Constructing Janus, by Dirk

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First cuts... Again!

Postby dirktheeng » Sun Oct 07, 2012 6:35 pm

After that big ordeal moving and having multiple kindey stones, I finally got the laser set up again... I don't have it vented yet, but I got it set up and cutting.

I'm going to cut a hole in the bottom of my exterior door in my garage like a doggy door, but it will house the fan. There is a screen door on that door as well that I can open and vent through. That also provides weather protection so I don't have to worry about leaks and such. I've got it designed and ready to cut. I'll probably go to the local home center and pick up some other parts and do it tomorrow.

Geting excited about this again. I'm going to also build some enclosures and stands to attach the radiator and power supply so it isn't so hokey anymore. Then christmas presents again and more stuf for fun!
dirktheeng
 
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Re: Constructing Janus, by Dirk

Postby educa » Sun Oct 07, 2012 7:00 pm

You don't have an engraver? And Janus? Or do you mean he is still in a box? How did you engrace with Janus or didn't you engrave at all
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Re: Constructing Janus, by Dirk

Postby dirktheeng » Tue Oct 09, 2012 2:19 pm

I don't have a controller that can do high speed engraving. I was looking into developing one a while ago and have come accross smoothie. The only other choise at this point is the DSP for $450. I've been resisting that and hoping that I or someone else can develop an open source controller. I haven't made up my mind as to what I will do yet. I've learned a lot about how stuff works in the process of looking into development, but I don't have anything but DotG and mach plugin to try to engrave. They are G-code engravers, which work, but are very slow.
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Re: Constructing Janus, by Dirk

Postby educa » Tue Oct 09, 2012 2:31 pm

okay, my purpose it to have a chipkit do all the stuff...

I also have my own aproach to do PPI calculations. I used additions and let the counter overflow.

Anyway, there is still a lot of work to do.


My biggest problem is in acceleration ramping.
My lasercutter can run at 15mm/s from step 1 and for faster speeds it has to accelerate (at 6000 mm/s^²)

So as long as I cut at speeds UNDER 15mm/s everything is extremely easy to do. For most products 15mm/s is also allready very fast.

Speed ramping is easily possible with a precalculated table (the chipkit has a 32 bits 40MHz counter variable) but my only concern is that during that ramping I must be sure that my controller can get the gcode data fast enough. For example if you make a circle with 1000 lines, then this is a very smooth circle and you shouldn't break and reaccelerate for each line (1000 times) , but at top speed (which is 1000mm/s for me) that means that you must be able to provide your data very fast. Its all about the extreme conditions. Normal use isn't that problematic but I see that you made your ppi counter also able to go way faster then your steppers will ever go to be sure that won't be a limiting factor.
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