot smaller but just how small is it ?. The highest (theoretical) resolution I can achieve on my machine is 0.00625mm – are the circular interpolation steps smaller than this ?.

Grateful for any comments or info on this one, thanks,

Tweakie.