Archive for November, 2011

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And then a step to the right

November 30, 2011

The search for replacement stepper motors is on. The first step was identifying what is there already.

Two of the 3 steppers (X & Z) are easily identifiable, as I can read the labels on them. The 3rd stepper (Y) unfortunately has had the label completely darkened from the fire to the point where all I can tell is that is is a 0.9 degree/step stepper from the one side that is still readable.  Luckily with a peek at the laser at the Hacklab, and at a picture posted by a user (lasersafe@buildlog.net) of another ULS laser rebuild, I was able to identify the make, and possibly model for the unknown stepper. It is definitely the same manufacturer / series based on what is still discernible on the label of the motor. However it is quite possibly a different model than the one that is in both the Hackalab’s laser, and lasersafe’s UL25E. (the part number, while unreadable appears to be different) Read the rest of this entry ?

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Like money in the bank

November 29, 2011

I took a 5 minute break at lunch to see if I could tackle the engraving table. As this part is $500 to replace, it will be a huge savings if I can de-laminate the top sheet of aluminum off of it.

As you can see from the picture above, the top surface is badly warped. Luckily this provided good access to insert a parting tool to try and separate the top from the bottom. The hardest part of the process was actually backing out the two thumb-screws that hold the rotary attachment alignment bracket in place [seen on the left edge above]. Once I got those out, it took less than a minute to break the top panel free. The heat appears to have pretty much completely released the panel from the inner structure.

The table, as you can see above, is actually composed of a fragile aluminum honeycomb structure glued between the two thin sheets of aluminum on the top and bottom. Around the edges is a 1/2in x 1/2in solid aluminum bar to provide additional rigidity and compression strength for the mounting points. On their own, each of the components is quite flimsy [with the exception of the bar that runs the perimeter] But once glued together, it is very strong, rigid, and lightweight.

The next step, for the table, will be to give the remaining part a wash, and perhaps rubbing with some steel wool to remove all the dirt from the remaining structure. Re-gluing a couple of points on the bottom sheet, as it has come lose in a few places. And then buying and machining a new top sheet with holes in the right places, before gluing it on. Luckily I can use the bottom half of the table as a template for the machining, so it should be quite easy to do.

All-in-all $500 savings for 5 min of work… I’d say it was a pretty good return on my investment! 🙂

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The price of admission

November 26, 2011

So I finally got my quote back for all the ULS parts this week. It came in quite a bit higher than I anticipated. While most of the items are tolerable, some aren’t. [all prices are Canadian, and don’t include the 13% tax I need to pay as well]

Optics: $460

This is where I expected to spend the most. So I’m okay with $460 for replacing everything in the optical path.

Timing Belts: $140

A bit pricey, but they are kevlar re-enforced timing belts, so I’ll let it slide.

Idlers: $90

Ok, these are a bit rich, I’ll need to see if I can find an alternative source. But in the grand scheme of things, just a drop in the bucket, so if I must, I can live with it.

Bearings: $200

Ouch! Not much I can do here, unless I can find them cheaper from another supplier. or machine my own alternatives. There are some custom components involved, so perhaps justifiable.

Lens/Focus carriage: $400

Thank the gods I was able to salvage this! Chalk Fridays efforts up in the WIN column for a second time 🙂

Engraving table: $500

This was an unexpected price, given that the engraving table is rather uninteresting. I will have to see if I can salvage the old one, by removing the top aluminum sheet, and replacing it. [probably next Fridays efforts/post]

X Rail: $370

WTF!!! This is an insane price. The X Rail is simply an anodized, light weight aluminum extrusion that is 27 inches long. Unless I can find some serious savings elsewhere in this project, it’s pretty much a given I’m going to have to engineer my own alternative solution. Sadly this one part is also a major hinge-pin for the entire project.

 

All-in-all the grand total came to ~$2,150 plus taxes to replace the optical & mechanical parts. Let’s not forget there’s still the control panel, and motors at a minimum that need to be replaced as well. Now thankfully I have salvaged the lens/focus carriage, and I’m hoping to salvage the cutting table, so that will bring it down to ~$1,250 + taxes, still up there, but much more manageable, and in the ball-park of what I was expecting.

Unfortunately life has thrown a couple of financial curve balls at me the past few weeks, so I’m going to have to re-visit my budget, and probably spread the costs out over a greater period than initially anticipated. My initial time line was to have all these bits in place by January, but now it will need to be quite a bit later than that, unless a money tree sprouts up in my back yard.

I wonder if I can start a charity to save a sick and dying laser? 😉

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One less thing

November 24, 2011

Well today I decided to try and salvage the flying head that carries the #3 mirror and focusing lens. I had pretty much written it off, as it was partially encased in molten glass & plastic. It also fell into the fire, so I assumed the worst for the parts of it that I could not see.

If you don’t remember from the earlier pictures, this is what I started with:

I grabbed some pliers and started tearing away at the globs of plastic & glass. To my surprise most of it peeled away fairly easily, with just a few stubborn bits left stuck to the head. Once I got the bulk of it off, I tried to remove the lens/mirror assembly via the two thumb screws on the front [it is mean to to be easily removed/replaced]. Unfortunately it didn’t want to budge. So I proceeded to fully disassemble the head, by removing every screw I could find. Eventually it all came apart. Some plastic had mad it’s way inside and was gluing the lens to the case. A little prying and I got it free. After that I cleaned each part individually, mostly by gently scraping with a bare box-cutter blade.  I then re-assembled it.  And this is where it’s at now:

While it doesn’t quite look like new, it is a stark contrast to what it was before.  With the exception of some chipping and pitting on the anodized coating, the head is in very good shape, and appears to be totally usable. The optics within are another story, they are unrecoverable, but easily replaced now. The 3 arms on the head also normally have rubber bearings/wheels on them, these need to be replaced as well [also easily done]. Luckily, the spring loaded mechanism on the 3rd arm is working perfectly. I may get the head re-anodized to give it a like new look, it will depend on the cost to do so, and how many other parts need/warrant anodizing. Having said all that, I am ecstatic that I was able to salvage the flying head, it is one less item I will need to buy or engineer to replace.

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On the mark

November 19, 2011

I decided to fire up the laser again, and get some pictures this time. So while I was at it, I decided to check the beam alignment between the visible and burning laser beams. I also got some pictures of the test set-up.

The key switch is for the safety loop, the burning laser will not fire unless the key is in, and turned. The trigger-switch is bi-directional, with one direction firing the red pointing laser, and the other firing the burning laser. There is no reason why the two cannot fire at the same time, it’s just what I had sitting on my shelf. The laser itself requires 12V for the safety loop [it can provide it, but my wiring harness does not have that pin connected] Also required is 5V for the firing control, this must be externally provided. Finally the laser needs 48V to power the laser itself. The 48V is taken from the original power supply, while I am providing the 12 & 5V from a lab supply.

To Check the laser up as above, with a piece of white card-stock taped to a concrete block wall, about 2ft away from the laser. I then fired the visible laser and marked the location of the spot with a pen on the paper.

One might notice that there are 4 red spots. One main bright spot, and 3 more smaller fainter ones. I’m not exactly sure why they’re there, but I’m assuming it is a result of the beam combining optics. They use what is known as a 45° hot-mirror, which reflects the IR light of the laser, but passes the visible light through. This is what allows the two laser beams to be perfectly aligned. So in the case of the ULS laser the setup is as follows.

I’m guessing the extra spots are the result of some internal reflections of the red laser within the mirror glass. Either way, they are not an issue. After marking the main spot, I proceeded to fire the CO2 laser, and then re checked with the visible laser. I tried my best to capture the moment of the laser firing, but it just shows up as a large bright white spot. This flash of light is from the material burning, not from the laser itself.

As you’ll see from the image below, the alignment is pretty darn good. So from my perspective, the laser is in perfect operating condition. I may just have to swap out it’s air-cooling fan, as it made some noise the first time I powered it on, though it did not make it again this time around.

So there it is, a fully functioning CO2 laser 🙂 This was probably the last time I fire the laser until I have it back in the enclosure. I don’t like to fire it in the open like this for safety reasons. So for now I’ve covered up the optical aperture on the laser to prevent it from getting dirty, and placed it on the shelf. Hopefully I’ll get a reply from the ULS rep soon, so I can start moving forward on the actual re-assembly of this thing.

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X marks the spot

November 19, 2011

Finally the X axis movement.

The X axis movement is constructed of a light-weight thin-walled extruded aluminum [or some other lightweight alloy] channel. It needs to be lightweight in order to minimize the mass, allowing for higher movement speeds without overshoot. On it, rides the lens and focusing carriage. There is a belt that runs along the front, and then returns inside the channel to the stepper motor on the truck/carriage of the right-hand Y axis rail that moves the cutting head. The laser beam comes in from the left, via a mirror that sits on the truck of the left hand Y axis rail.

Unfortunately, because it is so light weight, this axis suffered the most damage in the fire. It is completely unusable as it is. The rail itself is warped into an arc, the belt is all but gone, and the head is encased in the molten glass from the viewing window. [I found out the top window was indeed glass, and not acrylic as I had surmised in an earlier post] I am hoping to get a replacement rail from ULS, but this may not be possible. If I can’t I will likely use some stock aluminum extrusions one can find at the local hardware store. This solution will be slightly heavier, but should still work fine.

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Y oh Y

November 19, 2011

Onto the Y axis movement.

The Y axis movement consists of two linear slides that are mounted on either side of the Z platform. They are mounted to the deck, and not the the Z stage, so that the Z stage can be used to control the distance from the material to the cutting head. The slides themselves are machined out of a solid bar of aluminum and then anodized. They are quite heavy duty and in excellent condition. The trucks that ride on the rails are in relatively good shape as well, though they do need new wheels/bearings. The belts and idlers for the belts also need to be replaced [normal service items, so not a big problem]. The belts that move the trucks, and by extension the X axis, are driven by a dual shaft stepper. This configuration eliminates the possibility of X axis twisting or racking, as both sides move in unison. The hardest part will be squaring up the assembly when I put it back together. It is a very well thought out, and simple, design. Once again the stepper motor will be replaced, although it does turn freely as is. This is one area where I may elect to upgrade in order to have more power for moving a heavier Y axis / X gantry. This is because one of the upgrades I am thinking of doing is adding air-assist, which is going to add some mass. Unfortunately that’s about where the usability of the original parts end. On the left hand truck, is the #2 mirror which needs to be replaced. On the right hand truck, is the X-axis stepper motor, as well as a circuit board that contained the X & Y home sensors. The PCB burnt up, so it will need to be replaced entirely. [it also contained the flex circuitry that brought the signal/power to the X axis stepper motor] I’ll probably use heavier gauge wires for feeding the new stepper, and I’ll route the wires using a flexible cable carrier instead of using something like a flex-circuit. The cable carrier will also facilitate routing of the air line for the air assist.

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