Discussions and help on this commercial controller.

Moderator: twehr


Postby twehr » Wed Nov 23, 2011 4:30 pm

lasersafe1 wrote:You forgot a couple others:

1. Highly accurate pulsing engine within the DSP, as opposed to not so accurate when a PC is involved where it must hop out to handle interrupts. This allows steppers to run at much higher step rates without losing steps.

2. NO GCODE EVER! None, zip, zilch, bye bye. This is what sold me.

Remember, John. My forgetfulness is why you are here!
"The answer is usually easy and obvious once you know what it is." tw

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Postby r691175002 » Wed Nov 23, 2011 5:08 pm

Currently a PC is more cumbersome for laser control since it cannot engrave or control power very well (The frequency it operates at is far too slow). It also takes longer to go from a drawing to a finished part since you need to do the intermetiate g-code step.

If you are only doing cutting g-code can have advantages. It is hard to do proper tool radius compensation in graphics programs so g-code will generally be more accurate. People have been using g-code for a long time and there are lots of features that help with productivity such as work offsets. Finally, if you have a computer lying around it is a lot cheaper.

I would recommend getting a dsp or retina. IMO A laser is about making parts fast. With the retina I can sketch a plate with some holes in coreldraw and press print. I have made extremely accurate parts with great finish in less than 5 minutes. I feel like as you add steps between having a drawing and having a part you lose one of the major advantages of a laser.

If you are willing to spend time in CAD a router starts to compare favorably to a laser for some materials.
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Postby Knack » Thu Nov 24, 2011 9:58 pm

Thanks guys for all of the replies. Now it makes sense. Time to get a dsp when I order my electronics.
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Postby mikegrundvig » Fri Nov 25, 2011 6:00 pm

I'm in the process of designing my laser right now. I built a CNC milling machine (not router) a few years ago and used EM2 with CAMBam and then moved to Mach3 and CAMBam. I did enough with it to justify a much larger commercial CNC milling machine and use Mach3 and VisualMill/VisualCAM with it on a weekly basis. I consider myself pretty good at creating something in CAD and then generating g-code from it to then mill up in aluminum on the machine. If you've looked at my design thread in the general forum, all of those pics are things I will cut on my mill. I'm actually prototyping a bit of it this weekend in fact.

I have to be honest, I think people using g-code for a laser cutter are crazy if they can afford a DSP (don't get me started on GRBL w/Arduino :) ). I feel that r691175002 is 100% correct. G-code is powerful and capable. It's also a rather significant tool chain step that really slows down the use of a laser cutter. The process of drawing the image, going into a CAM program to annotate and generate g-code, then going into a controller program (EMC, Mach3, etc) to run the g-code is a pain in the butt. Revisions require a re-export of the CAD file unless you've got a very expensive "continuous-integration" setup OR you are drawing in the CAM package which can be very painful. I've spent well over 1000 hours using my big mill and I can tell you that once you really get into it, every step in the process becomes a burden. I recognize the need to use g-code on my mill because it does far more sophisticated things like 3d machining, tool compensation, ramping-in and out of cuts and holding tabs, re-machining, etc. I need the low-level abilities it supports. There is a fair bit of overlap between a laser cutter and mill/router at a low level but you add a lot of overhead to support using the same tools on both. So then people try and automate things by using good 2d CAM packages like Vectrix Cut2d which simplify 2d-only cutting as much as possible. The reality is that a DSP has all this built-in already and does a dang good job of it. A DSP is NOT as capable as a CAD/CAM system, but a great laser cutter is still far simpler and less capable than a 5-axis mill too. Less capable then even a 3-axis router.

Whew, long winded way for me to simply say - use the right tool for the job. Succinctly: in my opinion g-code is not ideal for a laser cutter, not because of the g-code but because of the tool chain and work flow.

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Postby kbob » Tue Aug 14, 2012 7:00 pm

Simplest imaginable question: What does DSP stand for? Is it just Digital Signal Process(ing|or), or is it a different acronym? I've been Googling like mad, but can't get an answer.

Second simplest question: If it does stand for Digital Signal Processor, why are these controllers called DSPs? There's a lot more to it than just signal processing.

The wiki link in the first post still doesn't point to anything, BTW.
"If you didn't code it, it will never own you." (-:
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Postby lasersafe1 » Tue Aug 14, 2012 7:34 pm

It stands for Daniel Sebastian Palmer, the little-known lab assistant to the inventor of the carbon dioxide laser.
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Postby macona » Wed Aug 15, 2012 1:03 am

The controllers use a DSP chip to handle the number crunching needed for stuff like engraving.
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