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501  General CNC Chat / Show"N"Tell ( Your Machines) / Re: The Laser Project. on: February 22, 2012, 04:45:54 AM
Hi Tweakie,

I agree with this. It's just that I think that using the word "power" to describe this process is misleading as the laser is being turned on to the same (predefined by some other means) power each time.

And to be more correct, I think that the laser never really does several pulses on top of one another (well if it's focused fine enough that is), as the axis is in a constant move. I think the correct way of thinking about it is the dots intensity. And the other thing to consider while at it is that the exposure time is determined by the axis feed rate.

Yes, I had read through your PDF and I must say you've done great job there!! Thanks for that!

Dan
502  General CNC Chat / Show"N"Tell ( Your Machines) / Re: The Laser Project. on: February 20, 2012, 01:09:39 PM
Well, I think the plugin doesn't control the laser power whatsoever. All it does is trigger it on and off.

Dan
503  General CNC Chat / Show"N"Tell ( Your Machines) / Re: The Laser Project. on: February 20, 2012, 12:43:59 PM
On it's own, the plugin will not always smooth a gradient of tone without producing 'steps' as can be seen in the background of this image which is a smooth transition from light to dark.

Tweakie, just out of curiosity I would try engraving the same image rotated by 90.

John, I think the plugin outputs equal length pulses for each pixel. As far as I understand it's the spacing which creates the toning.

Dan

EDIT: Found original Art's description:

http://groups.yahoo.com/group/mach1mach2cnc/message/74912

504  General CNC Chat / Show"N"Tell ( Your Machines) / Re: The Laser Project. on: February 20, 2012, 11:52:36 AM
Hi Tweakie,

So how does it vary from the Impact plugin which still fires the laser at the same power each time? Roughly speaking, if I understand correctly the way the plugin works, it does internally the same thing as that program does, but following a different algorithm.

Dan
505  General CNC Chat / Show"N"Tell ( Your Machines) / Re: The Laser Project. on: February 20, 2012, 09:20:27 AM
Can you explain please, Tweakie? The power supply still operates in digital mode so how does the image conversion help?

In the image the program outputs, are all the dots equal in size?

Dan

506  General CNC Chat / Show"N"Tell ( Your Machines) / Re: Just got a lathe to retrofit on: February 19, 2012, 05:59:01 AM
Yes, using the bolts against the turret would damage it.

You're lucky to have clean air Smiley

Dan
507  General CNC Chat / Show"N"Tell ( Your Machines) / Re: Just got a lathe to retrofit on: February 19, 2012, 05:16:10 AM
Thanks for the description, Hood. It is a nice solution. Just a thought here - looks like it might be better to have the screws' heads touching against the slot wall rather than the tool, as when tightened they would tend to drag the tool out of position.

So you have to use shims for height adjustments?

Interesting.. the sea here is a few kilometers away and everything picks up rust pretty quickly unless it is a good alloyed steel. Think it has to do with the air pollution levels as it's soaring here.

Dan

508  General CNC Chat / Show"N"Tell ( Your Machines) / Re: Just got a lathe to retrofit on: February 19, 2012, 03:51:58 AM
Hi Hood,

Can you please show how the tool is fixed in the slot?

What steel is it? Aren't you going to have it plated? Your weather is the worst one could imagine for machine tools.

Dan
509  G-Code, CAD, and CAM / G-Code, CAD, and CAM discussions / Re: Arcs not cutting smoothly on: February 16, 2012, 04:36:20 AM
In any case, this doesn't change anything about the segmented arcs I'm getting on this part. I tried exact stop this afternoon, and it didn't make a difference. Still getting the same behavior.   Huh

I think the answer lies right there, in the numbers of your test. X axis is pretty much obvious, heaving an absolute deviation of 0.002", which is enough for those segments to be seen. I would guess that if you did the test over a longer distance you would see a distinct repetitive nature of the numbers. Entering the numbers in Excel would make it easier to visualize.

Since you're not using a belt drive, you have to start looking elsewhere in the driver mechanism. For instance, what is the motor? Could be a stepper motor with poor accuracy - unevenly spaced poles or magnets on the rotor. Since your Y axis is much better than the X, you could try swapping the motors.

Dan
510  G-Code, CAD, and CAM / G-Code, CAD, and CAM discussions / Re: Arcs not cutting smoothly on: February 15, 2012, 11:42:27 AM
Sorry I missed this:

The length of the flats are .160" on the outside of the large diameter (0.75") and 0.120" on the outside of the smaller diameter. They're also not flat, now that I take a close look. They're definitely arcs in and of themselves.

Outside of the backlash, the axes are very consistent - example: I make a g0 move from x0 to x-3.7500, then from x-3.7500 to x-3.5000. I now zero the glass DRO, and I can make any move in the positive direction and be pretty much dead on (within a couple of ten thousandths, anyway).

Can you extend this test. Zero Mach3 and glass scales (after taking out any backlash) and then do short moves of 0.01" up to a total of about 0.15" and compare the numbers in Mach3 and the glass scale at each point and see if they correlate. Repeat on both axes.

Dan
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