UL-25E "surplus" Laser Engraver rebuild

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Re: UL-25E "surplus" Laser Engraver rebuild

Postby pixpop » Wed Feb 10, 2010 8:45 pm

I thought you had a picture showing the compartment where the original laser was mounted, but I can no longer find it.

The reason I'm interested is that I have one of those lasers and am trying to figure out how to mount it. There are no mounting holes anywhere on the thing, and it looks as though I need to build some kind of clamp that will attach it to a wall or base somehow. Mine is water cooled, so I don't need to allow space for the fans, and I could potentially clamp it anywhere along its length.

It does have a baseplate that's attached with a large number of countersunk screws. I could possibly remove a few of those screws, and use those (threaded) holes to mount it from below.

I'm surprised that they provide no mounting mechanism. I would think that any application would need a means to position the laser securely relative to some optical element, so the optical path is not affected by vibration, or thermal expansion, etc.

Anyway.. was there any evidence left in the machine that might show how the laser was attached?

Neil
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Re: UL-25E "surplus" Laser Engraver rebuild

Postby lasersafe1 » Thu Feb 11, 2010 1:41 am

pixpop wrote:I thought you had a picture showing the compartment where the original laser was mounted, but I can no longer find it.

The reason I'm interested is that I have one of those lasers and am trying to figure out how to mount it. There are no mounting holes anywhere on the thing, and it looks as though I need to build some kind of clamp that will attach it to a wall or base somehow. Mine is water cooled, so I don't need to allow space for the fans, and I could potentially clamp it anywhere along its length.

It does have a baseplate that's attached with a large number of countersunk screws. I could possibly remove a few of those screws, and use those (threaded) holes to mount it from below.

I'm surprised that they provide no mounting mechanism. I would think that any application would need a means to position the laser securely relative to some optical element, so the optical path is not affected by vibration, or thermal expansion, etc.

Anyway.. was there any evidence left in the machine that might show how the laser was attached?

Neil



I "think" the laser that came with this simply slid into the chamber with the fans. I don't know. I didn't have a still picture of it, only the video of arrival. Looking at the cover that I took off I can see a couple of screw holes in the back side, but they are tapped. This wouldn't make sense for grabbing a laser housing that might be tapped. I just don't know.
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Re: UL-25E "surplus" Laser Engraver rebuild

Postby lasersafe1 » Thu Mar 04, 2010 3:14 am

New pictures of some recent progress

The 40W DC High Voltage laser tube is now mounted in place of the original Synrad. Some might view this as a crime, but the more I use this tube, the more I like it. I may switch to an RF laser in the future, but I'm a year into my first tube and have seen no problems at all.

I used Tygon tubing exclusively for all water lines. The tube has a 1/4" ID that perfectly mated with the nipples on the laser tube. My pump actually had a 5/8" nipple on it, but with careful heating and stretching of the Tygon over a cone shaped object, (tip of a tube of silicone caulk), I was able to stretch the 1/4" ID tube all the way for a nice tight fit over the pump nipple. The Tygon can also be heated and stretched to reduce the diameter. It gets soft at 190F, so putting the end in a pot of boiling water makes it easy to work.

I made my water reservoir out of 2" schedule 40 PVC. A normal cap on the bottom and a screw-off cap on top for filling the system. I drilled and tapped the side of the PVC for hose nipples. Seems strong. No leaks.

I didn't go with a flow meter yet. The pump and radiator coils are from a surplus chiller, so they should be very reliable. I tapped a third hole in my reservoir that is presently plugged. This plug can be removed and I can insert a thermister in the return stream. This is the only place in the system where there is a "fountain" stream through air as the fluid enters the reservoir. I can build a circuit that applies current to the thermister to heat it and then reads the resistance once a second, which is proportional to temperature. If the stream is present over the thermister it will be held at the cool water temp and will not self heat. If the flow stops, the thermister will self heat and trip the laser off. It isn't as cute as the spinning flow meters, but it has no moving parts to fail and should be trouble free. The entire upper section gets covered by a steel enclosure that hangs off the yellow tabs up top. This covers all electrical lines and the laser tube. The only exposed items beneath this enclosure will be the water pump, the radiator, and the bottom of the reservoir.
DSC02049.JPG



The next picture shows my new adapter plate that lets me put the new DSP control interface on the front of the unit. I added an E-Stop button and a 12pin keypad. The keypad can be used for a number of functions once I program a PIC to read it. A couple example applications:
1. Password entry for machine startup.
2. Press * then enter desired table height. (for stepper controlled Z)
3. Code to start or stop exhaust fan. (Fan not needed for glass, granite, rocks, etc.)
4. ??? Many other things I haven't thought of yet.
Thought about adding an LCD for this keypad as well for better PIC to keypad user interaction. Can always add this later.

I may scrap this panel later and start over. I bought an Arduino with TouchShield Slide, so I could make an interactive control panel with touch screen. The TouchShield is really nice with bright colorful OLED display. Way overkill for this application though. http://www.liquidware.com/shop/show/TSL/TouchShield+Slide

DSC02050.JPG
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Re: UL-25E "surplus" Laser Engraver rebuild

Postby bdring » Thu Mar 04, 2010 3:54 am

That looks great.

There is no such thing as "overkill". Half the reason we do these things is to have something we can be proud of.
Bart
"If you didn't build it, you will never own it."
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Re: UL-25E "surplus" Laser Engraver rebuild

Postby buildsomething » Thu Mar 04, 2010 2:38 pm

Looking really good and well laid out.
I like your chiller unit and water resevoir...nice touch. Once I get mine up and running that I will have to do that as well. At preent its just a 5 gallon bucket with a small 12 volt boat bildge pump in the bottom.

Keep up the good work.

Richard
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Re: UL-25E "surplus" Laser Engraver rebuild

Postby lasersafe1 » Thu Mar 04, 2010 5:28 pm

There were a couple of "Gotchya" moments when I first laid out the water flow. An example: I initially went from the bottom of my reservoir to the top of the radiator. Then from the bottom of the radiator to the suction line of the pump. When I would fill the reservoir there was an air bubble trapped in the radiator that would not clear even when I started the pump. This is because the bubble would be forced downward but would overcome this force because it wanted to float.

I reworked the line so the bottom of the reservoir goes to the bottom of the radiator. Now when I fill the system it fills from the bottom up all the way through all components and clears the air from the lines.
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Re: UL-25E "surplus" Laser Engraver rebuild

Postby lasersafe1 » Tue Mar 09, 2010 1:56 am

Rebuild COMPLETE!
Yes, I will still continue to make small improvents, but for the most part I consider this unit to be complete since it buttons up tight and performs the tasks that I need it to perform. The thing runs great! I thought I may need to up the motor size for my X sweep motor, but I can make it fly quite fast and it doesn't ever slip. Video coming later.

DSC02054.JPG

There was less room than I thought there would be once I mounted all the various power supplies. It didn't help that I had a mix and match of items that needed various powers. 12V pump, 24V motor, etc.

DSC02060.JPG

Notice the piece of Tygon tubing at the front output of the laser tube? I did this because the whole corner lens assembly is sealed and there is a ZnSe window to let beam into the main work area. This tube now makes the seal complete. No dust means no mirrors to clean. I assume the original Synrad had something similar to seal it up.

Notice the ground lead going to the cathode? I don't use a connector at all on the anode or cathode. I scrape the lead with a razor blade to expose clean metal and then I wrap the freshly stripped wire around this lead. I then squirt hot glue over the wire and lead to seal it up. No air means no corrosion. I discovered in my day job that 1/4 inch of hot glue can hold off 100,000 volts, so now I use it everywhere whenever I want a nice insulator. It also makes a sturdy connection that can't accidentally fall off.

DSC02061.JPG

Closing up the corner mirror box.

DSC02062.JPG

Rear Covers now in place. Looking Tight!

DSC02063.JPG

Isometric view of rear enclosure.
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Re: UL-25E "surplus" Laser Engraver rebuild

Postby lasersafe1 » Tue Mar 09, 2010 2:06 am

Oh This really SUCKS!

DSC02056.JPG


Made a trip to the local dump to drop off an old lawnmower. Hey! What's that over in the scrap heap? An old furnace blower!
I snagged it and took it home. Runs great! Can't beat the price! It has something like a 1 HP direct drive motor (on the opposite view). Now I simply need to make adapter plates to adapt to my 4" laundry vent line.

The only downfall is that it needs 220V, but I can use an autotransformer to step up 120.
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Re: UL-25E "surplus" Laser Engraver rebuild

Postby bdring » Tue Mar 09, 2010 2:10 am

OK...I take back my statement on overkill !
Bart
"If you didn't build it, you will never own it."
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Re: UL-25E "surplus" Laser Engraver rebuild

Postby lasersafe1 » Tue Mar 09, 2010 2:25 am

bdring wrote:OK...I take back my statement on overkill !


Okay, it may be, but then again you should see the picture in the ULS tech manual. I would post it but the manual is copyrighted. It calls for a MINIMUM of 235 CFM at 6 inches of static pressure. That is for a 7 foot hose run. They have a table of various lengths. The 23-30 foot run requires a blower rated at 625 CFM at 6" static pressure. It goes on to say the blower must be mounted on the outside of the building either on the roof or on a cement pad next to the building.

I guess I don't understand this part?? Why outside?? Is it because the centrifugal fan is good for suction but not good for discharge through a long tube? Edit: I now know why. If there is any leak in the suction line there is no problem with poisoning the air inside the building. If there is a leak in the discharge, no problem, it's already outside.

Someone else posted the manual for this system. Section 2 discusses the air flow system. http://www.hltlasers.com/reference/25-50PSRevisionB1.pdf
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