Commercially available laser controllers

Electronics related to CNC

Re: Commercially available laser controllers

Postby lasersafe1 » Wed Jun 30, 2010 5:10 pm

I have to guess there must be some reason the US manufacturers are going with RF. I have found nothing wrong with the Chinese tubes I have purchased and I am about 2 years in now. It really is hard for me to justify the increased cost of the RF tubes, but there must be some motivating factor that the US companies use to choose the RF. Perhaps it is a simple answer. Perhaps the US just sucks at glassblowing technology and can't make the sealed tubes as well as the Chinese. I hope to someday learn the answer. I really don't understand why the Chinese haven't made an affordable RF laser yet.
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Re: Commercially available laser controllers

Postby lasersafe1 » Wed Jun 30, 2010 9:31 pm

Another possible reason for the need to go with an RF laser..... Back in an earlier post (http://www.buildlog.net/forum/viewtopic.php?f=6&t=36&start=20#p501 I provided the measurements coming out of my DSP controller during a raster. The power level was set to some constant power and the TTL line would bang on and off in order to tell the laser to fire. This TTL bit banging was occuring as fast as 15us on-off. The laser would turn on at the constant set power during the time period of the TTL high. In order to have true analog levels of power output, the DSP controller would need to be putting out the TTL for on-off (and) it would need an analog level coming out for setting power.

I have already proved to myself that I can go full-on and full-off within 15us on the DC CO2 tube. It could then be assumed that the tube can change power from one setting to another within 15us, but I think it is beyond the ability of the present state of the art for the power supplies to handle this control input. Somewhere I thought I read about tens of millisecond response times to a power level command change. I'm sure this number came directly from the PWM to analog conversion time of the Chinese power supplies, basically an RC time constant.

The RF is probably much easier to control. You can adjust the intensity of an RF amplifier in nano-seconds, and turn it on and off with a PIN diode (also within nano-seconds). Perhaps this is the reason the Synrads are so popular (and expensive).

There is good info at the FAQ section of Gantryco. http://www.gantryco.com/faqs-3d-256-grayscale-graphics.html
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Re: Commercially available laser controllers

Postby lasersafe1 » Wed Jun 30, 2010 10:26 pm

OK, Now I'm really confusing the hell out of myself. I go to the Jamieson laser website who "supposedly" handles 3D according to the Gantryco site and I see the following example:
3D%20Eagle.jpg


Now this output looks exactly like the output that my machine would produce. Clearly in my eyes I am seeing a Dithered bitmap depth contour. This is not an analog depth control. The Jamieson controller looks remarkably similar in origin to my DSP controller. (China) Yet they claim it is american made.

Next I go over to the Synrad web site and check the specs on their 100W laser and I see on-off control specs of (<75us). This blows away my theory of the RF laser being faster than the DC tube.

I am really confused now. Perhaps all the controllers are putting out this dithered burn pattern, but the examples they show on the Gantryco site have undergone some post production smoothing. I have sent out a few emails to the various companies to try to get an answer on this.
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Re: Commercially available laser controllers

Postby Tweakie » Thu Jul 01, 2010 7:40 am

This is most interesting information LS1 please keep posting the results of your findings / investigation on laser control.

Thanks,
Tweakie.
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Re: Commercially available laser controllers

Postby willyinaus » Thu Jul 01, 2010 7:46 am

Hi LS,

I have been thinking about his as well http://www.fullspectrumengineering.com said in their post that they think their new RetinaEngrave will be able to go head to head with an Epilogue or Universal be interesting to see and how well it can do carvings etc.

I had sent them an email but have had no reply on anything as yet so maybe they are just trying to get some traffic to their site anyway time will tell if what they have is the real deal and if they come to the DIY market with something.
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Re: Commercially available laser controllers

Postby Tweakie » Thu Jul 01, 2010 8:46 am

Hi Willy,

I am a bit wary of any business which claims to have many highly qualified staff but decline to include their address (other than Vegas) and only sees by appointment - it could be a kid operating from their bedroom for all I know. Certainly the Mach3 compatible setup doesn't hold up (at least not for me). http://www.fullspectrumengineering.com/ ... orial.html
I don't like being negative but this one doesn't ring true to me.

Tweakie.
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Re: Commercially available laser controllers

Postby willyinaus » Thu Jul 01, 2010 9:11 am

Yes mate I agree, the Mach3 setup from what I gather isn't what they are talking about.
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Re: Commercially available laser controllers

Postby lasersafe1 » Thu Jul 01, 2010 12:38 pm

I have had extensive conversations with Henry at FullSpectrumEngineering. He is a good guy. Yes, it is true that the business is just a couple guys who also have full time "day" jobs. Henry is a PhD physicist I beleive. It is wrong to think that just because a business is a garage setup that it can't produce a good product. Thorlabs was started as a guy with a Bridgeport mill in his garage. Now it is a billion dollar company. Oh, and then there is that little company named after an apple.

On the flip side of the coin, when your business is small you need to be extra careful not to announce something that you can't deliver or release a product that is not fully tested.
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Re: Commercially available laser controllers

Postby lasersafe1 » Thu Jul 01, 2010 12:50 pm

No replies yet on the post-processing, but I was thinking about this last night. Clearly something must be done to clean the wood after engraving. The wood on the Gantryco site is so clean that it looks like it came out of a precision CNC mill. There is no laser in the world that could leave this clean surface.

I mentioned earlier that I saw a tech note about using the "orange glow" hand cleaner and a toothbrush. I have tried this and it does remove the burnt sap and charred surface contamination. I am now thinking about a fine abrasive media blaster to carefully "knock down" the sharp points left behind after the 3D engraving. This would essentially be a 3D sanding of the surface to smooth it out and clean it. It needs to be done gently or we would give up too much detail.

I have one of these at work. It is a VERY nice unit for precision work. I think I shall borrow it to give it a try.
sandstorm-mobile.jpg
sandstorm-mobile.jpg (19.42 KiB) Viewed 19430 times


http://www.vaniman.com/sandstorm-mobile-80140.php
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Re: Commercially available laser controllers

Postby bdring » Thu Jul 01, 2010 12:50 pm

I have had dozens of conversations with Henry Liu, the head of Full Spectrum Engineering, since the very beginning of my laser project. He also teaches a computer control class at UNLV. I trust that he will not release a product until it does what he claims and believe he will stand behind his product. You may have noticed that I have provided a link to his web site on build log page at no charge to him due to the help he has given me.

I cannot vouch for his controller, because I have not used it yet (He has offered me one once they they are ready). I suggest anyone considering any controller product to contact the supplier and get a feel for their support. I think you will be pleasantly surprised. I know a lot of people using the Chinese controller have not been happy with the support (I don't think they were surprised though).
Bart
"If you didn't build it, you will never own it."
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