Posts Tagged ‘Enclosure’

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Possibilities

December 28, 2011

For those of you that have been following along, you will remember that the X rail for my old ULS-M25 is badly warped from the fire. To replace it with an official part from ULS will cost me $365 + taxes [or about $13.50/inch for the 27 inch extrusion]. Needless to say, this is a unpalatable price for an aluminum extrusion. So I’ve been trying to come up with possible replacement solutions that are more cost effective. The first step was to create a CAD model for the existing part to serve as a reference. While my model isn’t exact, as it is based on measurements of the damaged part, it should be close enough to serve its purpose.


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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! ๐Ÿ™‚

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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 ๐Ÿ™‚

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? ๐Ÿ˜‰

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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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Feeling Elevated

November 16, 2011

Up next is the Z-lift mechanics [pun intended].

From the mechanical parts of the laser enclosure, these are probably the best preserved. With the exception of one belt that runs from the stepper to the primary lead screw which was about to give [possibly damaged from the heat of the fire], they lift is fully functional. I’ve disassembled it here, in order to clean the parts, and to get the get them painted. The 3 acme lead screws and bearings are in excellent condition, as is the secondary drive belt that transfers power from the primary lead screw to the two secondary lead screws. The stepper motor still turns, but like all the other steppers, it is quite rusted, so I will be replacing it. The stage itself is not likely recoverable, but that is easily replaced. [it is pretty much a consumable, and intended to be replaced periodically] Also included in the Z-lift assembly is a set of upper and lower optical limit switches. [they can be seen in the right hand image along the left edge of the assembly] I have not tested the limit switches yet, but the PCB and components are in perfect condition. Worst case is I’ll have to replace the two optical sensors.

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When it comes to re-assembly, this may be one of the harder parts to do right. It may be a challenge to get all 3 screws set to the same level, so that there is not racking on the stage. Once set, all 3 move in unison, so there is no worries of additional racking during use. However, if I’m off, the stage may not move freely, and my etches and cuts will have varying quality from one side to the other, as the distance from the lens will not be constant. So getting it right is critical.

As mine is currently disassembled, here’s a quick youtube video by “lasersafe” showing the mechanism in action, and how it works.

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State of the chassis

November 16, 2011

So I took a few minutes this weekend to give the chassis a quick bath to get off any soot and loose dirt to get a better idea of the condition. I managed to get a few pics too.

As it turns out, the chassis is in remarkably good condition, considering its history.ย  Despite having been in a fire, and having been neglected for several years, the chassis appears to be completely salvageable. I have to give credit to ULS for making one high quality, solid chassis. These things cost over $10K new, and they certainly didn’t skimp on the quality of materials. The chassis is fully welded, and made of heavy gauge steel. If I had to guess, I’d say it was built to withstand [or more specifically, contain] a fire. Given the history of this unit, I’d say it passed with flying colours. Probably the biggest weakness in the design was the large acrylic window on top, that melted in the fire. I plan to use glass instead, and from what I can tell ULS has done the same on their current offerings. The next weakest point was the control panel, that didn’t have adequate protection from the fire, and burnt up as a result… I plan to address this somehow as well.

As for damage to the chassis itself, beyond the rust, some scalloping has formed on the long horizontal seams where the bottom and walls met, likely due to the heat from the fire.ย  Some similar scalloping is at the joint of the upper deck and rear wall as well. I should be able to bang these back,and seal any remaining gaps along the base. ย Then there is the warpage on the top door, and edge of the upper deck… both relatively minor, and should be easily fixable. There are some other minor tents in the bottom, likely from [mis]handling after the fire. Nothing so far seems to be a show-stopper.

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As it stands now, the chassis is ready to be stripped, and then painted. However, I’m going to hold off until I have finalized how I’m going to handle the replacement control panel in the font, as well as any other changes/upgrades I may want to perform. In case they require modification to the chassis. I could strip it now, but I’d rather leave it painted as long as possible, to minimize new rust formation.

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Powder or Liquid?

November 12, 2011

As I prepare to have the chassis stripped of its current paint & rust coating, I’ve been thinking about how I should refinish it. The chassis itself is built like a tank out of heavy gauge welded steel. It needs some sort of protective coating, or it will just rust into nothing. My initial intention was to have it powder-coated, but now I’m having second thoughts.

Powder coating is relatively expensive, and I’m worried about the paint that is currently on the unit. Even after I soda-blast the paint off, there will be areas with original paint left behind. This is because the chassis has several covered pockets and cavities. If the original paint is a powder coat, there should be no issue, but if it was a liquid paint, it may off-gas or release, compromising the powder-coat.

My other option is to spray paint the unit. This will be considerably cheaper, as I can do the work myself, but the finish will not be nearly as durable. The risk of imperfections in the finish is also higher, as there is a long dry time, allowing for anything floating in the air to land on the wet paint leaving a bump. Spray painting also won’t get into all the nooks and crannies as easily as powder-coating does, so I will have to rely on whatever paint is currently there being in good enough shape to protect the steel, in the places I can’t get to.

I’ll have to decide this soon, as the chassis needs to get painted before I can start moving forward with the rest of the project. It is, after all, the platform on which everything else sits.

So if there is anyone out there willing to chime-in and offer some advice or opinions on how to finish, I’m listening.

[Update Nov. 12, 2011] I’m going with powder coating on the large parts, and spray-paint on the smaller internal mechanical parts. After some more research, it appears that powder coating is not all that much more expensive. But due to the potential for loss of the small parts, I’ll spray paint them myself. The small parts don’t require the durable coating of the main chassis, so there is no real need for powder coating on them anyway.[/update]