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Messages - ART

1
Show"N"Tell ( Your Machines) / Re: The Laser Project.
« on: August 04, 2018, 11:23:12 AM »
Tweakie:

  Thx, nice to know. Nice to see lasers getting some respect. :)

Art

2
Show"N"Tell ( Your Machines) / Re: The Laser Project.
« on: March 15, 2018, 07:14:01 AM »
All G1's.. I turned off rapids for that test :)

Art

3
Show"N"Tell ( Your Machines) / Re: The Laser Project.
« on: March 14, 2018, 03:03:35 PM »
Tweakie:

    Just starting to test..

https://www.youtube.com/watch?v=5bOzb-32pa8

  Im impressed so far, but you know I see nwo speed wont help in photos at all.
The Laser is controlled in 1ms packets, so if you raster a photo at 1 second across,
it will have a resolutoin of 1000 pixels. At .5 seconds, only 500. Faster you go the
less res you have. In theory a 4k image at 4 seconds per raster sweep is the highest res.
one can get ..

  I'm finding galvos are great at vector works, infinite acceleration helps.. but for photos
I think speed is my enemy..

Art




4
Mach4 General Discussion / Re: Mach4 Printer Port Discussions
« on: March 02, 2018, 10:38:29 AM »
No Problem, glad it helped.

5
Mach4 General Discussion / Re: Mach4 Printer Port Discussions
« on: February 24, 2018, 02:59:01 PM »
Hi Alister:

  I happened to be in XP this week, and recompiled Darwin for a probe stop time of .1 seconds instead of .25

 Cant promise this runs, as the other attempt didnt, but was in Win7, but this was compiled under XP in the MAch4 system, so it should. If yourstill trying to speed up probing, you may want to try this plugin..

Thx
Art

6
Show"N"Tell ( Your Machines) / Re: The Laser Project.
« on: February 15, 2018, 08:38:38 AM »
Hi Tweaky:

   Thanks for the photo of the Z axis lens. I was aware of, but hadnt seen one. Synrads newest also uses this, they use a voice coil
lens to move it the required theta distance as the mirrors sweep.  The real problem I think with Galvos is the distance vs focus spot
formulas. For a TEM0 laser like the RF ones, focus size is  (4*wavelength*focal distance) / (PI * inputdiameter). InputDiam is ually around 2-3mm for a co2, but with an expander mine is 12mm or so.

   I have a beam expander to try to get the smallest dot possible. The formula shows how important the expander and focal distance is though. You can double the effective power of a laser by expanding its beam prior to focus or simply by using a smaller focal distance.
So galvos have it rough, to get a 12" field for example if that field requires a 12" focus length,  thats (4 * .01 * 304) / (3.14 * 12mm) = .322 and thats if its a good lens. When a focus gets that large you need alot of power as power reduces 4 times faster than its growth in distance.  Its this balance that Im currently working on as I puzzle out the size matrix I want from my galvo. I always knew smaller focus
distances were better, but till I crunched the numbers I didnt realize just how much better and why.

  When it comes to Depth engraving, I shoot one level, leasure the distance engraved, and then do multiple levels
using that initial test pass's depth as the multiplier for pass depth. It produces 3d images to a very close desired depth I find that way.
Each material being different, its only a guide but allows pretty good 3d.


7
Show"N"Tell ( Your Machines) / Re: The Laser Project.
« on: February 14, 2018, 09:40:45 AM »
Ive learned quite a bit on the galvo's.. I can see where the real problem is the F-Theta thing. Its
really not that expensive to do the rest. Ive used an arduino to convert step/direction to analogue
values and a DAC to control the galvos. Easy enough, but the pincusion and focus will be the real
challenge.. Ive a lot to learn there..

Art
 

8
Show"N"Tell ( Your Machines) / Re: The Laser Project.
« on: February 14, 2018, 07:57:26 AM »
Tweakie:

  Yes, I try to post in for archival purposes when I can so others following will have some data to find. Laser information can
be hard to find and hard to research.

  (btw: I now have my galvos working as step direction wiring and happily jogging around with Auggie and even homing nicely.. My problems now I think are mainly the damn theta lens, one of those things with very little information to go on. )

Art

9
Show"N"Tell ( Your Machines) / Re: The Laser Project.
« on: February 14, 2018, 07:18:52 AM »
>>Various tube manufacturer's (such as Synrad) withdraw their warranty if their tubes are mounted  beyond a defined angle to the horizontal.

   75 degrees to the vertical is the maximum allowed with SynRads.

(nice circuitry on a cable Tweak.. very tidy way to do it.)

Art


 

10
Show"N"Tell ( Your Machines) / Re: The Laser Project.
« on: January 19, 2018, 08:41:42 AM »
 Yup, typical problem. Best to just keep playing with material and such to find one that gives a
good grey scale on your machine, then photos shoudl start to look better.

Art