Constructing Janus, by Dirk

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Re: Constructing Janus, by Dirk

Postby steppenshoe » Sat Dec 03, 2011 11:38 pm

Oh no not at all! Obviously you understand electricity and are the one saying to ground and be safe! I applaud you!

It was a generic statement aimed at unknown people to me, but based on some of their comments they apparently don't know enough to build a laser.
They would be better off building a smaller CNC machine first, without a laser power supply.

I think some people take it as a put down being told they should not build the machine when I am saying that out of pure safety concerns for them. Some people take it the wrong way like who in the hell are you to tell me not to build a laser and I was preparing for some flaming based on that.

I was not commenting on any specific person at all.

I do notice every once in awhile Bdring makes a comment about this as well, instructing people that apparantly are not versed in elecronics or electricity to get help.

Just for the record I am not engineer and did not go to a big school, but I do have a BSEET(Bachelor of Science in Electrical Engineering Technology) so I do know my basics.
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Re: Constructing Janus, by Dirk

Postby dirktheeng » Sat Dec 03, 2011 11:54 pm

steppenshoe wrote:Oh no not at all! Obviously you understand electricity and are the one saying to ground and be safe! I applaud you!

It was a generic statement aimed at unknown people to me, but based on some of their comments they apparently don't know enough to build a laser.
They would be better off building a smaller CNC machine first, without a laser power supply.

I think some people take it as a put down being told they should not build the machine when I am saying that out of pure safety concerns for them. Some people take it the wrong way like who in the hell are you to tell me not to build a laser and I was preparing for some flaming based on that.

I was not commenting on any specific person at all.

I do notice every once in awhile Bdring makes a comment about this as well, instructing people that apparantly are not versed in elecronics or electricity to get help.

Just for the record I am not engineer and did not go to a big school, but I do have a BSEET(Bachelor of Science in Electrical Engineering Technology) so I do know my basics.


no worries... I understand now. I went back and reread it and it makes sense now. It's easy to misunderstand what people mean to say on these things.
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Re: Constructing Janus, by Dirk

Postby lasersafe1 » Sun Dec 04, 2011 2:10 pm

Back to your initial comment about the dielectric stength of the tube. After I realized that it is only occuring for a moment during firing I realize that it makes sense to me now. It doesn't really matter how strong the dielectric is (glass tube) when there is another dielectric sitting on the other side, in your case, an ungrounded water system. It's like two capacitors in series. The high dV/dT will pass a pulse through both capacitors. The ultimate charge depends on the value of the capacitors. The first time I witnessed this first hand was when I built a Tesla coil in high school. Using aluminum foil and plates of glass from a window to build the capacitor I was surprised to see the foil between each plate jumping around violently. It's not exactly the same situation, but obviously charge is transferred through the 1/8" glass window pane.
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Re: Constructing Janus, by Dirk

Postby bill.french » Mon Jan 02, 2012 3:20 am

Hey there! What sort of speed and ppi would you recommend I start with for 1/4" soild wood / plywood?

I've been playing with Ben Jackson's PPI setup in EMC2, and so far it seems like I have to slow way down.
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Re: Constructing Janus, by Dirk

Postby dirktheeng » Mon Jan 02, 2012 4:41 am

bill.french wrote:Hey there! What sort of speed and ppi would you recommend I start with for 1/4" soild wood / plywood?

I've been playing with Ben Jackson's PPI setup in EMC2, and so far it seems like I have to slow way down.


I haven't cut 1/4 on my machine since I made the PPI, so I haven't messed with the settings to find out for sure, but in general:

Start with 3ms pulse, 400mm/s, 400PPI, and 100% power.

If the laser doesn't penetrate, double PPI and half feedrate, adjust until you get all the way through.
Examine edges... if too dark slow down until the edges get to the color you want
Look at edges again for smoothness. If they aren't smooth enough proportionately increase PPI and decrease feed rate
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Re: Constructing Janus, by Dirk

Postby dirktheeng » Sun Jan 15, 2012 7:35 pm

It's been a little bit since I've posted. It's been busy at work and I haven't had the energy to work on the projects after work.

Anyhow, I decided to give EMC a go and see how I like the performance. I'm going to try Ben's setup. I like it because it is open source and has some potential to be quite good and it's free. If I like it, I'll start to do more development with it as well. I researched the FPGA's and I can get one that works well with EMC and can handle a lot of the extra stuff I want to do. They aren't too expensive either.
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Re: Constructing Janus, by Dirk

Postby educa » Mon Jan 16, 2012 6:41 am

Dirk, in you post of jan 2nd I suppose you were talking 400mm/MIN and not 400mm/sec .
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Re: Constructing Janus, by Dirk

Postby dirktheeng » Mon Jan 16, 2012 10:41 pm

educa wrote:Dirk, in you post of jan 2nd I suppose you were talking 400mm/MIN and not 400mm/sec .


yea your right
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Re: Constructing Janus, by Dirk

Postby dirktheeng » Mon Jan 16, 2012 10:44 pm

Ok,

it took some doing, but linux 10.04 is up on dual boot on my machine! I had a lot of trouble getting my USB wireless device working, but I am posting from that computer now... I guess it works ok. There are some other driver problems that I have to work out, but they won't impact emc, so that is ok. Mainly my sound isn't working right, but that is no problem. I just can't watch Youtube videos from this computer. Linux is pretty good, but it's a pain sometimes.
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Re: Constructing Janus, by Dirk

Postby educa » Wed Feb 01, 2012 1:08 pm

Did you get EMC working allready ?
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